CMI Annual Report 2022

Annual Report 2022

Matteo Detto, in collaboration with Oliver Sonnentag (Montreal University) and Kyle Arndt (Woodwell Climate Research 

Center), installing an eddy covariance flux tower for monitoring CO 2 

, CH 4 

gas exchanges and other bio-environmental 

variables at Scotty Creek (Northwest Territories, Canada) in March 2023 (Photo by Dominik Heilig) 

Cover 

Morrison Hall, Princeton University

Contents 

INTRODUCTION 1 

RESEARCH – AT A GLANCE 8 

RESEARCH HIGHLIGHTS 

REPEAT Project Assesses U.S. Climate Progress 13 

Overcoming Challenges Facing the Execution of 

Net-Zero Energy Ambitions 17 

IRA Impacts on Prospective Economics of 

Clean Hydrogen and Liquid Fuel 20 

India’s Deccan Traps Appear to Have Limited 

Capacity for Carbon Storage 26 

Pore Structure and Permeability of Alkali-Activated 

Metakaolin Cements with Reduced CO 2 

Emissions 30 

Projecting the Expansion and Impacts of Ocean 

Oxygen Minimum Zones 32 

Understanding Drivers of Hurricane Activity 35 

Critical Hydrogen Emission Intensity for Methane Mitigation 39 

The CMI Wetland Project: Understanding the Biogeochemical 

Controls on Wetland Methane Emissions for Improved Climate 

Prediction and Methane Mitigation 42 

Land Conversion to Store Carbon: 

The Costs and Benefits to Biodiversity 46 

Understanding How Economic Incentives Influence 

Land-Use Decisions 48 

How the Orography-Aware Land Model LM4.2 Improves our Understanding 

of Potentially Abrupt Changes in the Land Terrestrial Carbon Cycle 51 

Ongoing Research at the Pacala Lab 54 

THIS YEAR'S PUBLICATIONS 57 

ACKNOWLEDGMENTS 61

Introduction 

1 

Carbon Mitigation Initiative Twenty-second Year Report 2022

The Carbon Mitigation Initiative (CMI) is an 

independent academic research program that 

brings together scientists, engineers and policy 

experts to design safe, effective and affordable 

carbon mitigation strategies. Sponsored by 

bp and administered by the High Meadows 

Environmental Institute, CMI is Princeton 

university’s largest and most long-term 

industry partnership. Since its inception, CMI 

has been committed to the dissemination of its 

research findings in peer-reviewed academic 

literature so they may benefit the larger 

scientific community, government, industry 

and the general public. 

CMI, now in its twenty-third year, has left an 

immeasurable impact on how society deals with the 

climate problem. In 2022, over 50 researchers and 

students worked under the leadership of fourteen 

principal investigators to find ways to mitigate crises and 

help policymakers develop equitable solutions to 

environmental problems. The Research Highlights found 

in this report are prepared and written by lead faculty 

principal investigators and their research groups. At the 

end of the report, there is a list of publications in 2022 

from CMI and CMI-related projects. 

Carbon Mitigation Initiative Twenty-second Year Report 2022 

2

Ongoing Research 

Activities 

The world changed considerably in 2022 – the war in Ukraine 

demonstrated to everyone the vulnerabilities associated 

with reliance on fossil fuels. The United States passed two 

major climate bills, after discussion and debate significantly 

influenced by the CMI-led Net-Zero America project. An 

offshoot of Net-Zero America, the REPEAT project, provided 

specific and targeted analyses in real time to policymakers 

considering particular environmental legislation, and 

continues to do so today. Net-Zero Australia was developed 

using a similar modeling design, leading the way for more 

countries to develop their own versions of net-zero guidelines. 

CMI continues to conduct groundbreaking and foundational 

research in the areas of science, technology and policy. 

Research teams made progress on a number of ongoing 

initiatives: 

• The latest REPEAT project assesses U.S. progress on 

net-zero goals. It concludes that the spending and 

incentives included in the current climate legislation will 

not reduce emissions to the goal of 50% by 2030, but there 

are ways to close the gap. 

• Energy systems models identify the most critical barriers 

to successful implementation of current legislation, and 

focus attention on the pace of deployment in the electricity 

sector. 

• Clean fuels play a crucial role in the goal of reaching 

net-zero in 2050. Research explores how the Inflation 

Reduction Act impacts the economics of clean hydrogen 

and liquid fuel. 

• India needs large-scale carbon capture and storage to help 

it reach net-zero, but the Deccan Traps basalt province 

appears to be unsuitable for large-scale CO 2 

injection. 

• Sustainable cements can help the concrete manufacturing 

industry decarbonize but there are questions about their 

long-term performance. Examining pore structure can 

help predict how they stand up over time. 

• Oceans have been losing oxygen in response to climate 

change. Using Earth System Models, observations and 

simulations, researchers can predict how oxygen 

minimum zones will respond to future pollution, climate 

change and natural variability. 

• Tropical cyclone intensity and frequency are impacted by 

large-scale events and changes. Researchers use modeling 

to determine how climate drives changes in tropical 

cyclones. 

• Hydrogen plays a crucial part of the transition to net-zero, 

but hydrogen in the atmosphere can increase greenhouse 

3 


gases. Knowing how much hydrogen leakage can occur 

before its climate benefits are negated is crucial to scale up 

hydrogen use responsibly. 

• Wetlands are one of the largest natural sources of methane 

to the atmosphere. Research explored the responsible 

biochemical mechanisms and provided insights for 

mitigating wetlands emissions. 

• Land use changes designed to store more carbon could 

have beneficial or detrimental impacts on biodiversity. 

Research explores the connection between the two. 

• To understand the effectiveness of economic incentives for 

land-use change across the globe, researchers are using 

statistical models to analyze economic data on a national 

and global scale. 

• The latest climate models from CMI researchers and 

Geophysical Fluid Dynamics Laboratory (GFDL) account 

for the impacts of extreme weather on land carbon uptake. 

Therefore, these models provide more accurate 

assessments of the future of the land carbon sink and 

humanity’s remaining carbon emissions budget. 

• Researchers examined the impacts of drought on carbon 

uptake and storage in Panamanian rainforests and the 

long-term effects of drought and fire in the Amazon. 

Annual Meeting 

2022’s 21 st Annual Meeting marked its return to London after 

four years. CMI and bp enjoyed being together in person for the 

first time since the COVID pandemic imposed two years of 

virtual-only meetings. It also was the first fully hybrid 

meeting, where all sessions were both in-person and online. 

All attendees could participate in the lively discussions, with 

participants spanning the globe from China to California, 

Princeton and London. 

Ivanka Mamic, bp’s senior vice president for sustainability and 

relationship manager for CMI, opened the meeting by 

remarking, “What a privilege it is to hear about all the work 

being done for the entire energy transition and to engage in 

respectful conversations about research and policy. These 

conversations will help bp stay action-oriented and remain 

focused on our sustainability goals.” 

In an introductory overview of CMI, Stephen Pacala, the 

Frederick D. Petrie Professor in Ecology and Evolutionary 

Biology and the director of CMI, stated that while 

commitments to a net-zero transition were gaining ground in 

more and more places, the planet continued to sound alarms. 


4

21 st Annual Meeting 

attendees in London 

listen attentively. 

In 2022, “Climate science showed surprisingly alarming 

information about the nearness of a couple tipping points …. 

while unprecedented extreme weather made climate denial 

even more untenable,” said Pacala. 

Research discussed during the annual meeting focused on a 

wide variety of subjects including infrastructure for hydrogen 

and carbon capture and storage, policies to achieve net-zero in 

representative countries, and an exploration of land-based 

climate solutions that can help solve both climate and 

biodiversity problems. The research highlights section 

presented CMI research on extreme weather, interactions 

between cooling from cloud formation and reforestation or 

afforestation, carbon dioxide storage in basalt formations, 

carbon capture materials and methane emissions from 

wetlands. Lord Adair Turner captivated the dinner audience 

by discussing technological possibilities and barriers along the 

path to net-zero. 

In addition, Pacala announced the recipients of two awards 

named in honor of Robert H. Socolow, emeritus professor of 

mechanical and aeronautical engineering at Princeton and 

CMI co-director from 2000 – 2019. 

5 


Best Paper 

Awards 2022 

Since 2010, the CMI Best Paper Award for Postdoctoral Fellows 

has been presented annually to one or two CMI-affiliated 

postdoctoral research associate(s) or research scholar(s) 

selected for their contribution to an important CMI paper. In 

late 2019, CMI created a similar award honoring a CMIaffiliated 

doctoral student for their contributions to an 

important CMI paper. 

Former Princeton postdoctoral researcher Yujin Zeng received 

the Robert H. Socolow Best Paper Award for Postdoctoral 

Fellows for his paper, “Possible Anthropogenic Enhancement 

of Precipitation in the Sahel-Sudan Savanna by Remote 

Agricultural Irrigation,” published in Geophysical Research 

Letters in 2022. Zeng is now a research scientist at NASA. 

Former Civil and Environmental Engineering graduate student 

Tom Postma received the Robert H. Socolow Best Paper Award 

for Graduate Students for his paper, “Field-Scale Modeling of 

CO 2 

Mineral Trapping in Reactive Rocks: A Vertically 

Integrated Approach,” published in Water Resources Research 

in 2022. Postma is now a carbon capture and storage specialist 

at bp. 

Yujin Zeng (left), winner of 

the 2021 Best Paper Award for 

Postdoctoral Fellows. 

Tom Postma (right), winner of 

the 2021 Best Paper Award for 

Graduate Students. 


6

Collaborations 

CMI members continue to work with a wide variety of outside 

collaborators, including researchers in three other bpuniversity 

partnerships: the Center for the Environment at 

Harvard University; the Center for International Environment 

and Resource Policy at Tufts University; the Thermal 

Engineering Department and the Tsinghua-bp Clean Energy 

Research and Education Center at Tsinghua University; and 

governmental and nongovernmental organizations including 

the National Academies of Sciences, Engineering and 

Medicine and the President’s Council of Advisors on Science 

and Technology. 

CMI also continued its initiative, launched in 2021, with 

University of California Santa Barbara and the Environmental 

Defense Fund on using econometrics to understand how the 

outcome of policy incentives are affected by economic, 

institutional, political, and cultural differences. The analysis 

is expected to be completed by 2024. An update of the research 

can be found in this report. 

Awards and 

Appointments 

In 2022, CMI scholars received numerous honors and 

appointments, including: Jesse Jenkins, who received the 2022 

Engineering News-Record 2022 Top 25 Newsmakers Award for 

public research impact; Jonathan Levine, who was appointed 

faculty chair of Princeton’s Ecology and Evolutionary Biology 

Department and who was recognized as 2022’s Distinguished 

Ecologist Lecturer at the University of Wisconsin; and Elena 

Shevliakova, who received the silver medal in the area of 

scientific/engineering achievement from the US Department of 

Commerce for scientific leadership in leading, drafting, 

coordinating and communicating the findings of the IPCC’s 

Sixth Assessment Report. 

7 


Research – At a Glance 

REPEAT Project Assesses U.S. Climate Progress 

PRINCIPAL INVESTIGATOR: JESSE JENKINS 

With the dust settled on the 117th Congress, an updated 2023 analysis from REPEAT Project looks back at the 

progress made by the historic legislative session and the gaps remaining on the U.S. pathway to net-zero 

greenhouse gas emissions. Led by Jesse Jenkins of the Princeton ZERO Lab, the project’s latest report 

concludes that the more than $500 billion in public spending and incentives unleashed by the Inflation 

Reduction Act and Bipartisan Infrastructure Law will double the pace of U.S. decarbonization and cut annual 

emissions to 37-41% below peak levels by 2030. This is historic progress, but still short of the 50% cut to which 

President Biden has committed the United States. The report also looks sector-by-sector at remaining 

emissions and ways the United States could close this remaining gap. 

Overcoming Challenges Facing the Execution of Net-Zero 

Energy Ambitions 

PRINCIPAL INVESTIGATOR: CHRIS GREIG 

Attaining net-zero by midcentury requires the sustained development and deployment of energy and 

industrial infrastructure at a speed, scale and complexity that is unprecedented in human history. No major 

economy appears to be comprehensively on track to achieve its net-zero commitment. Models used to design 

policies that support preferred pathways currently lack consideration of many real-world conditions, which 

could hamper the speed at which nations, sectors and individual companies attempt to make the energy 

transition. This research tries to better understand the net-zero challenge, track progress, and identify and 

overcome these limits to the speed at which societies decarbonize. 

IRA Impacts on Prospective Economics of Clean Hydrogen and 

Liquid Fuel 

PRINCIPAL INVESTIGATORS: JESSE JENKINS AND ERIC LARSON 

In Princeton’s Net-Zero America study (Larson et al., 2021) electrification is a central feature of all modeled 

decarbonization pathways for the U.S. However, perhaps surprisingly, low-carbon fuels, including hydrogen (H 2 

) 

and Fischer-Tropsch liquids (FTL), still account for 40-55% of final energy use in 2050, when the goal of 

economy-wide net-zero emissions is reached. To help understand the prospective competitiveness of different 

clean fuels, Jenkins and Larson, together with researchers Fangwei Cheng and Hongxi Luo, carried out detailed 

lifecycle carbon and cost assessments of multiple technology pathways for producing clean fuels from natural 

gas, sustainable biomass or electricity (Cheng et al., 2023a). After passage of the 2022 U.S. Inflation Reduction 

Act (IRA), which provided unprecedented incentives for deploying low greenhouse gas-emitting fuels, the 

researchers extended the analysis to assess impacts of the IRA (Cheng et al., 2023b). The findings of the extended 

analysis can inform decision making regarding investments and further policies regarding clean fuels.

India’s Deccan Traps Appear to Have Limited Capacity for 

Carbon Storage 

PRINCIPAL INVESTIGATOR: MICHAEL CELIA 

To achieve net-zero emissions, India is expected to implement large-scale carbon capture and storage (CCS). 

The Deccan Traps basalt province has a total of around 300,000 km 3 of rock and is considered the most 

promising location for onshore geological storage in India. Despite the enormous rock volume, virtually none of 

it appears suitable for large-scale CO 2 

injection and storage, due to its shallow depth and the presence of 

extensive vertical dikes. This raises serious questions about India’s CCS-heavy pathways to net-zero, with 

potential consequences for carbon mitigation on a global scale. These findings will impact decisions that 

companies working towards net-zero in India will make in the future. 

Pore Structure and Permeability of Alkali-Activated Metakaolin 

Cements with Reduced CO 2 

Emissions 

PRINCIPAL INVESTIGATOR: CLAIRE WHITE 

Portland cement is currently the most common type of cement used in concrete manufacture, but it is a 

significant source of atmospheric CO 2 

due to the production process. To counter this, White and her group, 

including graduate student Anita Zhang, are developing sustainable cements that are alternatives to 

conventional Portland cement. These cements can reduce CO 2 

emissions but with limited in-field evidence of 

proven long-term performance. By understanding the pore structures of these alternative cements, and linking 

pore structure to permeability, the researchers aim to create a predictive phenomenological model that can be 

used to identify the most suitable alternative cement for a specific environmental application. Reducing 

concrete emissions in the construction industry would have a large impact on overall CO 2 

emissions, which 

aligns with bp’s ambition of helping the world get to net-zero. 

Projecting the Expansion and Impacts of Ocean Oxygen 

Minimum Zones 

PRINCIPAL INVESTIGATOR: LAURE RESPLANDY 

The Resplandy group studies global change in the biogeochemistry of the oceans and how this will affect other 

parts of the Earth system, with emphasis on the cause, magnitude, stability and longevity of the ocean carbon 

sink. In the last year, the Resplandy group’s research focused on the ocean’s response to climate change, in 

particular the ocean’s loss of oxygen associated with warming. They studied how this warming trend 

influences ecosystems, ecosystem services (e.g., fisheries) and the climate itself via the production of nitrous 

oxide, which occurs in low oxygen ocean waters. This work led to three publications in 2022, including one 

highlighted by the American Geophysical Union Newsroom that focuses on the fate of oxygen minimum zones 

and coastal “dead zones,” which are open ocean and coastal ocean areas with very low oxygen levels unsuitable 

for most organisms. It is important for companies and policymakers to learn how oxygen minimum zones may 

behave in a warming world and how plans for the energy transition may impact these zones. 

9 


Understanding Drivers of Hurricane Activity 

PRINCIPAL INVESTIGATOR: GABRIEL VECCHI 

Tropical cyclones (TCs) impact society and ecosystems through extreme wind, rain and surge. A better 

understanding of TC frequency, track, and wind and rainfall intensity are key to building strategies to mitigate 

their damages for the public and private sectors. The goal of the Vecchi group is to understand the mechanisms 

behind tropical cyclone activity changes over recent and future decades. The researchers’ main tools of study 

are climate and atmospheric models. The researchers combine modeling studies with analyses of the historical 

record (i.e., the written recording of weather data over a period of years) to help distinguish the extent to which 

observed multi-decadal-to-centennial changes in TC activity have been driven by large scale factors. These 

factors include ocean temperature changes, greenhouse gases, volcanic eruptions and El Niño oscillations, as 

opposed to random atmospheric fluctuations. 

Critical Hydrogen Emission Intensity for Methane Mitigation 

PRINCIPAL INVESTIGATORS: MATTEO BERTAGNI, STEPHEN PACALA, FABIEN PAULOT AND AMILCARE PORPORATO 

Hydrogen (H 2 

) energy will play a crucial role in decarbonizing some energy sectors to reach worldwide net-zero 

carbon emissions. However, atmospheric hydrogen interferes with greenhouse gases like methane, water vapor 

and ozone. This means that hydrogen losses across the supply chain may offset some of the climate benefits of 

hydrogen adoption. Hydrogen's interaction with atmospheric methane, the second most important greenhouse 

gas, is of particular importance because methane mitigation is recognized as the most effective solution for 

near-term climate change mitigation. The research explored the impact of hydrogen emissions on atmospheric 

methane, quantifying a critical hydrogen emission rate (HEI) above which methane increases despite reducing 

fossil fuel use. This information will help inform bp about the importance of minimizing hydrogen losses to 

limit hydrogen climate impact. 

The CMI Wetland Project: Understanding the Biogeochemical 

Controls on Wetland Methane Emissions for Improved Climate 

Prediction and Methane Mitigation 

PRINCIPAL INVESTIGATOR: XINNING ZHANG 

Methane is the second most important anthropogenic climate forcer after carbon dioxide (CO 2 

). Determining 

the importance and mechanisms of different anthropogenic and natural methane sources and sinks across 

temporal and spatial scales remains a fundamental challenge for the scientific community. Wetlands are 

dominant but highly variable sources of methane and are predicted to play a critical role in carbon-climate 

feedbacks. Methane emissions from these areas are shaped by a complex and poorly understood interplay of 

microbial, hydrological and plant-associated processes that vary in time and space. The factors responsible for 

the greatest methane emissions from wetlands remain unknown. 

The CMI Wetland Project, conducted by the Zhang lab and led by researcher Linta Reji, aims to identify the 

biological and chemical mechanisms that promote methane emissions from wetlands. The goal is to improve 

predictions of carbon-climate feedbacks and strategies for methane mitigation. Understanding the 

mechanisms that cause the greatest natural source of methane emissions and ways to mitigate it is critical for 

companies that aim towards net-zero.

Land Conversion to Store Carbon: The Costs and Benefits to 

Biodiversity 

PRINCIPAL INVESTIGATOR: JONATHAN LEVINE 

Harnessing the power of land to store carbon is essential to meeting worldwide net-zero targets. However, the 

impacts such actions have on global biodiversity are highly uncertain and poorly understood. Research in 

Jonathan Levine’s group is exploring the conflicts and synergies between society’s portfolio of land-based 

climate solutions and biodiversity. Addressing this interaction is critical for conservation groups, companies, 

and governmental agencies that promote natural climate solutions and offsets under the assumption that 

benefits to biodiversity are clear. 

Understanding How Economic Incentives Influence Land-Use 

Decisions 

PRINCIPAL INVESTIGATORS: KATHY BAYLIS, ROBERT HEILMAYR AND ANDREW PLANTINGA 

To help combat climate change, several countries have programs that incentivize landowners to make land-use 

decisions that reduce net greenhouse gas emissions—like avoiding deforestation, planting trees or practicing 

no-till farming. The Environmental Markets Laboratory (emLab) at the University of California, Santa Barbara 

(UCSB) is conducting econometric analyses, (i.e., using statistical models to analyze economic data) to 

understand the effectiveness of these incentives on a national and global scale. The goal is to explore how 

responsive land-use decisions are to market prices, and the political, cultural and economic factors that 

influence these responses. Research findings will help policy makers understand the potential impact that 

incentives for land-based climate solutions could have on land use and associated emissions and help 

companies with ambitious net-zero goals utilize land in an optimal way. 

11 


How the Orography-Aware Land Model LM4.2 Improves Our 

Understanding of Potentially Abrupt Changes in the Land 

Terrestrial Carbon Cycle 

PRINCIPAL INVESTIGATOR: ELENA SHEVLIAKOVA 

The latest Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) found that 

“Limiting global temperature increase to a specific level would imply limiting cumulative CO 2 

emissions to 

within a carbon budget.” This budget is estimated to be 500 gigatonnes of CO 2 

from the beginning of 2020 to 

cap temperatures at 1.5 °C. To arrive at this number, scientists use climate models that include representations 

of terrestrial ecosystems, including processes that release carbon to the atmosphere like wildfires and forest 

diebacks due to droughts and heat. The Geophysical Fluid Dynamics Laboratory (GFDL) at the National 

Oceanic and Atmospheric Administration (NOAA) and CMI have developed one of the few existing models that 

accounts for the impacts of more frequent extreme weather in today’s warming world. This is important for bp 

because land models are significant tools in understanding the impact of extreme weather on land carbon 

uptake and are critical in designing standards to achieve net-zero global emissions. 

Ongoing Research at the Pacala Lab 

PRINCIPAL INVESTIGATOR: STEPHEN PACALA 

Over the course of last year, the Pacala lab was involved in several research projects focused on the interaction 

between climate change, the global carbon cycle and biodiversity. Notably, their work in the Panamanian 

rainforest examined the dynamics of carbon uptake and storage during drought conditions. The researchers 

found that moderate drought conditions did not have a detrimental effect on carbon uptake and storage, and 

that, in fact, the flora of the region stored more carbon during moderate drought conditions than normal 

conditions. A separate research project, which was a collaboration between CMI and NOAA’s Geophysical Fluid 

Dynamics Laboratory (GFDL), explored the fate of the Amazonian rainforest over the next several decades. This 

research projected that the long-term effects of drought and fire will hamper carbon storage and consequently 

that portions of the rainforest will switch to savanna as early as 2035. The two studies are relevant to bp’s 

interests because a collapse of one of the Earth’s largest carbon sinks would amplify demands for an increase in 

the global pace of decarbonization and would also imperil forestry offsets that had been established in the 

region. The implication of the two together is that effective fire suppression in the face of increasing drought 

might increase Amazonian carbon storage. 


12

REPEAT Project Assesses U.S. Climate Progress 

PRINCIPAL INVESTIGATOR: JESSE JENKINS 

At a Glance 

With the dust settled on the 117 th Congress, an updated 2023 

analysis from REPEAT Project looks back at the progress made 

by the historic legislative session and the gaps remaining on 

the U.S. pathway to net-zero greenhouse gas emissions. Led by 

Jesse Jenkins of the Princeton ZERO Lab, the project’s latest 

report concludes that the more than $500 billion in public 

spending and incentives unleashed by the Inflation Reduction 

Act and Bipartisan Infrastructure Law will double the pace of 

U.S. decarbonization and cut annual emissions to 37-41% 

below peak levels by 2030. This is historic progress, but still 

short of the 50% cut to which President Biden has committed 

the United States. The report also looks sector-by-sector at 

remaining emissions and ways the United States could close 

this remaining gap. 

Students and researchers in the ZERO Lab, led by Prof. Jesse Jenkins, work collaboratively to assemble a lego 

model of a solar PV array during a group retreat. From left to right: Malini Nambiar (G4, SPIA), Dr. Fangwei 

Cheng (associate research scholar), Emilio Cano Renteria (senior CEE), and Edmund "Ned" Downie (G2, SPIA).

Research Highlight 

The Biden Administration took office in January 2021 with a 

promise to pursue a “whole of government” approach to tackle 

climate change and cut emissions of greenhouse gases at least 

50% below peak levels by 2030 and to net-zero by 2050. 

With the conclusion of the 117th Congress, which sat from 

January 2021 to January 2023, the United States has now made 

historic progress towards those goals with passage of the 

Bipartisan Infrastructure Law, also known as the 

Infrastructure Investment and Jobs Act, and the Inflation 

Reduction Act (IRA). The two bills represent a sizable public 

investment to accelerate the clean energy transition, and total 

well over $500 billion over the next ten years. They provide 

incentives for nearly the entire suite of clean energy and 

climate mitigation solutions, including clean electricity and 

fuels, hydrogen, carbon capture, electric vehicles, building 

efficiency and electrification. This package of laws represents a 

turning point in U.S. decarbonization efforts—but how far do 

they get us on the path to net-zero? 

Over the past two years, the REPEAT (Rapid Energy Policy 

Evaluation and Analysis Toolkit) Project, led by Jesse Jenkins, 

has consistently provided regular, timely and independent 

environmental and economic evaluation of federal energy and 

climate policies. Offering near real-time analysis of 

Congressional legislation as it was debated and enacted, the 

REPEAT Project established itself as a critical resource that 

has shaped policy negotiations, reporting and public 

understanding of federal policy making. Throughout the 117th 

Congress, the REPEAT Project released multiple analyses of 

proposed legislation, frequently publishing new analysis 

within days or weeks of major milestones in the progression of 

each piece of legislation through the Senate and House of 

Representatives. The Project’s reports have been accessed 

thousands of times and their analysis has been featured in 

dozens of news stories to date (www.repeatproject.org/media), 

ranging from The New York Times and Washington Post to 

Nature, Axios and The New Yorker. 

Now, with the dust settled on the 117th Congress, the REPEAT 

Project is releasing a new report that takes a revised and more 

careful look at the progress made to date, and the gaps that 

remain. REPEAT analysis concludes that the package of laws 

passed by the 117th Congress could roughly double the pace of 

decarbonization in the United States to about 4% per year, 

cutting U.S. greenhouse gas emissions to about 37-41% below 

peak historical levels reached circa 2005. That gets the U.S. 

much closer to the goal of a 50-52% reduction in emissions 


14

targeted by the Biden Administration in the United States’ 

National Determined Contribution to the UN Framework 

Convention on Climate Change. Yet gaps remain. 

Figure 1.1. 

Historical and modeled 

net U.S. greenhouse gas 

emissions, 2005-2035.2021). 

The REPEAT Project highlights the potential for additional 

emissions reductions by accelerating the retirement of 

remaining coal-fired power plants and substituting natural 

gas-fired power generation (~0.2 GtCO 2 

-e/year in 2030). This 

step could improve industrial process efficiency (~0.1 GtCO 2 

-e/ 

year) and additional cost-effective abatement of methane 

pollution in the oil and gas sectors and make improvements in 

carbon uptake in agricultural and forestry lands (~0.2-0.3 

GtCO 2 

-e/year). In total, these measures could get the U.S. 

within striking distance of 2030 climate goals and on track for 

net-zero emissions by 2050. 

With support from the Hewlett Foundation, REPEAT plans 

annual updates in 2023 and 2024 on the United States’ 

progress on the path to net-zero. This will include analyses of 

proposed and finalized federal regulations and a stock take of 

the latest changes in costs and macro-economic conditions. 

Find the latest analysis and data at repeatproject.org. 

15 


Figure 1.2. 

Difference in sectoral 

emissions vs. net-zero 

pathway (including land 

carbon sinks, non-CO 2 

₂ 

abatement of greenhouse 

gases, buildings, industry, 

power and transportation). 


16

Overcoming Challenges Facing the Execution of Net-Zero 

Energy Ambitions 

PRINCIPAL INVESTIGATOR: CHRIS GREIG 

At a Glance 

Attaining net-zero by midcentury requires the sustained 

development and deployment of energy and industrial 

infrastructure at a speed, scale and complexity that is 

unprecedented in human history. No major economy appears 

to be comprehensively on track to achieve its net-zero 

commitment. Models used to design policies that support 

preferred pathways currently lack consideration of many 

real-world conditions, which could hamper the speed at which 

nations, sectors and individual companies attempt to make 

the energy transition. This research tries to better understand 

the net-zero challenge, track progress, and identify and 

overcome these limits to the speed at which societies 

decarbonize. 


At its core, the net-zero transition is a coordination challenge 

involving vast numbers of independent actors across multiple 

sectors. These players in energy, industry and materials 

ecosystems deliver supply- and demand-side assets and invest 

in and connect infrastructure. Integrated assessment and 

other macro-scale energy systems models (IAMs) that explore 

decarbonization pathways are influential in shaping energy 

and climate policy. They also play a role in determining 

whether nations, sectors and individual companies are on 

track to meet various commitments, such as the Paris 

Agreement. However, these IAMS do not adequately represent 

how such assets are conceived, developed and built in this 

complicated landscape. Consequently, they frequently miss 

critical constraints and bottlenecks that hold back progress in 

different settings and at different scales. 

In 2022, the researchers sought to capitalize on the Net-Zero 

America study, thus commencing a similar one for Australia. 

There, the objective is to describe pathways that decarbonize 

Australia’s relatively small domestic economy while also 

transitioning its very large-scale coal and liquified natural gas 

exports to zero-carbon, hydrogen-based carriers. The Net-Zero 

Australia study will release its final report in 2023. 

17 


Figure 2.1. 

Stylized project investment 

decision sequence. 

Researchers have developed 

a framework to identify and 

overcome the limitations 

of existing decarbonization 

modeling frameworks 

that do not truly represent 

the way risk-capital is 

mobilized. As successful 

projects advance from left 

to right in sequence, the 

level of project definition, 

confidence in the business 

case and availability of 

capital increase, while the 

investment risk profile and 

cost of capital decrease. 

(Greig et al., 2023). 

Other research explored the issue of capital discipline (i.e. 

processes undertaken by investors to limit investment risks) 

and its speed-limiting effect on the transition for both largerand 

smaller-scale projects. A conceptual framework was 

developed to reverse engineer the sequence of decisions in 

development and construction activities represented by 

macroscale transitions (e.g., Net-Zero America’s gigatonne per 

year carbon capture and storage projections to 2050). This 

allows one to identify critical “chicken-or-egg” challenges that 

create investment hesitancy and design policy interventions to 

speed up decisions (Uden et al., 2022). 

In an extension of the capital discipline theme, further 

research examined the investment decision-making and 

capital formation processes applied by developers and 

investors in the energy transition. Looking at the transition 

through this lens highlighted a critical disconnect between 

the risk profile of project development and the very large pools 

of capital claiming to be ready to fund the net-zero transition 

(Greig et al., 2023; Figure 2.1). 


18

Finally, research sought to understand what it means when 

companies claim to be ‘Paris-aligned.’ This means that the 

pathways chosen by various companies must limit carbon 

budgets to levels consistent with an average global 

temperature rise of no more than 1.5 °C (Rekker et al., 2022). To 

this end, the researchers developed a methodology to provide a 

more robust assessment of the alignment of corporations’ 

current portfolios and announced plans with an example 

pathway (IEA B2DS) generally consistent with the Paris 

Agreement (Rekker et al., 2022). It was found that nine of ten of 

Australia’s largest power generators and all ten of the largest 

listed global cement producers were not on a trajectory 

consistent with the Paris goals. 

References 

Uden, S., R. H. Socolow, and C. Greig, 2022. Bridging capital 

discipline with energy scenarios. Energy and Environmental 

Science 8:3114-3118. (https://doi.org/10.1039/D2EE01244H). 

Greig, C., D. Keto, S. Hobart, B. Finch, and R. Winkler, 2023. 

Speeding up risk capital allocation to deliver net-zero 

ambitions. Joule 7(2):239-243. (https://doi.org/10.1016/j. 

joule.2023.01.003). 

Rekker, S., M. Ives, B. Wade, L. Webb, and C. Greig, 2022. 

Measuring corporate Paris compliance using a strict sciencebased 

approach. Nature Communications 13:4441 (https://doi. 

org/10.1038/s41467-022-31143-4). 

19 


IRA Impacts on Prospective Economics of Clean 

Hydrogen and Liquid Fuel 

PRINCIPAL INVESTIGATORS: JESSE JENKINS AND ERIC LARSON 

At a Glance 

In Princeton’s Net-Zero America study (Larson et al., 2021) 

electrification is a central feature of all modeled 

decarbonization pathways for the U.S. However, perhaps 

surprisingly, low-carbon fuels, including hydrogen (H 2 

) and 

Fischer-Tropsch liquids (FTL), still account for 40-55% of final 

energy use in 2050, when the goal of economy-wide net-zero 

emissions is reached. To help understand the prospective 

competitiveness of different clean fuels, Jenkins and Larson, 

together with researchers Fangwei Cheng and Hongxi Luo, 

carried out detailed lifecycle carbon and cost assessments of 

multiple technology pathways for producing clean fuels from 

natural gas, sustainable biomass or electricity (Cheng et al., 

2023a). After passage of the 2022 U.S. Inflation Reduction Act 

(IRA), which provided unprecedented incentives for deploying 

low greenhouse gas-emitting fuels, the researchers extended 

the analysis to assess impacts of the IRA (Cheng et al., 2023b). 

The findings of the extended analysis can inform decision 

making regarding investments and further policies regarding 

clean fuels. 


The U.S. goal of net-zero greenhouse gas (GHG) emissions by 

2050 has become a major policy driver, with the 2022 Inflation 

Reduction Act (IRA) providing unprecedented incentives for 

deploying low GHG emissions technologies. Incentives include 

Section 45V credits for clean H 2 

, 45Q credits for carbon capture 

and storage (CCS), 45Z credits for sustainable liquid fuels, 45Y 

credits for clean electricity generation and others. To better 

understand the prospective competitiveness of different clean 

fuels under the IRA, Larson and colleagues extended their 

recently published (Cheng et al., 2023a) lifecycle carbon and 

cost assessments of multiple pathways (P#) for fuels 

production. For technologies anticipated to be commercially 

deployable in the early 2030s, researchers examined the 

impacts of IRA provisions on costs of producing H 2 

and 

Fischer-Tropsch liquid fuels using natural gas, electricity, or 

net-carbon-neutral biomass as feedstocks (Cheng et al., 2023b) 

(Table 3.1). 

Carbon Mitigation Initiative Twenty-second Year Report 2022 20

Table 3.1. 

Hydrogen and 

Fischer-Tropsch 

liquids production 

pathways.* 

Hydrogen 

With credits from 45Q, H 2 

produced by reforming natural gas 

with CCS (P2 or P3) is cost-competitive with conventional 

carbon-intensive H 2 

from natural gas without CCS (P1) (Figure 

3.1a; P1-13 defined in Table 3.1). Also, because of its zero-carbon 

footprint, electrolytic H 2 

(P3) is eligible for the maximum 

available 45V credit and is consequently less costly than P2 or 

P3. Thus, the IRA incentives promise to encourage deployment 

of H 2 

production via P2, P3 and P4 pathways. H 2 

made by 

biomass gasification (P5) has a non-zero carbon footprint due 

to emissions from upstream biomass collection and transport, 

so the available 45V incentive is less than for P4. The P5 

pathway is not cost-competitive with incumbent H 2 

(P1). The 

same is true for biomass gasification with CCS (P6), despite this 

pathway being able to garner the full 45V credit because 

negative emissions more than offset the upstream emissions. 

The P6 pathway could instead collect 45Q credits for its CCS, 

but the 45V credits are larger, and an individual facility may 

only collect one type of IRA credit. 

Figure 3.1b demonstrates that the size of a pathway’s IRA 

incentive is not uniformly proportional to the emissions 

reduction it achieves. IRA incentives for the P2 and P3 

21 


Figure 3.1a. 

Levelized cost of fuel (LCOF) and lifecycle GHG emissions 

for conventional (high carbon intensity) H 2 

and five clean 

H 2 

pathways. Negative values are co-product revenues 

or IRA credits. The IRA disallows any one facility from 

claiming more than one type of credit. For a pathway for 

which multiple credits may apply, the one that provides the 

highest benefit is taken. 

Figure 3.1b. 

Level of IRA tax credits for each clean H 2 

option (P2 through 

P6) as a function of lifecycle GHG emissions reduced 

relative to conventional H 2 

(P1). The slope of a line drawn 

from P1 to any of the points plotted for a clean H 2 

pathway 

represents the IRA incentive for that pathway in units of $ 

per tonne of CO 2 

reduced. 

pathways (about $75/tCO 2 

e reduced) are ostensibly designed to 

reward emissions reductions, because the underlying 

technologies are arguably commercially mature today. In 

contrast, P4 technologies are not yet mature and are projected 

to experience significant cost reductions with further 

technology development and deployment. The additional 

“bonus” IRA incentive for P4 ($143/tCO 2 

e reduced), therefore, 

appears aimed at promoting technology advancement and cost 

reduction. 

Meanwhile, the biomass H 2 

pathways (P5 and P6) have little to 

no “bonus” IRA incentive (Figure 3.1b). The inherent 

asymmetry in the bonus incentive between P4 and P5/P6 may 

be explained in part by the more intrinsically modular nature 

of P4 technology. Modularity is among the most important 

features of energy technologies that have seen rapid cost 

reductions in the past as deployments have accelerated, such 

as wind turbines and solar PV panels (Malhotra and Schmidt, 

2020). A sizeable IRA bonus incentive for P4, therefore, seems 

well aligned with the ambitious goal of rapid clean H 2 

expansion in support of rapid decarbonization of the economy. 

On the other hand, with a comparatively small bonus incentive 

for P6, the pathway with the highest carbon mitigation 

potential, the IRA misses an opportunity to boost a technology 


22

that might also contribute significantly to rapid 

decarbonization goals. 

Fischer-Tropsch liquid fuels 

The IRA liquid fuels incentive, 45Z, will be discontinued in 

2027, so it will not be available in the 2030s timeframe of our 

analysis without an extension. Liquid fuel pathways might still 

derive some benefit from 45V and 45Q incentives, however, as 

reflected in pathways P7-P9 (Figure 3.2a). These pathways 

represent facilities synthesizing liquid fuels from inputs of H 2 

and CO 2 

. They incorporate 45V credits for H 2 

production (at 

separate facilities, P2 – P4) and 45Q credits for CO 2 

from 

separate direct air capture facilities. Pathways P10 and P11 

synthesize fuels using H2 from P5 and P6, respectively, and 

carbon-neutral biogenic CO 2 

recovered from the P5 and P6 

facilities. The liquids costs for P10 and P11 incorporate 45V 

credits associated with P5 and P6 facilities, which are assumed 

to be adjacent to, but separate from, the liquids production 

facility. CO 2 

removal is intrinsic to making H 2 

from biomass, 

and so it is assumed that the liquids producer incurs no extra 

cost for the CO 2 

, beyond what is reflected in the cost of the 

delivered H 2 

. As Figure 3.2a quantifies, the production cost for 

only one of the low-carbon liquid fuels pathways, P9, falls 

within the range of U.S. wholesale jet fuel prices observed over 

the past decade. 

Figure 3.2a also shows results for P12 and P13 pathways, 

neither of which qualify for any credit under the IRA, because 

the current 45Z credit will end in 2027. These represent 

facilities that integrate biomass gasification with Fischer- 

Tropsch synthesis to produce liquid fuels without and with 

CCS, respectively. Pilot and demonstration scale projects using 

technology configurations that resemble these are under 

development today (Mesfun, 2022). Note that pathways P10 

and P11 also produce bio-derived fuels but are somewhat 

artificial configurations designed specifically to maximize the 

capture of IRA credits. The integrated P12 and P13 facilities 

have lower capital costs and higher energy conversion 

efficiencies than their counterpart two-facility configurations, 

P10 and P11, but they are unable to exploit IRA credits. On 

balance, P10 has slightly lower production costs than P12 

because the embedded 45V credit for P10 offsets the lower 

capital and fuel costs for P12. The large 45V credit embedded 

in P11 more than compensates for the lower capital and 

biomass costs for P13. 

23 


Figure 3.2a. 

Levelized cost of fuel (LCOF) and lifecycle GHG emissions 

for petroleum jet fuel and eight alternative clean liquid fuel 

pathways. The jet fuel range covers the 10-90 th percentile 

range in wholesale jet fuel prices in the U.S. during 2012- 

2022, when the median value was $2.2/gallon. 

Figure 3.2b. 

Levelized cost of fuel (LCOF) for clean fuel pathways 

as a function of assumed duration of 45Z credits. The 

gray shading represents the 10-90 th percentile range in 

wholesale jet fuel prices in the U.S. during 2012-2022, when 

the median value was $2.2/gallon. 

Renewal and extension of the IRA 45Z credit into the 2030s 

would impact the relative competitiveness of liquid fuel 

pathways. In the following analysis, it is important to note that 

the value of a 45Z credit increases with decreasing lifecycle 

emissions of a fuel pathway. Figure 3.2b shows fuel production 

costs for P7-P13 as a function of the duration over which a 45Z 

credit is assumed to be available. Not surprisingly, longer 45Z 

durations provide for lower production costs. However, 

pathways P7, P8, P10 and P12 remain uncompetitive with jet 

fuel prices regardless of the 45Z duration because the 45Z 

credit is relatively modest for these pathways, all of which have 

positive lifecycle emissions. 

As noted earlier, the cost for the electrolysis-based pathway, P9, 

which has zero emissions, falls within the recent historical 

range in jet fuel prices, even without any 45Z credit. If the 45Z 

duration is at least two or five years, then fuel production costs 

for a second pathway (P11) and a third pathway (P13), 

respectively, also fall within the competitive range. The P11 

pathway captures both 45V and 45Z credits, while P13 captures 

only a 45Z credit, which helps explain the lower cost for P11 

than P13 at any given 45Z duration. Costs for both P11 and P13 

fall rapidly with increasing durations of 45Z because their 

negative lifecycle emissions (Figure 3.2a) lead to high 45Z 

credit values. The P11 cost falls more rapidly than for P13 


24

ecause the lower overall energy conversion efficiency of P11 

means it sacrifices fuel production for additional byproduct 

CO 2 

capture. This results in more negative lifecycle emissions 

per unit of fuel produced and a larger 45Z credit than for P13. 

One final observation concerns P11 and P13 pathways, both of 

which start with biomass and end with liquid fuel produced. In 

one situation, without considering 45Z credits (Figure 3.2a), 

the IRA credits that P11 garners leads it to have considerably 

lower production costs than P13, which does not receive any 

IRA incentive. In another situation, when 45Z credits are 

additionally considered (Figure 3.2b), the cost differential 

between P11 and P13 grows as the duration of the 45Z credit 

grows. Thus, in both situations, IRA credits are incentivizing a 

more capital-intensive and less-efficient (P11) over a moreefficient 

(P13) approach to biofuel production. This is 

concerning because sustainable biomass energy feedstock is a 

limited resource. 

Additional analysis reported elsewhere (Cheng et al., 2023b) 

evaluates the impact on clean-fuel production costs of 

garnering IRA credits along with credits available under 

California’s Low Carbon Fuel Standard and the federal 

Renewable Fuel Standard. This “stacking” of credits appears to 

be allowable under the IRA. 

References 

Cheng, F., H. Luo, J.D. Jenkins, and E.D. Larson, 2023a. The 

value of low- and negative-carbon fuels in the transition to 

net-zero emission economies: Lifecycle greenhouse gas 

emissions and cost assessments across multiple fuel types. 

Applied Energy 33:120388. (https://doi.org/10.1016/j. 

apenergy.2022.120388). 

Cheng, F., H.Luo, J.D. Jenkins, J.D., and E.D. Larson, 2023b. 

Inflation Reduction Act impacts on the economics of clean 

hydrogen and liquid fuels. Submitted to Joule, April 2023. 

Larson, E. et al., 2021. Net-Zero America: Potential pathways, 

infrastructure, and impacts final report, Princeton University. 

(https://doi.org/10.5281/zenodo.6378139). 

Malhotra, A. and T.S. Schmidt, 2020. Accelerating low-carbon 

innovation. Joule 4(11):2259-2267. (https://doi.org/10.1016/j. 

joule.2020.09.004). 

Mesfun, S.A., 2022. Biomass to liquids (BtL) via Fischer- 

Tropsch – a brief review, European Tech. & Innovation 

Platform – Bioenergy. (https://www.etipbioenergy.eu/images/ 

ETIP_B_Factsheet_BtL_2021.pdf)

India’s Deccan Traps Appear to Have Limited Capacity 

for Carbon Storage 

PRINCIPAL INVESTIGATOR: MICHAEL CELIA 

At a Glance 

To achieve net-zero emissions, India is expected to implement 

large-scale carbon capture and storage (CCS). The Deccan 

Traps basalt province has a total of around 300,000 km 3 of 

rock and is considered the most promising location for onshore 

geological storage in India. Despite the enormous rock volume, 

virtually none of it appears suitable for large-scale CO 2 

injection and storage, due to its shallow depth and the 

presence of extensive vertical dikes. This raises serious 

questions about India’s CCS-heavy pathways to net-zero, with 

potential consequences for carbon mitigation on a global scale. 

These findings will impact decisions that companies working 

towards net-zero in India will make in the future. 

The Western Ghats hills at Matheran in Maharashtra, India (Photo by Nicholas)


India is the third largest and fastest growing emitter of CO 2 

globally. India’s energy mix includes a large fleet of coal-fired 

power plants whose operational lifetimes extend decades into 

the future. As a result, proposed pathways to net-zero include 

carbon capture and storage at a rate of hundreds of millions of 

tonnes of CO 2 

(MtCO 2 

) per year by 2035. This will require large 

amounts of accessible storage capacity in subsurface rock 

formations. The sedimentary formations usually relied upon 

to provide that capacity are severely limited in India, where 

the geology is characterized by ancient granitic basement rock 

and the Deccan Traps, a large deposit of flood basalt (Figure 

4.1a). A growing body of research on rapid carbon 

mineralization in basalt formations has suggested that the 

Deccan Traps may be able to provide significant storage 

capacity for CCS. 

To assess whether the Deccan Traps are likely to be able to 

accommodate large-scale CCS, the Celia lab, led by graduate 

student Tom Postma, (1) mapped the area in three spatial 

dimensions; (2) considered necessary constraints on injection 

depth; and (3) analyzed the geology of the rock volume 

residing at suitable depths to gauge the likelihood of finding 

viable injection targets. 

In the absence of basin-wide three-dimensional geological 

datasets, Postma and Celia combined data from many different 

sources to obtain a large, internally consistent dataset that 

covers the whole region of interest (Figure 4.1b). After mapping 

the surfaces that mark the top and base of the Deccan Traps, 

they estimated the total basalt thickness at every location 

(Figure 4.1c). The resulting volume of basalt was around 

300,000 km 3 , which is consistent with estimates found in the 

literature. 

Virtually all proposed implementations of CCS involve 

injection of separate-phase, supercritical CO 2 

, which has a 

much higher density than CO 2 

in the gas phase. To inject and 

store CO 2 

as a supercritical fluid, the pressure and temperature 

in the target formation must exceed the critical pressure and 

temperature for CO 2 

: 7.4 MPa and 31.1°C, respectively. In 

practice, this imposes a minimum injection depth of around 

750 m. Because the top of the Deccan Traps largely coincides 

with the ground surface, the depth requirement implies that 

the top 750 m of basalt are not suitable for CO 2 

storage. Only 

28% of the total rock volume found at depths greater than 750 

m remains viable. This deeper basalt is found only in limited 

areas, imposing significant geographical constraints on 

available injection locations (Figure 4.1d). 

27 


Figure 4.1a-d. 

Mapping the Deccan 

Traps basalt province. 

(a) Geological map 

of the Deccan Traps 

and surrounding area, 

West-Central India. 

(b) The combined set 

of data points used 

to map the Deccan 

Traps, with markers 

colored to show the 

thickness of the basalt 

at that location. 

Each marker shape 

corresponds to a 

different data source, 

with filled markers 

used for those that 

report direct field 

measurements. 

(c) The estimated 

basalt thickness at 

each location, with a 

combined bulk rock 

volume of around 

300,000 km 3 . 

(d) The estimated 

thickness of the 

basalt satisfying the 

minimum depth 

requirement of 750 

m, with a combined 

bulk rock volume 

of around 84,000 

km 3 . Vertical and 

horizontal features 

such as those 

on the western 

margins of the Main 

Deccan Province 

are interpolation 

artifacts. 

It is possible to circumvent the depth requirement by premixing 

CO 2 

in water and then injecting the aqueous solution 

into the rock. Because dissolved CO 2 

concentration is limited 

to a few percent, this kind of injection involves 20 to 40 times 

the volume of fluid compared to separate-phase CO 2 

injection. 

This method is being used by Carbfix, an academic-industrial 

partnership developing CCS in shallow basalt formations in 

Iceland. While this method is feasible for small-scale 

injections, like the Iceland project, the water requirements 

become exorbitant and infeasible for large-scale injections like 

those envisioned in India. As such, it is not possible to 

circumvent the depth requirement. 

The depth constraint of 750 m is not the only requirement for 

viable geological storage. CO 2 

must be injected into permeable 

rock formations that have large, continuous lateral extent. 

Otherwise, the pressure buildup associated with the injection 

operation becomes excessive. In parts of the Deccan Traps, 

magmatic activity caused extensive fractures that became 

filled with the intruding magma, which cooled and solidified 

to form dikes: vertical, sheet-like intrusions that cut across the 

horizontal layering of the basalt formation. Dikes typically 

form in large numbers, giving rise to dike swarms involving 


28

thousands of dikes of varying sizes (Figure 4.2a). These dikes 

form vertical barriers that limit horizontal connectivity. In the 

Deccan Traps, the regions where basalt can be found at 

sufficient depth for CCS coincide almost exactly with the 

regions where dikes are most prevalent (Figure 4.2b). The large 

number of dikes casts significant doubt on the existence of 

laterally extensive flow systems, which are required for CO 2 

to 

be injected for long periods of time. 

Figure 4.2a-b. 

Large dike swarms disrupt 

lateral continuity of 

potential target formations. 

(a) Geological map 

of the Deccan Traps 

and surrounding area, 

including the location of 

magmatic dikes mapped 

by the Geological Survey of 

India (GSI). While GSI data 

is limited to dikes that form 

visible outcrops on satellite 

imagery, additional dikes 

could be present below the 

surface. 

(b) The location 

of magmatic dikes 

superimposed on a map 

highlighting the areas 

where basalt can be found 

at sufficient depth. 

In conclusion, both the lack of sufficient depth and extensive 

lateral continuity combine to render almost all the basalt in 

the Deccan Traps unsuitable for geological storage of captured 

CO 2 

. 

29 


Pore Structure and Permeability of Alkali-Activated 

Metakaolin Cements with Reduced CO 2 

Emissions 

PRINCIPAL INVESTIGATOR: CLAIRE WHITE 

At a Glance 

Portland cement is currently the most common type of cement 

used in concrete manufacture, but it is a significant source of 

atmospheric CO 2 

due to the production process. To counter 

this, White and her group, including graduate student Anita 

Zhang, are developing sustainable cements that are 

alternatives to conventional Portland cement. These cements 

can reduce CO 2 

emissions but with limited in-field evidence of 

proven long-term performance. By understanding the pore 

structures of these alternative cements, and linking pore 

structure to permeability, the researchers aim to create a 

predictive phenomenological model that can be used to 

identify the most suitable alternative cement for a specific 

environmental application. Reducing concrete emissions in 

the construction industry would have a large impact on overall 

CO 2 

emissions, which aligns with bp’s ambition of helping the 

world get to net-zero. 


Hard-to-decarbonize industries such as cement face the 

daunting task of lowering their CO 2 

emissions while 

maintaining product quality and performance. This is 

particularly challenging for cement and steel, where any 

change to the chemistry of the material can have long-term, 

significant ramifications on performance and safety. After 

water, concrete is the second most consumed resource in the 

world and is essential to modern infrastructure. However, one 

key ingredient of concrete, Portland cement powder, currently 

accounts for approximately 8% of global anthropogenic CO 2 

emissions. Alternative cements can be more sustainable 

options for the production of concrete, thus avoiding a 

significant portion of CO 2 

emissions in the industry. However, 

our ability to predict long-term performance of these more 

sustainable materials is severely hampered by the time it takes 

to obtain pore structure data of the binder material that 

controls ingress of harmful chemicals such as CO 2 

and sulfate 

(SO 4 

2- 

) and chlorine (Cl - ) ions. 

White and her group are utilizing key pore size 

characterization techniques and beam-bending to investigate 

the pore structure and permeability of alkali-activated 


metakaolin cements. Their aim is to further reduce CO 2 

emissions without adversely impacting long-term performance 

(i.e., retain low permeability). In addition to linking changes in 

permeability with the evolution of nanosized pores over time, 

they have also explored a unique approach for lowering 

activator concentrations (and thus CO 2 

emissions). This 

involves using a small amount of calcium hydroxide to help 

offset reduced performance at lower activator concentrations. 

A preliminary life cycle assessment of the CO 2-eq 

emissions has 

shown reduced emissions for these novel systems while lower 

permeability values show the beneficial effects of the calcium 

hydroxide addition on long-term performance. 

Ongoing research is focused on utilizing rapid, nondestructive 

small-angle X-ray scattering (SAXS) 

characterization to obtain nanopore structural information. 

This information will be used to compute the susceptibility of 

a concrete system to diffusion-controlled degradation 

processes (i.e., permeability). By connecting SAXS-derived 

pore structure attributes with intrinsic permeability data for a 

range of sustainable cement chemistries, White’s research 

aims to predict permeability of future systems from relatively 

quick and non-destructive measurements. This stands in 

contrast to the destructive and cumbersome testing methods 

currently used for pore structure characterization. 

Figure 5.1. 

(Left) Small-angle X-ray scattering curve of alkali-activated 

metakaolin cement and analysis used to determine average 

nanopore size. 

(Right) Beam-bending relaxation curves used to extract 

permeability values from the cement samples. 

31 


Projecting the Expansion and Impacts of Ocean Oxygen 

Minimum Zones 

PRINCIPAL INVESTIGATOR: LAURE RESPLANDY 

At a Glance 

The Resplandy group studies global change in the 

biogeochemistry of the oceans and how this will affect other 

parts of the Earth system, with emphasis on the cause, 

magnitude, stability and longevity of the ocean carbon sink. In 

the last year, the Resplandy group’s research focused on the 

ocean’s response to climate change, in particular the ocean’s 

loss of oxygen associated with warming. They studied how this 

warming trend influences ecosystems, ecosystem services (e.g., 

fisheries) and the climate itself via the production of nitrous 

oxide, which occurs in low oxygen ocean waters. This work led 

to three publications in 2022, including one highlighted by the 

American Geophysical Union Newsroom that focuses on the 

fate of oxygen minimum zones and coastal “dead zones,” 

which are open ocean and coastal ocean areas with very low 

oxygen levels unsuitable for most organisms. It is important 

for companies and policymakers to learn how oxygen 

minimum zones may behave in a warming world and how 

plans for the energy transition may impact these zones. 


The ocean has lost dissolved oxygen as a result of global 

warming in the past 50 years. A serious threat of this 

systematic ocean deoxygenation is the expansion of tropical 

oxygen minimum zones (OMZs) located in the subsurface 

ocean (Figure 6.1). An equally serious and more frequent threat 

is the occurrence of coastal dead zones, places where pollution 

originating from land, such as fertilizers, urbanization and 

wastewater, reinforces the depletion of oxygen. Uncertainties 

in the spatial and temporal evolution of OMZs and coastal 

dead zones severely restrict the ability to anticipate their 

ecological, climatic and societal impacts (Resplandy, 2018). 

In this project, the Resplandy group leveraged state-of-the-art 

observations, the latest generation of Earth System Models 

(CMIP6 ESMs) and newly developed ocean model simulations 

to examine the evolution of the tropical OMZs in the global 

ocean and coastal dead zones in the densely populated and 

understudied Indian Ocean. A major outcome of this work is 

the first robust projections of tropical OMZs. This was achieved 

using a more holistic approach than the one used in prior work 


and that considers the different layers of the OMZs. 

Another major finding is the crucial role of natural climate 

variability and ocean physical and biological complexity, such 

as ocean turbulence and ecosystem structure. These factors 

can reinforce and/or offset the effect of climate change on 

oxygen minimum zones and coastal dead zones, and 

ultimately influence the risk for ecosystems. 

Figure 6.1. 

The extent of the Pacific oxygen minimum zone in the 

World Ocean Atlas. 

33 


References 

Busecke, J.J.M., J. Resplandy, S.L. Ditkovsky, and J.G. John, 

2022. Diverging fates of the Pacific Ocean oxygen minimum 

zone and its core in a warming world. AGU Advances 

3:e2021AV000470. (https://doi.org/10.1029/2021AV000470). 

Lévy, M., L. Resplandy, J.B. Palter, D. Couespel, and Z. Lachkar, 

2022. Chapter 13: The crucial contribution of mixing to present 

and future ocean oxygen distribution. Ocean Mixing (329–344). 

Elsevier. (https://doi.org/10.1016/B978-0-12-821512-8.00020-7). 

Pearson, J., L. Resplandy, and M. Poupon, 2022. Coastlines at 

risk of hypoxia from natural variability in the Northern Indian 

Ocean. Global Biogeochemical Cycles 36(6):e2021GB007192. 

(https://doi.org/10.1029/2021GB007192). 

Resplandy, L., 2018. Will ocean zones with low oxygen levels 

expand or shrink? Nature 557:314–315. (https://doi.org/10.1038/ 

d41586-018-05034-y). 

Climate change will cause Pacific’s low-oxygen zone to expand 

even more by 2100, 2022. AGU Newsroom website (accessed 

Jan. 5, 2023). (https://news.agu.org/press-release/climatechange-will-cause-pacifics-low-oxygen-zone-to-expand-evenmore-by-2100/). 


34

Understanding Drivers of Hurricane Activity 

PRINCIPAL INVESTIGATOR: GABRIEL VECCHI 

At a Glance 

Tropical cyclones (TCs) impact society and ecosystems 

through extreme wind, rain and surge. A better understanding 

of TC frequency, track, and wind and rainfall intensity are key 

to building strategies to mitigate their damages for the public 

and private sectors. The goal of the Vecchi group is to 

understand the mechanisms behind tropical cyclone activity 

changes over recent and future decades. The researchers’ main 

tools of study are climate and atmospheric models. The 

researchers combine modeling studies with analyses of the 

historical record (i.e., weather data over a period of years) to 

help distinguish the extent to which observed multi-decadalto-centennial 

changes in TC activity have been driven by large 

scale factors. These factors include ocean temperature 

changes, greenhouse gases, volcanic eruptions and El Niño 

oscillations, as opposed to random atmospheric fluctuations. 


Tropical cyclones (TCs) are of profound societal and economic 

significance. TC characteristics, such as their track, frequency, 

wind and rainfall intensity, exhibit variations on a range of 

timescales. Predicting these variations with greater accuracy 

requires improved understanding of the character of and 

mechanisms behind these changes. Throughout this year, the 

Vecchi group has worked to understand the climatic controls 

on TC frequency (Hsieh et al., 2022, 2023), track (Kortum et al., 

2023), rapid intensification (Bhatia et al., 2022) and rainfall 

(Liu et al., 2022). 

All TC impacts are fundamentally modulated by TC frequency. 

Understanding TC frequency—the number of storms that form 

in a region or globally over a period of time, such as a season— 

remains a challenge for the scientific and forecasting 

community (Knutson et al., 2021; Sobel et al., 2021). In recent 

years, the researchers have developed a physics-based 

framework to understand the mechanisms controlling tropical 

cyclone frequency (Vecchi et al., 2019; Hsieh et al., 2020). This 

has led to a new paradigm in which the change in the number 

of pre-tropical cyclone vortices (or “TC seeds”) is a main driver 

of changes in TC frequency. Guided by this paradigm, the 

Vecchi group has developed the groundwork to understand the 

climatic drivers of the changes in TC seeds (Hsieh et al., 2020, 

35 


2022, 2023). This work has enabled the researchers to build a 

physically consistent framework that connects changes in 

atmospheric energy balance in locations across the globe. 

A study published this past year (Hsieh et al., 2022) explores 

the impact of TC seeds on cyclone genesis across a broad range 

of climates and climate model configurations. The study 

develops a theory to link seed frequency to large-scale 

environmental factors. This work has shown that inter-model 

spread in TC genesis sensitivity to changing climate is largely 

driven by differences in the response of pre-TC synoptic 

disturbances (“seeds”). This can be connected to large-scale 

changes in vorticity and ascent – and can be understood in 

terms of atmospheric energy flux convergence. This study 

connects observed and modeled changes in TC frequency to 

large-scale climatic parameters using first principles, such as 

conservation of energy, mass and momentum. The goal is to 

build a theoretical constraint on tropical cyclone frequency 

and its response to climate perturbations—for example, the 

greenhouse-induced warming of the planet. 

TC rapid intensification (or RI) is a phenomenon by which a 

TC’s wind intensity will increase by a substantial amount 

(approximately 35 knots) in less than 24 hours. RI remains 

difficult to predict and results in TCs that have a great 

potential to produce damage because of their intensity. 

Understanding RI is consequently a topic of growing scientific 

and societal interest. It has been observed that the fraction of 

TCs undergoing RI has increased substantially over recent 

decades (Bhatia et al., 2019). The likelihood of RI is projected to 

increase over the current century in response to greenhouseinduced 

warming (Bhatia et al. 2018). The Vecchi group found 

that the recent increase in RI was fueled in part by recent 

surface warming and was unlikely to have occurred due to 

random climate fluctuations (Bhatia et al., 2022). Researchers 

are currently building on these results to better understand 

whether the recent (1980s-present) increase in RI proportion 

was driven by greenhouse-induced warming or other climate 

forcing agents, such as atmospheric aerosols, to better 

constrain predictions of future RI. 

Another area of study for the Vecchi group researchers this 

year was an analysis of the notable eastward shift that North 

Atlantic hurricanes have exhibited in their tracks between 1971 

and 2020. They worked to understand whether this track shift 

was driven by climate factors or by random atmospheric 

fluctuations (Kortum et al., 2023). They found that, unlike the 

changes in RI (Bhatia et al., 2022), the multi-decadal shift in 


36

North Atlantic hurricane tracks includes a substantial 

component arising from weather-scale fluctuations, which can 

be thought of as effectively random. This implies that 

predicting multi-decadal changes in hurricane tracks will 

remain challenging and require a probabilistic framework. 

Figure 7.1. 

Percentage of the 10 

highest flood peaks on 

record (left) and yearly 

flood peaks (right) that 

were produced by TCs. 

Each symbol represents 

a stream gage (Liu et al., 

2022). 

Finally, the researchers explored the characteristics of 

hurricane-induced flooding in the Carolinas, by looking at 

recent, observed TCs (Liu et al., 2022). They found that in the 

Carolinas TCs are a dominant driver of floods (Figure 7.1); the 

top 10 TCs account for 2/3 of the record floods in the Carolinas 

– which highlights the impact of these rare extreme events in 

flooding. These results highlight local vulnerability to 

warming climates in the Carolinas, since the peak rainfall of 

TCs is expected to increase considerably in response to a 

warming climate (Liu et al., 2019). 

References 

Bhatia, K. et al, 2022. A potential explanation for the global 

increase in tropical cyclone rapid intensification. Nature 

Communications 13:6626. (https://doi.org/10.1038/s41467-022- 

34321-6). 

Bhatia, K., G. Vecchi, H. Murakami, S. Underwood, and J. 

Kossin, 2018. Projected response of tropical cyclone intensity 

and intensification in a global climate model. Journal of 

Climate 31(20):8281-8303. (https://doi.org/10.1175/ 

JCLI-D-17-0898.1). 

Bhatia, K., G.A. Vecchi, T. Knutson, H. Murakami, J. Kossin, 

K.W. Dixon, and C.E. Whitlock, 2019. Recent increases in 

tropical cyclone intensification rates. Nature Communications 

10,635. (https://doi.org/10.1038/s41467-019-08471-z). 

37 


Hsieh, T. L., G.A. Vecchi, W. Yang, I.M. Held, and S.T. Garner, 

2020. Large-scale control on the frequency of tropical cyclones 

and seeds: a consistent relationship across a hierarchy of 

global atmospheric models. Climate Dynamics 55:3177–3196. 

(https://doi.org/10.1007/s00382-020-05446-5). 

Hsieh, T.L., W. Yang, G.A. Vecchi, and M. Zhao, 2022. Model 

spread in the tropical cyclone frequency and seed propensity 

index across global warming and ENSO-like perturbations. 

Geophysical Research Letters 49(7): e2021GL097157. (https:// 

doi.org/10.1029/2021GL097157). 

Hsieh, T.L. et al, 2023. The influence of large-scale radiation 

anomalies on tropical cyclone frequency. 

Kortum, G., G. Vecchi, T.L. Hsieh, and W. Yang, 2023. Influence 

of weather and climate on multidecadal trends in Atlantic 

hurricane genesis and track. 

Knutson, T. R., M.V. Chung, G. Vecchi, J. Sun, T.L. Hsieh, and 

A.J.P. Smith, 2021. ScienceBrief Review: Climate change is 

probably increasing the intensity of tropical cyclones. In: 

Critical Issues in Climate Change Science, edited by: Corinne 

Le Quéré, Peter Liss & Piers Forster. (https://doi.org/10.5281/ 

zenodo.4570334). 

Liu, M., G.A. Vecchi, J. Smith, and T. Knutson, 2019. Causes of 

large projected increases in hurricane precipitation rates with 

global warming. Npj Climate and Atmospheric Science 2:38. 

(https://doi.org/10.1038/s41612-019-0095-3) 

Liu, M., J.A. Smith, L. Yang, and G.A. Vecchi, 2022. Tropical 

cyclone flooding in the Carolinas. Journal of 

Hydrometeorology 23(1):53-70. (https://doi.org/10.1175/ 

JHM-D-21-0113.1). 

Sobel, A., S.J. Camargo, C.Y. Lee, C. Patricola, M. Tippett, G.A. 

Vecchi, and A.A. Wing, 2021. Tropical cyclone frequency. 

Earth’s Future 9(12):e2021EF002275. (https://doi. 

org/10.1029/2021EF002275). 

Vecchi, G.A., et al., 2019. Tropical cyclone sensitivities to CO 2 

doubling: Roles of atmospheric resolution and background 

climate changes. Climate Dynamics 53:5999–6033. (https://doi. 

org/10.1007/s00382-019-04913-y). 


38

Critical Hydrogen Emission Intensity for Methane Mitigation 

PRINCIPAL INVESTIGATORS: MATTEO BERTAGNI, STEPHEN PACALA, FABIEN PAULOT AND AMILCARE PORPORATO 

At a Glance 

Hydrogen (H 2 

) energy will play a crucial role in decarbonizing 

some energy sectors to reach worldwide net-zero carbon 

emissions. However, atmospheric hydrogen interferes with 

greenhouse gases like methane, water vapor and ozone. This 

means that hydrogen losses across the supply chain may offset 

some of the climate benefits of hydrogen adoption. Hydrogen's 

interaction with atmospheric methane, the second most 

important greenhouse gas, is of particular importance because 

methane mitigation is recognized as the most effective 

solution for near-term climate change mitigation. The research 

explored the impact of hydrogen emissions on atmospheric 

methane, quantifying a critical hydrogen emission rate (HEI) 

above which methane increases despite reducing fossil fuel 

use. This information will help inform bp about the 

importance of minimizing hydrogen losses to limit hydrogen 

climate impact. 


The use of H 2 

will be essential toward decarbonizing the 

energy and transport sectors where direct electrification may 

not be feasible, like heavy industry, heavy-duty road transport, 

shipping and aviation. H 2 

fuel also offers a promising solution 

to reduce air pollution and store intermittent renewable energy. 

However, the impact of future hydrogen losses due to leakages, 

venting, purging and incomplete combustion are not clearly 

understood and may complicate hydrogen’s future role. 

H 2 

is neither a pollutant nor a direct greenhouse gas. It is, 

however, an indirect greenhouse gas because it interferes with 

methane, water vapor and ozone in the atmosphere. Most 

recent evaluations give H 2 

a global warming potential of 

around 10 for a 100-year time horizon and about 35 for a 

20-year time horizon (Warwick et al., 2022) demonstrating that 

the potential climate impact of H 2 

emissions is significant. The 

feedback of hydrogen on atmospheric methane is particularly 

important to climate change. Methane has been the second 

largest contributor to atmospheric warming since the 

beginning of the industrial era, and there are global efforts to 

mitigate its atmospheric level. 

Porporato’s group has been addressing this problem by 

developing a box model for the coupled atmospheric system of 

39 


methane and hydrogen (Bertagni et al., 2022). The hydrogen 

and methane budgets are deeply interconnected for several 

natural and anthropogenic reasons (Figure 8.1). First, both 

gases are removed by the radical hydroxide (OH), the 

‘atmosphere detergent’. An increase in the concentration of 

tropospheric H 2 

would reduce the availability of OH for 

methane oxidation. This, in turn, would increase the amount 

of atmospheric methane. Second, methane oxidation leads to 

hydrogen formation. Third, hydrogen and methane are linked 

at the industrial level because most of the current and nearterm 

future H 2 

production comes from steam methane 

reforming. 

Figure 8.1. 

Sketch of H 2 

and CH 4 

tropospheric budgets and 

their interconnections: 

1) the competition for 

hydroxide (OH); 

2) the production of H 2 

from CH 4 

oxidation; and 

3) the potential emissions 

[minimum-maximum] 

due to a more hydrogenbased 

energy system. Flux 

estimates (Tg/year) are 

from Ehhalt et al. (2009) 

and Saunois et al. (2020). 

Arrows are scaled with 

mass flux intensity, the 

CH 4 

scale being 10 times 

narrower than H 2 

scale. 

The research finds that hydrogen displacement of fossil fuel 

energy can have very different consequences for atmospheric 

methane, depending on the amount of hydrogen lost and the 

methane emissions associated with hydrogen production. The 

research defines a critical hydrogen emission intensity (HEI) at 

which hydrogen losses completely offset the reduction in 

methane emissions as a result of lower fossil fuel use (Figure 

8.2). For green H 2 

, which is hydrogen obtained from renewable 

sources, the critical HEI is around 9%. This has an uncertainty 

of ±3%, which is related to how OH consumption is partitioned 

among the atmospheric gases and how much atmospheric H 2 

is 

consumed by soil bacteria. For blue H 2 

, which is hydrogen 

obtained from steam methane reforming coupled with carbon 

capture and storage, the critical HEI is much lower and greatly 

depends on the methane emissions associated with hydrogen 

production. Notably, if methane losses are above 1%, blue 

hydrogen displacement of fossil fuel energy offers no benefit 

for methane mitigation. 


40

The critical hydrogen emission intensity is a benchmark that 

can be used to evaluate the impact of hydrogen use, which can 

be beneficial or detrimental, on atmospheric methane. Clearly, 

this requires detailed estimates of future hydrogen emissions. 

Figure 8.2. 

Critical hydrogen 

emission intensity 

(HEI) of green and 

blue H 2 

(with 0.2, 

0.5, 1% CH 4 

leak 

rates) as a function 

of the OH excess, 

i.e., the amount of 

OH that reacts with 

other gases besides 

methane. Triangles 

mark the critical HEI 

for the best estimates. 

Dashed (dotted) lines 

are obtained for a 20% 

increase (decrease) in 

the H 2 

uptake rate by 

soil bacteria. 

References 

Bertagni, M. B., S.W. Pacala, F. Paulot, and A. Porporato, 2022. 

Risk of the hydrogen economy for atmospheric methane. 

Nature communications 13(1):7706. (https://doi.org/10.1038/ 

s41467-022-35419-7). 

Ehhalt, D. and F. Rohrer, 2009. The tropospheric cycle of H 2 

: a 

critical review. Tellus B: Chemical and Physical Meteorology 

61(3):500–535. 

(https://doi.org/10.1111/j.1600-0889.2009.00416.x). 

Saunois, M. et al., 2020. The global methane budget 2000–2017. 

Earth System Science Data 12(3):1561-1623. (https://doi. 

org/10.5194/essd-12-1561-2020). 

Warwick, N. et al., 2022. Atmospheric Implications of 

Increased Hydrogen Use. Technical Report (Policy Paper from 

UK’s Department for Energy Security and Net Zero and 

Department for Business, Energy & Industrial Strategy). (www. 

gov.uk/government/publications/atmospheric-implications-ofincreased-hydrogen-use). 

41 


The CMI Wetland Project: Understanding the 

Biogeochemical Controls on Wetland Methane Emissions 

for Improved Climate Prediction and Methane Mitigation 

PRINCIPAL INVESTIGATOR: XINNING ZHANG 

At a Glance 

Methane is the second most important anthropogenic climate 

forcer after carbon dioxide (CO 2 

). Determining the importance 

and mechanisms of different anthropogenic and natural 

methane sources and sinks across temporal and spatial scales 

remains a fundamental challenge for the scientific community. 

Wetlands are dominant but highly variable sources of methane 

and are predicted to play a critical role in carbon-climate 

feedbacks. Methane emissions from these areas are shaped by 

a complex and poorly understood interplay of microbial, 

hydrological and plant-associated processes that vary in time 

and space. The factors responsible for the greatest methane 

emissions from wetlands remain unknown. 

The CMI Wetland Project, conducted by the Zhang lab and led 

by researcher Linta Reji, aims to identify the biological and 

chemical mechanisms that promote methane emissions from 

wetlands. The goal is to improve predictions of carbon-climate 

feedbacks and strategies for methane mitigation. 

Understanding the mechanisms that cause the greatest 

natural source of methane emissions and ways to mitigate it is 

critical for companies that aim towards net-zero. 


Atmospheric methane has risen to levels roughly 150% above 

preindustrial concentrations due to human activities. These 

levels continue to rise despite a short period of stabilization 

between 1999 and 2006. Wetlands are geographically and 

biogeochemically diverse environments that together 

constitute the largest and most variable sources of methane to 

the atmosphere. CMI Wetland Project researchers are 

investigating the microbial, chemical and hydrological 

pathways that regulate methane emissions from diverse 

wetland soils and that vary in biogeochemical composition 

and hydrologic environment. 

Ongoing research builds on prior CMI discoveries that 

transient oxygenation associated with hydrological variability 

unlocks a microbial “latch” on wetland carbon flow that 


ultimately makes mineral-poor, peaty wetlands drastically 

more methanogenic (Wilmoth et al., 2021). The researchers 

have pieced together fragments of genetic information from 

Sphagnum peat microbiomes to recreate microbial genomes. 

This has allowed the researchers to show that transient 

oxygenation selects for different keystone microorganisms at 

multiple steps of the microbial food chain underlying peat 

carbon conversion into methane (Figure 9.1, Reji et al., 2022). 

Figure 9.1. 

Compared to continuously 

oxygen-free conditions, 

additional methane 

formation can occur when 

transient oxygen exposure 

triggers a shift in microbial 

community succession 

during microbial 

degradation of complex 

aromatic peat carbon (Reji 

et al., 2022). 

The current work (Reji et al., in preparation) examines 

wetlands along a freshwater to saltwater continuum, including 

organic-rich peat composed of a different plant (Tree Moss 

instead of Sphagnum), mineral-soil marsh, and saltmarsh 

sediments. The goal is to better constrain the effects of 

hydrologically driven oxygen variability on methane 

emissions from a greater diversity of wetlands. Results point to 

highly variable responses of different wetland types to changes 

in oxygen levels. Unlike in Sphagnum peat (Wilmoth et al., 

2021), methane emissions in Tree Moss peat were largely 

unaffected by oxygen exposure (Figure 9.2a). While a similar 

trend was observed for the freshwater marsh, saltmarsh 

sediments did not release any methane. In contrast, CO 2 

emissions were generally higher (up to ~threefold) in oxygenshifted 

samples across all three wetland types. This was 

43 


particularly pronounced during the oxic period in both Tree 

Moss peat (Figure 9.2b) and freshwater marsh. The flow of 

carbon following an oxygen shift was mostly directed towards 

CO 2 

, suggesting a fundamentally different mechanism 

regulating the flow towards methane in these wetlands 

compared to that in Sphagnum peat. 

Figure 9.2a-c. 

(a) Fold change in total 

methane yield between 

oxygen-shifted versus 

continuously anoxic peat. 

Both peat types were 

exposed to oxygen for one 

week, followed by three 

weeks of anoxic incubation. 

(b) CO 2 

emissions in Tree 

Moss peat over incubation 

time. Green shaded area 

indicates the period of 

oxygen exposure. 

(c) Relative abundances 

of major microbial taxa in 

Sphagnum and Tree Moss 

peat incubations. Green 

shading indicates the oxic 

period. Taxa present in 

both peat types are in bold 

letters. 

Geochemical data indicated that the Tree Moss peat and the 

freshwater marsh were much more resilient to short-term 

(one-week) oxygen exposure compared to Sphagnum peat. In 

agreement with this, the microbial data indicated no 

significant changes in community composition across the 

oxygen shift. In contrast, community composition in oxygenshifted 

Sphagnum peat was significantly different compared to 

anoxic controls (Figure 9.2c). These observations further 

suggest that microbial community composition can be a 

powerful indicator of wetland responses to pulse disturbances 

(in this case, changes in oxygen that are driven in nature by 

shifts in hydrology). 

The next phase of the project will test the threshold 

disturbance level required to shift the resilience patterns 

observed here (i.e., would a longer period of oxygen exposure 


44

change the carbon flow in these wetlands?). Further 

investigations will compare microbial functional profiles 

across wetland types (using metagenomes) to better constrain 

the microbial mechanisms resulting in differential response of 

wetlands to transient oxygen shift. 

The CMI Wetland Project has identified the influence of 

environmental conditions (e.g., oxygen, soil saturation, water 

table, salinity) and soil molecular form on microbial 

biodiversity as keys to better constrain and mitigate wetland 

methane emissions. The researchers urge the adoption of 

strategies to limit greenhouse gas emissions from natural and 

constructed wetlands as part of land-based climate solution 

initiatives in freshwater wetlands (e.g., Wilmoth et al., 2021; 

Calabrese et al., 2021). Ongoing collaborations with the Bourg, 

Stone and Porporato groups from the Princeton University 

School of Engineering and Applied Sciences (Yang et al., 2021) 

address how soil mineralogy and biophysics can be 

manipulated to support soils-based carbon mitigation efforts. 

References 

Calabrese, S., A. Garcia, J.L. Wilmoth, X. Zhang, and A. 

Porporato, 2021. Critical inundation level for methane 

emissions from wetlands. Environmental Research Letters 16: 

044038. (https://doi.org/10.1088/1748-9326/abedea). 

Reji, L., and X. Zhang, 2022. Genome-resolved metagenomics 

informs functional ecology of uncultured Acidobacteria in 

redox oscillated Sphagnum peat. mSystems 7(5):e00055-22. 

(https://doi.org/10.1128/msystems.00055-22). 

Reji, L., and X. Zhang. Effects of oxygen variation on wetland 

microbial ecology and biogeochemical resilience. In 

preparation. 

Wilmoth J., J.K. Schaefer, D. Schlesinger, S. Roth, P. Hatcher, J. 

Shoemaker and X. Zhang, 2021. The role of oxygen in 

stimulating methane production by wetlands. Global Change 

Biology 27(22):5831-5847. (https://doi.org/10.1111/gcb.15831). 

Yang, J. Q., X. Zhang, I. Bourg, and H. Stone, 2021. 4D imaging 

reveals mechanisms of clay-carbon protection and release. 

Nature Communications 12:622. (https://doi.org/10.1038/ 

s41467-020-20798-6). 

45 


Land Conversion to Store Carbon: The Costs and Benefits 

to Biodiversity 

PRINCIPAL INVESTIGATOR: JONATHAN LEVINE 

At a Glance 

Harnessing the power of land to store carbon is essential to 

meeting worldwide net-zero targets. However, the impacts 

such actions have on global biodiversity are highly uncertain 

and poorly understood. Research in Jonathan Levine’s group is 

exploring the conflicts and synergies between society’s 

portfolio of land-based climate solutions and biodiversity. 

Addressing this interaction is critical for conservation groups, 

companies and governmental agencies that promote natural 

climate solutions and offsets under the assumption that 

benefits to biodiversity are clear. 


Land-based climate solutions are actions aimed at increasing 

carbon storage or reducing greenhouse gas emissions through 

exploiting the natural processes occurring in vegetation and 

soils. The Levine group has developed quantitative approaches, 

based on a statistical modeling approach, for evaluating how 

the conversion of land for carbon storage affects species 

worldwide. 

The conversion of habitat for better carbon storage affects 

biodiversity in two distinct pathways. First, land use change 

directly affects the suitability of a given location for species 

persistence. For example, planting trees in a natural grassland 

reduces the use of that location by grassland-specialist bird 

species. Second, the conversion of habitat for the sequestration 

of carbon stabilizes the climate, and that climate stabilization 

impacts the global suitability of the planet for biodiversity. 

Many stakeholder groups advocate nature-based solution 

“win-wins.” These are cases where an action such as 

reforestation is expected to benefit biodiversity through both 

land use change and carbon storage. Despite this, the 

quantification of these impacts is rare, and is almost never 

done in a way that can be compared across the climate 

stabilization and land use change pathways. 

Over the last year, the Levine group has developed a new 

approach for assessing how land conversion for carbon storage 

affects biodiversity. This approach is based on statistical 


models that relate species occurrences to both climate and 

habitat type. These analyses quantify the local effects of a 

land-based climate solution through land use change, and the 

global effects, through climate stabilization, on global 

biodiversity. Moreover, these impacts are measured in the 

same biodiversity currency, and the analysis can assess the 

effects of habitat conversion at all locations across the globe. 

Results show that for birds, mammals, reptiles and 

amphibians, the effects of land conversion on habitat 

suitability tend to outweigh the impacts from climate 

stabilization. However, the extent to which this is true varies 

across the globe. For example, preliminary analyses show that 

the reforestation of relatively species-poor north temperate 

grasslands has benefits for global bird biodiversity through 

climate stabilization that begin to approach the local impacts 

on species through land use change (Figure 10.1). By contrast, 

the reforestation in tropical habitats affects biodiversity 

through habitat conversion. 

Figure 10.1. 

Relative impact of habitat 

change versus climate 

stabilization effects on bird 

biodiversity resulting from 

reforestation. 

Future work will examine how the range of land-based 

solutions, including reforestation, afforestation, and bioenergy 

cropping systems, impact global biodiversity and assess where 

they can be deployed to maximize the biodiversity co-benefits 

of carbon storage. 

47 


Understanding How Economic Incentives Influence 

Land-Use Decisions 

PRINCIPAL INVESTIGATORS: KATHY BAYLIS ROBERT HEILMAYR AND ANDREW PLANTINGA 

At a Glance 

To help combat climate change, several countries have 

programs that incentivize landowners to make land-use 

decisions that reduce net greenhouse gas emissions—like 

avoiding deforestation, planting trees or practicing no-till 

farming. The Environmental Markets Laboratory (emLab) at 

the University of California, Santa Barbara (UCSB) is 

conducting econometric analyses, (i.e., using statistical 

models to analyze economic data) to understand the 

effectiveness of these incentives on a national and global scale. 

The goal is to explore how responsive land-use decisions are to 

market prices, and the political, cultural and economic factors 

that influence these responses. Research findings will help 

policy makers understand the potential impact that incentives 

for land-based climate solutions could have on land use and 

associated emissions and help companies with ambitious 

net-zero goals utilize land in an optimal way. 


The Earth’s land has the ability to store or release carbon into 

the atmosphere, depending on management choices 

landowners make. To help meet climate goals, policy makers 

and practitioners across the world are exploring programs that 

incentivize private landowners to manage their land in a way 

that reduces net greenhouse gas emissions. These efforts 

include practicing climate-smart agriculture, avoiding 

deforestation or pursuing an array of other “land-based 

climate solutions” (e.g., wetland restoration or afforestation). 

In addition to mitigating climate change, these solutions have 

the potential to protect biodiversity and affect food production. 

However, the impacts of land-based climate solutions on 

climate, biodiversity and food security may be limited by 

socioeconomic constraints. In particular, there is little 

evidence detailing how responsive private landowners will be 

to incentives that seek to encourage changes in land use. The 

emLab project seeks to fill this gap by quantifying how 

responsive land use decisions are to financial opportunities, 

and whether this responsiveness varies across regions, 

political regimes, cultures and economic systems. 


Understanding if and how much land-use decisions respond to 

financial incentives across different locations will help policy 

makers and practitioners find the most effective solutions that 

balance climate mitigation, biodiversity protection and food 

production. 

There are two main components of this research project. The 

first investigates how local changes in financial opportunities 

for crop production affect landowners’ land use decisions to 

convert forests to croplands, or to allow croplands to revert to 

forests. By quantifying landowners’ responsiveness to local 

increases in crop prices, the research team can simulate how 

land use decisions might change in the presence of new 

incentives such as payments for reforestation, or taxes 

discouraging forest clearing. The emLab team is combining 

econometric methods that seek to isolate causal relationships 

with remotely-sensed maps of forest and cropland areas, and 

global datasets detailing crop prices, potential yields and 

market integration. The aim is to capture global trends in 

land-use responsiveness to market prices of crops and 

variations across different regions and scenarios (Fischer et al., 

2021; Hansen et al., 2013; IMF 2022; Nelson et al., 2019; Potapov 

et al., 2021). Initial findings indicate a positive relationship 

between potential crop revenues and deforestation (see Figure 

11.1). Outliers to this relationship are located in rather remote 

places with limited market access. 

Figure 11.1. 

The amount of 

deforestation occurring 

in a location (y-axis) 

tends to rise as the 

potential revenues 

from crop production 

(x-axis) increase. Outliers 

with unusually low 

deforestation and high 

potential revenues tend 

to be in locations that are 

located far away from the 

nearest market (colors). 

49 


The second part of our project dives deeper into a country-level 

case study of land-based climate solutions in Brazil. Brazil 

currently has a suite of different policies in place that 

individually seek to encourage climate-smart agriculture, 

reduce deforestation and accelerate forest restoration. This 

project explores how these different incentives interact with 

each other to re-enforce, or undermine, broader climate, 

biodiversity and food production goals. For example, payments 

for forest restoration may push additional agricultural 

expansion into primary forests, undermining carbon and 

biodiversity benefits. EmLab researchers are exploring these 

dynamics by developing a high-resolution land use model at 

the national scale. The goal is to simulate a variety of policy 

mixes to identify how policies can be integrated to maximize 

their collective impact. 

References 

Fischer, G., F.O. Nachtergaele, H.T. van Velthuizen, F. Chiozza, 

G. Franceschini, M. Henry, D. Muchoney, and S. Tramberend, 

2021. Global agro-ecological zones V4 – model documentation. 

Rome, FAO. (https://doi.org/10.4060/cb4744en). 

Hansen, M. C., P. V. Potapov, R. Moore, M. Hancher, S. A. 

Turubanova, A. Tyukavina, and D. Thau, et al., 2013. Highresolution 

global maps of 21st-century forest cover change. 

Science 342(6160):850–53. (https://doi.org/10.1126/ 

science.1244693). 

IMF. 2022. Primary Commodity Price System. (accessed Feb. 13, 

2023). (https://data.imf.org/?sk=471DDDF8-D8A7-499A-81BA- 

5B332C01F8B9) 

Nelson, A., D.J. Weiss, J. van Etten, A. Cattaneo, T.S. 

McMenomy, and J. Koo. 2019. A suite of global accessibility 

indicators. Scientific Data 6(1):266. (https://doi.org/10.1038/ 

s41597-019-0265-5). 

Potapov, P., S. Turubanova, M.C. Hansen, A. Tyukavina, V. 

Zalles, A. Khan, X. Song, A. Pickens, Q. Shen, and J. Cortez. 

2022. Global maps of cropland extent and change show 

accelerated cropland expansion in the twenty-first century. 

Nature Food 3:19-28. (https://doi.org/10.1038/s43016-021- 

00429-z). 


50

How the Orography-Aware Land Model LM4.2 Improves 

Our Understanding of Potentially Abrupt Changes in the 

Land Terrestrial Carbon Cycle 

PRINCIPAL INVESTIGATOR: ELENA SHEVLIAKOVA 

At a Glance 

The latest Sixth Assessment Report (AR6) of the 

Intergovernmental Panel on Climate Change (IPCC) found that 

“Limiting global temperature increase to a specific level would 

imply limiting cumulative CO 2 

emissions to within a carbon 

budget.” This budget is estimated to be 500 gigatonnes of CO 2 

from the beginning of 2020 to cap temperatures at 1.5 °C. To 

arrive at this number, scientists use climate models that 

include representations of terrestrial ecosystems, including 

processes that release carbon to the atmosphere like wildfires 

and forest diebacks due to droughts and heat. The Geophysical 

Fluid Dynamics Laboratory (GFDL) at the National Oceanic 

and Atmospheric Administration (NOAA) and CMI have 

developed one of the few existing models that accounts for the 

impacts of more frequent extreme weather in today’s warming 

world. This is important for bp because land models are 

significant tools in understanding the impact of extreme 

weather on land carbon uptake and are critical in designing 

standards to achieve net-zero global emissions. 


The IPCC AR6 bases estimates of their carbon budget on the 

relationship between cumulative CO 2 

emissions and global 

average temperature change predicted by climate models. 

Most of the Earth System Models (ESMs) in the AR6 predicted 

that about half of the cumulative emissions would continue to 

be removed by the land biosphere and oceans, with the land 

responsible for marginally more net uptake than the oceans. 

However, these models have a limited representation of 

terrestrial ecosystem complexity, including extreme fires and 

forest diebacks due to droughts and heat. There are only four 

ESMs, including NOAA/GFDL ESM4.1, that represent changes 

in vegetation distribution because of the impacts of climate 

change. 

Last year, a team of CMI and NOAA/GFDL scientists, including 

researchers Sergey Malyshev, Isabel Martinez Cano, and Yujin 

Zeng, used ESM.1 to demonstrate that under the extreme 

greenhouse gasses emission scenario SSP5-8.5, Amazon forests 

51 


may begin to convert to savanna before mid-century because 

of increased forest fires. To explore the robustness of this 

conclusion in the tropics and to investigate the possibility of 

abrupt changes in other regions, the team implemented 

several improvements to the land component of the ESM4.1 

and developed a new land model, LM4.2. This new model 

included a new representation of nutrient limitation nitrogen 

(N) on carbon uptake and a refined representation of grass-tree 

competition for both seedlings to mature trees. It also included 

a suit of parameterizations accounting for effects of orography, 

or mountainous geography, on soil moisture (via hillslopes), 

surface radiation (via mountain shading), and orographic 

scaling of atmospheric forcing (surface temperature, 

precipitation, and specific humidity) (Martinez Cano et al., 

2022). 

Figure 11.1. 

Diameter growth rates 

from the open N cycle 

simulation experiments. 

Panels a, b, and c show 

the results of Oak Ridge 

(OKR), Harvard Forest 

(HFR), and the Northern 

Old Black Spruce (NOBS) 

sites, respectively. The 

diameter growth rate is 

the mean of the cohorts 

of a PFT (deciduous 

or ‘evergreen’) in the 

canopy layer. At a low N 

mineralization rate, the 

diameter growth rates of 

‘evergreen’ trees are greater 

than those of deciduous 

trees at the three sites. At a 

high N mineralization rate 

however, the ‘evergreen’ 

trees grow more slowly 

than the deciduous trees 

at OKR and HFR (Wang et 

al., 2017). 

Previously, the Pacala lab 

demonstrated in a theoretical 

analysis that soil nitrogen 

availability plays a critical role 

in shaping the competition 

between long-lived leaves (i.e., 

evergreen) trees and short-lived 

leaves (i.e., deciduous) trees 

(Weng et al., 2017; figure 12.1). 

The new N scheme in LM4.2 will 

enable CMI scientists, including 

researcher Enrico Zorzetto, to 

explore how competition 

between evergreens and 

deciduous trees in high latitudes 

and high altitudes under a 

changing climate may accelerate 

the warming through 

biophysical feedbacks. As ESMs 

remain computationally 

expensive and typically simulate 

atmosphere and land at 50-100 

km resolution, the ability to 

resolve sub-grid orographic 

heterogeneity allows LM4.2 to 

better characterize both wet 

(floods) and dry extremes (droughts and fire). Both extreme wet 

and dry conditions could accelerate tree mortality, which in 

turn will lead to shifts in the wildfire regimes. These processes 

could affect carbon uptake on land and, thus, the remaining 

carbon budgets. 


52

The orography-aware new land model LM4.2 provides CMI and 

NOAA/GFDL researchers with a unique tool to understand the 

implications of dry and wet extremes for future carbon uptake 

at a higher resolution than typically afforded by the 

atmospheric components of the ESMs. 

References 

Martinez Cano, I.M., E. Shevliakova, S. Malyshev, J. John, Y. 

Yu, B. Smith, and S.W. Pacala, 2022. Abrupt loss and uncertain 

recovery from fires of Amazon forests under low climate 

mitigation scenarios. Proceedings of the National Academy of 

Sciences 119(52):e2203200119. (https://doi.org/10.1073/ 

pnas.2203200119). 

Weng, E., C.E. Farrior, R. Dybzinski, and S.W. Pacala, 2017. 

Predicting vegetation type through physiological and 

environmental interactions with leaf traits: evergreen and 

deciduous forests in an earth system modeling framework. 

Global Change Biology 23(6):2482-2498. (https://doi.org/10.1111/ 

gcb.13542). 

53 


Ongoing Research at the Pacala Lab 

PRINCIPAL INVESTIGATOR: STEPHEN PACALA 

At a Glance 

Over the course of last year, the Pacala lab was involved in 

several research projects focused on the interaction between 

climate change, the global carbon cycle and biodiversity. 

Notably, their work in the Panamanian rainforest examined 

the dynamics of carbon uptake and storage during drought 

conditions. The researchers found that moderate drought 

conditions did not have a detrimental effect on carbon uptake 

and storage, and that, in fact, the flora of the region stored 

more carbon during moderate drought conditions than normal 

conditions. A separate research project, which was a 

collaboration between CMI and NOAA’s Geophysical Fluid 

Dynamics Laboratory (GFDL), explored the fate of the 

Amazonian rainforest over the next several decades. This 

research projected that the long-term effects of drought and 

fire will hamper carbon storage and consequently that 

portions of the rainforest will switch to savanna as early as 

2035. The two studies are relevant to bp’s interests because a 

collapse of one of the Earth’s largest carbon sinks would 

amplify demands for an increase in the global pace of 

decarbonization and would also imperil forestry offsets that 

had been established in the region. The implication of the two 

together is that effective fire suppression in the face of 

increasing drought might increase Amazonian carbon storage. 


A paper by Detto and Pacala (2022), which was published in 

Global Change Biology, analyzes data that the Pacala lab has 

been collecting in a Panamanian rainforest for several years. 

The data were collected with a device called an eddy 

covariance tower, which measures carbon and water fluxes 

between the forest and atmosphere. This work shows that 

forest carbon uptake and storage were not impaired by the 

moderately severe drought conditions that occurred several 

times during the measurement period. Instead, the forest 

captured and stored more carbon during the droughts (Figure 

13.1). This is because the extra power that photosynthesis 

received from the sunny conditions that occurred during 

drought overcame any limitations a water shortage imposed 

on carbon gain. Although this is good news for rainforest 

carbon uptake and storage and for nature-based climate 

solutions, the result could be reversed by very severe droughts. 


Figure 13.1. 

Images taken by a 

phenocam (NetCam SC, 

StarDot Technologies) 

located at the highest 

point on Barro Colorado 

Island in the middle of 

the 2015 dry season and 

during the beginning 

of the 2015 wet season. 

The images show several 

leafless deciduous trees 

(left panel) completely 

recovered just before two 

anomalous dry spells 

during the El Niño event. 

Note how the vegetation 

looks, in general, much 

brighter green in the right 

picture despite different 

illumination conditions 

[from Detto et al., 2022]. 

A much more pessimistic take on the problem was provided by 

Martinez Cano et al. (2022) in the Proceedings of the National 

Academy of Sciences, which is a collaboration between the CMI 

and NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL). 

This paper was highlighted in the 2022 CMI report, when the 

paper had not yet been published, and is included here 

because of its relationship to the Detto and Pacala paper. The 

Martinez Cano et al. paper used the state-of-the-art Earth 

System Model that the Pacala lab has been working on for a 

decade to predict the fate of the Amazon rainforest over the 

next several decades. The model predicts that drought 

prolongs the time required for rainforests to outcompete 

grasses and reestablish themselves after fire. It also predicts 

that fire frequency will progressively increase both because of 

increasing drought and because grasses are highly flammable 

during periods of drought. As a result, the model forecasts that 

large portions of the Amazonian rainforest will degrade and 

store less carbon and some will switch to savanna, beginning 

as early as 2035. These results require the unique capabilities 

that the CMI-GFDL collaboration has built into GFDL models. 

The Pacala lab also continues to work on greenhouse 

implications of fugitive methane and hydrogen, and a variety 

of modeling problems focused on interactions between 

biodiversity and carbon cycling. Additionally, two other large 

projects dominated Pacala’s time in the past year. Although 

neither was funded by the CMI, both are highly relevant to the 

CMI. First, Pacala chaired a committee of the National 

Academies of Sciences, Engineering, and Medicine, which has 

now produced a policy manual for the U.S. to effectively 

implement the Inflation Reduction Act and the Infrastructure 

Investment and Jobs Act recently passed by the U.S. Congress. 

The report will appear this spring and focuses on filling gaps 

and overcoming barriers on the way to a fair and just energy 

transition. Second, Pacala chaired, with economist and 

55 


Stanford Business School Dean Jon Levin, a study and report 

for the President on how to safeguard the U.S. population and 

economy against climate change-enhanced extreme weather. 

References 

Martinez Cano, I.M., E. Shevliakova, S. Malyshev, J. John, Y. 

Yu, B. Smith, and S.W. Pacala, 2022. Abrupt loss and uncertain 

recovery from fires of Amazon forests under low climate 

mitigation scenarios. Proceedings of the National Academy of 

Sciences 119(52):e2203200119. (https://doi.org/10.1073/ 

pnas.2203200119). 

Detto, M., and S.W. Pacala, 2022. Plant hydraulics, stomatal 

control and the response of a tropical forest to water stress over 

multiple temporal scales. Global Change Biology 28(5):4359- 

4376. (https://doi.org/10.1111/gcb.16179). 


56

This Year’s Publications 

Anand, S.K., S. Bonetti, C. Camporeale, M. Hooshyar, and A. Porporato, 2022. Comment 

on “Groundwater affects the geomorphic and hydrologic properties of coevolved 

landscapes” by Litwin et al. Journal of Geophysical Research: Earth Surface 

127(10):e2022JF006669. (https://doi.org/10.1029/2022JF006669). 

Anand, S.K., S. Bonetti, C. Camporeale, and A. Porporato, 2022. Inception of 

regular valley spacing in fluvial landscapes: A linear stability analysis. Journal 

of Geophysical Research: Earth Surface 127(11):e2022JF006716. (https://doi. 

org/10.1029/2022JF006716). 

Bertagni, M.B., S.W. Pacala, F. Paulot, and A. Porporato, 2022. Risk of the hydrogen 

economy for atmospheric methane. Nature Communications 13:7706. (https://doi. 

org/10.1038/s41467-022-35419-7). 

Bertagni, M.B. and A. Porporato, 2022. The carbon-capture efficiency of natural water 

alkalinization: Implications for enhanced weathering. Science of the Total Environment 

838(4):156524. (https://doi.org/10.1016/j.scitotenv.2022.156524). 

Bhatia K., A. Baker, W. Yang, G.A. Vecchi, T. Knutson, H. Murakami, J. Kossin, K. Hodges, 

K. Dixon, B. Bronselaer, and C. Whitlock, 2022. A potential explanation for the global 

increase in tropical cyclone rapid intensification. Nature Communications 13:6626. 

(https://doi.org/10.1038/s41467-022-34321-6). 

Busecke, J.J.M., L. Resplandy, S.J. Ditkovsky, and J.G. John, 2022. Diverging fates of the 

Pacific Ocean oxygen minimum zone and its core in a warming world. AGU Advances 

3(6):e2021AV000470. (https://doi.org/10.1029/2021AV000470). 

Cabal, C., L. Rodriguez-Torres, N. Mari-Mena, A. Mas-Barreiro, A. Vizcaino, J. Vierna, F. 

Valladares, and S.W. Pacala, 2022. Comparing two field protocols to measure individual 

shrubs’ root density distribution. Plant and Soil 481:691–699. (https://doi.org/10.1007/ 

s11104-022-05657-1). 

Calabrese, S., B. Wild, M.B. Bertagni, I.C. Bourg, C. White, F. Aburto, G. Cipolla, L.V. Noto, 

and A. Porporato, 2022. Nano-to-global-scale uncertainties in terrestrial enhanced 

weathering. Environmental Science and Technology 56(22):15261–15272. (https://doi. 

org/10.1021/acs.est.2c03163). 

Cerasoli, S. and A. Porporato, 2023. California’s groundwater overdraft: An 

environmental Ponzi scheme? Journal of Hydrology 617(C):239081. (https://doi. 

org/10.1016/j.jhydrol.2023.129081). 

Cheng, F., H. Luo, J.D. Jenkins, and E.D. Larson, 2022. The value of low- and negativecarbon 

fuels in the transition to net-zero emission economies: Lifecycle greenhouse 

gas emissions and cost assessments across multiple fuel types. Applied Energy 

331:20388. (https://doi.org/10.1016/j.apenergy.2022.120388). 

Cheng, F., N. Patankar, S. Chakrabarti, and J.D. Jenkins, 2022. Modeling the operational 

flexibility of natural gas combined cycle power plants coupled with flexible carbon 

capture and storage via solvent storage and flexible regeneration. International Journal 

of Greenhouse Gas Control 118:103686. (https://doi.org/10.1016/j.ijggc.2022.103686). 

57 


Cipolla, G., S. Calabrese, A. Porporato, and L.V. Noto, 2022. Effects of precipitation 

seasonality, irrigation, vegetation cycle and soil type on enhanced weathering– 

modeling of cropland case studies across four sites. Biogeosciences 19(16):3877– 

3896. (https://doi.org/10.5194/bg-19-3877-2022). 

Darnajoux, R., L. Reji, X.R. Zhang, K.E. Luxem, and X. Zhang, 2022. Ammonium 

sensitivity of biological nitrogen fixation by anaerobic diazotrophs in cultures and 

benthic marine sediments. JGR Biogeosciences 127(7):e2021JG006596. (https://doi. 

org/10.1029/2021JG006596). 

Detto, M. and S.W. Pacala, 2022. Plant hydraulics, stomatal control, and the response 

of a tropical forest to water stress over multiple temporal scales. Global Change 

Biology 28(14):4359-4376. (https://doi.org/10.1111/gcb.16179). 

Greig, C. and A. Sharma, 2022. “Why India’s clean energy future lies with green 

hydrogen – not blue,” World Economic Forum Annual Meeting, 13 May. (https://www. 

weforum.org/agenda/2022/05/why-indias-future-lies-with-green-hydrogen-notblue/). 

Greig, C., S. Uden, and R. H. Socolow, 2022. “Maximizing the impact of a history-making 

federal clean energy investment program,” The Hill, 9 September. (https://thehill.com/ 

opinion/energy-environment/3636069-maximizing-the-impact-of-a-history-makingfederal-clean-energy-investment-program/). 

Greig, C., D. Keto, S. Hobart, B. Finch, and R. Winkler, 2023. Speeding up risk capital 

allocation to deliver net-zero ambitions, Joule 7(2):239-243. 

(https://doi.org/10.1016/j.joule.2023.01.003). 

Gunawan, T.A., M. Cavana, P. Leone, and R.F.D. Monaghan, 2022. Solar hydrogen for 

high capacity, dispatchable, long-distance energy transmission – A case study for 

injection in the Greenstream natural gas pipeline. Energy Conversion and Management 

273(1):116398. (https://doi.org/10.1016/j.enconman.2022.116398). 

Hsieh, T.L., W. Yang, G.A. Vecchi, and M. Zhao, 2022. Model spread in the tropical 

cyclone frequency and seed propensity index across global warming and ENSO-like 

perturbations. Geophysical Research Letters 49(7):e2021GL097157. (https://doi. 

org/10.1029/2021GL097157). 

Jackson, R.B., A. Ahlström, G. Hugelius, C. Wang, A. Porporato, A. Ramaswami, J. Roy, 

and J. Yin, 2022. Human well-being and per capita energy use. Ecosphere 13(4):e3978. 

(https://doi.org/10.1002/ecs2.3978). 

Kleinhesselink, A.R., N.J.B. Kraft, S.W. Pacala, and J.M. Levine, 2022. Detecting and 

interpreting higher-order interactions in ecological communities. Ecology Letters 

25(7):1604-1617. (https://doi.org/10.1111/ele.14022). 

Ku, A.Y., C. Greig, and E.D. Larson, 2022. Traffic ahead: Navigating the road to carbon 

neutrality. Energy Research & Social Science 91:102686. (https://doi.org/10.1016/j. 

erss.2022.102686). 

Lau, M., W. Ricks, N. Patankar, and J.D. Jenkins, 2022. Europe’s way out: Tools to 

rapidly eliminate imports of Russian natural gas. Joule 6(10):2219-2224. (https://doi. 

org/10.1016/j.joule.2022.09.003). 


58

Luxem, K.E., A.J. Nguyen, and X. Zhang, 2022. Biohydrogen production relationship 

to biomass composition, growth, temperature and nitrogenase isoform in the 

anaerobic photoheterotrophic diazotroph Rhodopseudomonas palustris. International 

Journal of Hydrogen Energy 47(66):28399-28409. (https://doi.org/10.1016/j. 

ijhydene.2022.06.178). 

Martinez Cano, I., E. Shevliakova, S. Malyshev, and S.W. Pacala, 2022. Abrupt loss 

and uncertain recovery from fires of Amazon forests under low climate mitigation 

scenarios. PNAS 119(52):e2203200119. (https://doi.org/10.1073/pnas.2203200119). 

Mohan, A., S. Sengupta, P. Vaishnav, R. Tongia, A. Ahmed, and I.L. Azevedo, 2022. 

Sustained cost declines in solar PV and battery storage needed to eliminate coal 

generation in India. Environmental Research Letters 17:114043. (https://doi. 

org/10.1088/1748-9326/ac98d8). 

Pascale, A., S. Chakravarty, P. Lant, S. Smart, and C. Greig, 2022. Can transitioning to 

non-renewable modern energy decrease carbon dioxide emissions in India? Energy 

Research & Social Science, 91:102733. (https://doi.org/10.1016/j.erss.2022.102733). 

Pearson, J., L. Resplandy, and M. Poupon, 2022. Coastlines at risk of hypoxia from 

natural variability in the Northern Indian Ocean. Global Biogeochemical Cycles 36(6): 

e2021GB007192. (https://doi.org/10.1029/2021GB007192). 

Perri, S., A. Molini, L.O. Hedin, and A. Porporato, 2022. Contrasting effects of aridity 

and seasonality on global salinization. Nature Geoscience 15:375-381. (https://doi. 

org/10.1038/s41561-022-00931-4). 

Postma, T.J.W., K.W. Bandilla, and M.A. Celia, 2022. Implications of CO 2 

mass 

transport dynamics for large-scale CCS in basalt formations. International Journal of 

Greenhouse Gas Control 121: 103779. (https://doi.org/10.1016/j.ijggc.2022.103779). 

Puy, A. et al., 2022. The delusive accuracy of global irrigation water withdrawal 

estimates. Nature Communications 13:3183. (https://doi.org/10.1038/s41467-022- 

30731-8). 

Reji, L. and X. Zhang, 2022. Genome-resolved metagenomics informs the functional 

ecology of uncultured acidobacteria in redox Oocillated Sphagnum peat. mSystems 

7(5): e00055-22. (https://doi.org/10.1128/msystems.00055-22). 

Rekker, S., M.C. Ives, B. Wade, L. Webb, and C. Greig, 2022. Measuring corporate Paris 

compliance using a strict science-based approach. Nature Communications, 13: 4441. 

(https://doi.org/10.1038/s41467-022-31143-4). 

Ricks, W., Q. Xu, and J.D. Jenkins, 2023. Minimizing emissions from grid-based 

hydrogen production in the United States. Environmental Research Letters 

18(1):014025. (https://doi.org/10.1088/1748-9326/acacb5). 

Schwartz, J.A., W. Ricks, E. Kolemen, and J.D. Jenkins, 2023. The value of fusion 

energy to a decarbonized United States electric grid. Joule. (https://doi.org/10.48550/ 

arXiv.2209.09373). In press. 

59 


Uden, S., and C. Greig, 2022. “Why direct-action technology, not taxes, is a better 

climate bet,” The Australian Financial Review, 21 August. (https://www.afr.com/policy/ 

energy-and-climate/why-direct-action-technology-not-taxes-is-a-better-climatebet-20220818-p5batb). 

Weng, E. et al., 2022. Modeling demographic-driven vegetation dynamics and 

ecosystem biogeochemical cycling in NASA GISS’s Earth system model (ModelE- 

BiomeE v.1.0). Geoscientific Model Development 15:8153-8180. (https://doi. 

org/10.5194/gmd-15-8153-2022). 

Yin, J. and A. Porporato, 2023. Global self-similar scaling of terrestrial carbon with 

aridity. Geophysical Research Letters 50(3):e2022GL101040. (https://doi.org/10.48550/ 

arXiv.2208.00437). In press. 

Zhang, C., H. Yang, Y. Zhao, L. Ma, E.D. Larson, and C. Greig, 2022. Realizing ambitions: 

A framework for iteratively assessing and communicating national decarbonization 

progress. iScience 25(1):103695. (https://doi.org/10.1016/j.isci.2021.103695). 


60

Acknowledgments 

Principal funding support for the Carbon Mitigation Initiative has been provided by 

bp International Limited. 

April 2023 

Carbon Mitigation Initiative Leadership and Administration 

Stephen W. Pacala, director 

Jonathan Levine, leadership team 

Amilcare Porporato, leadership team 

Kristina Corvin, program manager 

Rajeshri D. Chokshi, departmental computing support specialist 

Stacey T. Christian, manager, finance and administration 

Katharine B. Hackett, executive director, High Meadows Environmental Institute 

Hans Marcelino, web developer 

Stephen Nappa, IT manager 

Mae-Yung Tang, program tech support specialist 

Contributing Editors 

Kristina Corvin 

Thomas Garlinghouse 

For more information, visit us at CMI’s website – cmi.princeton.edu – or 

email us at cmi@princeton.edu. 

61 


The cover and text pages of this report were printed on carbon neutral, 100% recycled FSC-certified 

paper. The Forest Stewardship Council (FSC) certification guarantees that trees used to produce this 

paper were procured from responsibly managed forests. All copies were printed on a Xerox iGen5 

digital color production press. The Xerox iGen5 is eco-friendly; up to 97% of the machine’s components 

are recyclable or remanufacturable. 


62

2022 ANNUAL REPORT CARBON MITIGATION INITIATIVE 

Guyot Hall, Room 129 

Princeton University 

Princeton, New Jersey 08544 

(609) 258-3832 

cmi@princeton.edu

CMI Annual Report 2022

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