As the nation faces record heat, storms,drought, and wildfires, California has anadvantage in its scientific understanding ofclimate change. A solid body of vital data isavailable to assist state and local leaders tobetter understand how climate change is affecting us now,what is in store ahead, and what we can do about it.State-sponsored research has played a major role inrecent advances in our understanding of the potentialimpacts of climate change on California. A first assessment,published in 2006, made clear that the level of impactsis a function of global emissions of greenhouse gasesand that lower emissions can significantly reduce thoseimpacts. The second study,released in 2009, made the casefor adaptation as a necessaryand urgent complement toreducing emissions.The 2012 Vulnerability andAdaptation Study, the State’sthird major assessment onclimate change, is summarizedhere. In contrast to theprevious two assessments,this one explores local andstatewide vulnerabilities toExtended droughts have poseddifficult challenges for California inrecent years and could pose increasingproblems with climate change.climate change, highlightingopportunities for takingconcrete actions to reduceclimate-change impacts.This assessment examinesadaptation options in regional case studies and offersinsights into regulatory, legal, socioeconomic and otherbarriers to adaptation so that they can be addressedeffectively at the local and state levels. A regionalstudy of the nine-county San Francisco Bay Area isalso included.The third assessment, like its two predecessors, reflectsa powerful collaborative process. Guided by a SteeringWHAT’S NEW IN 2012?Our Changing Climate 2012 highlightsimportant new insights and data, usingprobabilistic and detailed climate projectionsand refined topographic, demographic andland use information.The findings include:• The state’s electricity system is more vulnerablethan was previously understood.• The Sacramento-San Joaquin Delta is sinking,putting levees at growing risk.• Wind and waves, in addition to faster rising seas,will worsen coastal flooding.• Animals and plants need connected “migrationcorridors” to allow them to move to more suitablehabitats to avoid serious impacts.• Native freshwater fish are particularly threatenedby climate change.• Minority and low-income communities face thegreatest risks from climate change.• There are effective ways to prepare for and manageclimate change risks, but local governments facemany barriers to adapting to climate change; thesecan be addressed so that California can continueto prosper.Committee of senior technical staff from State agenciesand outside scientific experts, 26 research teams from theUniversity of California system and other research groupsproduced more than 30 peer-reviewed papers. They offercrucial new insights for the energy, water, agriculture,public health, coastal, transportation, and ecologicalresource sectors that are vital to California residents,businesses and government leaders.Executive Order #S-3-05, signed on June 1, 2005, called for the California Environmental Protection Agency (Cal/EPA) to prepareperiodic science reports on the potential impacts of climate change on the California economy. Cal/EPA entrusted the CaliforniaEnergy Commission and its Climate Change Center to lead this effort. The 2009 Adaptation Strategy prepared by the CaliforniaNatural Resources Agency also called for a statewide vulnerability and adaptation study. This report summarizes the third of theseperiodic assessments, the product of a multi-institution collaboration among Cal/EPA, Natural Resources Agency, Department ofWater Resources, Energy Commission, Air Resources Board, Ocean Protection Council, Department of Public Health, Departmentof Forestry and Fire Protection, Bay Conservation and Development Commission, Department of Transportation, Office ofEnvironmental Health Hazard Assessment, State Coastal Conservancy, Department of Fish and Game, Department of Food andAgriculture, and State Parks. It keeps Californians apprised of new scientific developments, documents the emerging impactsof climate change, and alerts them to the increasing risks of a warming climate. Clear awareness of these risks is an importantprerequisite for Californians to fully engage in efforts to reduce greenhouse gas emissions, and to prepare and plan for thoseimpacts that cannot be avoided by emission reduction efforts.1 OUR CHANGING CLIMATE 2012
Observed changes over the last severaldecades across the western United Statesreveal clear signals of climate change.Statewide average temperatures increased byabout 1.7°F from 1895 to 2011, and warminghas been greatest in the Sierra Nevada. Throughout thepast century, precipitation (rain and snow) has followedthe expected pattern of a largely Mediterranean climatewith wet winters anddry summers, andconsiderable variabilityfrom year to year. Noconsistent trend inthe overall amount ofprecipitation has beendetected, except thata larger proportion oftotal precipitation isfalling as rain insteadof snow. In addition,during the last 35years, the SierraNevada range haswitnessed both thewettest and the driestyears on record ofmore than 100 years.While intermittentdroughts have beena common feature ofthe state’s climate,evidence from treerings and otherindicators reveal thatover the past 1,500years, California hasCalifornia’s Changing ClimateHow Likely Are Future Climate Changes?The third assessment offers a key innovation overprevious ones: probabilistic climate and sea-level-riseprojections. The likelihood of possible climate futuresrepresents the best estimate of what may happen underspecified emissions scenarios, given current scientificunderstanding of the climate system. Resourcemanagers have requested this type of informationto start putting long-term planning into a risk-basedframework.San Joaquin ValleyDaily Minimum Temperatures in January 2060This figure shows how the probability of certain dailyminimum temperatures occurring will shift in 2060 (redcurve) relative to their historical distribution (blue curve).It illustrates that the most frequently occurring (that is,the most likely) daily minimum temperatures will shiftupward, reflecting the expected overall warming trend.Extremely cold nights with below freezing temperatureswill decrease in frequency, but not completely disappear.This finding has important implications for farmers’adaptation choices as they may plant new crops that aremore resilient to high temperatures but still robust in theface of occasional freezes or choose fruit trees that areless dependent on extended chill hours.experienced dryspells that persistedfor several years oreven decades.Warmer temperaturescombined withlong dry seasons overthe last few decadeshave resulted in more severe wildfires. Substantiallyhigher temperatures, more extreme wildfires, andrising sea levels are just some of the direct impactsexperienced in California that can be attributed, atleast partially, to climate change. Projections ofCalifornia’s future climate served as the basis for allstudies in the third assessment.Projected Changes for the Remainder of this CenturyProjecting future climate requires sophisticated computermodels. Studies from the third assessment used projectionsfrom six global climate models, all run with two emissionsscenarios, one lower (B1) and one higher (A2) (the same aswere used in the 2009 assessment). Both the models andscenarios are well established, but future emissions maybe even higher or lower depending on the choices societymakes, resulting in greater or smallerclimate changes. Global modelingresults were then “scaled down” usingtwo different methods to obtain regionaland local information. In addition toprojections of future climate, severalstudies in the third assessment also usedseveral scenarios of population growthand land use policy (Business as Usual,Smart Growth, Infill, Fire Risk Avoidance,Agricultural Land Preservation, andBiodiversity Preservation) to shed lighton how development patterns couldmake California more or less vulnerableto climate change.Temperatures in California willrise significantly during this centuryas a result of the heat-trapping gaseshumans release into the atmosphere.This broad conclusion holds regardlessof the climate model used to projectfuture warming. However, warmingwill be significantly greater with higheremissions than with lower emissions.In the early part of this century —warming under the higher emissionsscenario differs little from what isseen in the lower emissions scenario,largely because temperature increasesover the next few decades are alreadydetermined by past emissions. Bythe latter part of this century, studyfindings show that the climate choicessociety makes today and in the comingyears can have a profound impact onfuture conditions.• By 2050, California is projected to warm by approximately2.7°F above 2000 averages, a threefold increase in therate of warming over the last century.• By 2100, average temperatures could increase by 4.1–8.6°F, depending on emissions levels.• Springtime warming — a critical influence on snowmelt— will be particularly pronounced.OUR CHANGING CLIMATE 2012 2
AllEmissionsScenarios• Summer temperatures will rise more than wintertemperatures, and the increases will be greater in inlandCalifornia, compared to the coast.• Heat waves will be more frequent, hotter, and longer.There will be fewer extremely cold nights.Projected Average Temperatures in California2005–203411˚F109876543210HigherEmissionsScenarioLowerEmissionsScenario2035–206411˚F109876543210HigherEmissionsScenarioLowerEmissionsScenarioCalifornia is expected to experience dramatically warmer temperaturesduring this century. The figure shows projected increases in statewide annualtemperatures for three 30-year periods. Ranges for each emissions scenariorepresent results from state-of-the-art climate models.SacramentoNumber of Extreme Heat Days2070–209911˚F109876543210ProjectedHigherWarmingRange(4.6-8.6ºF)ProjectedLowerWarmingRange(2.8-6.0ºF)“Extremely hot” days in Sacramento (at least 105°F) will become morecommon with climate change. By the middle of this century, the number ofextremely hot days could increase fivefold (up to 20 days) compared to thehistorical period (black curve). By the end of this century, under the higheremissions scenario (red curve), they could occur as much as ten times moreoften than historically. Following a lower emissions scenario (green curve)could make a big difference: Sacramento would see only half that increase.Model projections for precipitation over Californiacontinue to show the Mediterranean pattern of wetwinters and dry summers with seasonal, year-to-year, anddecade-to-decade variability. For the first time, however,several of the improved climate models shift toward drierconditions by the mid-to-late 21st century in Central and,most notably, Southern California.• By mid-century, some climate models show that the 30-year average precipitation in the San Diego region willdecrease by more than 8 percent compared to historicaltotals, even under a lower emissions scenario.• By late-century, all projections show drying, and half ofthem suggest 30-year average precipitation will declineby more than 10 percent below the historical average.This drying trend is caused by an apparent decline inthe frequency of rain and snowfall. Even in projections withrelatively small or no declines in precipitation, central andsouthern parts of the state can be expected to be drier fromthe warming effects alone as the spring snowpack will meltsooner, and the moisture contained in soils will evaporateduring long dry summer months.Wildfire risk in California will increase as a result ofclimate change. Earlier snowmelt, higher temperaturesand longer dry periods over a longer fire season willdirectly increase wildfire risk. Indirectly, wildfire risk willalso be influenced by potential climate-related changesin vegetation and ignition potential from lightning.Human activities will continue to be the biggest factor inignition risk. Previous research estimated that the longtermincrease in fire occurrence associated with a higheremissions scenario is substantial, with increases in thenumber of large fires statewide ranging from 58 percent to128 percent above historical levels by 2085. Under the sameemissions scenario, estimated burned area will increase by57 percent to 169 percent, depending on location.New studies in the third assessment demonstrate thatthe distribution of where and to what degree wildfire riskincreases in California will also be driven to a large extent bychanges in land use and development. Modeled simulationsestimate that property damage from wildfire risk could beas much as 35 percent lower if smart growth policies wereadopted and followed than if there is no change in growthpolicies and patterns.VULNERABILITY AND ADAPTATION DEFINEDVulnerability, in the most general sense, is the susceptibility to harm. Vulnerability to climate change is understood asthe degree to which a system is exposed to, sensitive to, and unable to cope with or adapt to the adverse effects of change, includingclimate variability and extremes. It is determined by the character, magnitude, and rate of climate change (the climate hazard), aswell as by non-climatic characteristics of the system that might experience such a hazard. The third assessment breaks new groundin understanding the differential levels of vulnerability and related equity concerns for California, the causes of vulnerability, and therange of interventions that could be used to make a system less vulnerable and more resilient.Adaptation to climate change involves a myriad of small and large adjustments in natural or human systemsthat occur in response to already experienced or expected climate changes and their impacts. The goal ofadaptation is to minimize harm and take advantage of beneficial opportunities that may arise from climate change. Adaptationinvolves a wide range of planning and management activities that can be taken well in advance of the manifestation of impacts, orreactively, depending on the degree of preparedness and the willingness to tolerate significant risk.3 OUR CHANGING CLIMATE 2012
Health: Many Opportunities toReduce Social VulnerabilitiesClimate change could have major impacts onpublic health and well-being throughoutCalifornia if adequate adaptation measuresare not taken. However, many climate adaptationopportunities exist for protecting the publicwelfare, many of which have already proven effective.Strategic placement of cooling centers, for instance, hasbeen clearly shown to save lives during heat waves.Many of the gravest threats to public health in Californiastem from the increase of extreme conditions, principallymore frequent, more intense, and longer heat waves.Particular concern centers on the increasing tendency formultiple hot days in succession, and heat waves occurringsimultaneously in several regions throughout the state.Public health could also be affectedHeat waves areexpected to occurmore frequently andgrow longer andmore intense, posingparticular risk to themost vulnerable.by climate change impacts onair quality, food production, theamount and quality of watersupplies, energy pricing andavailability, and the spread ofinfectious diseases. These impactscould have potentially long-termrepercussions, and the severity oftheir impacts depends largely onhow communities and families canadapt.Studies in the third assessmentimprove our understanding of Californians’vulnerability to extreme heat events and otherextreme climate events. Some segments of the populationare more sensitive than others and may have lessability to prepare for, cope with, or adapt to changingconditions, and will be impacted disproportionately.Understanding these characteristics (age, sex, race,education level, income, air conditioner ownershipand others) can be helpful to develop and prioritizeadaptation options that target those in greatest need.For example, one study shows that mortality fromvarious cardiovascular conditions on extremely hotdays is up to 28 percent higher than normal backgroundmortality. New studies also show elevated risks forhospitalization for stroke, diabetes, acute kidneyfailure, dehydration, and pneumonia for those 65 yearsand older, infants under 1 year of age, and AfricanAmericans. The need for emergency room visits for avariety of conditions also increase for many segmentsof the population, while preterm delivery is more likelyfor all pregnant women, especially for younger, AfricanAmerican and Asian American women.The use of air conditioners significantly reduces therisk of mortality and hospitalization in times of extremeOutdoor workers are extensively exposed to extreme heat and, withfewer options to cope, they will be affected disproportionately by theimpacts of climate change.heat, which makes air conditioner ownership a usefulindicator of short-term coping capacity. However,increased use of air conditioners should not be reliedon as an effective long-term strategy given the risks ofpower outages during peak-demand periods and relatedhigher energy demand, both of which increase coststo individual households and overall greenhouse gasemissions if the electricity comes from fossil fuel sourcessuch as natural gas.New studies for the SanFrancisco Bay Area and FresnoCounty find minority and poorerpopulations, have significantlylower access to common adaptationoptions for dealing with healththreats from climate change, suchas tree canopy for shading or carownership to go to public coolingcenters than other segments ofthe population. Another studyfinds Los Angeles to have a disproportionatelylarge number ofhighly vulnerable people at riskduring extreme heat.Higher temperatures alsoincrease ground-level ozonelevels. Furthermore, wildfires canincrease particulate air pollution inthe major air basins of California.Together, these consequences ofclimate change could offset airquality improvements that haveFocus on adaptation planningis growing in public healthdepartments across the state.Several universities and theCalifornia Department ofPublic Health are workingtogether to identify climaterelatedhealth risks and thosegroups particularly susceptibleto risks such as extreme heatand air pollution.successfully reduced dangerous ozone concentrations.Given this “climate penalty,” as it is commonly called, airquality improvement efforts in many of California’s air basinswill need to be strengthened as temperatures increase inorder to reach existing air quality goals.OUR CHANGING CLIMATE 2012 4
Water: Every Drop CountsIn California’s semi-arid, Mediterranean climate, safeand reliable supplies of clean water are critical. Thestate’s urgent water management challenges posedby climate change include increasing demand froma growing population as temperatures rise, earliersnowmelt and runoff, and faster-than-historical sea-level risethreatening aging coastal water infrastructure and levees inthe Sacramento-San Joaquin Delta. Climate change effectson water supplies and stream flows are also expectedto increase competition among urban and agriculturalwater users and environmental needs. Finally, increases inextreme precipitation and runoff are likely due to warmerstorms and extreme “atmospheric rivers” — narrow bandsover the Pacific Ocean that carry huge amounts of moistureinto the state in occasional series of winter storms.Water studies in the third assessment analyzewater management options under these expectedchanges, and also examine the sector’s sensitivity andcapacity to adapt to climate change. They explore feasibleadaptation strategies at the state and local levels, revealingmajor barriers hindering adaptation. Policies to overcomethese barriers will be needed to ensure that Californians arewell-prepared for climate change.One study illustrates problems in California’s water supplyallocations (the amount of water that goes to different userseach year) if the current allocation criteria and decisionmakingprocedures continue to be used as the climatechanges. Many water management decisions in Californiarely on a classification scheme of the year’s water availability(distinguishing “wet,” “normal,”The single mostimportant step towardpreparing for climatechange in the watersector is to implementan accurate monitoringsystem that recordswater diversions.“dry,” and “critically dry” years).Depending on what type of yearit is, different amounts of waterare allocated among the state’smany users. Using the currentallocation thresholds, the studyprojects changes in stream flowfor the Sacramento and SanJoaquin valleys, showing that bythe latter half of the 21st centurycritically dry water years couldoccur substantially more often(8 percent more frequently inthe Sacramento Valley and 32percent more often in the San Joaquin Valley), comparedto the historical period (1951-2000). During such criticallydry years it is nearly impossible to satisfy the state’s waterneeds, including those for agricultural and environmentalpurposes, which could affect the farm economy andendangered species. Adaptive changes in the waterallocation framework could help lessen this problem.Percent of wet/critical dry water years within time periodSan Joaquin and Sacramento ValleysWet and Critical Dry YearsReductions in stream flow by the latter half of the century areestimated to lead to more frequent critically dry water years,resulting in less water available to support already threatenedecosystems and species.The third assessment also highlights notableprogress in adapting water management inCalifornia, but difficult legal and political barriersimpede implementation of some of the most feasible andpotentially most effective strategies. Clearly, adaptationrequires much more than technical solutions; societalbarriers must be addressed in appropriate forums to beovercome with durable commitments.Another study, focusing on legal and institutionalbarriers to adaptation suggests that climate change willexacerbate ongoing conflicts over water by increasingdemand and decreasing supply. The study concludesthat the most important step toward preparing forclimate change would be to implement and enforcean accurate monitoring system that records who isdiverting water, in what quantities, and when. This wouldsignificantly improve decision-making compared to thecurrent water management in which groundwater isessentially unmanaged.5 OUR CHANGING CLIMATE 2012
Increases in average temperature and higherfrequency of extreme heat events combined withnew residential development across the state willdrive up the demand for cooling in summertime.This growing demand will only partially be offset bydecreased heating needs in the wintertime and improvedenergy efficiency. Californians derive about 15 percent oftheir electricity from hydropower with more than half of thisenergy generation occurring above 1,000 feet elevation inrelatively small systems. Hydroelectricity is a premium assetduring the peak-demand summer months. Past studieshave already shown that this hydropower generation isdeclining, and it is expected to decrease more substantiallyas climate change progresses due to reduced snowpack,earlier runoff, and higher rates of evaporation.Energy demand is increasing. The third assessmentconfirms that climate change will increase demand forcooling in the increasingly hot and longer summer seasonand decrease demand for heating in the cooler season.California’s residential sector uses relatively little electricityfor heating, and it is therefore expected that the demandfor electricity will increase as householdsClimate changewill increasedemand forcooling in theincreasinglyhot and longersummer season.7 OUR CHANGING CLIMATE 2012Energy: Meeting Growing Demandin a Warming Worldoperate existing air conditioners morefrequently. It is also expected that inmany regions where currently thereare few air conditioners, more will beinstalled. Using household level data toestimate how electricity consumptionresponds to hotter weather, researcherscan project increases in annual electricityconsumption at the ZIP code level.Their study finds that predominantlynon-minority and wealthier ZIP codesare projected to experience smallerincreases inenergy consumption, while ZIPcodes with a higher share of Latinoand lower-income residents areprojected to experience largerincreases in energy use. This mayin part be driven by the fact thatwealthier people more often livenear the coast where cooler oceanbreezes reduce the amount ofwarming. In the near term, highertemperatures in the next decadecould increase demand by upto 1 Gigawatt during hot summermonths — a substantial amount that would require theconstruction of one large new power plant in California orthe purchase of costly peak power from external sources.Increase in Electricity Demand by the End of this Century(higher emissions scenario, compared to historical conditions, in percent)PercentIncrease inElectricityDemandby 210015-5010-155-100-5-25-0no dataClimate warming will decrease hydropower generationmostly in the summer months when hydropowergeneration is needed most to meet peak demand.Higher summer temperatures will notably increase the annualhousehold electricity consumption for air conditioning (by ZIP code).Because inland areas will warm more, and are often home to lesswealthy populations, energy use will grow most in the hottest areaswhere those who can least afford it reside.Energy supply from hydropower is generated inmore than 150 high-elevation hydropower plants(above 1,000 feet). These units supply about 75 percent ofall the hydropower produced in California. The small sizeof the high-elevation hydropowerreservoirs allows little flexibility inoperations and might make highelevationhydropower plants morevulnerable to climate change andreduced snowpack. Researchershave developed a multi-purposewater resources managementsimulation model for the westernslope of the Sierra, from theFeather River watershed in thenorth to the Kern River watershedin the south. Their study finds —importantly — that electricitygeneration will be reduced substantially in the summerwhen hydropower generation is needed most to meetpeak demand.
For low-elevation hydropower, typically associatedwith larger reservoirs, there are ways to reduce climatechange impacts using modern hydrological forecastingtools. The INFORM project demonstrates that probabilistichydrologic forecasting could substantially reduce thenegative impacts of climate change on water supply,hydropower generation, revenues, and flood protection.Managers of high-elevation hydropower plants have some,but generally less, flexibility to manage water adaptively.For example, changing the operating rules of the reservoirscan help minimize revenue losses in case of a drier,warmer climate withHigh-elevationhydropower isparticularly vulnerableto climate changeand reduced snowpack.lower water flows.If hydropower plantswere to generate20 percent lesspower annually in adrier, hotter climate,they could seerevenue losses of8 percent, comparedto current averagerevenues. While the high-elevation hydropower systemcan benefit from additional storage and generationcapacities, more studies are needed to determine whetherthe expected increase in revenues will outweigh theexpected economic and environmental costs of potentialenergy and storage capacity expansions.Transmission of electricity will also be affectedby climate change. In addition to reduced efficiency inthe electricity generation process at natural gas plants,reduced hydropower generation, losses at substations,and increasing demand during the hottest periods(resulting in more than 17 Gigawattsor 38 percent of additional capacityneeded by 2100 due to highertemperatures alone), transmissionlines lose 7 percent to 8 percentof transmitting capacity in hightemperatures while needing totransport greater loads. This meansthat more electricity needs to beproduced to make up for the loss incapacity and the growing demand.In addition, key transmissioncorridors are vulnerable toincreased frequency of wildfire.For example, one study in thethird assessment finds a 40 percentKey electricitytransmissioncorridors areincreasinglyvulnerableto increasedfrequency ofwildfire.increase in the probability of wildfire exposure for somemajor transmission lines, including the transmissionline bringing hydropower from the Pacific Northwestinto California during peak demand periods. Otherkey transmission lines at high risk bring power to theLos Angeles Metropolitan Area. These risks can bereduced by introducing more locally produced anddistributed electricity.Wildfire Risk to Electricity Transmission Lines(Changing probability in fire risk by end of centurycompared to 1961-1990, higher emissions scenario)Climate change will bring earlier snowmelt, higher temperatures,and longer dry periods over a longer season — exactly the conditionsthat increase the risk of wildfire. With more development and criticaltransmission lines at risk, property damages and firefighting costscould rise dramatically.OUR CHANGING CLIMATE 2012 8
New decision-support tools that incorporate sea-level rise intoinvestment decisions for upgrading coastal infrastructure are vitalto California’s economy.region could become inaccessible. Findings also showhow extreme events with higher sea levels could lead tosignificantly longer driving times as some transportationcorridors could be cut off. Adaptation measures thatprotect or relocate critical infrastructure, while expensive,could reduce the vulnerabilityof the transportation sector.Other coastal regions such asLos Angeles and Santa Barbaracould similarly benefit from suchadvanced mapping tools.Sea-level rise and associatedcoastal flooding are expectedto put critical infrastructure atrisk, including ports that supportthe economy and provide criticalgoods to the state and nation.How to alter port infrastructure toprepare for serious risks with lowor unknown probability is a majorchallenge because substantialfinancial investments are atstake. The optimal time to alterinfrastructure is during scheduledupgrades. One study in thethird assessment applies a newapproach to facilitate decisionmakingby port authorities inLos Angeles by incorporatinglow-probability high-impactuncertainties into planning forinfrastructure upgrades. It showsthat the costs of upgradinginfrastructure for extreme sealevelrise at this time are toohigh to warrant incorporation for most of the facilitiesanalyzed. However, the approach proves useful in helpingthe port authority to use sea-level rise scenarios todetermine the most robust course of action in a scientificallyinformed way. Future infrastructure placement and upgradedecisions in Los Angeles and elsewhere will benefitfrom using a similar approach.A statewide survey of coastal managers in 2011 updatesa previous effort that tracked progress on adaptation incoastal California. Findings show a remarkable increasein awareness, concern, and understanding about climatechange impacts and the need to adapt. But planning forthe future with climate change in mind is still in the veryearly stages. The most familiar strategies to deal withsea-level rise are those that were used historically such as“coastal armoring,” while more innovative approaches suchas “planned retreat” and integrating natural ecosystems asbuffers against sea-level rise and storms (“ecosystem-basedadaptation”) are less familiar. Findings are in line withresults of a detailed set of case studies of local governmentand regional adaptation processes in San Francisco Bay,which show that communities are just beginning adaptationplanning. Despite economic constraints and otherobstacles, coastal communities with strong leadershipand commitment to collaboration and communication aremaking important progress in preparing for the future.Flooding Threatens Critical Transportation RoutesEmergency Response Delays Increase Vulnerability for Local ResidentsImproved elevation data and mapping and modeling techniques better capture existing shorelineprotection structures and more clearly identify the most vulnerable transportation access andconnection points. In Richmond, emergency response could be delayed (dark orange, indicatingdelays up to nine minutes) or become unavailable (black) due to roadway flooding as shown for onearea of the city in the inset aerial photo.OUR CHANGING CLIMATE 2012 10
Ecosystems: Changing Landscapes,Vulnerable Species, More FiresCalifornia is one of the most ecologicallydiverse places in the world. The state’secosystems also provide a wide spectrum ofgoods and services supporting the economyof California and human well-being, includingfresh water, fertile soil, biological and genetic diversity,crop pollination, carbon storage, climate stabilization, andrecreational opportunities. All of these values and benefitscan be lost when species are lost or ecosystems becomeunhealthy and fragmented, or burn in wildfires.Studies from the third assessment refine estimatesof future wildfires, this time also considering variouspopulation growth scenarios. Several studies have helpedgenerate a better understanding of how California’secosystems are sensitive to climate change and hownatural resource managers can assist in their adaptation.An increase in the frequency and extent of wildfiresdue to a hotter and possibly drier future,leading to significant property damage to homes, wasalready established in previous studies. The extent ofthe increased economicloss from fire, however,also depends onpopulation growthand development infire-prone areas. Studiesfrom the third assessmentrefine the estimatesby exploring the variedeffects of emissionsWildfire risk is expected to increase — even scenarios, populationunder a lower emissions scenario — almosteverywhere in the state. By 2050, annual growth, and exposurefire damage could be between $200 million at the wildland–urbanand $2.5 billion, largely driven by differences interface.in human development at the wildland–urban interface.Even with loweremission levels, wildfirerisk still increasesthroughout most of the state. But the extent to whichwildfire risk increases depends also on the way humandevelopment advances at the wildland–urban interface.In some instances, this factor is even more importantthan climate change alone. The most extreme increasesin residential fire risks result from a combinationof high-growth/high-sprawl/warmer-drier climatechange scenarios, especially in San Francisco Bay andSouthern California counties.Improving knowledge of California’s species andecosystems provides a deeper understanding of theservices they provide to society. Studies in the thirdassessment improve this understanding, especially whichspecies and habitats are most exposed, sensitive, and ableWildfire Risk in San Francisco Bayunder Different Population Growth ScenariosALowpopulationgrowthBHighpopulationgrowthIncrease in fire riskby end of centurycompared to the baseperiod (1971-2000)1 3 5 7 9-foldFire risk is expected to increase in much of the San FranciscoBay Area. Population growth will be a major factor, even if littlechanges at the wildland–urban interface. Yellow hues indicate smallerincreases in fire risk, and darker reds and browns indicate greaterincreases compared to the risk during the base period (1971-2000).Green represents reductions in risk, white indicates areas thatwere not modeled.to adapt to climate change over time. They also revealadaptation options specifically geared toward addressingunderlying vulnerabilities, thus identifying and helping toprioritize management actions.Several studies focus on how vegetation could shiftwith climate change and the capacity of species to migrateand keep up with geographic changes. We now know that11 OUR CHANGING CLIMATE 2012
Identifying migration corridors is critically important: As species try to keep pace with changing climate conditions, their chance of survival isgreater when they can reach more suitable habitat.ecological impacts of climate change could be more severethan anticipated if species are unable to overcome physicalbarriers (such as human settlements) to migrate to areas withsuitable climatic conditions. Identifying migration corridorshas important practical applications for land use planning.Areas that may not be of particular ecological importanceat present and that may be considered for developmentcould play a key role in the preservation of ecologicallyrich conditions in California asthe climate changes.Another study uses 100 yearsof historical observations ofspecies behavior to understandwhat could happen in the future.Findings show that climate ischanging conditions so rapidlythat some vegetation cannotkeep pace. In fact, some climatesthat currently still exist (such asalpine climates) could disappearentirely in the future, whileother regional climates (such asdesert climates) could expandsignificantly, resulting in some species losing their habitatsand others expanding theirs. To the extent that there areno similar suitable habitats nearby that species can reach ontheir own, managers may need to assist them in relocatingto new suitable environments.To the extent that thereare no suitable habitatsnearby that speciescan reach on theirown, managers mayneed to assist themin relocating to fittinghabitats elsewhere.California’s Native Freshwater FishMany of California’s 121 native freshwater fish species arealready in decline and are particularly vulnerable to climatechange, with 83 percent being at high risk of extinction asthe climate changes. Commercially important species, suchas coho salmon and steelhead trout, are particularly at riskfor extinction because they require cold water below 72°F.In contrast, the 43 non-native species examined appearedto fare much better with many thriving and expanding theirrange, and only 19 percent falling into the high-vulnerabilitycategory. Managing invasive species, providing shadingalong river banks, and reducing other stresses on freshwaterfish are among the most important adaptation options.OUR CHANGING CLIMATE 2012 12
Agriculture in California generates morethan $30 billion per year, the highestcrop value in the nation, provides more than1 million jobs, and serves as animportant source of the nation’sfood supply. The sector is already understress from competing and growing urbanand environmental water demands andcontinuing development on agriculturalland. Climate change is expected toexacerbate stresses on the agriculturalsector. Changes in temperature and wateravailability — annual and seasonal shiftsas well as extremes — affect both cropyield and quality, making the sector highlysensitive to climate change.Indirect impacts will also take a toll,including possible further decreases ofpollinators and increases of pests and disease. Studies inprevious assessments established that many impacts onperennials (such as peaches, strawberries, and almonds)vary by crop, while nearly13 OUR CHANGING CLIMATE 2012Agriculture: Vulnerable but AdaptiveTotal AgriculturalVulnerability IndexVery HighHighModerately HighNormalModerately LowLowVery LowAgriculture varies in its vulnerabilityto climate change. The map shows acomposite index of vulnerability revealingthe Sacramento-San Joaquin Delta, SalinasValley, Imperial Valley, and the corridorbetween Merced and Fresno as particularlyvulnerable. Underlying factors vary amongregions, including differences in climate,crops, land use and socioeconomic factors.all annual crops (such aswheat and sunflowers)are expected to declineunder climate change.Agriculture will continueto be an important economicsector but somelosses will be incurredand the ultimate impactswill be a function of howeffectively farmers adoptadaptation measures.Planning for agriculturalresponses toclimate change inCalifornia involvesconsideration of manyfactors — biological,environmental andsocioeconomic — thatinfluence the sector’s vulnerability and resilience. Thethird assessment advances the understanding ofvulnerability at the state and regional levels, reportson farmers’ perspectives on adaptation, and highlightspotential benefits of innovative adaptation practices thatsimultaneously contribute to reducing greenhouse gasemissions. Results point to the need for crop-specific andplace-based approaches to reducing farmers’ vulnerabilityto climate change.California is one of the nation’slargest producers of a diverseset of crops. While many factorswill determine the choice ofcrops and production costs,many experts believe costs toconsumers could go up.Innovative practices illustrate mitigation andadaptation opportunities for the agricultural sector.The third assessment highlights farmers’ interest inadopting certain adaptation and mitigationoptions. Some management practicessimultaneously achieve co-benefits forboth, such as irrigation technologiesthat provide a reliable water supply andalso reduce emissions of nitrous oxide(a greenhouse gas).Other examples includesoil carbon storage,renewable energy, andcrop diversification inlocal farming systems.Overall, adopting adaptationstrategies thatwork for specific locationsand crops will increase farmers’capacity to manage changes whileaddressing the needs of naturalresources and social issues such asfarm labor and urbanization pressure.One study of Yolo County farmersreveals that growers worry mostSome agriculturalmanagementpracticessimultaneouslyachieve co-benefitsfor climate changeadaptationand mitigation.about a potentially hotter and drier future even thoughthey show little awareness of the industry’s vulnerabilityto climate change. Several strategies show high potentialfor increasing the sector’s resilience, but these requireinvestment and training for farmers.Average Likelihood of Yolo County Farmers AdoptingAdaptation and Mitigation PracticesYolo County farmers prefer to adopt certain adaptation and mitigationpractices over others. However, preferable options may not necessarily bethe most effective or reliable over the long term, or may have negative sideeffects, such as pumping more ground water in times of drought.
San Francisco Bay: A Regional FocusThe third assessment breaks new ground byexplicitly including a regional focus. Elevenstudies focus exclusively on the San FranciscoBay Area to integrate findings across sectorsand to better support adaptation planning andimplementation processes precisely at the level at whichmost adaptation decisions are made: locally.The San Francisco Bay Area was selected because ofits economic importance to the state, coverage of bothrural and urbanized land uses, its diverse coastal andinland geography, and the many climate change risks thenine-county region will experience simultaneously. Alsoimportant was the willingness and high interest of regionaldecision-makers (the Joint Policy Committee) in policy- andmanagement-relevant scientific information. Key climatevulnerabilities were examined for coastal areas, publichealth, ecosystems, agriculture, wildfire, transportation andenergy infrastructure, and water resources.Local governments face considerable barriers toadaptation. One study offers an in-depth analysisof adaptation initiatives to date in the San FranciscoBay Area (Marin and Santa Clara Counties, the cities ofSan Francisco and Hayward, and the Bay Area-wideadaptation effort under the Joint Policy Committee).The study reveals institutional and governance issuesas the most important barriers for local governments,followed by attitudinal issues and economic hurdles,even in wealthy communities.The study shows that whilemany issues can be addressedlocally, state and federalassistance is needed toensure that communities canadequately prepare for theimpacts of climate change.Other studies reveal howdifferences in social vulnerabilitymake for inequalityof impacts. Such studiesprovide crucial informationto local governments fordetermining where to focuslimited resources for adaptiverisk management. Equippedwith such locally specificSummer Temperaturesin San Francisco Bay Areaby Mid-CenturyProjections of temperature across theBay Area (under the higher emissionsscenario) largely reflect differences intopography and distance from the ocean.information and a history of innovative leadership, theSan Francisco Bay Area will be in a good position to createa safe and prosperous future.Our Resilient FutureStrengthening mitigation: California has been aglobal and national leader in developing solutionsto energy security and climate change. The state’slandmark Global Warming Solutions Act (AB 32,passed in 2006) established greenhouse gasemission reduction targets for 2020. A separate ExecutiveOrder established a goal for even more dramatic reductions(80 percent below 1990 levels) by 2050 and beyond.A study in the third assessment shows both thechallenges for the existing energy system emerging fromclimate change and the possibilities for moving towardclean, renewable energy and more robust, distributedelectricity production and transmission. Given the State’scommitment to reducing emissions, the energy sectoris changing rapidly. This presents both challenges andtremendous opportunities to change the sector to be moreresilient to climate change. Solar photo-voltaic and windenergy are less vulnerable than conventional power plantsto climate change, and these renewable sources use muchless water than fossil fuel or nuclear power plants. These areimportant advantages in light of projected climate changesfor California and the western United States.Advancing adaptation: At the same time, the State hasrecognized the need to adapt to climate change impacts thatcan no longer be avoided. Currently, the State is developingits second adaptation strategy, acknowledging the steadyprogress made since the first one in 2009 and recognizingthe enormous challenges ahead. The strategy will need tobe updated periodically in the future. The many adaptationplanning efforts underway in virtually every State agency, inlocal communities such as Chula Vista, San Diego, Los Angeles,Santa Barbara, Santa Cruz, San Francisco, Hayward, MarinCounty, and others, as well as in private businesses suggestthat CEOs, elected officials, planners, and resource managersunderstand the reality that California and the world is facing.In fact, the latest climate science makes clear that State,national and global efforts to mitigate climate change mustbe accelerated to limit global warming to levels that do notendanger basic life-support systems and human well-being.Success in mitigation will keep climate change within thebounds that allow ecosystems and society to adapt withoutmajor disruptions. Further advances in integrated climatechange science can inform California’s and the world’s climatechoices and help ensure a resilient future.OUR CHANGING CLIMATE 2012 14
Steering Committeefor the Third Assessment:Daniel Cayan, Susanne Moser,Michael Hanemann,John Andrew, Sarah Pittiglio,and Guido FrancoAuthors of Our ChangingClimate 2012:Susanne Moser, Julia Ekstrom,and Guido Franco(Additional help and reviewswere provided by Dan Cayan,John Andrews, Mark Wilson,Bart Ostro, Alison apRoberts,Lauren Oliver, Ana Toscano,Janna Franks, Mary Tyree,Myoung-Ae Jones, andLaura Myers Design)Photo credits (listed sequentially bypage, top to bottom, left to right, at firstappearance only): [C] Center for DiseasePrevention and Control (Jim Gathany);California Parks; California Departmentof Water Resources (DWR); National ParkService (NPS); DWR; US Department ofAgriculture, Agricultural Research Service(Bob Nichols); Wikimedia Commons(Rich Niewiroski Jr.); California EmergencyManagement Agency (Robert A. Eplett); DWR;  Natural ResourcesConservation Service (Tim McCabe); Rani McLean; Center for DiseasePrevention and Control (AmandaMills);  DWR; Wikimedia Commons(“Anynobody”); DWR;  DWR; Federal Emergency ManagementAgency (Andrea Booher); Wikimedia Commons (Nick C. Prior); US Fish & Wildlife Service (USFS); US Geological Survey; USFS;California Department of Public Health,Network for a Healthy California;[BC] Department of Energy/NationalRenewable Energy Laboratory(Warren Gretz).Thank you! More than 120 researchers from California research institutions and othersparticipated in the 2012 California Vulnerability and Adaptation Study. Space limitationsallow only the principal researchers to be listed here, in alphabetical order, but the effortsof each and every researcher are gratefully acknowledged.David D. Ackerly, University of California, BerkeleyMaximilian Auffhammer, University of California, BerkeleyRupa Basu, California Office of Environmental Health Hazard Assessment, OaklandGreg S. Biging, University of California, BerkeleyPeter D. Bromirski, University of California, San DiegoBenjamin A. Brooks, University of HawaiiBenjamin P. Bryant, Pardee RAND Graduate School, Santa MonicaDaniel R. Cayan, University of California, San DiegoRebecca Chaplin-Kramer, Stanford University, Palo AltoHeather Cooley, Pacific Institute, OaklandWilliam Cornwell, University of California, Berkeley; Vrije University, NetherlandsLarry Dale, Lawrence Berkeley National Laboratory, BerkeleyJulia Ekstrom, University of California, BerkeleyDaniel Farber, University of California, BerkeleyCatalina Garzon, Pacific Institute, OaklandKonstantine P. Georgakakos, Hydrologic Research Center, San DiegoJeffery Greenblatt, Lawrence Berkeley National Laboratory, BerkeleyGary Griggs, University of California, Santa CruzMarion Guegan, Lund University, SwedenVan R. Haden, University of California, DavisMichael Hanemann, University of California, BerkeleyLee Hannah, University of California, Santa BarbaraMatthew Heberger, Pacific Institute, OaklandLouise Jackson, University of California, DavisMichael Jerrett, University of California, BerkeleyMeg Krawchuk, University of California, BerkeleyDeborah Lambe, University of California, BerkeleyRuth Langridge, University of California, Santa CruzRobert Lempert, RAND Corporation, Santa MonicaJay R. Lund, University of California, DavisKaveh Madani, University of California, Riverside; University of Central Florida, OrlandoSara Moore, University of California, Santa CruzCraig Moritz, University of California, BerkeleyMax Moritz, University of California, BerkeleySusanne C. Moser, Susanne Moser Research & Consulting, Santa Cruz; Stanford University, Palo AltoPeter B. Moyle, University of California, DavisSarah E. Null, University of California, DavisBart Ostro, California Office of Environmental Health Hazard Assessment, SacramentoJohn D. Radke, University of California, BerkeleyDavid E. Rheinheimer, University of California, DavisMaria Santos, University of California, BerkeleyJayant Sathaye, Lawrence Berkeley National Laboratory, BerkeleyWilliam S. Sicke, University of California, Davis, Jason G. Su, University of California, BerkeleyJames H. Thorne, University of California, DavisMary Tyree, University of California, San DiegoJoshua H. Viers, University of California, DavisAnthony L. Westerling, University of California, MercedErika Zavaleta, University of California, Santa CruzSupport was provided in part by the California Energy Commission and theNatural Resources Agency. The material contained in this document does notnecessarily represent the views of the funding agencies or the State of California.July 2012 / CEC-500-2012-007