IPCC Expert Meeting on Geoengineering

Annex 5: Breakout Group Reports
Breakout Group I.4: Carbon Dioxide Removal Options and Methods
Chair: Dieter Wolf-Gladrow
Rapporteur: Robert Scholes
The summary that follows, written by the Chair and Rapporteur, characterizes the main points of the BOG I.4 discussion. It
may not reflect the personal views of the BOG’s Chair and Rapporteur. The summary is intended for consideration by <strong>IPCC</strong>
authors of the Fifth Assessment Report (AR5), but is neither endorsed nor approved by the <strong>IPCC</strong> or its Working Groups.
Participants in the BOG considered a series of questions related to geoengineering research, developed by the meeting’s
Scientific Steering Group.
Questions suggested for discussion:
What are the most important Carbon Dioxide Removal approaches that <strong>IPCC</strong> authors might want to consider in the
AR5?
What are the most important aspects of these approaches to evaluate (e.g., physical impacts, time scales, system
boundaries, spatial scales, direct/private costs)?
Can the most important aspects of these issues be supported by reference to the peer-reviewed literature, ideally
drawing from multiple lines of independent evidence? What is the available evidence and what are relevant
references?
Introduction
The BOG discussed the characteristic features of geoengineering in terms of Carbon Dioxide Removal (CDR) options and
methods. Considerations also included direct and indirect consequences over a range of temporal and spatial scales,
associated with economic considerations as well as risks and uncertainties. Important CDR approaches for land and ocean
were listed. The group discussed criteria for assessing geoengineering methods and considered review papers, recent
development papers and classical papers. The group was of the opinion that current knowledge and peer-reviewed
literature is not sufficient to assess all important issues of geoengineering.
Definition of geoengineering
The BOG discussed that it could be useful to prioritize the <strong>IPCC</strong> AR5 geoengineering discussion by focusing on those
actions with potentially large consequences and technologies that are relatively poorly understood. However, it was also
recognized that the technologies fall on a continuum of scale and risk, and any delimitation is necessarily arbitrary. Rather
than getting stuck in an endless debate about what is and is not geoengineering, the group suggested, for the purposes of
the <strong>IPCC</strong> and in the immediate term, a core definition (based on Schneider (2001), Royal Society (2009) and the CBD
definition):
‘Geoengineering’ consists of actions taken with the intent of controlling the global climate.
And then reducing the scope by specific exclusions. Some of the key criteria for including or excluding topics are:
1. Scale – this is ‘climate scale’ rather than ‘geographical scale’
2. Consequence – are there potentially significant or poorly understood undesired impacts on either the
climate system or on other issues of concern, such as biodiversity?
3. Reversibility – is it easy to return to the pre-action state, and will rapid climate change result from
discontinuation of the activity?
<strong>IPCC</strong> <strong>Expert</strong> <strong>Meeting</strong> on Geoengineering - 78