Expert Meetings Central to WG II AR5 Development Cycle

14-16 September, 2009 — Geneva, Switzerland

The WGI report of the IPCC Fourth Assessment Report (AR4) concluded that "it is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica," but that "difficulties remain in reliably simulating and attributing observed temperature changes at smaller scales." Combining this with several sets of evidence including that "Observational evidence from all continents and most oceans shows that many natural systems are being affected by regional climate changes, particularly temperature increases," WGII concluded that "Anthropogenic warming over the last three decades has likely had a discernible influence at the global scale on observed changes in many physical and biological systems."

Improving technical aspects of detection and attribution, especially harmonizing terms and definitions, is an important goal to advance this topic, with emphasis on impact-relevant changes in the climate system and impacts in natural and human systems. A joint expert meeting of WGI and WGII was held in Geneva, Switzerland, 14-16 September, 2009, covering the full set of fundamental detection and attribution issues, including techniques, interpretation and specific examples that are relevant to changes in climate and impacts for the Fifth Assessment Report (AR5). A meeting report is forthcoming.

25-27 January, 2010 — Boulder, Colorado, USA

Projections in the IPCC's Fifth Assessment Report (AR5) will be based largely on the Coupled Model Intercomparison Phase 5 (WCRP CMIP5), a collaborative process in which the community has agreed on the type of simulations to be performed. The widespread participation in CMIP5 provides some perspective on model uncertainty. Nevertheless, these intercomparisons are not designed to yield formal error estimates and remain "ensembles of opportunity."

The reliability of projections could be improved if the models were weighted according to some measure of skill and if their interdependencies were taken into account. Recent studies have started to address these issues by proposing ways to weight or rank models, based on process evaluation, agreement with present day observations, past climate or observed trends, but there is no consensus on how such a model selection or weighting process could be agreed upon.

This expert meeting will provide tentative best practices in selecting and combining results from multiple models for IPCC AR5; in short the beginning of a quantitative framework for analysis and assessment of the models. The meeting will help to bring the community into a position to make better use of the new model results and provide more robust and reliable projections of future climate, along with improved estimates of uncertainty. Specific aims of the meeting will be to maximize the robustness and policy relevance of the projections provided in the presence of model error, projection uncertainty, observational uncertainties and a heterogeneous set of models. Interactions between WGI and WGII will be ensured by the participation of a number of representatives from WGII with broad expertise on impacts and user needs.

22-24 March 2011 — Calcutta, India

Cities and other human settlements are at the forefront of climate change. As large emitters of GHG emissions, they significantly contribute to climate change. Simultaneously, due to their concentration of population and infrastructure assets, cities are especially vulnerable to the impacts of climate change. Infrastructure investments in the near future will determine the emission paths of cities in the long-run. Hence, cities are a point where adaptation is necessary and mitigation is possible, in a context of sustainable development.

While urban planning is referenced in IPCC Fourth Assessment Report (AR4) at times, there is no comprehensive survey on the role which urban planning can play in adaptation and mitigation, let alone a quantitative overview of the possible contributions of different measures and their costs. Encompassing strategies for urban areas are not discussed. Neither are there estimates on current GHG emissions related to infrastructure. If infrastructure is mentioned, only case studies are presented, stating nothing about general applicability. AR4 states that a credible assessment on general adaptation prospects and on mitigation in the transport sector is limited due to the number and scope of available studies of mitigation potential and cost. This expert meeting will further explore issues related to human settlements and infrastructure as an input to the AR5 process.

IPCC Working Group III information on the Expert Meeting:
http://www.ipcc-wg3.de/meetings/expert-meetings-and-workshops/em-infrastructure

20-22 June 2011 – Lima, Peru

Geoengineering, or the deliberate large-scale manipulation of the planetary environment, is increasingly being discussed as a potential strategy to counteract anthropogenic climate change. Prevailing uncertainty in the sensitivity of the climate system to anthropogenic forcing, inertia in both the coupled climate-carbon cycle and social systems, and the potential for irreversibilities and abrupt, nonlinear changes in the Earth system with possible significant impacts on human and natural systems suggest that research is needed into geoengineering options as a possible complement to climate change mitigation efforts. Current discussions that suggest geoengineering as an option to support climate mitigation efforts remain rather abstract and lack comprehensive risk assessments that take into account possible adverse impacts over short and longer time frames. Major uncertainties exist regarding the effects of these techniques on the physical climate system and on biogeochemical cycles, their possible impacts on human and natural systems, and their effectiveness and costs. Unilateral action may have environmental side effects on other countries and regions, and may not appropriately address the global scale of the issue.

The understanding of the physical science basis of geoengineering is still limited and IPCC will, for the first time, assess this in several chapters of the WGI contribution to AR5. Improved scientific understanding of the impacts of geoengineering proposals on human and natural systems will be assessed by WGII. WGIII needs to take into account the possible impacts and side effects and their implications for mitigation cost in order to define the role of geoengineering within the portfolio of response options to anthropogenic climate change. Furthermore, this includes an evaluation by WGIII of options for appropriate governance mechanisms.

An IPCC Expert Meeting will provide a platform for exchange and discussion among experts from the different disciplines in order to better address this important cross-cutting issue, and encourage the consistent treatment of geoengineering options across the Working Group AR5 assessments.

IPCC Working Group III information on the Expert Meeting:
http://www.ipcc-wg3.de/meetings/expert-meetings-and-workshops/em-geoengineering

23-25 June 2011 – Lima, Peru

At the IPCC Fifth Assessment Report (AR5) scoping meeting (13-17 July, 2009, Venice, Italy), the need to clarify a number of cost and valuation concepts and their underlying rationale emerged. In particular, this includes problems with representing climate impacts in monetary and non-monetary terms, and with aggregating benefits and costs and the implications for cost-benefit analysis (CBA) and other methods. Furthermore, the ethical dimensions of estimating costs of mitigation, adaptation and residual damages are in need of assessment.

An expert meeting will address these issues, congregating a diverse set of views to make suggestions for creation of assessment frameworks. In particular, the meeting will address topics such as identification and comparison of metrics, measuring risk and valuing information, technical change, adaptation as an economic process, integrated assessment, behavioral dimensions, intra- and intergenerational justice and costs, economic and ethical implications of decision making under uncertainty, social cost-benefit analysis, and optimal carbon prices in second-best settings.