Expert Meetings and Workshop 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.

17-19 JANUARY 2011 — Okinawa, JAPAN

The oceans currently absorb about one-third of fossil fuel CO2 emitted to the atmosphere and have, as a consequence, been increasing in acidity. Ocean acidification is now recognized as a critical component of global change, potentially responsible for a wide range of impacts on ecosystems, with subsequent consequences on livelihoods and food security. Further, one important aspect is that more CO2 mitigation may be required to achieve particular stabilization targets, because acidification limits the ability of the oceans to continue to absorb CO2. Previous IPCC assessment reports considered biogeochemical and temperature effects of anthropogenic carbon on the oceans, but the direct impacts of ocean acidification, its combined effects with ocean warming on marine ecosystems and productivity, and potential feedbacks to the climate system have not been fully assessed.

Since the publication of the Fourth Assessment Report (AR4), ocean acidification research, especially experimental studies of the impact of increased concentrations of seawater CO2 on marine biology in different regions, and modeling studies of future ocean environments, has been advancing rapidly. Given this progress and increasing interest from stakeholders in understanding the implications of ocean acidification, an IPCC Expert Meeting will discuss the rapidly advancing scientific findings on ocean acidification and its impacts since the publication of IPCC AR4, and to provide scientific information as input to Fifth Assessment Report (AR5).

March 2011 (exact dates TBD) — 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.