What is the IPCC? IPCC = Intergovernmental Panel on Climate Change.

What’s the IPCC?

What is the objective of the report? The objective of the contribution of IPCC Working Group I to the AR5 “Climate Change 2013: The Physical Science Basis” (WGI AR5) is to provide a comprehensive and robust assessment of the physical science basis of climate change. In order to achieve this, the report has 14 topical chapters and a number of Annexes including, for the first time in IPCC, a comprehensive Atlas of Global and Regional Climate Projections, plus supplementary material

How does the IPCC accomplish these goals? IPCC does not perform science, but… … implicitly, the IPCC process stimulates climate science. How does it do this? –Puts together a report that summarizes current state of the science. –Tries to distance itself from political issues.

How does the IPCC accomplish these goals? The IPCC is an intergovernmental body, and it is open to all member countries of UN and WMO. Governments are involved in the IPCC work, as they can participate in the review process and in the IPCC plenary sessions, where main decisions about the IPCC work are taken and reports are accepted, adopted, and approved. But governments are not involved in writing the report (exception: they go through the SPM line by line!) Thousands of scientists from all over the world contribute to the work of the IPCC on a voluntary basis. These scientists work to summarize everything that we know about human-induced climate change. Review is an essential part of the IPCC process, to ensure an objective and complete assessment of current information (more on this later). Differing viewpoints existing within the scientific community are reflected in the IPCC reports, because different scientists participate in both the writing and review of the report.

Example from last time Ex:RCPs, “representative concentration pathways.” IPCC doesn’t talk/research/anything about policies that would give rise to these GHG concentrations. Why would they do that?

Last time: The reasons why: –This allows the IPCC to remain policy-relevant and yet policy-neutral, never policy-prescriptive. –IPCC = the scientific perspective. Does its best to provide both rigorous and balanced scientific information to decision makers. –Were it to become involved in the decision making, this could impact whether they are viewed as impartial This is just what the IPCC has decided to do. You may or may not agree!

Previous IPCC reports FAR (first assessment report, 1990) SAR (second assessment report, 1995) TAR (third assessment report, 2001) AR4 (fourth assessment report, 2007) AR5 (fifth assessment report, 2014)

IPCC report in three parts Working group 1 (WGI, this class): –“The physical science basis” Working group 2 (WGII, much of Jen’s class): –“Impacts, Adaptation, and Vulnerability” Working group 3 (WGIII): –“Mitigation of Climate Change”

IPCC AR5, WG1 259 Lead Authors, nearly 1000 scientists 4 Lead Author meetings on 4 continents 14 Chapters + 1 Atlas Lead authors of 39 Countries Review comments 193 member countries >9200 references to peer-reviewed literature. 2,000,000 GB of data.