Climate Change 2013 Working Group I: The Physical Science Basis

“Peer beyond the headlines as experts explain what the IPCC report really says about global warming and what it means for our planet and for mankind…”

By Malcolm Dean

Last Friday evening, Annie and I attended a public lecture here in San Francisco by several members of the IPCC’s Working Group I, which focuses on the physical science behind global climate change. They are the first of the IPCC’s working groups to publish their 5th Assessment findings, and their message was short and sweet: it’s real, we’re causing it, and we have a choice: make the policy changes necessary to maintain a world approximately like the one we grew up in, with the rise in temperature restrained to less than two degrees, or contend with the enormous social and environmental disruptions of a radically different world with a temperature rise of four degrees or greater. And for the first time, with their global carbon budget, they were able to quantify not only the amount of carbon we’re releasing into the atmosphere each year, but how much time we have left: less than thirty years.

I was glad to see them so outspoken. The IPCC* is a intergovernmental panel sponsored by the United Nations, requiring consensus among all 194 countries participating — and so it’s by nature a political, as well as a scientific body. But they pulled no punches Friday night. Check out the video above, and the detailed Summary for Policymakers below:

Summary for Policymakers (this is a large PDF, and may take a moment to load)

* The Intergovernmental Panel on Climate Change (IPCC) is the international body for assessing the science related to climate change. The IPCC was set up in 1988 by the World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP) to provide policymakers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation. IPCC assessments provide a scientific basis for governments at all levels to develop climate- related policies, and they underlie negotiations at the UN Climate Conference – the United Nations Framework Convention on Climate Change (UNFCCC). The assessments are policy-relevant but not policy-prescriptive: they may present projections of future climate change based on different scenarios and the risks that climate change poses and discuss the implications of response options, but they do not tell policymakers what actions to take. The 5th assessment report is a worldwide scientific collaboration between 259 scientific authors from 39 countries who took some 55,000 comments in finalizing it.