The Fifth Assessment Report – AR5 for short – kicked off this morning in Stockholm. The Intergovernmental Panel on Climate Change, co-winner of the Nobel Peace Prize in 2007, held a press conference to announce the findings of the first working group (WG1) on “The Physical Science Basis.” (The rest of the AR5 will roll out in three more reports culminating in the Synthesis Report in October of next year.)
The lead in the press release today is “Human influence on the climate system is clear.” That’s for those who have been living in another solar system for the past ten years. For the rest of us, the report underlines a lot of what we already have learned. It is a herculean task for the 259 authors from 39 countries to look at, digest and report on the body of scientific evidence that has been building over the past several decades, and especially the new data, modeling and analysis that has come in over the past six years since the last Assessment Report. Remember these people are assessing the enormous body of science. Although nearly all of them are producing original science in their day jobs, the IPCC work is done ad hoc and is meant to provide a solid foundation for policymakers.
I will revisit the report next week when it is fully released, but for now, the Summary for Policymakers (SPM) is available. (Graphics for this will also be included next week. These are usually extremely helpful, particularly for non-scientists like me, in illustrating the key findings.) For now, let’s just look at some of the Headline Statements from the SPM:
- Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.
- Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010.
- The atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. Carbon dioxide concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification.
- Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.
More from me next week.