Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”
The U.N.’s Intergovernmental Panel on Climate Change (IPCC) is nearing the final stages of its Fifth Assessment Report (AR5)—the latest, greatest version of its assessment of the science of climate change. Information is leaking out, with some regularity, as to what the final report will contain (why it is secretive in the first place is beyond us).
A few weeks ago, The Economist reported on some of the information from the new IPCC report that was leaked. The key piece of information concerned the IPCC’s assessment of the equilibrium climate sensitivity—how much the earth’s average surface temperature increases as a result of a doubling of the atmospheric carbon dioxide concentration. As we have been reporting, the research now dominating the scientific literature indicates that the equilibrium climate sensitivity is around 2.0°C. This value is about 40% lower than the average climate sensitivity value of the climate models used by the IPCC to make their future projections of climate change, including among other projections, those for temperature and sea level rise. The Economist suggested that the IPCC was going to lower their assessed value for the equilibrium climate change based on the mountain of evidence from the literature, but gave no indication whether the IPCC was also going to, accordingly, lower all the projections made throughout their report.
The IPCC has three options:
1. Round-file the entire AR5 as it now stands and start again.
2. Release the current AR5 with a statement that indicates that all the climate change and impacts described within are likely overestimated by around 50%, or
3. Do nothing and mislead policymakers and the rest of the world.
We’re betting on door number 3.
In its article earlier this week reporting on its own acquired leaked information from the IPCC AR5 report, the New York Times basically proved us right.