Draft IPCC report has increased confidence in human influence on climate

Today, a draft of the upcoming report from the Intergovernmental Panel on Climate Change was leaked to major news organizations including Reuters and The New York Times. The draft is scheduled to go through one more round of revisions at a meeting with both diplomats and scientists later this year. Typically, this changes the wording of passages but not the basic conclusions of the scientists who wrote the draft.

For those who have followed scientific results in the years since the previous report was released, the new report won't be much of a surprise. As the Times emphasizes, our confidence in humanity's influence on the recent warming has only increased. In the report's terms, it jumps from a 90 percent confidence to 95 percent. In addition, further studies of the behavior of the Greenland and Antarctic ice sheets, along with reconstruction of past sea levels, has led to a better understanding of the expected future sea level rise. The new report will suggest that the end of the century will see ocean levels 30-80cm (one to three feet) higher than at present.

The Reuters report largely corroborates the outline, but it emphasizes other things. These include a detailed look at where the heat added to the climate system over the last decade has gone, given that surface temperatures have varied within a relatively narrow range during that span (the report suggests a number of factors, including volcanic aerosols and ocean warming, may all have contributed). It also mentions that regional forecasting, which is essential for any plans to adapt to the changing climate, remains a weak spot.