First the bad news, which is not exactly new but is getting new attention.
In the absence of strong policy interventions, warming may be much worse than the IPCC’s projections. MIT’s Joint Program on the Science and Policy of Global Change issued a report in January projecting median surface warming in a “business as usual” scenario of more than 5° C (9° F) by 2100, roughly twice what the most recent IPCC report predicted. The MIT group believes there is more than a 90% probability that temperature increases will exceed the IPCC prediction of 2.4° C. The report got relatively little press coverage when it was issued, but now that it’s been published in the peer reviewed Journal of Climate (subscription required), more papers are running the story.
But there is also some good news. The economic recession, while it may be complicating the politics of controlling greenhouse gas emissions, may be providing a little bit of breathing room for policy development. The SF Chronicle reports that the US had a “record decline” in carbon emissions in 2008. It’s not a very impressive record — the decline is only 2.8% from 2007, not nearly enough for a bad economy to actually save us from global warming. But at least the problem of controlling emissions is, for the moment, not getting tougher as the U.S. continues to stall. The raw data, reported by the Energy Information Administration, are here. The greatest decline came from the transportation sector, leading the EIA to attribute it both to last summer’s sky-high fuel prices and to the nation’s subsequent economic malaise.