Chilly but dry conditions continue across the metro Washington DC region this afternoon with temperatures near or a little above 50. The near-term outlook is well covered in Josh's earlier post, so let's take a longer-range view (about 130,000 years).
Hot off the Press Release
Earlier this afternoon, the National Center for Atmospheric Research (NCAR) in Boulder announced the publication of 2 papers by NCAR scientist Bette Otto-Bliesner and University of Arizona Environmental Studies Laboratory Director Jonathan Overpeck in tomorrow's issue of the journal Science. While not a smoking gun, the new studies help build a picture of the potentially catastrophic consequences of global warming. Combining paleoclimate records (such as ancient coral reefs and ice cores) with output from the NCAR Community Climate System Model (CCSM), the researchers found that a 5-8° F warming of Arctic temperatures by the end of this century from increased greenhouse gases would produce conditions as warm as those of 130,000 years ago. That was the period between the last great ice age and the previous one, when sea level was 20 feet (6 meters) higher than today. This is a much faster rate of sea-level rise than has previously been assumed.
The notion of abrupt climate change was unfortunately distorted out of all recognition by the recent movie, "The Day After Tomorrow", but it has been receiving much more serious attention in the last decade. The graph, from a National Academy of Sciences report, "Abrupt Climate Change", shows a very rapid warming from the so-called "Younger Dryas" period about 12,000 years ago. At that time, the temperature increased by 8° C in only a decade.
Dr. Overpeck presented an excellent overview of the abrupt climate change theory in a lecture at the American Geophysical Union (AGU) annual meeting in 2002. For some other intriguing speculation on modes of climate shift, check out the Charney lecture by MIT Prof. Kerry Emanuel (of hurricane intensity fame) from 2001. The AGU lecture archives, which I just discovered yesterday, are a treasure trove of interesting material from AGU meetings back to 1999. The two which I have sampled so far should be quite accessible to a general audience.