BOULDER--Boston buried under ice? Idaho sun-dried into desert? No, this isn't Hollywood's latest foray into climate change. Benjamin Felzer, a climatologist and geologist at the National Center for Atmospheric Research in Boulder, has used NCAR computer models of climate and vegetation to find which plant types our ancestors would have wandered among during the last glacial maximum (LGM) 21,000 years ago. Felzer presented his work on Wednesday, October 30, at the annual meeting of the Geological Society of America in Denver.
These models present a world blanketed by massive ice sheets over Canada and Eurasia, with tundra covering much of Europe and North America as the Sahara Desert crept southward toward central Africa. Rain forests existed in South America and Africa, as now, but there were fewer trees globally. The whole world was colder in both summer and winter, with a global average temperature four degrees Celsius lower than now and atmospheric carbon dioxide (a greenhouse gas) at just over half of today's levels.
Felzer's study checks the NCAR model's reliability by simulating past climates and comparing its results to geological data, such as pollen deposited in lake sediments at the time, fossilized, and recently retrieved from lake cores. Once verified, the model can be used to estimate what will happen to today's plants in the next century as increasing greenhouse gases warm the climate by several degrees.
"The plants we see around us today had 21,000 years to adapt to a several- degree warming. Now these same plant types may have a hundred years or less to make the same transition," explains Felzer. Will they have time to migrate and adapt or will they die? The model may eventually shed light on such questions as Jon Bergengren, an NCAR colleague, shifts the model's gaze out of the distant past and into the next century.
In the real world, the growth and melt o
National Center for Atmospheric Research/University Corporation for Atmospheric Research