by Beth Ulion
Jan 28, 2009
While Chicagoans shiver through some of the coldest weather in years, climate scientists continue to report global temperature increases. Through their layers of scarves many are asking, what happened to the warming in global warming?
“If you take the global average, it’s definitely getting warmer,” said David Archer, a climate scientist at the University of Chicago. Worldwide temperatures have increased about 0.3 degrees Fahrenheit. But “in Chicago I don’t think it has gotten much warmer over the past two decades.”
Reports showing a global temperature increase may seem implausible with the mercury barely visible. But there is a key difference between the past few weeks of cold and the ongoing worldwide trend.
“There is weather and there is climate,” said Richard Alley, a climate scientist at Pennsylvania State University who specializes in paleoclimatology, a field that explores geologic evidence of past climate change.
People are “cherry picking a hot year or a cold year to say, global warming or ice age!” Alley said. “You really need to average over years of statistics.”
This winter of aching ears and frozen feet is not indicative of a reversal in the warming trend of climate change. In fact, emissions of greenhouse gases could cause drastic changes within 20 years.
“By 2030, Illinois summers may resemble those of Oklahoma or Arkansas in terms of average temperature and rainfall,” according to a report from the Union of Concerned Scientists on climate change in the Great Lakes region.
Projections show the state’s climate could feel more like Texas and Oklahoma by the end of the century.
Illinois is facing potential temperature increases of 7 to 13 degrees Fahrenheit for winter and 9 to 18 degrees Fahrenheit for summer by 2095, the report states.
Projections in the report show an increase in precipitation of 10 to 25 percent during winters and a decrease of 5 to 20 percent during summers, a looming problem for agriculture.
A map of temperature changes worldwide since 1901 created by the Intergovernmental Panel on Climate Change illustrates the large-scale warming trend. “Some places’ temp has gone up a lot in the last 20 or 30 years, other places it hasn’t really,” Archer said.
“If you try to find Chicago on [the map], our pixel didn’t seem to have much change,” he said.
The most extreme increases, between 2.5 and 3.6 degrees Fahrenheit, are concentrated in the more sensitive, higher latitudes, according to the report.
Temperatures in areas with extensive ice cover increase faster because initial heating sets into motion a cycle that leads to further warming, said Mark Serreze of the National Snow and Ice Data Center.
The Arctic is covered with bright ice and snow. This reflects heat from the sun back into space. But as temperatures rise, the ice melts and exposes dark areas of land and sea that absorb the heat, Serreze said.
At the same time, the sea ice covering the inland Arctic Ocean acts as insulation. It keeps the warm sea and the cooler atmosphere separate. Without the cover of the sea ice, heat from the ocean can transfer to the atmosphere, further warming the area.
While computer climate models predicted the warming of high latitudes, reality is ahead of the models.
We are seeing larger ice melts than projected, Serreze said. “We are on the fast track of change.”