Many scientists cite world-impacting weather phenomena-melting glaciers, vanishing snowcaps-as proof of a warming planet. But what does that mean for Chicago? The models that most scientists use to study Earth’s fate don’t really work as well when looking at smaller, more specific areas, like cities or even states. But predictions are being made. Here’s what some scientists are saying Illinois might look like 70 to 100 years from now.

 
Best Guess: According to  one prediction by the Union of Concerned Scientists, a scientific research and advocacy group that has studied global warming, Chicago’s weather by the end of this century might resemble East Texas: hotter, but with more precipitation. However, this warmer climate may also increase evaporation, and that will leave the overall area drier with more summertime droughts. Confusing? “It’s not like Tom Skilling giving the forecast for tomorrow,” explains Jim Angel, a climatologist with the Illinois State Water Survey. “It’s sort of a guessing game.”

Projected Climate Change
The prevailing scientific view among climatologists is that, without big changes in emission rates, carbon dioxide levels will double worldwide over the next  100 years. Assessments of local climate change vary, depending on whom you talk to. Here are three possible scenarios:

 Temperature
  Winter  Spring Summer Fall Annual
Current Chicago Averages (°F) 25.6 48.3 71.6 52.2 49.5
Temperature change (°F) by year 2100:          
CSM: “The American Model” +2.4 +1.1  +3.0 +3.1 +2.4
CCCma: “The Canadian Model” +8.4 +9.7 +7.2  +6.4 +7.9
HadCM3: “The British Model”  +6.6 +5.9 +9.1 +7.1 +7.2

 

Precipitation
  Winter  Spring Summer Fall Annual
Current Chicago Averages (inches) 5.81 9.71 11.76 8.99 36.27
Precipitation change (in.) by year 2100:          
CSM: “The American Model” –0.03 +0.09 –0.94 –1.18 –2.06
CCCma: “The Canadian Model” –0.33 –0.63 –2.49 –0.96 –4.34
HadCM3: “The British Model” +0.27 +1.46 +3.16 –0.37 –1.79

CSM: Climate System Model, created by the National Center for Atmospheric Research, USA
CCCma: Canadian Centre for Climate Modeling and Analysis, Canada
HadCM3: Hadley Centre for Climate Prediction and Research, created by the United Kingdom Meteorological Office, UK

What’s to Blame?

 

Source: US Environmental Protection Agency, 2003

Is Chicago Getting Warmer?

Yes, but don’t blame global warming just yet. The temperature increase (2.8°F since the 1870s) could be caused by city expansion or changes in weather monitoring equipment.
 

Source: National Oceanic and Atmospheric Administration’s National Weather Service Weather Forecast Office Database

Illustration: (Top) Peter And Maria Hoey