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Is Illinois Turning into Texas?

If current climate trends continue, Illinois summers might feel like eastern Texas.

heat map

Illinois is drifting toward Texas. Or at least its climate is moving in that direction.

LAS atmospheric scientist Don Wuebbles projects that if current climate trends continue and emissions from a heavy reliance on fossil fuels continue, the summer heat index in Illinois—a combination of temperature and humidity—could feel like that of eastern Texas by the end of the century. In other words: sweltering.

Wuebbles helped lead the first effort to assess the impact of climate change in Illinois and six other Midwestern states, as well as in nine major Midwest cities, including Chicago. The report, issued by the Union of Concerned Scientists, projects that if significant cuts in carbon dioxide emissions are not made, Chicago could bake. By the end of this century, the city could average 70 days exceeding 90° F every summer; and of those days, 30 could top the 100-degree mark.

To put this in perspective, the baseline years in Chicago—1961 through 1990—averaged only 15 days over 90° F and less than two days over 100° F each summer.

By mid-century, the norm could be summers like those in 1983 and 1988, when there were many more hot days, Wuebbles adds. As the Midwest climate report describes it, “The unusual heat of 1988 combined with widespread drought to cause an astonishing $40 billion in losses to agriculture and related industries nationwide—the United States’ second costliest weather-related disaster in modern times (after Hurricane Katrina).”

The report, which based its projections on thousands of climate measurements going back over 100 years, assumed two different scenarios for the future. The “higher emissions scenario” assumes the world would continue to heavily use fossil fuels, replacing consumption by 25 percent through alternative energy sources by the end of the century, with average carbon dioxide concentrations in the atmosphere reaching 940 parts per million (ppm) by 2100. Current carbon dioxide concentrations are roughly 390 ppm.

Researchers also looked at a “lower emissions scenario,” which assumes a much more dramatic switch to alternative energy sources—a cut in fossil-fuel consumption closer to 80 percent. This would put average carbon dioxide concentrations at 550 ppm by 2100. Under this scenario, Chicago might average closer to 35 days over 90° F, rather than 70 days; and southern Illinois might feel more like New Orleans than east Texas by 2100.

Carbon dioxide, the most notorious greenhouse gas, traps heat in the atmosphere, acting like a blanket. It and other greenhouse gases make Earth comfortable and habitable for life, Wuebbles says. “But we’re now adding an extra blanket,” he says, and the increased heat could affect severe weather and the potential for floods and droughts.

Under the high scenario, the report predicts one-third more precipitation during winter and spring, but about 10-percent less rainfall during the summer by the end of the century. What’s more, Wuebbles says the rain will fall in the form of much heavier storms, which drop more than 2 inches at a time. This could translate into increased flooding.

For Illinois agriculture, all of this means more heat stress on animals and crops, unless genetic modifications make the plants more adaptable to higher heat and drought. Changes in temperature could also increase the risk of certain pests, such as corn borers, especially in southern Illinois.

According to Wuebbles, seven Midwest states combined emit more carbon dioxide than any nation on Earth, except for Russia, China, and the United States.

“The physics say that these emissions are going to heat the Earth’s atmosphere,” he says. “That doesn’t mean it is going to heat everywhere the same. But overall the climate has to warm. The physics is as simple as that.”

By Doug Peterson
Spring 2010