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For the first time, a study shows significant changes in summer temperatures on a local scale, according to the American Association for the Advancement of Science. The study is published this month in Geophysical Research Letters.


Study shows warmer summers hurting crops, animals

by Anthony Raap
Nov 27, 2012


Sizzling summer heat linked to climate change is scorching crops and stressing animals in many regions across the globe, according to a recent study.

The study supports other research showing that the world’s coral reefs, for example, are already shedding their color because of heat and rising ocean acidity due to climate change.

The study, published this month in Geophysical Research Letters, tracks 90 years of summers to show they have gotten warmer in many regions. Global temperatures have risen about 1.5 degrees Fahrenheit on average.

It’s the first time a study has shown significant changes in summer temperatures on a local scale, according to the American Association for the Advancement of Science.

In some areas, temperature changes began as early as the 1960s, the new study concludes. Changes were most common in tropical regions, according to the study.

Such changes are harder to prove in mid-latitude places such as New York and Chicago, where temperatures vary widely from year to year, making it difficult for scientists to show clear changes in summer climate, the researchers point out. 

But other evidence shows the impact of warming trends. Chicago has suffered through scalding heat waves in recent years, including the 1995 heat wave where more than 700 people died. By the end of August, 2012 became the hottest summer on record in the U.S., with drought taking a toll on crops across the Midwest. Record heat and drought in 2011 spread wildfires in Texas and elsewhere.

In 2003, severe summer heat caused Italy’s corn production to plunge 36 percent, and France’s corn harvest fell 30 percent, according to a separate study referenced in the new findings.

“Other studies usually looked at the trend, but the trend doesn’t tell you how it’s going to impact the region you’re interested in,” said climate scientist Irina Mahlstein, the study’s lead author.

“Emerging local warming signals in observational data,” is based on 90 years of weather station data between 1920 and 2010. It focuses on temperature distribution, said Mahlstein, a researcher with the Cooperative Institute for Research in Environmental Studies in Boulder. The insitute partners the University of Colorado at Boulder and the National Oceanic and Atmospheric Administration.

If humans keep pumping greenhouse gases into the atmosphere, the weather will keep “getting weirder,” said David Archer, a geophysical sciences professor at the University of Chicago.

“This is nothing compared to what they’re talking about for 50 years from now,” said Archer, who was not involved in the study.

The obvious solution, he said, is to curb carbon dioxide emissions from fossil fuels, a key greenhouse gas linked to global warming. It’ll take time for nations to change their energy infrastructure. It isn’t something that can be done overnight, Archer said.

The findings used the 30-year interval from 1920 to 1949 as the base period. Other 30-year intervals were then compared to this period.  Natural temperature variability was taken into account.

“The key point is that significant changes have happened,” according to the study.

“The emergence,” the authors wrote, “is due to a changing climate, not to very small-scale changes or inhomogeneous records.”

A two-week United Nations climate summit kicked off Monday in Doha, Qatar, where countries will discuss reducing fossil fuel emissions. The U.S. has said it doesn’t plan to change its emission targets.

If the U.S. and other industrialized countries began decreasing greenhouse gas emissions by, say, 3 or 4 percent a year, then that would be “a start,” Archer said.

“It’s very stupid to keep putting it into the atmosphere,” he said of carbon dioxide. “It’s like letting an oil spill happen because you don’t bother to put your finger in the hole.”