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A study led by a The study also showed a reduction in greenhouse gas emissions could reduce the intensification of dangerously hot days projected in the scenario by up to 50 percent. "Rare events today, like the 2003
heat wave in A 2003 heat wave led to 15,000 deaths
in "The thresholds of the 2003 event are
substantially
exceeded in the future in both of our research scenarios," said
Diffenbaugh, who is a member of Purdue's In addition to the human health
risks, extremely high
temperatures could impact the economy of this region, which includes
metropolitan areas such as The study covered the entire
Mediterranean area, which
includes 21 countries in "When high temperature extremes increase, it could have significant negative impacts on human health, water resources, agriculture and energy demand," Pal said. The results of the study, which
originated at the
International Centre for Theoretical Physics in In addition to Diffenbaugh and Pal,
Filippo Giorgi of the
International Centre for Theoretical Physics and Xuejie Gao of the The model offers a resolution of 20 kilometers, about 12.5 miles, and is believed to have the highest spatial resolution available for the Mediterranean region. Much like increased resolution in a photo makes a clearer picture and allows one to zoom in without blurring the image, the powerful resolution of the climate model allows researchers to gather detailed information about particular areas. Giorgi, who is head of the Earth
System Physics Section of
the International Centre for Theoretical Physics, said the "In the global warming scenario,
there is more warming
and drying in the Mediterranean than in other regions of the world,
which makes
the Mediterranean a climate change 'hotspot,'" Giorgi said. "The The researchers found that this warming and reduced precipitation contribute to a preferential warming of the hottest days of the year. "We found that the hottest days of the year, or the 'hot tail,' warm more than the typical summer days warm," Diffenbaugh said. "One might expect that an average warming of four degrees would equate to each day warming by four degrees, but in fact the hottest days warm quite a bit more." This is due, in large part, to a surface moisture feedback. The surface gets dryer as it gets hotter and the dry soil leads to less moisture in the area and less evaporative cooling. The locations of intensified warming on hottest days of the year matched the locations where surface drying occurred, Diffenbaugh said. With the projected shift to more severe temperatures, the daily temperatures currently found in the hottest two weeks of the summer instead are found in the coldest two weeks of the summer in the future climate scenario, Diffenbaugh said. "The hottest temperatures we are used
to experiencing
will become the normal temperatures of the summer, and the hot periods
will be
magnified," Diffenbaugh said. "Take The study used the National Weather Service Heat Index in the analysis of the heat stress response to increasing greenhouse gas concentrations. The researchers found that areas most likely to face substantial increases in the dangerous heat index were concentrated largely in coastal areas. "Coastal regions were more affected
than inland
regions, which is of particular importance because many large cities in
the Diffenbaugh said without the high resolution of the climate model, the researchers would not have been able to identify the coastal effects. "This underscores the importance of advancing our technology and examining a number of scenarios in great detail," he said. "If we want to quantify the risks associated with climate change, it is critical to understand the local and regional impacts as well as the global impacts." For the study's standard future scenario, the research group used a commonly accepted emissions scenario from the Intergovernmental Panel on Climate Change that assumes greenhouse gas emissions continue to increase exponentially. The reduced emissions scenario incorporated a reduction in population growth and greater environmental concern, Diffenbaugh said. The researchers are currently using the high-resolution model to further evaluate the effects that increased temperatures and surface drying could have on agriculture and energy and water resources. This research was funded by the Italy-USA collaborative agreement on climate change research and in part by the National Science Foundation.
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