Reduced greenhouse gas emissions required to avoid dangerous increases in heat stress, researchers say

Cleanbiotech.org, via Purdue University News: A study led by Purdue University researcher projects a 200 percent to 500 percent increase in the number of dangerously hot days in the Mediterranean by the end of the 21st century if the current rate of greenhouse gas emissions continues. The study found France would be subjected to the largest projected increase of high-temperature extremes. 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 Europe, will become much more common as greenhouse gas concentrations increase," said Noah Diffenbaugh, the Purdue assistant professor of earth and atmospheric sciences who led the study. "The frequency at which that scale of event occurs at high greenhouse gas concentrations is staggering. Rare events become the norm, and the extreme events of the future are unprecedented in their severity."

A 2003 heat wave led to 15,000 deaths in France and almost 3,000 in Italy. The researchers found that global warming causes summer temperatures to dramatically exceed the range that was correlated with the increased number of deaths.

"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 Climate Change Research Center. "This research is about understanding the response to different emissions levels. We find that decreases in greenhouse gas emissions greatly reduce the impact, but we see negative effects even with reduced emissions. Technological and behavioral changes that are made now will have a big influence on what actually happens in the future."

In addition to the human health risks, extremely high temperatures could impact the economy of this region, which includes metropolitan areas such as Rome, Paris and Barcelona, said Jeremy Pal, co-researcher and associate professor of civil and environmental engineering at Loyola Marymount University. The study covered the entire Mediterranean area, which includes 21 countries in Europe, Africa and Asia. Major cities covered in the study include: Prague, Zurich, Bucharest, Athens, Istanbul, Tel Aviv, Cairo, Algiers and Casablanca.

"When high temperature extremes increase, it could have significant negative impacts on human health, water resources, agriculture and energy demand," Pal 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 Paris: If we look at the temperatures that occurred there during the heat wave in 2003, when 15,000 people died, those temperatures are exceeded a couple dozen times every year in the future projection. That means that severe heat waves, such as those rare events that have occurred in the past couple of years, are likely to become far more common."

….This research was funded by the Italy-USA collaborative agreement on climate change research and in part by the National Science Foundation.

The Purdue Climate Change Research Center is affiliated with Purdue's Discovery Park. The center promotes and organizes research and education on global climate change and studies its impact on agriculture, natural ecosystems and society. It was established in 2004 to support Purdue in research and education on regional scale climate change, its impacts and mitigation, and adaptation strategies. The center serves as a hub for a range of activities beyond scientific research, including teaching, public education and the development of public policy recommendations.