Deadly heat will rise by 2100, even with emissions cuts: study


Much of the world will face a significant increase in deadly heat waves by the end of the century, even if countries manage to meet their agreed emission reduction targets, according to a new study.

Such heat events will be three to 10 times more frequent in 2100 than they are today in the United States, Western Europe, China and Japan, regardless of efforts to keep global warming below by 2 degrees Celsius (3.6 degrees Fahrenheit), according to the study, Posted in Earth & Environment Communications Thursday.

As part of the Paris climate agreement that was signed at the 2015 United Nations Climate Change Conference, participating countries agreed to stick to this limit, hoping to keep the increase to an even lower level of 1.5 degrees Celsius (2.7 degrees Fahrenheit).

To improve their chances of success, each nation submitted its own climate action plan to reduce greenhouse gas emissions. But the authors of Thursday’s study fear that these efforts may not be enough to bring the temperature down.

“Record-breaking heat events in recent summers will become much more frequent in places like North America and Europe,” said lead author Lucas Vargas Zeppetello, a doctoral student at the University of Washington at the time of the study. A declaration.

“For many places close to the equator, by 2100 more than half the year will be a challenge to work outdoors, even if we start to reduce emissions,” added Vargas Zeppetello, who is now a postdoctoral researcher at Harvard University.

Vargas Zeppetello and his colleagues evaluated projections of the future “heat index,” a combination of temperature and air humidity that measures the impact of heat on the human body.

A “dangerous” heat index is defined by the National Weather Service as 103 degrees Fahrenheit, the authors explained. Meanwhile, an “extremely dangerous” heat rating is 124 degrees Fahrenheit and is considered unsafe for humans for some time.

“These standards were first created for people working indoors in places like boiler rooms – they were not considered conditions that would occur in outdoor ambient environments. But we see them now,” Vargas Zeppetello said.

The scientists said they used a probability-based method to calculate a range of possible future scenarios, combining historical data with population projections, economic growth and carbon intensity.

They observed that even if countries met Paris Agreement commitments, the United States, Western Europe, China and Japan would cross the ‘dangerous’ heat index threshold three to 10 times more. than they do today by the end of the century.

In that same scenario, the tropics could see their “dangerous” days double – spanning half the year, according to the study.

And in a worst-case scenario – a scenario in which emissions remain unchecked until 2100 – “extremely dangerous” conditions could become common in countries close to the equator, such as those in sub-Saharan Africa and India, have determined the authors.

“These are scary scenarios that we still have the ability to prevent,” Vargas Zeppetello said. “This study shows you the chasm, but it also shows you that we have some agency to prevent these scenarios from happening.”


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