About 30% of the world’s population is now exposed to potentially deadly heat for 20 days per year or more.
If emissions continue to rise at their current pace, three in four people in the world will face deadly heat by the turn of the century, a study published today said.
Researchers also added that even with reductions, one in two people by 2100 will likely face at least 20 days of extreme heat that can kill them. He explained that they are very common.
“Our attitude towards the environment has been so reckless that we are running out of good choices for the future”, said Camilo Mora, associate professor at the University of Hawaii at Manoa and lead author of the study. The 2003 European heatwave alone killed almost 70,000 people – a number greater than those dying in the 9/11.
Risky heatwaves are far more common than anyone realized, killing people in more than 60 different parts of the world every year.
Heatwaves have also claimed victims more recently.
“Many people around the world are already paying the ultimate price of heat waves, and while models suggest that this is likely to continue to be bad, it could be much worse if emissions are not considerably reduced”.
“When it is both very hot and humid outside, heat in the body can not be expelled”, said Mora.
In particular, New York City would see 50 days over the threshold considered deadly, while Los Angeles would see 30, and Orlando and Houston would be above those conditions for the entire summer under the latter scenario. Analyzing data, researchers find that the people at the most risk are those in the wet tropics. Right now, temperatures in Pakistan and India have reached a scorching 128 degrees.
When heat and humidity exceed a person’s core body temperature – about 37°C – they person can not dissipate heat into the environment, researchers said.
The human body’s internal thermostat is set between 98.6 to 100.4 degrees Fahrenheit (37 to 38 degrees Celsius). As temperatures rise, the body reacts by sweating to try and cool down. Temperatures in the United States broke records in California yesterday. Body temperatures above 104 degrees are extremely unsafe and require immediate medical attention.
In this photograph from August 9, 2010, people rest on the Manezhaya Square just outside the Kremlin in Moscow, Russia.
Although lethal heatwaves are often mentioned as a key effect of ongoing climate change, with reports typically referencing past major events such as Chicago in 1995, Paris in 2003, or Moscow in 2010, this study suggests that lethal heat events already occur frequently and in many cities worldwide.
So far in 2017, there have been several heat-related deaths in the United States.
“Increasing inequality leads to increased deaths from heat extremes”, says Keller.
“Even if we “successfully” mitigate climate change, and do follow a strong policy of reducing greenhouse gases here on, we should still expect to see a substantial increase in heat stress worldwide”, Matthews said.
Mora said that even though deadly heat events will rise under more moderate warming, the need for action was akin jumping from a building.
Thousands of people have died in India from deadly heatwaves in the past years. Surface temperature measurements have shown that the Earth has warmed around 1.8 degrees Fahrenheit (1 degree Celsius) since preindustrial times, but these additional degrees aren’t evenly distributed.
Small increases in mean temperatures can have a major impact in tropical countries, especially amongst the poor who are extremely vulnerable, Davis notes. And because it is based on documented cases of real people across the globe, it makes it that much more credible and relevant.
Temperature measurements reveal that summers in 92 percent of US cities have become hotter since 1970.
“Climate change has put humanity on a path that will become increasingly risky and hard to reverse if greenhouse gas emissions are not taken much more seriously”, Mora said. “For heatwaves, our options are now between bad or awful”.