Courtesy: The Straits Times

Climate change will sharply boost the frequency of lethal heatwaves even if humanity caps global warming at 2°C, the core goal of the Paris Agreement, scientists said on Monday.

A heat wave is a prolonged period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is measured relative to the usual weather in the area and relative to normal temperatures for the season. Temperatures that people from a hotter climate consider normal can be termed a heat wave in a cooler area if they are outside the normal climate pattern for that area.

The term is applied both to hot weather variations and to extraordinary spells of hot which may occur only once a century. Severe heat waves have caused catastrophic crop failures, thousands of deaths from hyperthermia, and widespread power outages due to increased use of air conditioning. A heat wave is considered extreme weather, and a danger because heat and sunlight may overheat the human body.

Hyperthermia is elevated body temperature due to failed thermoregulation that occurs when a body produces or absorbs more heat than it dissipates. Extreme temperature elevation then becomes a medical emergency requiring immediate treatment to prevent disability or death.

Heat waves are notoriously deadly, as the human body can only function in a narrow range of body temperatures around 98.6 degrees Fahrenheit (37 degrees Celsius).

Deadly heat waves are going to be a much bigger problem in the coming decades, becoming more frequent and occurring over a much greater portion of the planet because of climate change, according to a study published Monday in Nature Climate Change.

Extreme heat waves, such as the one torching the southwestern United States and the one plaguing Western Europe, which has sparked wildfires in Portugal that have killed more than 60 people, are frequently cited as one of the most direct effects of man made climate change.

Fulfilling that 196 nation pledge would, by 2100, still leave nearly half the world’s population exposed at least once a year to bouts of heat and humidity that have proven deadly in the past, they reported in the journal Nature Climate Change.

Since the start of the 21st century, heatwaves have claimed tens of thousands of lives, even in countries best equipped to help their citizen cope. In western Europe, for example, there were more than 70,000 excess death during the blistering summer of 2003.

‘We found that killer heatwaves around the world are becoming more common and that this trend already seems unavoidable,’ said Camilo Mora, a professor at the University of Hawaii and lead author of the study.

‘Even if we outperform the Paris targets, the population exposed to deadly heat will be about 50 percent by 2100,’ he told Agence France-Presse.

Already today, 30 percent of Earth’s inhabitants encounter super hot spells at some point in the year.

In even the bleakest climate change scenarios for the end of this century, science has offered hope that global warming would eventually slow down. But a new study published Monday snuffs out such hope, projecting temperatures that rise lockstep with carbon emissions until the last drops of oil and lumps of coal are used up.

Under a business as usual scenario, in which greenhouse gases continue pouring into the atmosphere at current rates, three quarters of humanity will annually face what the researchers call ‘lethal heat events.’

The number of “lethal heat days” does not tell us how many people will die, the authors point out. If everyone is living in air-conditioned environments 50 or 75 years from now, they will be shielded.

But that is not the case today, and protracted heatwaves are also taxing for energy grids and critical infrastructure.

“Our attitude towards the environment has been so reckless that we are running out of good choices for the future,” said Camilo Mora. “For heat waves, our options are now between bad or terrible,” Mora said.

But a hotter world doesn’t necessarily mean more deaths everywhere across the globe, Mora pointed out. He found that over time, the same sweltering conditions of heat and humidity killed fewer people than in the past mostly because of air conditioning and governments doing a better job keeping people from dying in the heat.

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.

In future, the tropics will be hit hardest, according to the study, which forecasts year by year, for each square kilometer on Earth the number of deadly days under three different carbon pollution scenarios laid out by the UN Intergovernmental Panel for Climate Change (IPCC).

Killer heat due to global warming means much of the planet faces rising fatalities, a study shows. By 2100, almost half of people on the planet will be at risk of heat-related illness or death even if emissions fall.



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