20/06/2017 17:48 BST | Updated 22/06/2017 21:38 BST

Deadly Heat Waves Could Threaten 3 in 4 People By 2100

Even with aggressive reductions in carbon emissions, extreme heat is going to get worse, a new study has found.

WASHINGTON — If humans fail to drastically cut carbon emissions, 3 in 4 people on the planet could be exposed to deadly heat waves by the end of the century, a new study has found. 

And even if countries take action to reverse climate change with aggressive emissions reductions, up to 48 percent of the global population will be plagued by at least 20 days of lethal heat per year by 2100. 

Camilo Mora, the study’s lead author and an associate professor of geography at the University of Hawaii at Manoa, told HuffPost that our “assault on the planet has been so massive” that we’ve left ourselves without a good option.

“When it comes down to heat waves, our choices right now are between bad and terrible,” Mora said. “Unfortunately, I wish there were better news ... This is already bad and it’s not going to get any better, but it could get a lot worse if we don’t do anything.” 

And the problem isn’t just for the future. The threat is already here, with roughly 30 percent of the human population exposed to deadly conditions each year.

“We are talking thousands of people who have been killed by this,” Mora said. “People need to realize that this is the closest I know about the definition of torture. I don’t believe there is a worse way than to die by a heat wave. Imagine that.” 

To complete the study, published Monday in the journal Nature Climate Change, Mora and 17 other researchers analyzed about 1,900 cases in which high temperatures killed people in dozens of cities worldwide since 1980. In doing so, the team worked out a threshold for when heat and humidity become lethal, which varies by location. 

Since 1980, the number of lethal heat waves has been steadily rising, according to the team’s findings. 

The study comes as extreme heat is scorching the U.S. Southwest. In Death Valley, California, the temperature is expected to climb to as high as 127 degrees. And in Phoenix, American Airlines canceled flights because temperatures were anticipated to reach 120 degrees — beyond the point that certain types of commercial aircraft can function. 

Meteorologist Eric Holthaus tweeted that the average number of 100-degree days in Tucson, Arizona, has increased 55 percent in the last three decades.  

Over the weekend in Portugal, at least 62 people died in a series of massive forest fires fueled by a heat wave on the Iberian Peninsula that brought temperatures as high as 104 degrees in some areas. 

Extreme heat can lead to a number of dangerous and even fatal health conditions, including heat stroke and cardiovascular and respiratory disorders. Children, the elderly and low-income populations are most at risk. U.S. cities including St. Louis, Philadelphia and Chicago have seen “large increases in death rates during heat waves,” according to the Centers for Disease Control and Prevention.

Mora’s study highlighted deadly events like the 1995 heat wave in Chicago, which brought temperatures as high as 106 degrees and killed more than 700 people; a 2003 event in Paris, which resulted in nearly 5,000 deaths; and the 2010 heat wave in Moscow, when more than 10,000 people perished. 

The threat that more people will die from such events “now seems almost inevitable, but will be greatly aggravated if greenhouse gases are not considerably reduced,” the study states. 

Earlier this month, President Donald Trump announced he will withdraw the U.S. from the historic Paris Agreement, an international accord aimed at cutting carbon emissions to ward off the worst effects of global climate change.

It’s a move that Mora summed up as “stupid.” 

“The science of climate change is so solid that for him to pull out from from that agreement, knowing the consequences of that for humanity, is just the definition of what I find stupid,” he said. “I don’t mean any offense there.”

We can’t afford not to fix the problem, said Mora, who said he’s frustrated that people are willing to ignore climate change or treat it as a future threat. What gives him hope is the cities and states that have vowed to take action when Trump has refused to. 

“We are assaulting our planet,” Mora said. “We are dumping all kinds of crap into the atmosphere. We are destroying ecosystems like it’s nobody’s business. How is it that we can expect anything good [to come] out of it?”

Photo gallery Climate Visuals For The Climate Change Denier In Your Life See Gallery