>
Current climate policies will expose more than a fifth of humanity to dangerously high temperatures by 2100, a study warns.
Led by scientists at the University of Exeter, the study found that the legally binding measures currently in place will lead to global warming of 2.7°C by the end of the century.
This means that two billion people – about 22 percent of the projected population at the end of the century – will be exposed to dangerous heat, with average temperatures of 84.2F (29C) or more.
These high temperatures can put pressure on water resources, increase mortality, reduce economic productivity, prevent animals and crops from thriving, and allow large numbers of people to migrate.
Worldwide, 60 million people are already exposed to this heat.
A wildfire burns a forest in the vicinity of the village of Memoria, in the municipality of Leiria, in central Portugal, on July 12
This map shows the difference between the number of areas worldwide with average temperatures above 84.2F (29C) – represented by the black mesh cover. The top map is how many areas would see these temperatures below the projected global warming of 4.9F (2.7C). The bottom chart is the difference if warming is limited to 2.7F (1.5C)
However, the researchers suggest there is “enormous potential” for decisive climate policies to limit the human costs of climate change.
They say the predictions show that limiting global warming to 2.7F (1.5C), in line with the Paris Agreement, would mean five times fewer people exposed to extreme heat.
The study, which was conducted in collaboration with scientists from the Earth Commission and Nanjing University in China, also found that the lifetime emissions of 3.5 average global citizens today would expose one future person to the hazardous conditions.
And in the US, this was even more concerning, as it was found that the emissions of just 1.2 US citizens would have the same result. This means that for almost every average person in America, their individual contribution to climate change during their lifetime could cause another person to live in dangerous heat in the future.
The authors said this highlights the disparity of the climate crisis – as the people living in areas that will see extreme heat are unlikely to be responsible for it.
In fact, the study found that people exposed to dangerous temperatures will live in places where emissions today are about half the global average.
The countries most at risk of exposure to extreme heat in the future are India and Nigeria, with 600 million people in the former and 300 million in the latter potentially exposed by 2100.
Other countries where large populations are at risk include Indonesia, the Philippines, Pakistan and Sudan.
And nearly 100 percent of Burkino Faso and Mali — countries with a smaller population of about 21 million — could be dangerously hot for people.
Professor Tim Lenton, director of the Global Systems Institute at the University of Exeter, said: ‘Our study highlights the phenomenal human costs of not addressing the climate crisis.
“For every 0.1°C (0.18°F) of warming above current levels, about 140 million more people will be exposed to dangerous heat.”
Professor Lenton said this highlights both the magnitude of the problem and the importance of decisive action being taken by officials to reduce carbon emissions.
An aerial photo shows smoke after a massive bushfire on Australia’s Fraser Island, also known by its native name K’gari, on Nov. 30
This graph shows how many people (left) and what percentage of the country (right) could be exposed to dangerous heat by 2100
“Limiting global warming to 1.5°C instead of 2.7°C would mean five times fewer people exposed to dangerous heat by 2100,” he added.
The research team, made up of scientists from around the world, says the worst of these impacts can be avoided by taking swift action to reduce greenhouse gas emissions.
Wendy Broadgate, Executive Director of the Earth Commission at Future Earth, said: ‘We are already seeing the effects of dangerous heat levels on people in different parts of the world.’
She added that this will only accelerate unless “immediate and decisive action” is taken to reduce greenhouse gas emissions.
Professor Marten Scheffer, from Wageningen University, who co-authored the report, said: ‘We were triggered by the fact that the economic costs of carbon emissions barely reflect the impact on human well-being.’
“Our calculations now help bridge this gap and should encourage new, unorthodox questions about justice.”
The article, titled Quantifying the Human Cost of Global Warming, was published in the Nature Sustainability log.