A scorching, unrelenting heat lashes large regions of the Earth, killing millions who have no way to escape. Shadows are useless and surface water bodies are warmer than the blood that runs in the veins.
This is a scene from “The Ministry for the Future”, Kim Stanley Robinson’s new science fiction novel. But the suffocating terror the book describes may be closer to science than fiction, according to the draft of a report by the IPCC, an advisory panel of UN climate scientists, obtained exclusively by AFP.
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In the document, experts warn of the catastrophic consequences of uncontrolled global warming for billions of people.
Older climate models suggested that it would take nearly another century of massive carbon emissions to generate heat waves that exceeded the absolute limit of human tolerance.
But updated projections warn that unprecedented heat waves are closer, according to the 4,000-page report by the Intergovernmental Panel on Climate Change (IPCC), which AFP had exclusive access to and which is due to be published in February 2022.
The chilling document paints a grim and deadly portrait of a warming planet.
In a 1.5°C warmer world, 14% of the population will be exposed to severe heat waves at least once every five years, “a significant increase in the magnitude of heat waves,” according to research cited by the IPCC .
Raise the temperature another half a degree, reaching 2°C, and things get even worse.
Hardest hit will be the burgeoning megacities of the developing world, which generate additional heat of their own, from Karachi to Kinhsasa, from Manila to Mumbai, from Laos to Manaus.
Thermometer readings aren’t the only ones making a difference. Heat is often more lethal when combined with high humidity.
In other words, it’s easier to survive a high-temperature day in a dry environment than a day of very high humidity.
This steam bath combination has its own measurement, called the wet bulb temperature.
Experts agree that a wet bulb temperature of 35°C is beyond the capacity of a healthy human adult to handle the situation, even in the shade and with an unlimited supply of fresh water.
“When wet bulb temperatures are extremely high, there is so much moisture in the air that sweat is ineffective in removing excess heat from the body,” explains Colin Raymond, lead author of a recent study that identified two locations in the Persian Gulf where the 35°C (TW) in this type of measurement has been reached.
“At some point, maybe after six or more hours, this will lead to organ failure and death in the absence of access to artificial cooling.”
– Heat strokes and heart attacks –
We’ve already seen the impact of damp and lethal heat with much lower temperatures, especially among the elderly and infirm.
In June 2015, two 30°C (TW) heat waves in India and Pakistan left more than 4,000 dead.
And the 2003 heat wave that killed more than 50,000 people in Western Europe recorded wet bulb temperatures of just 20°C (TW).
Scorching heat waves that hit the northern hemisphere in 2019 – the second hottest year on record in the world – also caused a large number of excess deaths, but the wet bulb data is still lacking.
A study by the Institute of Health Metrics and Assessments (IHME) reported just over 300,000 temperature-related deaths worldwide from all causes in 2019.
About 37% of heat-related deaths – just over 100,000 – can be attributed to global warming, according to scientists led by Antonio Gasparrini of the London School of Hygiene & Tropical Medicine.
In half a dozen countries – Brazil, Peru, Colombia, Philippines, Kuwait and Guatemala – the percentage was 60% or more.
Most of these deaths were likely caused by heat-related strokes, heart attacks, and dehydration from heavy sweating, and many would likely be preventable.
– Cities at risk –
Dangerous peaks above 27°C (TW) have more than doubled since 1979, according to Raymond’s findings.
His study predicts that wet bulb temperatures will “regularly exceed” 35ºC (TW) in some locations over the next few decades if the planet warms 2.5 degrees based on pre-industrial levels.
Human activities have caused temperatures to rise 1.1°C so far.
The Paris Agreement requires a ceiling for the “well below” increase of 2°C, 1.5°C if possible.
Even if the Paris Agreement’s temperature targets are met, hundreds of millions of city dwellers in Sub-Saharan Africa, as well as in South and Southeast Asia, will likely be hit by at least 30 days of deadly heat every year until 2080, according to the report.
“In these regions, the population of cities is growing dramatically and the threat of deadly heat is approaching,” notes Steffen Lohrey, lead author of the peer-reviewed study, from which the numbers were extracted.
These calculations, Lohrey added, do not even take into account the so-called urban heat island effect, which adds 1.5°C on average during heat waves compared to nearby areas.
Asphalt and heat-absorbing buildings, exhaust air conditioning systems and the density of urban housing all contribute to this increase in cities.
– Areas more susceptible to heat waves –
Sub-Saharan Africa is especially vulnerable to lethal heat waves because it is designed to withstand more lethal days than any region except Southeast Asia, but also because it is less equipped to deal with them.
“Both real-world observations and climate modeling show sub-Saharan Africa as a hotspot for heat wave activity,” explains Luke Harrington, postdoctoral researcher at Oxford University’s Institute for Environmental Change and author of a study on the lack of data from the continent.
Meanwhile, in central China and West Asia, “extreme wet bulb temperatures are predicted and will likely exceed physiological limits to human adaptability,” warned the IPCC.
The Mediterranean is also vulnerable to the deadly journeys of a warmer climate.
“In Europe, up to 200 million people will be at high risk of heat stress by mid-century if the world experiences a temperature increase of up to 2°C by 2100,” the report noted.
Fundamental to mortality rates is the population’s ability to adapt, explains Jeff Stanaway, a researcher at IHME.
“There is a greater sensitivity to heat in Western Europe and North America,” he tells AFP.
“That’s because in North America everyone has air conditioning and modern, well-insulated buildings. It’s just a difference in infrastructure,” he says.
– ‘Cooling gap’ –
But like many impacts related to climate change, the effects of heat waves will not be felt by everyone in the same way.
In some developing countries, economic development does not keep pace with population cooling costs, exposing a race between global warming and the ability to adapt to it.
A study of retrofit techniques in Hanoi, Vietnam, found that many people did not use air conditioning in their rooms because of their high cost of electricity. Alternatively, some wrap themselves in wet sheets before bed during severe heat waves.
In short, high temperatures will almost certainly destroy more lives indirectly, rather than reaching levels where the body simply stops functioning, the report says.
Warmer temperatures will be vectors of disease, reduce crop yields and nutrient values, halve labor productivity and make outdoor activities potentially fatal.
If the world is to avoid the cataclysm envisioned by Robinson, countries will need to honor the Paris climate agreement and limit global warming as close as possible to 1.5°C, the scientists point out.
But even so, with temperatures rising twice the global average in many regions, some severe impacts are on the way.
“Children today will witness more days of extreme heat, when manual labor outdoors will be physiologically impossible,” warns the IPCC report.
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