Heat waves will become so extreme in certain regions of the world decades from now that human life there will be unsustainable, the United Nations and the Red Cross said on Monday.

Heat waves are forecast to "exceed human physiological and social limits" in the Sahel, the Horn of Africa, and South and Southwest Asia, with extreme events triggering "large-scale suffering and loss of life," the organizations.

The latest report titled "Extreme Heat: Preparing for the heatwaves of the future" from the UN body indicates that, while before an extreme heat event could occur once every 50 years, now it is almost five times more likely due to human influence.

"Silent Killer"

According to estimates, even if we keep the temperature below the 2ºC goal of the Paris Agreement, these waves are expected to be almost 14 times more likely and generate much more dangerous levels of heat and humidity.

However, limiting global warming to 1.5°C could result in up to 420 million fewer people being frequently exposed to extreme heat waves.

This year, regions or entire countries of North Africa, Australia, Europe, South Asia and the Middle East have suffocated under record temperatures, also China and the western United States.

"The humanitarian system does not have the means to resolve a crisis of such magnitude on its own. We are already short of funds and resources to respond to some of the worst ongoing humanitarian crises this year," Martin Griffiths, head of the UN humanitarian agency, told reporters.

According to the report, almost everywhere reliable statistics are available, heat waves are the deadliest weather hazard. They already kill thousands of people each year and will become increasingly deadly as climate change increases.

Overall, experts predict very high extreme heat-related death rates, "comparable in magnitude, by the end of the century, to all cancers," the report said.

The report recalls that extreme heat is "a silent killer" whose effects will amplify, posing enormous challenges to sustainable development while creating new humanitarian needs.

Massive humanitarian crisis

"The humanitarian system does not have the means to solve a crisis of this magnitude on its own. We already lack the funds and resources to respond to some of the worst humanitarian crises in progress this year", underlined in front of the journalists' Martin Griffiths, head of the UN humanitarian agency.

According to a study cited by the report, the number of poor people living in extreme heat conditions in urban areas will jump by 700% by 2050, particularly in West Africa and Southeast Asia.

Important investments

The organizations call on countries to urgently make significant and sustainable investments to mitigate the impact of climate change and support the long-term adaptation of the most vulnerable populations.

According to a study cited by the report, the number of poor people living in extreme heat conditions in urban areas will jump by 700% by 2050, particularly in West Africa and Southeast Asia. The UN and the Red Cross emphasize that it is equally important to recognize that adaptation to extreme heat has limits.

Some of the measures taken, such as increasing energy-intensive air conditioning, are costly, and environmentally unsustainable and they contribute to climate change.

If greenhouse gas emissions that are responsible for climate change are not 'aggressively' reduced, the world will face 'extreme heat levels hitherto unimaginable', the two organizations warn.