By 2050, about 350 million people die each year from climate change

It is estimated that by 2050, about 350 million people living in big cities can die from heat stress (heat burden) every year.

The Paris Agreement on Climate Change is the first global commitment to climate to limit global warming to no more than 2 ℃ (the desired target is only 1.5 ℃) compared to the pre-existing air temperature. The industrial era in the late 19th century. Many people believe that it is a safe heat increase.

However, in the latest study examining the impact of rising global temperatures in megacities, scientists found that even if the limit of 1.5 ℃ was reached, there would still be a Large increase in deadly heat frequency.

Accordingly, they predict, by 2050, about 350 million people living in big cities can die from heat each year.

People become "heat stressed" (evaluated through indicators such as rectal temperature, heart rate, amount of sweat .) when the body absorbs more heat than tolerated. If the body temperature rises only above 37 ℃ a few degrees, it can lead to deadly heat shock.

The global temperature has increased slightly, the heat burden on people is still very large - (Photo: NCCS).

Normally, by using a cooling system (sweating), the human body can maintain a safe temperature even when the air temperature rises above 37 ℃. This mechanism works better in dry air conditions (which is why the steam room is hotter than a sauna, even at the same air temperature).

The heat index (Heat Index) is a combination of temperature and relative humidity to give the equivalent temperature that the body feels - ie how hot it feels. Heat index above 40.6 ℃ is considered dangerous to human health.

Observations and experiments on many climate models show that, when global temperatures rise, the moisture content in the atmosphere also escalates. This means that the heat index will increase faster than air temperature. In addition, because the amount of air moisture can increase faster at higher temperatures, the heat index also increases faster (non-linear reaction).

This non-linear reaction caused the researchers to define the "global stress stress burden" - determine the average number of days per year in the area with a heat index above 40.6 ℃. They used a large number of climate simulation models and found that the number of such days increased faster as the average temperature increased.

The megacities are the first places where the population suffers from the consequences of the heat burden - (Photo: Climatestate).

The sudden increase in this global heat burden has serious consequences.First , any increase in global heat burden from warming up to now will be smaller than the heat burden caused by future temperature rise. That is, we have seen an increase in the global temperature of 0.8 ℃ for the first time, another 0.8 ℃ warming will increase the heat burden for the first time.

Secondly , the team's analysis showed that if the global warming was 1.5 ℃, heat stress would be nearly six times higher than what had happened during the period 1979 - 2005.

However, heat stress will be 12 times greater if the heat is up to 2 ℃. With 4 ℃ warming (will happen if minimized efforts like committed agreements fail), the global stress stress burden can be greater than 75 times.

For example, in 2015, Karachi and Kolkata of India suffered a deadly heat wave. The team's analysis showed that if the world heated to 2 ℃, both cities would have to undergo this deadly condition at least once a year. If the temperature rises to 4 ℃, the record temperature in 2015 will become popular, lasting 40 days a year.

Reducing global warming and reducing population growth is a possible way to limit heat stress to a dangerous level for millions of Earth residents - (Photo: Getty Images).

With only 1.5 ℃ warming, super cities (with a population of more than 10 million people, including Lagos, Nigeria, and Shanghai, China) may begin to suffer from the heat stress often. If the temperature rises by 2 ℃, Tokyo (the world's most populous city) is affected, and New York suffers when the temperature rises by 4 ℃.

Besides, if the global population increases as expected in this century, it is possible to increase global heat stress. The situation in Lagos is an example: If the temperature rises by 1.5 ℃ at the end of the century (when Lagos's population can increase 10 times and the temperature is 100 times higher), heat stress will be greater than fold. thousands of times compared to the present.

In 2050, if the 1.5 ℃ limit is violated, 350 million people around the world can often be exposed to dangerous heat stress. This figure is four times higher than the period 1979 - 2005.

Heat stress is sensitive to an increase in global temperatures and potential human impacts - even when heat only rises at 1.5 ℃ compared to pre-industrial times - has created a strong incentive for humans. Try to limit global warming.

The analysis of scientists has shown, even if ambitious mitigation goals are achieved, such as in the Anti-Climate Change Agreement, adaptation to extreme temperatures will still be necessary for the future. humanity later.