It is predicted that by the year 2050, some 350 million people living in large cities may die from heat stress (heat load) each year.
The Paris Climate Change Agreement is the first global commitment to climate change to limit global warming by no more than 2 ℃ (the desired target is only 1.5 ℃) Many believe it is a safe heat boost.
However, in the latest study examining the effects of rising global temperatures in the megacities, scientists found that even if the 1.5-giới limit was reached, there would still be Large increase in fatal heat frequency.
According to them, they predict that by 2050, about 350 million people living in major cities could die of heat each year.
Humans become “heat stressed” (measured by indicators such as rectal temperature, heart rate, sweat …) as the body absorbs more heat than is tolerated. If your body temperature rises to just over 37 ℃ degrees, it can lead to fatal heat shock.
Normally, using the cooling system (sweat), the human body can maintain a safe temperature even when the air temperature rises above 37 ℃. This mechanism works better in dry air conditions (that is why steam rooms are hotter than sauna, even at the same air temperature).
Heat Index (Heat Index) is an index that combines temperature and relative humidity to produce the equivalent temperature that the body feels – ie how hot it feels. Heat index above 40.6 ℃ is considered hazardous to human health.
Observations and experiments on many climate models show that, as global temperatures increase, atmospheric moisture levels also escalate. This means that the heat index will rise faster than the air temperature. In addition, because the amount of moisture the air can grow faster at higher temperatures, the heat index also rises faster (non-linear response).
This nonlinear response led researchers to define the definition of “global heat stress burden” – defining the average number of days per year in the area covered by the heat index above 40.6 ℃. They use a large number of climate simulation models and find that the number of such days increases faster as the average temperature rises.
This sudden increase in global warming has serious consequences. First , any increase in global heat load from the warming of the climate up to now will be less than the thermal burden caused by future temperature increases. That is, we have witnessed a global warming increase of 0.8 ℃ for the first time, another 0.8 sự warming will increase the burden of heat more than the first.
Second , the team’s analysis showed that if global warming was 1.5 ℃, heat stress would increase nearly six-fold over what happened during the 1979-2005 period.
However, heat stress is 12 times greater if heat is up to 2 ℃. With 4 ℃ warming (which would occur if mitigation efforts such as the pledged pledged to fail), the global warming stress burden could be 75 times greater.
For example, in 2015, Karachi and Kolkata of India suffered a lethal heat wave. The team’s analysis suggests that if the world gets heated up by 2 ℃, both cities will experience this fatal 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.
With just 1.5 ℃ warming up, the super-city (which has a population of more than 10 million people, including Lagos, Nigeria, and Shanghai, China) can often begin to suffer a heavy burden of heat. If the temperature rises 2 ℃, Tokyo (the most populous city in the world) is affected, and New York is hit when the temperature rises 4 ℃.
In addition, if the global population increases as predicted in this century, it can cause further global warming. The situation in Lagos is exemplary: If the temperature rises 1.5 ℃ at the end of the century (when the population of Lagos can be increased by 10 times and the temperature is 100 times higher) Thousands of times the present.
In 2050, if the limit of 1.5 ℃ is violated, 350 million people around the world can be permanently exposed to dangerous heat stress. This number is four times higher than the 1979-2005 period.
Heat stress is sensitive to global warming and potential human impacts – even when the heat only increases by 1.5 ℃ compared to the pre-industrial phase – which has created a strong impetus for human development. Try to limit global warming.
The analysis of scientists has shown that, even with the ambitious mitigation targets set in the Climate Change Agreement, extreme temperature adaptation will remain a necessity for the future. Humanity later.