Excessive heat can have serious consequences for the health of the human body. This realization is certainly not new. However, these impacts of climate change seem to have been largely neglected until now. In addition, not only the temperature is a factor for health damage due to heat, but also the humidity. Model calculations conclude that advancing climate change, especially in Southeast Asia, will create more and more potentially deadly conditions in the future.
The risk of heat increases
In 2017, a research team led by Camilo Mora, a climate scientist at the University of Hawaii, published a study analyzing hundreds of extreme heat events around the world. Researchers wanted to determine which weather events are most likely to be fatal, as well as identify areas where such events are likely to increase in the future. According to the results of the studies, about 30 percent of humanity is already exposed to conditions where the combination of heat and humidity can lead to an acute health risk for at least 20 days a year. And even if we succeed in drastically reducing greenhouse gas emissions by 2100, this value will increase by about half by then.
Humans are warm-blooded. That means our body has a temperature regulator that tries to maintain a constant body temperature of around 37 degrees. This regulation system also kicks in when the body gets too hot. † When the human body is exposed to heat, the hypothalamus triggers a cardiovascular response that widens blood vessels to direct blood from the core to the periphery.“If the heat dissipation has to be sustained for too long and too intensively, there is a reduced blood flow to internal organs, which can lead to long-term damage. This damage can be so severe that the consequences are acutely fatal.
We can’t adapt infinitely
Depending on which climate model is taken as the basis, we will reach cool limit temperatures above 35 degrees Celsius by the middle of this century. Such conditions are already being achieved in some places in Southeast Asia, the Middle East and the US Southwest – albeit for only one to two hours a day.
These zones will continue to expand both geographically and temporarily. One of the realities of climate change is that more and more people will live in areas so hot and humid that settlement in such areas is only possible if technical precautions are taken.
Because even though the human body can adapt to rising temperatures to a certain extent, this is only possible within narrow limits. People who are more accustomed to high temperatures perspire more and have a thinner sweat, so they lose fewer electrolytes when they are formed. In this way, the body can be protected from the effects of heat, such as dehydration and kidney damage from electrolyte deficiency.
The global south is most at risk
However, there are limits to this human acclimatization ability. In addition, other factors must be taken into account. For example, if you spend a lot of time outside and have to do physical work there, even lower temperatures can be dangerous. Because when you move, the body has to dissipate more heat, so that the heat tolerance is lower.
A heat wave hit India around 2010 and killed more than 1,300 people. This is not only a good example of the dangers described, but also illustrates another factor: the effects of global warming will mainly affect the Global South, where income levels are significantly lower than in the Global North. †The most striking aspect of the expected effects of extreme heat – and a particular challenge from a policy perspective – is that they are highly regional in nature, with severe or life-threatening effects in some locations in stark contrast to benign effects in others.”, writes a team around Colin Raymon in the “Oxford Handbook of Planning for Climate Change Hazards”.