How much heat is there for the human body?

For one examination Published in the journal Nature Climate Change in 2017, Mora and his team studied hundreds of extreme heat events around the world to determine what could be the most deadly combinations of heat and humidity and what these conditions might be like in the future.

They found that while about 30% of the world’s population currently suffers from a deadly combination of heat and humidity for at least 20 days a year, that percentage will increase by almost half by 2100, even with the most drastic reductions in greenhouse gases. emissions.

Other researchers have found that climate change causes extreme heat waves hundreds of times More likely and causing more than a third heat-related deaths. We are changing our planet. What are the limits of what we can bear?

Cool

Because they are warm-blooded mammals, humans have a constant body temperature, around 37 ° C (98 ° F). And our bodies are pretty much designed to work at that temperature, so there’s a constant balance between heat loss and heat gain.

Problems start when our body doesn’t lose heat fast enough (or they lose heat too fast, but let’s get warm for now). When your core temperature is too hot, everything from organs to enzymes can be turned off. Extreme heat can cause severe kidney and heart problems, as well as brain damage. Liz Hanna, A former public health researcher at the Australian National University, who studies extreme heat.

Your body maintains its core temperature in hot environments especially by using a powerful tool: sweat. The sweat you create evaporates into the air, absorbing hot skin and cooling you.

Humidity interferes with this method of cooling; if it is so wet, if there is already a lot of water vapor in the air, the sweat cannot evaporate so quickly, and the sweat will not cool you so much.

Researchers like Mora and his team often use measures such as the heat index or the temperature of a wet light bulb to study how excessive heat and humidity interact. Thus, they can rely on a single number to identify non-living conditions.

The heat index is a calculation you’ve probably seen in weather reports; heat and humidity factors to indicate how the weather feels. It is the temperature of the wet bulb that the thermometer measures if it is literally surrounded by a wet cloth. (The forecast temperature is technically a dry bulb, as it is measured with a dry thermometer.) The wet bulb temperature can be calculated if your skin temperature could be constantly sweating, so how people would roughly use it at a high heat rate.

Wet bulbs with temperatures around 35 ° C or 95 ° F are the absolute limit of human tolerance, he says Zach Schlader, Indiana University physiologist Bloomington. On top of that, your body will not be able to lose heat to the environment effectively enough to maintain its basic temperature. This doesn’t mean that the heat will kill you immediately, but if you can’t cool down quickly, brain and organ damage will begin.

The conditions a wet bulb can change drastically to a temperature of 95 ° F. With no wind and no sunny skies, an area with 50% humidity will have an unstoppable wet bulb temperature around 109 ° F, and especially in dry air, temperatures would have to exceed 130 ° F to reach this limit.