If we can achieve the most aggressive targets set by the Paris Agreement, we could avoid the worst health effects for people living in one of the most vulnerable climatic zones on Earth. A study published Monday in Nature Geoscience projects that the tropics will remain habitable for humans if we can continue to warm below 1.5-degree-Celsius (2.7-degree-Fahrenheit) prag.
The world’s tropical regions are some of the most worrying areas of the globe when we think of the coming decades and climate change. The area includes all of Central America, much of South America, a large area of Africa, and many countries in South and Southeast Asia. It is home to 3.3 billion people – inclusive 85% of the world’s poorest population“And the population is.” INCREASE. The tropics are also a time bomb when it comes to climate change, especially when it comes to extreme heat.
With almost half of the world’s population living in such a crucial area, it is important to realize the impact of rising temperatures on human health, on which this study focused. Using different climate models and observations, the study authors drew the correlation between global temperature changes and an important value for human health, known as the wet bulb temperature.
While we often talk about how hot it is outside, the temperature of the wet bulb, which measures humidity and heat, can matter to our health even more than what the outside thermometer tells us. Research has shown that our bodies have reached their limits at about a 95 degree Fahrenheit (35 degree Celsius) wet bulb temperature. A The estimated 2015 study that anything exceeding six hours spent in these conditions “would probably be intolerable even for the fittest of men.”
This study described in detail how the temperatures of wet bulbs in the tropics actually work. Humidity and heat are not always fully synchronized. The study notes that some regions of the world have seen a decrease in humidity on warmer days, so determining how humidity changes in tandem with rising temperatures is important to think about the future of wetlands such as the tropics. However, tThe researchers found that humid bulb temperatures in the tropics appear to be governed by the same types of atmospheric dynamics as dry bulb temperatures, which means we can predict that with increasing general temperatures in this region, so will humidity.
G / O Media may receive a commission
“A degree Celsius [1.8 degrees Fahrenheit] The average tropical warming corresponds to about 1 degree Celsius to the annual increase in the maximum temperature of the wet bulb, ”wrote Yi Zhang, a Princeton researcher and lead author of the study, in an e-mail. “A unique element in this paper is that we have a theory for wet bulb temperature changes and it works very well for climate model projections. It is also an important finding that the observations confirm our theory. “
And that means we have a clearer picture of how much the world can warm before the tropics reach that uninhabitable 95-degree Fahrenheit mark: We can keep it region habitable if we continue to warm below 1.5 degrees Celsius, the more aggressive target detailed in the Paris Agreement.
What this study does not take into account is the health impact associated with even smaller increases in temperature and the changes we are already seeing with warming in the tropics right now, not to mention what it could have in the coming decades. After all, “at what humidity human beings can no longer survive” is a fairly low bar to set – and one that does not encapsulate all the health complications that occur when our bodies work hard to overcome high humidity. The tropics have already seen oppressive heat waves with wet bulb temperatures pushing the edge of what people can survive with only about 1.8 degrees Fahrenheit heating only in the last century.
“To communicate the health implications of our results, we need to know more about wet bulb temperatures than just a survival limit,” Zhang said. “In-depth knowledge of the health impact of the intensity, frequency and duration of high wet bulb temperatures is required.”
Nor, of course, does this study consider the overwhelming challenges of keeping warming below 1.5 degrees Celsius. But it seems pretty clear that if we want to keep one of the most populous regions of the Earth habitable, we’d better get to work.