Heat And Humidity Could Make Many Regions Uninhabitable

Climate change could trigger a wide range of environmental catastrophes, such as melting glaciers, rising sea levels, floods, droughts, and forest fires. According to a new study, the combination of high heat and humidity due to climate change could lead to an increase in heat-related deaths and make many regions of the world uninhabitable.

Using interdisciplinary expertise from Purdue University and other research facilities in the United States, the new study explored interactions between real-world problems like climate change and human health.

Combined heat and humidity can be devastating to the human body, as it can only withstand certain combinations of heat and humidity before developing heat-related health problems, such as heat stroke or heart attacks. The specific threshold for any individual at a specific moment also depends on their exertion level and other environmental factors, such as wind speed and solar radiation.

An increase of 1.5 degrees Celsius (°C) or more than current levels could expose billions of people to extreme heat and humidity, preventing their bodies from cooling themselves naturally. In order to identify areas of the globe where global warming would lead to levels of heat and humidity that are beyond human tolerance, the researchers modeled global temperature increases ranging between 1.5°C and 4°C.

Over the course of several years, the team conducted more than 460 experiments to determine how much heat, humidity, and physical exertion humans can tolerate before their bodies no longer maintain a stable core temperature.

As people become warmer, they sweat, and more blood is pumped to their skin so they can lose heat to the environment by maintaining their core temperatures. Body core temperature rises at certain levels of heat and humidity when these adjustments are no longer sufficient.

As long as the body has immediate access to some form of relief, the rise in core temperature is not a threat. Heat exhaustion, heat stroke, and strain on the cardiovascular system can cause heart attacks in people who aren't able to cool down within hours.

According to the study, people can tolerate lower levels of heat and humidity than previously thought. The ambient wet-bulb temperature limit for young, healthy people is 31°C at 100 percent humidity. Researchers found that babies, older adults, and people with cardiopulmonary vulnerabilities were more likely to experience heat stress and its associated health risks at lower temperatures and humidity levels than young people.

In the Middle East and Southeast Asia, temperatures and humidity exceeding human limits have only been recorded a handful of times in human history - and for only a few hours at a time. Since the start of the industrial revolution, when humans began to burn fossil fuels in machines and factories, temperatures around the world have increased by nearly 1℃. In 2015, 196 countries signed the Paris Climate Agreement, aiming to limit global temperature increases to 1.5°C above pre-industrial levels.

According to the study, 2.2 billion people in Pakistan and India's Indus River Valley, one billion people in eastern China, and 800 million people living in sub-Saharan Africa will experience hours of heat that exceeds human tolerance if global temperatures increase by 2°C above pre-industrial levels.

Heatwaves with high humidity would primarily affect these regions. As humidity increases, heatwaves are more dangerous because the air cannot absorb excess moisture, limiting sweat evaporation from human bodies and moisture from some infrastructure, such as evaporative coolers. Worryingly, these regions are also in lower-to-middle income nations, so many of the affected people may not have access to air conditioning or any effective way to mitigate the negative health effects of the heat.

Continuing to warm the planet by 3°C above pre-industrial levels, the researchers concluded, would result in heat and humidity levels that are beyond human tolerance. This would increase health risks and fatalities among billions of people in areas of the United States, in South America, in Australia, and elsewhere.

It is important to remember that while climate models, such as those used in the above study are good at predicting trends, they often do not account for most unusual weather, as well as for specific events like the heatwave in Oregon in 2021 that killed more than 700 people despite the fact that the temperatures were below human tolerance levels.

Around the world, official strategies for adapting to the weather focus only on temperature. The new study, however, shows that humid heat is much more dangerous than dry heat. The government and policymakers need to reevaluate heat-mitigation strategies to invest in programs that will address the greatest dangers.

Unless mitigation measures are introduced to curb the use of fossil fuels, which is the main source of greenhouse gas (GHG) emissions that contribute to recent higher temperatures and changing weather patterns, we will soon face a world where food insecurity is rising, and billions of people are migrating out of uninhabitable regions.

Comments Post Comment

Leave a Comment

Submit