To assess the risks associated with extreme heat, scientists rely on wet bulb temperature, which is the point at which the human body can no longer cool itself effectively.
Many countries have recently experienced extreme heat, but in most inhabited areas around the world, temperatures rarely become so hot that they are unlivable, particularly in relatively dry climates. When it is hot outdoors in dry areas, the human body can usually cool itself by evaporating water and heat from the skin through sweating. However, there are some places that can become dangerously hot and humid, especially in hot deserts adjacent to warm oceans. When the air is humid, sweat does not evaporate quickly, so sweating does not cool the body as effectively as it does in drier environments, according to Live Science.
Amritsar, India, is one of the places with high temperatures and humidity. (Photo: Hindustan Times)
In some areas of the Middle East, Pakistan, and India, summer heat waves can combine with humid air blowing in from the sea. This combination is particularly dangerous. Hundreds of millions of people live in these regions, most of whom do not have air conditioning in their homes.
Scientists use the “wet bulb thermometer” to better visualize this risk. The wet bulb thermometer allows water to evaporate by blowing air from the surrounding environment over a wet cloth. If the wet bulb temperature exceeds 35 degrees Celsius, the human body cannot cool itself adequately. Prolonged exposure to such a combination of temperature and humidity can be life-threatening.
During a severe heatwave in 2023, the wet bulb temperature was extremely high in the Mississippi Valley, although it did not reach lethal levels. In Delhi, India, where air temperatures exceeded 49 degrees Celsius for several days in May 2024, the wet bulb temperature approached dangerous levels. Some individuals died from heat strokes in the humid weather. Under such conditions, everyone must take precautions.
When humans burn carbon, whether from coal in power plants or gasoline in vehicles, this process produces carbon dioxide (CO2). This invisible gas accumulates in the atmosphere, trapping the Sun’s heat near the Earth’s surface, leading to climate change. Every bit of coal, oil, or natural gas burned contributes to rising temperatures. As temperatures rise, dangerous hot and humid weather begins to spread to many other areas. Regions in the Gulf of the United States, particularly Louisiana and Texas, are increasingly at risk of experiencing hot conditions in the summer due to irrigation on farmland increasing humidity in the air.
Climate change causes many more problems than just hot weather. Hot air causes water to evaporate more, putting crops, forests, and land in some arid regions at greater risk for wildfires. Every degree Celsius increase in temperature can increase wildfire risk sixfold in the western United States. Warming also causes sea levels to rise, threatening to flood coastal areas. Rising sea levels could displace 2 billion people by 2100.
All these impacts mean that climate change threatens the global economy. Continuing to burn coal, oil, and natural gas could result in a 25% drop in global income by the end of the century. However, we can replace fossil fuels with clean energy sources like solar and wind power. Humanity has made significant strides in the past 15 years to make clean energy cheaper and more reliable. Today, virtually every country on Earth agrees to work together to combat climate change before it is too late.
