Climate change is increasing temperatures as well as making heat waves occur more frequently and more intensely. The humidity factor and extreme weather tested the limits of the human body.
In 2022, as intense heat hit India, Pakistan, Bangladesh, Nepal and Sri Lanka, New Delhi recorded a record temperature of more than 49 degrees Celsius. By one estimate, 90% of the population 1.4 billions of Indians have suffered severe health or economic damage during this heat wave.
This year, experts have issued severe weather warnings for many parts of India for the coming June – bad news for the electricity grid, crops and hundreds of millions of workers. Unusually hot and dry weather will also wreak havoc this summer in Europe.
1. What makes extreme heat dangerous?
There are many reasons . Humans are prone to dehydration at high temperatures, which increases the risk of heart attack and stroke. High heat can worsen breathing problems, especially in places with high levels of pollution.
High heat stress also makes it harder for people to work and increases the risk of injury. It’s hard to know exactly how many people die from heat each year because most are unaccounted for.
There is no official figure for the 2022 bushfire damage in India and Pakistan, but the initial figure of 90 deaths is certainly too low. Emerging economies are more affected than developed economies, because they often get less respite from the sun. Most people work outdoors, while indoor spaces are not cooled effectively. Concrete and asphalt in urban environments can store heat, increasing nighttime temperatures and contributing to heat stress.
Women and the elderly are believed to be the most affected according to a 10-year study of extreme heat events conducted in Hong Kong, China.
2. What is a wet bulb thermometer?
Forecasters are increasingly using a variety of measures of heat stress and discomfort – such as humidity, heat index or apparent temperature – to understand more about the health risks posed by high temperatures. go out. A wet bulb thermometer is one of these measures. This index is the lowest temperature at which an object can cool itself when the moisture has evaporated. It explains the effect of humidity, which makes it difficult for the human body to cool itself by sweating.
Example: If it’s 42 degrees Celsius with 40% humidity – as in Phoenix, Arizona, in July – there is a wet bulb temperature of about 30 degrees Celsius. Lower temperatures, such as 38 degrees Celsius, but with humidity higher than 80% will result in a wet bulb of about 35 degrees Celsius. That temperature is high enough to cause heatstroke even in healthy people, despite the unlimited source of shade and drinking water. In fact, shade and drinking water are often limited, and heat can be deadly at much lower wet bulb temperatures.
A 2020 study published in the journal Science shows that the areas affected by the 2003 European heatwave and in Russia in 2010, which killed thousands of people, temperature values wet bulb then not more than 28 degrees Celsius.
Pedestrians wear scarves to avoid the heat in Amritsar, India. (Photo: AFP/VNA).
3. How is wet bulb temperature measured?
Initially, a wet cloth was wrapped around the thermometer bulb. The scientists will record how much after evaporation cools it, the same way the body cools down by sweating. Now, wet bulb temperatures are measured electronically at weather stations. Further studies are supported by satellite data from sources such as the US Space Agency (NASA) and the International Space Station (ISS).
The National Oceanic and Atmospheric Administration in the US has also developed a more advanced tool to forecast heat stress, global wet bulb temperatures, factors that affect wind speed, surface angles, and more. sky and cloud cover.
4. Where is wet bulb temperature important?
Traditionally, temperatures and humidity are highest in South Asia and subtropical climates. Some parts of India have wet bulb temperatures higher than 32 degrees Celsius. The United Nations predicts this will be one of the first countries to surpass 35 degrees Celsius wet-bulb temperatures. A new El Nino weather
pattern is pushing the mercury line on the thermometer to unprecedented levels in the region. Pakistan, the Middle East and Mexico are also likely to experience high temperatures and high humidity.
However, more and more places, typically temperate regions, are also seeing extremely hot days. Britain recorded a record temperature of 40.3 degrees Celsius in July 2022 and Portugal hit 47 degrees Celsius, but the low relative humidity in both places has kept wet bulb temperatures around 25 degrees Celsius.
Spain and Portugal recorded their hottest April on record in 2023 when a hot air mass brought temperatures near 40 degrees Celsius in some areas at the end of the month. The heatwave comes amid widespread drought that is hitting the region for the second year in a row.
5. What are the economic and social impacts?
In places with extreme heat, every aspect of life becomes more difficult and inequality becomes more acute, especially in cities . But even cooler places feel the effects of the heat, typically due to higher food and energy prices.
For example, India’s scorching hot summer of 2022 reduced wheat production and forced the world’s second-largest producer to ban exports. This raised concerns about global food shortages and inflation amid the war in Ukraine, although India is not a major exporter. This concern could be repeated again this year, affecting wheat, rapeseed and chickpeas. Power consumption also increases during peak heat, straining the grid and consumers’ pockets as prices simultaneously climb. High heat also exacerbates drought, placing additional strain on hydroelectricity and nuclear power generation.
6. How are extreme heat related to climate change?
Heat waves are most directly linked to humanity’s greenhouse gas pollution. And the heat, along with drought and wind, causes wildfires. That’s why scientists now believe climate change is exacerbating wildfires in the western US, Australia and elsewhere. The US wildfire season is two months longer than it was in the 1970s and 1980s.
Global warming is making tropical cyclones, or hurricanes, more intense. Warmer water and wetter air – two results of global warming – fuel such storms. In India and Pakistan, extreme heat is 30 times more likely to occur because of climate change.
