The National Weather Office has forecast rising temperatures in the coming weeks after India experienced its hottest February since 1901. That raised concerns that last year’s record heatwave would be repeated. , causing widespread crop damage and lasting hours. power-off. While temperatures as high as 50 degrees Celsius (122 degrees Fahrenheit) are unbearable under any conditions, the damage is worse for India’s 1.4 billion people stranded. in crowded cities and without access to housing or fresh air. -air conditioning.
“Heat stress for humans is a combination of temperature and humidity,” said Kieran Hunt, a climate researcher. scientist at the University of Reading, who studied the country’s weather patterns. “India is generally wetter than comparable hot places, like the Sahara. This means sweating is less effective or not effective at all.”
This is why in India, a measurement known as the wet bulb index — a combination of air temperature and relative humidity — provides a better measure of heat stress on the body. human body. November report of World Bank warns that India could become one of the first places in the world where wet bulb temperatures can surpass the survivable threshold of 35°C. “The question is, are we used to heat-induced suffering?” speak Abhas Jha, one of the report’s authors. “Because it wasn’t a disaster that happened suddenly, because it started slowly, we didn’t reverse it.”
While there is no country unaffected by global warming, there are many reasons that make India an exception. The following interview with Hunt, which considers those factors, has been edited for length and clarity.
What is the climate science behind India’s more intense heatwaves?
It helps to separate the temperature of a heat wave into two parts — the background or average monthly temperature, and the anomaly or part added or subtracted by the specific weather that occurred at the time. In India, since pre-industrial times, the base has increased by about 1.5°C. Therefore, everything else being equal, today’s heatwave weather pattern would involve temperatures about 1.5°C warmer than those occurring a hundred years ago. There are other confounding factors: in some cities, the urban heat island effect has added about 2°C to the background. Deforestation also contributes.
Why do they happen more often?
This can also be divided into two parts. Firstly, the Indian government definition of heatwave is fixed, so as the base temperature rises, fewer strong anomalies are required to cross the threshold of the heatwave definition. Second, it appears that the weather patterns – high pressure over northern India, leading to dry, sunny, clear conditions with weak winds – associated with these anomalies are also increasing in frequency.
And what makes them more dangerous?
Hotter heat waves, in which temperatures are higher for longer periods of time, tend to lead to more deaths. In India, this is exacerbated by rapid population growth over the past few decades.
[The danger lies with] India’s temperature is already too high. In May, for example, the only places on the planet with temperatures comparable to northern India are the Sahara Desert and parts of the inland Arabian peninsula, both of which are very sparsely populated. With temperatures already too high, above 40°C, even a slight increase is likely to push humans close to the limit of survival.
How do heat waves affect people?
There are wide-ranging effects on Indian society. Prolonged heat waves lead to significant soil drying over large areas. Besides the obvious impacts on agriculture, this could impact the monsoon that starts a month later… and could negatively affect agriculture, water security and even lead to local flooding. walk when heavy rain makes the soil dry and cannot be absorbed.
Unusually hot periods before the monsoon are also associated with reduced productivity, especially in outdoor sectors such as agriculture and construction; increased cooling demand, which can overload the grid and lead to increased greenhouse gas emissions; and general health risks, such as heatstroke, affect children, the elderly and low-income communities.
So what can be done to minimize the damage?
Some ideas often talked about in this context are, at the policy level, implementing urban planning guidelines that prioritize green space, shade and ventilation in building design. They are becoming increasingly popular in many Mediterranean cities. At the corporate level: invest in research and development of low-energy cooling solutions, such as passive cooling systems, and promote energy-efficient building designs. And for the community, encourage the use of cool roofs, green roofs, planting trees to reduce the urban heat island effect.
What will India’s future look like as the planet continues to heat up?
Currently, India sometimes crosses a bit [a wet-bulb temperature of] 32°C, so we need more heating to reach the limit of survivability. That said, with increasing urbanization, the urban heat island effect and more warming, the risk of fatal heat waves is always increasing.
