India May See High Wet-Bulb Temperature In Summer: How Can It Affect Your Body?

"This summer may push India closer to the limits of human survival," environment policy expert Peter Dynes wrote.

Wet bulb temperature explained: What is wet-bulb temperature that experts are worried of?

(Image: Aroop Mishra/Quint FIT)

As we gear up for summer this year, experts are already warning of people living in the Indian subcontinent of the extreme temperatures and impending heatwaves that await us in the months to come.

The latest warning comes from environmental policy expert Peter Dynes, who has predicted a serious risk of 'dangerous wet-bulb temperatures' in parts of India.

"This summer may push India closer to the limits of human survival," he wrote, in a viral tweet.

What is wet-bulb temperature? How is it different from regular outdoor temperature? And more importantly, how does it impact your health?

FIT explains.

What Is Wet-Bulb Temperature?

Wet-bulb temperature is the temperature of the environment determined by not just the heat in the area, but also the humidity. The human body can't tolerate wet bulb temperatures that cross 35°C.

The presence of high humidity in the air prevents sweat from evaporating efficiently, and so your body can't compensate for the heat outside by simply sweating.

Multiple parts of India like Rajasthan, Maharashtra, Tamil Nadu and Andhra Pradesh recorded temperatures crossing 45°C in March and April 2022. This heat coupled with humidity in the 40 -65 percent bracket creates extremely high wet-bulb temperatures.

What Happens If The Wet Bulb Temperature Gets Too High?

The human body's internal temperature is around 36.8°C. When the outside temperature falls or rises our bodies compensate by either sweating to cool off or warming ourselves up by burning fat.

But here are the two important points about sweating and heat:

• When we sweat, the body cools off, but only if the sweat evaporates from our skin.

• Our bodies can only cool themselves up to a certain extent. Air conditioning and cool water can help ease this.

Beyond a certain point, our bodies will overheat and we experience fatigue, dehydration, confusion, cramps, and eventually heat stroke and death.

Now the sweat on our skin can only evaporate if atmospheric moisture and water content is low enough to allow this to happen. This is where relative humidity comes into the equation. Sweat can't evaporate well if you're in a humid place with high atmospheric moisture content.

Typically, the average outside temperature needs to reach 55°C to create a wet-bulb temperature of above 32°C.

However, with India's high humidity, many parts of the country have already reported wet bulb temperatures crossing this dangerous threshold.

The equation for calculating wet bulb temperature is kind of complex, so here's a calculator to simplify it.

India's Heat Crisis: Not An Optimistic Future

As we mentioned earlier, wet bulb temperatures that exceed 35°C can be life-threatening.

32°C is the normal wet bulb temperature threshold that most humans can continue working and functioning in without major issues. But many parts of India already report wet bulb tempertatures exceeding 32°C, especially in coastal states where the humidity generally tends to be high.

The Economist tracked weather data from six big cities across the country to arrive at some troubling conclusions.

Wet-bulb temperatures crossed 32°C in four of the cities in the last five years.

On 1 May 2022 the wet bulb temperature in Chennai touched 32.6°C, the highest in a decade.

Kolkata and Ahmedabad both reported uncomfortably high wet bulb temperatures of 31°C in 2020, as well.

While Delhi became even hotter, crossing the 40°C mark, it recorded a lower wet-bulb temperature of around 24°C because of relative humidity staying at just under 24 percent.

However, Delhi isn't immune either, recording wet bulb temperatures of 32°C in 2018.

Multiple weather stations including Lucknow, across other parts of India also reported the all-time highest temperatures they've ever recorded in the months of March and April 2022.

This, coupled with the wealth gap making air conditioners a luxury that most of India cannot afford, will mean the deaths of millions of Indians from heat-related problems.

What Can We Do About It?

One immediate solution would be to find affordable ways to provide air conditioning, hydration, and "cool off" zones for everyone, which may not be the most doable considering India's population of more than 1.7 billion.

The obvious solution is putting an end to climate change. But, according to studies, even if we limit climate change now the earth will get hotter by 1°C by the end of the 21st century.

Experts argue that a spike in health issues and even fatalities related to high temperatures is inevitable in the near future, however long term measures to minimise the impact of climate change is the only way to ensure any kind of sustainable respite.