What if summers in India turn 8-month long?

The world is getting not only hotter but also more humid.

As a result of global increases in both temperature and specific humidity, heat stress is projected to intensify throughout the 21st century. Some of the regions most susceptible to dangerous heat and humidity combinations are also among the most densely populated.

The combined scientific measure of heat and humidity is called wet-bulb temperature, which hardly ever crossed 32°C between 1985 and 2005. The nature of such heat waves has since changed because of rapidly growing greenhouse gas emissions, exacerbating climate change.

India’s energy future could tip the scales of global climate change, but the extreme weather is already here. The Indo-Gangetic Plain, also known as the Indus-Ganga Plain and the North Indian River Plain, is one of the world’s most climate-sensitive regions. The wet-bulb temperatures currently touch 31°C, on average, one day every year. By the 2070s, these heat waves may become 100 to 250 times more frequent, said the study by Environmental Research Letters. It may breach 35°C, the maximum heat that humans can endure, giving rise to new diseases. And, air pollution has already made India slip to 177th position in green rankings.

The people working outdoors with no access to air conditioning are more vulnerable to lower productivity, heat stroke and in the worse case, to death caused by heat than the people working indoors. Many of India’s poor farmers would fall in this category. In addition, any existing health problems, especially cardiovascular and respiratory conditions, make heat illness more likely. People without access to safe water will be particularly at risk of rapid dehydration in extreme heat waves.

If greenhouse gas emissions are not cut, we would approach a time when every human outdoor activity would be impacted by the wet-bulb temperature.