The Earth is warming because of what humans have been doing to the atmosphere. Global Warming has a lot of effects many of which we’ve discussed here, but the most obvious one is, well, it gets warmer. At present, India is experiencing record breaking heat and people are dying.
It is very difficult to say how many people die from the heat in any region. We can use a standard approach used by epidemiologists to estimate this number. This involves simply looking at mortality rates as they change over time to try to detect a signal, an increase, associated with the variable in question. If all sources of mortality remain the same over a period of time, but a heat wave occurs during that period and with it comes an increase in mortality, then it is possible that those extra deaths are due to the heat. Nothing, of course, is that simple, but epidemiology has some fancy tools to try to tease out reasonable numbers.
I’m reminded of the Ituri Forest, where I worked for a few years. We kept track of births and deaths, and it became apparent that deaths tended to be seasonal. More people seemed to die during the annual “hunger season.” This season occurred around June, when the first wet season crops (there are two wet seasons) were not ready, and the previous wet season’s crops were mostly used up. At the same time, other crops were not abundant and wild foods (both plants and animals) tended to be hard to come by, as the forest experienced a coeval reduction in productivity of human edible foods. But the people who died during that period rarely seemed to die of hunger. They died of other things, such as infectious disease, but presumably these other causes of mortality were more effective when combined with food stress. One hunger season, two people died in a murder-suicide. An elderly couple lived in a small village, alone, with an orphaned grandchild. It was a bad hunger season for them since their village lacked the resources to produce enough food. It is believed the elderly woman, depressed by the hunger, harvested poisonous wild yams and made a meal of them, knowingly, and fed them to her family. She and her husband died, but the child vomited up the deadly meal and survived. Those were hunger-related deaths, but as is the case with many such deaths, were embedded in a much more complicated scenario.
Right now people in parts of India are dying of the heat, but many more than those known to die of heat stroke are also dying in this more complicated way. Indian heat waves are increasing in their frequency, being one third more common by the end of a study period covering 1961-2010, according to a 2014 study. The problem has become worse due to anthropogenic global warming, and it is made even worse in El Niño years. And, we seem to be entering an El Niño period. Changes in land use and urbanization are also probably contributing factors in India.
Heat wave related death spells produce numbers in the hundreds. Something like 500 people are known to have died directly of the heat over the last few days in India. But other deaths caused by multiple factors where heat is a sort of final straw would be in the thousands.
Right now, India is very hot, and some areas are expected to become even hotter over the next several days.
Fred Barbash at the Washington Post has a good writeup on the current situation there.
UPDATE: Jeff Masters has a current write-up of the heat wave in India. At present the death rate (which is certainly an underestimate) for India places it fifth in known historic deadly heat waves.