The death toll from India’s horrid May heat wave has risen to 1,826, making this year’s heat wave the second deadliest in India’s recorded history–and the fifth deadliest in world history. According to statistics from EM-DAT, the International Disaster Database, India’s only deadlier heat wave was in 1998, when 2,541 died. With over 400 deaths recorded in just the past day and the heat expected to continue over India for another week, the 1998 death toll could well be exceeded in this year’s heat wave. However, death tolls from heat waves are very difficult to estimate, since excess heat is typically not listed as the primary cause of death in cases where the victim has a pre-existing condition such as heart or lung disease. For example, the U.S. National Climatic Data Center (NCDC) lists the total direct deaths from the U.S. heat wave of 1980 at 1,260, but estimates that the combined direct and indirect deaths (i.e., excess mortality) due to heat stress was 10,000. Below is the list of top ten deadliest heat waves in world history as compiled by EM-DAT, the International Disaster Database, which uses direct deaths for their statistics, and not excess mortality.
The 10 Deadliest Heat Waves in World History
1) Europe, 2003: 71,310
2) Russia, 2010: 55,736
3) Europe, 2006: 3,418
4) India, 1998: 2,541
5) India, 2015: 1,826+
6) U.S. and Canada, 1936: 1,693
7) U.S., 1980: 1,260
8) India, 2003: 1,210
9) India, 2002: 1,030
9) Greece and Turkey, 1987: 1,030
It’s the heat and the humidity
Temperatures across much of India have been 5°C (9°F) above average this May, with very high humidity. In many of the hardest-hit areas of eastern India, the heat index dropped below 100°F for only four hours each night for several consecutive days this week. This sort of day-after-day heat stress is very hard on vulnerable people, and leads to high mortality. For example, in Channai (Madras) on May 24, the high temperature reached 108°F and the heat index topped out at 123°F, and never dropped below 97°F the entire day. Far more extreme heat index values have been observed in some areas. For example, on May 23 at 14:30, Bhubneshwar recorded a temperature of of 42.2°C (108°F) with a dew point of 29.3°C (84.7°F), giving an astonishing heat index of 62°C (143.6°F.) According to weather records researcher Maximiliano Herrera, a heat index of up to 65°C (149°F) has been measured at some stations in eastern India during the heat wave.
Climate change and India
This year’s deadly heat wave in India was made much more probable by the fact that Earth is experiencing its hottest temperatures on record–the past twelve months were the warmest twelve-month period in recorded history, and so was the January – April 2015 period. According to the India Meteorological Department, a warming climate increased heat waves in India by a third between 1961 to 2010. As the planet continues to warm due to human-caused global warming, heat waves will become more frequent and more intense, and heat-related deaths will soar unless we take strong measures to adapt. An April 2015 paper published in Regional Environmental Change, Intensification of future severe heat waves in India and their effect on heat stress and mortality, warned that “heat waves are projected to be more intense, have longer durations and occur at a higher frequency and earlier in the year. Southern India, currently not influenced by heat waves, is expected to be severely affected by the end of the twenty-first century.” Perhaps a bigger concern for India with climate change is drought, though. Many climate models show that climate change might increase the average rainfall in India from the monsoon, but when dry years occur, the hotter temperatures accompanying the dry years will drive much more intense droughts capable of causing significant challenges to growing food in India.
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