Heat stress will aggravate in 9 Indian cities every year: Report
Kolkata continues to be the worstaffected among 44 cities in study
NEW DELHI: At least 9 major cities in India will witness intensifying heat stress even if 2015 Paris climate targets are achieved. They could experience extremely hot days every year in the future, a new study has said.
The study, published on Monday in US journal Proceedings of the National Academy of Sciences, looked at 44 cities across the world. Kolkata, Bengaluru, Delhi, Mumbai, Chennai, Pune, Surat, Hyderabad and Ahmedabad were selected from India.
The Paris Agreement seeks to limit the usage of fossil fuels in the world in the second half of the century, limiting the rise in average world temperatures to “well below” 2°C above preindustrial times.
The study said at the global level, a warming of 1.5°C above the pre-industrial time will feed into heat stress that is 5-6 times worse than in the recent past (1979-2005) and 350 million people in these 44 megacities will face heat stress year after year.
It added Delhi, Kolkata, Chennai and Ahmedabad are already affected and that the West Bengal capital is the most heatstressed among the 44.
Heat stress broadly refers to the human body experiencing more heat than it can tolerate, and is calculated using the heat index that incorporates both air temperature and humidity.
Junior minister for science and technology and earth sciences, YS Chowdary, told Lok Sabha this week that “frequency of severe heat waves increased sharply in recent years.”
Heat stress burden is greater in places with more people because the impact of the heat is larger and it is the “perfect storm,” Tom Matthews, a climatologist at Liverpool John Moores University in the UK who led the study, told HT.
“The challenge posed by heat stress is likely to increase in the future because of two things: Rising air temperatures from global warming and population growth,” Matthews explained.
This is especially true for Kolkata, which will likely remain the most heat-stressed city of the century. Its population could be 3 times higher by the end of the 21st century and even if temperatures do not rise, heat stress would increase.
“The climate will continue to warm, so both factors will drive up the heat stress challenge,” Matthews added. If global average temperatures rise by 1.5°C, Mumbai will be added to the list of heat-stressed cities.
With a 2.7°C warming, that might be the result of the currently pledged targets for emissions reductions, both Hyderabad and Pune will become heat stressed. With 4°C warming, Bengaluru will also enter the heat stressed zone. Heat wave conditions usually form in India between March and June. Experts have listed increasing greenhouse gas emissions and the warming of the sea surfaces over the equatorial Indian and Pacific Oceans as factors.