High heat and humidity will take an increasing toll in death and ill-health in India and other tropical countries unless global temperature rise is limited to 1.5 degrees Celsius
By Soumya Sarkar
La Niña, a weather pattern in the Pacific Ocean, usually heralds a cooler Indian summer. But that’s not going to happen this year, going by early summer temperature predictions by the India Meteorological Department. And perhaps never, as average temperatures rise across India in the wake of global warming.
Declaring the onset of summer, the Met department said in its seasonal outlook from March to May that maximum temperatures will be above normal in most parts of northern India and the southern peninsula.
“Currently, moderate La Niña conditions are prevailing over the equatorial Pacific and sea surface temperatures are below normal over the central and eastern equatorial Pacific Ocean. The latest MMCFS (Monsoon Mission Coupled Forecasting System ) forecast indicates that La Niña conditions are likely to sustain during the upcoming hot weather season,” the Met said in its outlook.
Although La Niña usually means cooler temperatures in India in the summer, it does not seem to hold true this year.
“The La Niña’s cooling effect has started diminishing. We have seen 30 degrees Celsius plus temperatures in the last week of February in the past also, but this time the average maximum temperature is definitely higher,” Kuldeep Shrivastava, head of IMD’s regional weather forecasting centre, said.
The year 2020 was tied with 2016 for the hottest year since reliable records have been kept, as global warming linked to greenhouse gas emissions have shown no signs of diminishing, despite a significant fall in human activity due to lockdowns imposed in large parts of the world to contain the Covid-19 pandemic.
Intense heatwaves
India will face worse heatwaves unless urgent action is taken, according to the Indian government’s first comprehensive report on current climate change impacts and future scenarios till the end of the century.
India’s average temperature has risen by around 0.7 degrees Celsius during 1901-2018, said the Assessment of Climate Change over the Indian Region, a report by India’s Ministry of Earth Sciences.
Unless steps are taken, average temperature over India will rise by approximately 4.4 degrees Celsius relative to the recent past (1976–2005 average) between 2070 and 2099, the report said in June 2020.
Such rise in temperatures will have dire consequences for Indians. Unless emissions are cut sharply to curb global warming to 1.5 degrees Celsius from pre-industrial times, large parts of the tropics will see increasing episodes of high heat and high humidity that go beyond the limits of human survival, according to new research.
The research, published in March in the Nature Geoscience journal, focused on tropical regions between 20 degrees latitude north and 20 degrees latitude south, which are some of the hottest places on the planet. The region, home to over three billion people, includes South and East Asia, Central America and Central Africa.
The study — Projections of tropical heat stress constrained by atmospheric dynamics — looked at the so-called wet-bulb temperatures, which accounts for a combination of heat and humidity, and how much people can cool off during extreme heat by sweating.
Intolerable heat
The study found that if global temperature rise is limited to 1.5 degrees, wet-bulb temperatures will not exceed 35 degrees in the tropics. The human body cannot cool down above a wet-bulb temperature of 35 degrees Celsius because body sweat can no longer evaporate.
Prolonged exposure to such conditions could prove fatal even to healthy people, the researchers said in the study. The effects of high heat and humidity is worse for women, children and the elderly, scientists have found.
Increasing heat-related deaths due to climate change has revealed an unequal world, with people in poorer countries at much higher risk, according to an August 2020 study.
In the largest international study till now on health and financial impacts of temperature-related deaths, the Climate Impact Lab said climate change’s effect on temperatures could raise global mortality rates by 73 additional deaths per 100,000 people in 2100 under a continued high emissions scenario, compared to a world with no warming.
Working outdoors, which is a must for the majority of poor people in India engaged in farming and construction, is likely to worsen the effects of extreme heat.
“The data show that poor communities don’t have the means to adapt, so they end up dying from warming at much higher rates,” said study co-author Tamma Carleton of the University of California. “In poor hot countries, the heat may be even more threatening than cancer and heart disease are today,” said Michael Greenstone of the University of Chicago, another co-author of the study.
This is not the first time a study has revealed the stark inequality in the effect of ambient temperatures on death in human populations.
Using district-level daily weather and annual mortality data from 1957 to 2000 in India, researchers at the Energy Policy Institute at the University of Chicago (EPIC) in 2017 found that hot days led to substantial increases in mortality in rural but not urban India.
An October 2019 study by the Climate Impact Lab had found that by 2100, around 1.5 million more people are likely to die every year in India as a result of climate change, a rate that is as high as the death rate from all infectious diseases in the country today.
High rise
With continued high emissions, the average annual temperature in India is projected to increase from about 24 degrees Celsius to about 28 degrees by the end of the century, the 2019 study had found.
“These findings are a reminder that we have to keep making concerted, long-term efforts to build resilience to extreme heat,” Kamal Kishore, a member of India’s National Disaster Management Authority, had said in October 2019.
Extreme heat is an occupational health hazard, the International Labour Organisation said in a report in 2019. Most people can work only at half their capacity when temperatures are high, it said in the Working on a Warmer Planet report.
South Asia and West Africa are expected to be the worst affected because of high heat and humidity, and the high levels of poverty in these regions, the ILO had said. Impoverished communities are less capable of adapting to extreme temperatures and have low or no cooling options, either at work or at home.