This column has been tracking the effects of increasing heat, the calling card of the climate crisis, for many months now. And yet, almost every passing week offers a new clue to how the world is going to change in the not-so-distant future because of rising temperatures.
This week, a fresh correlation has been drawn between heat stress and global deaths in a study prepared by the US-based Climate Impact Lab and published by the American policy think tank National Bureau of Economic Research. A part of the institution’s working paper series, Valuing The Global Mortality Consequences Of Climate Change Accounting For Adaptation Costs And Benefits posits that by 2100, global mortality rates could be as high as 221 deaths per 1,00,000 people. This is the rough equivalent of all global deaths due to cardiovascular disease today.
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In countries with higher incomes, this mortality rate decreases to 104 deaths per 1,00,000 people. Accounting for adaptation to climate change impacts reduces this further to 73 deaths per 1,00,000 people. But even this number, the study says, will be almost as high as present death rates due to infectious diseases like AIDS, dengue, malaria and tuberculosis. The study gathered data on mortality and heat from 41 countries (including India), covering 55% of the global population. However, India’s data wasn’t used in the final calculation as the country doesn’t register age-wise mortality data.
The paper looks at the global economic costs of such deaths. In the business-as-usual scenario of greenhouse gas (GHG) emissions, these deaths will cost the world 3.2% of its economic output by 2100. In a high emissions world, every metric tonne of CO2 released into the atmosphere will cost the world $36.6 (around ₹2,740) in damages. In a mid-emissions scenario, where the world goes carbon neutral by 2050, this will reduce to $7.1.
Be it deaths or costs, ultimately poorer, already heat-stressed nations are going to bear a heavier burden. “The data show that poor communities don’t have the means to adapt, so they end up dying from warming at much higher rates,” says Tamma A. Carlton, an environmental economist at the Bren School of Environmental Science and Management at the University of California, and a co-writer of the report. According to an interactive map on the Climate Impact Lab website, a high emissions scenario would see mortality costs for India rise to 4% of the GDP by 2080. It will be as bad, if not worse, for all South Asian countries.
Meanwhile 2020 is well on its way to becoming either the hottest or the second-hottest year on record. And, as this column noted earlier, on 26 May, Delhi recorded an 18-year high of 47.6 degrees Celsius, while Churu in Rajasthan touched 50 degrees Celsius. This was during an intense heatwave that swept through north India this summer. In 2019, a study conducted by the Climate Impact Lab in collaboration with the Tata Centre for Development (TCD) said that around 1.5 million more people may die in India each year due to extreme heat by 2100. The only way to avoid this fate is to cut GHG emissions drastically and quickly.
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