India's climate crisis: Early heatwaves, Himalayan glaciers melting and a biodiversity collapse

Climate Change & You’ is a fortnightly newsletter by Bibek Bhattacharya and Sayantan Bera. Subscribe to Mint's newsletters to get them directly in your email inbox.

Dear Reader,

Even a few years ago, it would have seemed ridiculous to suggest that Delhi might hit a daytime high of 40 degrees Celsius in late March. The climate crisis, though, has a way of turning even the most unthinkable weather phenomena into the new normal. And so it came to pass that on 26 March, Delhi touched a scorching 40.5 degrees Celsius. It was a seasonal high, beating the heat record from just the previous day—that of 37.1 degrees Celsius.

The daytime temperature on the 26th was 6.3 degrees Celsius above normal for this time of the year, and over the years, the hottest March day has been getting hotter: 37.8 degrees Celsius in 2024 and 34.3 degrees Celsius in 2023. But this isn't an isolated anomaly. Heat has been striking ridiculously early all across India, and it is now clear that our seasons are shifting, sometimes by a whole month. This shift in seasons (or the complete erasure of specific seasons) is striking enough that even ordinary people can feel and comment on it.

However, this is also evident in hard data. Hindustan Times analysed the India Meteorological Department's (IMD) temperature-gridded data and found that the key heat threshold temperature of 40 degrees Celsius arrives earlier across the country and lasts longer. The analysis found that 56.7% of the regions that crosses 40 degrees Celsius each year hit the mark a week in advance.

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The IMD has warned of an intensely hot summer this year, especially in Northwest India. While Northwest India usually experiences about five to six heatwave days every summer, this year, this could rise to 10-12 days, double the normal. The question is, will 2025 be as hot as last year? 2024 was India's hottest year on record, with 554 heatwave days. The IMD has forecast above-normal day and nighttime temperatures across the country between March-May,

STATE OF THE CLIMATE

Since November 2024, it has been evident that last year was the hottest the world had seen in 175 years when records began. This fact was confirmed by the World Meteorological Organization's (WMO) State of the Global Climate Report 2024, which was published on 19 March.

The world's hottest decade has been in the last ten years, and 2024 shattered all heat records, as the global average temperature was 1.55 degrees Celsius hotter than the pre-industrial baseline. This is especially alarming when the international effort against climate change is to limit warming to a 1.5-degree Celsius rise by 2100. At this rate, our planet will likely cross 1.5 degrees of warming permanently by the end of this decade.

Of course, this is being caused by planet-heating carbon emissions due to human industrial activity and intense energy use. In 2024, CO2 emissions hit 420ppm (parts per million), a whopping 151% above pre-industrial levels. The report also notes that emissions are rising at a time when they should be falling dramatically. Methane and nitrous oxide levels, too, hit record levels last year.

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No wonder, then, that people around the world experienced extreme weather events. According to WMO's data, there were 152 unprecedented weather events in 2024, the most significant being heatwaves, followed by extreme rains and floods. In the count, the WMO included India's intense heatwaves from May and June last year. Between 30 March and 2 June, over 200 people died due to intense heatwaves across Bihar, Uttar Pradesh, Odisha, Chhattisgarh and Maharashtra. The report also mentions other unusual weather events in India, like excessive lightning strikes in north India during the monsoon and the disastrous Wayanad landslide in Kerala in July.

THE NEWS IN BRIEF

-In this primer for Mint, my newsletter co-author Sayantan Bera explains the forecasts of extreme heat in India in 2025 and how that would affect our economy.

-How does one read the omens of India's climate breakdown? In my latest column, I track how India's seasons are shifting and, in some cases, disappearing altogether.

-The IMD is seeking to improve its weather prediction models by installing more radars and automated stations. This article explores how India's Met department hopes to provide panchayat-level forecasts by 2026.

CLIMATE CHANGE TRACKER

Himalayan glaciers melt away

The Hindu Kush Himalaya (HKH) region, comprising ranges such as the Himalaya, the Hindu Kush, the Karakoram, the Pamirs, Kun Lun Shan, and others, is often called the Third Pole. This is because it is home to 87,340sqkm of glaciers, the largest concentration of ice and snow outside the two poles.

However, snow and ice in the region are collapsing at an alarming rate due to climate change. The unprecedented rate of glacial loss in major ranges such as the Himalayas was confirmed by both the WMO report and a separate Unesco report on the world's glaciers, released on 20 March.

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The main finding that pertains to the HKH is that the glaciers in the region melted 65% faster in 2011-2020 than in the decade before that. If we limit heating to 1.5-2 degrees Celsius by 2100, the HKH will lose up to 50% of its glaciers. If warming exceeds this limit, 65% or more of the glaciers may be gone by the end of the century. The study also finds that glaciers in the eastern Himalaya are melting faster than the global average.

This degree of glacier loss is catastrophic. The HKH is the source of over ten major river systems (including the Ganga, Brahmaputra and the Indus) that support nearly 2 billion people who live downstream. As the world heats up, and Himalayan glaciers melt away, perennial rivers like the Ganga, Indus and the Brahmaputra will soon flood and then run dry.

KNOW YOUR JARGON

Biodiversity Loss

Human environmental pressures on the planet, such as pollution, habitat changes, and climate change, are causing unprecedented biodiversity loss. Basically, human activity is killing off our partner species on the planet. A recent synthesis of over 2,000 studies found that human pressures have decreased local biodiversity across the planet. This die-off is especially being recorded among reptiles, mammals, and amphibians.

Last year, the annual Living Planet Report, prepared by the World Wildlife Fund, found that global wildlife populations have declined by 73% between 1970 and 2020, with an annual decline of 2.6%. The index monitors nearly 5,500 species around the world. According to the report, while marine and terrestrial animals have declined by 56% and 69%, respectively, freshwater species have declined by 85%.

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The most significant declines have been in Latin America and the Caribbean (95%) and Africa (76%), while Asia Pacific, North America and Europe and Central Asia registered 60%, 39% and 35% respectively. This global loss of biodiversity has been referred to as the sixth extinction. There have been five known extinction-level events over the last 445 million years, four due to natural processes and the last and most recent due to an asteroid impact.

In February, the COP16 global summit on biodiversity established the "Cali Fund", under which governments worldwide have pledged to mobilize $200 billion annually by 2030 to finance global biodiversity conservation goals.

PRIME NUMBER

36

This is the number of fossil fuel companies responsible for half the world's planet-heating carbon emissions. According to the Carbon Majors database, in 2023, 169 companies emitted 33.9 gigatons of CO2 equivalent (GtCO2e) into the atmosphere. These emissions accounted for 78.4% of all global fossil fuel and cement emissions for the year. Just 36 state-owned and private firms were responsible for 50% of these emissions.

Of these 36 firms, Coal India, with 3.68% of these emissions, was the second highest contributor after the Saudi Arabia-owned oil company Aramco. Other firms on the list include private entities such as Shell, ExxonMobil, BP, and Chevron, as well as state-owned ones like China's CHN Energy and Iran's National Iranian Oil Company.

The Carbon Majors database is maintained by InfluenceMap, a global nonprofit think tank, and contains historical emissions data from 1854 to 2023. It has gained international importance in recent years, with its data being cited as evidence in important lawsuits in the US that seek compensation from fossil fuel companies for damage caused by climate change. Coal India is responsible for 1.53% of historical emissions and is at number 10.

BOOK OF THE MONTH

The Sixth Extinction: An Unnatural History by Elizabeth Kolbert

When journalist Elizabeth Kolbert's landmark book was published in 2014, it revolutionized how we view the influence of human beings on the planet. The Pulitzer Prize-winning book joined the dots to show how human impact kills off other species at a rate comparable to the five previous mass extinction events in the Earth's history.

Kolbert's incisive reportage and vivid, conversational writing style make the book especially powerful. It was also one of the first books to show how climate change affects biodiversity loss worldwide. Her follow-up book, 2022's Under A White Sky, is another classic, butThe Sixth Extinction remains a work of genius.

So that's it for this edition of Climate Change and You, dear Reader. See you again in a fortnight when Sayantan writes the newsletter.

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