Global warming is creeping up on South Asia, but not how you’d expect. Despite being one of the hottest regions on Earth, South Asia has warmed far more slowly than the rest of the world. This might sound like good news, but it is not.
Scientists now believe that pollution and over-irrigation have been masking the true rise in temperatures. As these practices decline, the region could face a sudden and deadly surge in heat.
The Toxic Blanket That Has Been Cooling South Asia
South Asia’s surprising immunity to rapid warming isn’t because of clean energy or sustainable development. It is because of something far more sinister: dirty air. Over the past 40 years, the region has become a “warming hole,” a zone where temperatures rose just 0.09°C per decade, far below the global land average of 0.30°C.
The cause? Aerosols are tiny particles from fossil fuels, crop burning, traffic, and industries. These include sulphates, black carbon (soot), and dust. They either reflect sunlight back to space or absorb it before it hits the ground, cooling the surface. While greenhouse gases warm the Earth, aerosols create a toxic sunshade.
The Indo-Gangetic Plain, home to over 500 million people, is one of the most polluted places on the planet. Cities like Delhi, Kanpur, and Patna regularly breach safe air quality levels. Aerosols in this region have not only contributed to respiratory illnesses but have also offset global warming by up to 0.4°C, according to the IPCC.
But there is a catch. As India reduces air pollution, especially under the National Clean Air Programme (NCAP), this artificial cooling will disappear. A Harvard study warns that cleaner air could unleash hidden warming, accelerating climate risks. The aerosol curtain is lifting, and what it reveals could be dangerous.
Loretta Mickley, Harvard University Atmospheric Chemist, warns, “If India continues to clean up its air, the cooling effect of aerosols will disappear, and we will see temperatures spike in ways we are not ready for.”
Cooling The Air, Draining The Ground
Another surprising reason South Asia stayed cooler? Water. As irrigation expanded, especially across Punjab, Haryana, and Uttar Pradesh, it added moisture to the air. Water evaporates and cools the surrounding area, a process known as evaporative cooling.
Since 1980, India’s irrigated land area has doubled. A 2020 study in Nature Communications estimated that without widespread irrigation, South Asia would have experienced two to eight times more extreme heat days than it currently does. While this helped delay warming, it came at a cost: rapid groundwater depletion. Dr Rohini Kumar, Climate Scientist, Helmholtz Centre for Environmental Research, says, “Without irrigation, South Asia would have experienced two to eight times more extreme heat days. But now the water is running out.”
Today, water tables are falling fast. According to the Central Ground Water Board, many parts of North India are in a semi-critical or over-exploited state. As groundwater runs dry, irrigation will inevitably decline. When that happens, the cooling effect will vanish and temperatures will rise fast.
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When Pollution and Irrigation Decline Together
Both aerosols and irrigation cool the land only as they increase. Once they stop growing or begin to drop, the masked warming kicks in. That is what is starting to happen in India.
At a scientific summit in Delhi, Dr David Battisti of the University of Washington warned that over the next 20 years, India is “pretty much assured” to warm at twice the rate of the past 20 years. Dr Daniel Schrag of Harvard echoed this, saying India’s temperatures could soon rise faster than the global average.
This means even if emissions remain stable, the hidden warming from past decades will now start showing. With groundwater scarcity limiting irrigation and air quality policies reducing aerosols, India could face a perfect storm of rising heat.
The Heat Is Already Here
The danger isn’t just theoretical. In 2024, temperatures in parts of India, like Nagpur, Delhi, and Jhansi, hit 44°C even before peak summer. More than 40% of people facing strong or extreme heat stress globally now live in South Asia.
The Universal Thermal Climate Index (UTCI) shows how humidity worsens the danger. A “feels-like” temperature of 45°C with 50% humidity is near the limit of human survivability. In cities like Kolkata, Lucknow, and Ahmedabad, this threshold is being crossed more frequently.
Despite this, heat mitigation in urban India remains weak. A 2022 Hindustan Times analysis showed that while cities like Ahmedabad and Surat have heat action plans, most cities are not doing enough to ensure water access, shade, or green cover.
Can Sustainable Development Keep Up?
India’s efforts to fight air pollution and protect water must now go hand in hand with climate adaptation. The National Clean Air Programme aimed to cut particulate matter by 30-40% by 2026; however, most cities missed the 2024 target. Nevertheless, improved monitoring has shown some pollution reduction, offering hope.
Meanwhile, policies like the National Solar Mission, PM-KUSUM for solar irrigation pumps, and urban cooling initiatives show that India is trying to integrate sustainability into its future. Increasing tree cover, green roofs, and reflective building materials could help cities adapt to the new heat reality.
Other countries have led the way. Japan, once heavily polluted, passed strict laws in the 1970s and drastically cleaned its air. China has also significantly reduced aerosol levels over the past decade. India must learn from these examples and move fast.
The Calm Before The Scorch
What looks like a climate miracle in South Asia is actually a mirage, one built on smog and overuse of water. As we clean the air and face water scarcity, temperatures will rise dramatically. According to projections, by 2047, the average Indian could experience four times more days of dangerous heat stress.
Dr R. Ramanathan, Atmospheric Scientist, UC San Diego, says, “What we thought was protection was actually pollution. Now that it is clear, the real climate crisis will begin.”
Without urgent reforms, rising temperatures could lead to mass health crises, lower productivity, and even climate migration. Cleaner air and sustainable farming are non-negotiable, but so is preparing for the heatwave future that is no longer just coming. It is already here.
Image Credits: Google Images
Sources: The Economist, Hindustan Times, Firstpost
Find the blogger: Katyayani Joshi
This post is tagged under: climate change, heatwave crisis, South Asia climate, aerosol cooling, India environment, sustainable development, global warming, urban heat, air pollution, irrigation crisis, climate adaptation, clean air mission, groundwater depletion, heat action plans, extreme heat, Delhi pollution, India heatwave, environmental policy, climate resilience, future of India
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