South Asia enjoyed the dubious benefit of being both polluted and poor for decades. Its skies were thick with smog, its fields saturated with groundwater and its atmosphere curiously cooler than expected. Whereas the rest of the planet warmed by 0.27°C per decade, South Asia inched ahead at 0.09°C, an outlier in an overheating world. Scientists dubbed this the “South Asian warming hole”, a phrase as peculiar as the phenomenon it described. But like most holes this one is closing.
The region’s inadvertent climate shield—composed of choking aerosols and evaporating aquifers—is eroding. With air pollution on a slow decline and irrigation reaching its hydrological limits the region is now confronting the full, unfiltered force of global warming. The transformation will be quick and punishing, particularly in the Indo-Gangetic Plain and the Himalayan foothills of Nepal.
Few places illustrate the climate paradox better than South Asia. The same aerosols that turn lungs grey have been keeping the soil cool. Sulphates and carbon particulates scatter sunlight, suppressing surface temperatures even as they wreak havoc on monsoons and human health. This “global dimming” has given the region a peculiar advantage: cooler land temperatures, at least temporarily.
Yet pollution is no longer the policy of least resistance. India’s National Clean Air Programme, launched in 2019, plans to reduce particulate pollution by 40% in 131 cities by 2026. Progress is halting and data often creative, but the trend is unmistakable: as the region breathes a little easier, it begins to burn. In Nepal the story is similar. Kathmandu’s basin traps emissions from traffic, stoves and factories, turning the capital into a soot bowl. Still, moves toward hydropower, vehicle regulation and cleaner fuels are thinning the haze. As clarity returns to the skies, temperatures are beginning to climb.
Another buffer is disintegrating: the region’s dependence on irrigation-fed evaporation is reaching its limits. Irrigation, especially from groundwater, has provided a vital cooling effect by facilitating evapotranspiration—a natural, energy-intensive process that draws heat away from the land. In northern India and Nepal’s Tarai plains, tube wells have long served agriculture and climate mitigation. Now they are running dry.
In Punjab and Haryana water tables have plunged by over a metre a year. In Nepal’s southern belt smallholder farmers report failing boreholes and saline intrusion. A study in Nature Communications suggests without irrigation the number of extreme heat days across the region would rise two- to eightfold. Remove the water and the region’s meteorological mildness vanishes.
What comes next is not gradual discomfort but abrupt danger. Climatologists project South Asia will warm at twice its recent pace over the next two decades. The base level is already brutal. This year parts of Bihar and the Nepali Tarai recorded 44°C before June rains arrived. With humidity, conditions approached the “wet bulb” threshold—where the body can no longer cool itself and death occurs within hours of exposure.
Even conservative forecasts predict by 2047 India will experience four times as many days of extreme heat stress. Should air pollution fall and groundwater dry up—as they almost certainly will—that figure could be wildly optimistic. Nepal meanwhile is acutely exposed. More than half its population lives in the Tarai, a region with scant infrastructure, unreliable electricity, little access to cooling. Urban resilience is sparse and rural adaptability scarcer still.
South Asia’s institutional response to heat has, thus far, been mostly nominal. Municipalities have drafted heatwave action plans, distributed water in buckets and installed occasional shade structures. In Kathmandu a handful of such measures exist—early warning systems, public announcements, vague adaptation targets. None address the structural issues like fragile grids, uncoordinated urban expansion and underfunded health systems.
Air conditioning is a luxury. Only 8% of Nepalese households have access, and blackouts are frequent even in the capital. In rural Tarai districts families depend on hand pumps for water and fans powered by erratic solar panels. These are not conditions under which one adapts to 45°C with grace.
What can be done? At one level the region must sprint to adapt: heat-resilient urban planning, agricultural shifts toward less thirsty crops, mandatory rest breaks for outdoor labourers and investment in public cooling infrastructure. At another it must confront the fiscal and institutional bottlenecks that prevent such change.
Comparisons with East Asia are tempting but misleading. Japan’s transformation from a smog-choked industrial hub to an environmental paragon was financed by an export boom and enforced by a capable bureaucracy. China, too, paired pollution reduction with infrastructural overhaul, underwritten by state-led investment. South Asia has no such luxury. Nepal, in particular, suffers from political volatility and weak central planning. Its National Planning Commission, once the linchpin of developmental ambition, now resembles a filing cabinet for unrealised schemes.
For years South Asia’s climate trajectory looked strangely benign. The region appeared to have dodged the worst of global warming, thanks not to foresight but to filth and overpumping. That is dissolving. The pollutants are thinning, the water is vanishing and the sun, no longer scattered or absorbed, is bearing down with unmediated intensity.
Apocalypse now
Nepal, perched between Himalayan cool and Gangetic heat, must prepare for its climate reckoning. There are no more buffers left. The warming hole is closing. What remains is exposure—raw, unfiltered and deadly, like the searing 45°C recorded in Nepalgunj in May 2023, where classrooms emptied, hospital wards overflowed and even shade offered little reprieve. ■