Extreme heat poses existential threat to India's workers, Harvard report warns

India faces an accelerating heat crisis that threatens the health, livelihoods, and economic stability of hundreds of millions of people — and current policy responses are failing to keep pace, according to a new white paper published in April 2026 by Harvard University's Salata Institute for Climate and Sustainability.

The report, Critical Perspectives on Extreme Heat in India, draws on an interdisciplinary workshop held in New Delhi in March 2025 and brings together 17 authors spanning climate science, public health, medicine, urban planning, labor law, and finance. Its conclusions are stark: India's adaptation tools — from heat action plans and cool roofs to parametric insurance — are individually insufficient, poorly implemented, and in some cases misaligned with the realities of those most at risk.

A Crisis Already Underway

The report -- produced with institutional support from the Lakshmi Mittal and Family South Asia Institute at Harvard University and India's Ministry of Environment, Forest and Climate Change -- opens with a sobering assessment of India's warming trajectory. 

Area-averaged maximum temperatures have risen by approximately 0.28°C per decade since 1980, with 2025 recorded as the warmest year on record. Around 380 million workers — roughly three-fourths of the country's workforce — are engaged in heat-exposed labor, spanning agriculture, construction, and the informal economy. Up to 200 million people could face lethal heat conditions as early as 2030, the report warns, citing projections from the International Labour Organization.

Yet the adaptation gap remains severe. Only about 8 percent of Indian households currently have access to air conditioning, leaving the vast majority of the population with limited means to cope with rising temperatures.

Critically, the report cautions that even India's observed warming trends may be understating what lies ahead. Climate scientist Peter Huybers of Harvard explains that the Indo-Gangetic Plain — among the most densely populated and agriculturally vital regions on Earth — has actually seen cooling of winter daytime temperatures since 1980, driven by aerosol pollution and expanding irrigation. Both of these suppressive mechanisms are now under threat: India's clean air programs will reduce aerosol loading, while groundwater depletion across Punjab, Haryana, and the western Ganges basin will eventually constrain irrigation intensity.

"The historical temperature record cannot be taken at face value as a planning baseline for Northern India," Huybers writes. Heat action plans, agricultural forecasts, labor protections, and financial instruments calibrated to historical averages "risk systematic underestimation of the exposures populations will face."

"How Hot Is Too Hot?" — A Question Without a Simple Answer

A central chapter of the report challenges the popular framing that a wet-bulb temperature of 35°C represents the physiological limit of human survival — a threshold frequently cited in scientific and policy discourse. The authors, including emergency medicine physician and lead editor Dr. Satchit Balsari of Harvard Medical School, argue that this framing is both scientifically contested and dangerously incomplete.

Recent laboratory studies suggest the true physiological limit for thermoregulatory failure is considerably lower — potentially as low as 26°C wet-bulb under hot, dry conditions for young healthy adults. But the report notes that this research was conducted on participants from temperate climates in the Global North, making it difficult to generalise to India, where populations are both physiologically and socially acclimatised to heat.

More fundamentally, the report argues that heat kills through indirect pathways — cardiovascular strain, kidney injury, disrupted sleep, and exacerbation of chronic illness — at temperatures well below any physiological survival threshold. Work productivity begins to decline at much lower temperatures still, cascading into wage losses, reduced ability to afford food or medicines, and compounding health burdens over weeks and months.

"The seemingly straightforward question of 'how hot is too hot?' cannot be answered without first asking: too hot for what? And also, too hot for whom?" the authors write.

Heat Action Plans: Well-Intentioned, Poorly Enforced

India has been internationally recognised as an early mover in heat action planning, but the report delivers a sobering critique of how these plans function in practice. Author Aditya Valiathan Pillai finds that existing plans focus disproportionately on short-term emergency responses — water stations, public cooling designation — while falling short on structural changes such as updating building codes, expanding shade coverage, or preparing electricity grids for rising cooling demand.

"Reviews of heat plans in democracies across the world, from India to the U.S. and Europe, suggest that they generally lack legislative or financial backing which makes them less likely to be implemented," Pillai writes. The problem, he argues, is that plans are written to appear comprehensive rather than to be implementable. Without redesigned incentive structures that reward politicians and bureaucrats for long-term action, heat plans risk becoming, in his words, mere "signals of intent" that can lead to maladaptive outcomes when officials earn credit simply for commissioning them.

Parametric Insurance: Promising, But Not a Fix

Perhaps the report's most pointed critique is directed at parametric heat insurance — financial products that have attracted growing interest from development funders and insurers, including pilots run by the Self-Employed Women's Association (SEWA) covering informal women workers in Gujarat.

Epidemiologists Caroline Buckee and Owen Gow of Harvard acknowledge the appeal: unlike traditional indemnity insurance, parametric products offer speed, transparency, and lower administrative burden. But they identify a fundamental structural flaw. Daily wage workers must decide whether to stop working before knowing whether payout conditions will be met on a given day. Since heat waves are defined as consecutive days above a threshold, workers face near-impossible uncertainty. "For households living in or near poverty, the immediate necessity of income often outweighs the uncertain protection of future insurance payouts," the authors write.

In practice, they conclude, the payouts function more as hazard compensation than health protection — workers continue to labour in dangerous conditions and receive money retrospectively. As heat becomes more chronic and prolonged, the underlying logic of insurance — protecting against rare, unpredictable losses — will erode entirely. Premiums will rise or trigger thresholds will be made more severe, widening the gap between what harms health and what triggers a payout.

"Parametric heat insurance is thus a promising innovation, but it likely remains a transitional and complementary mechanism, not a durable or stand-alone solution," the authors conclude.

Ninety Percent of Workers Lack Any Enforceable Protection

Labour law scholars Rajesh Nayak and Sharon Block document the scale of India's workforce protection gap in stark terms: informal workers constitute as much as 90 percent of India's workforce, placing them entirely outside the reach of traditional occupational health and safety frameworks. Employer-based protections are structurally inapplicable to the self-employed, piece-rate workers, street vendors, and gig workers who bear the greatest heat exposure.

The authors point to international models — including the Dindigul Agreement in Tamil Nadu's leather sector and the Coalition of Immokalee Workers' Fair Food Program in the United States — as examples of legally binding, worker-monitored frameworks that have successfully extended enforceable protections through fragmented supply chains. Both models, they argue, offer templates for embedding heat-related standards in India's informal economy, without waiting for comprehensive regulatory reform.

"Governments should not use informality as an excuse to avoid imposing enforceable protections," Nayak and Block write.

A Data Crisis Undermining Public Health Response

The report identifies weak and fragmented data systems as a foundational obstacle to any credible health response. Heat-related deaths are routinely misclassified or unrecorded; private healthcare providers, who deliver nearly two-thirds of all inpatient care in India, contribute almost nothing to national health registries. India's most recent census was conducted in 2010, undermining accurate disease burden estimation. Meteorological data, which should be a public good, is monetised by national agencies — creating barriers to the research community.

Current thresholds for declaring heat waves in India are meteorological, not epidemiological, meaning they do not reflect the actual temperature levels at which mortality and morbidity rise. Authors Nitya Mohan Khemka and Bhargav Krishna call for a three-pronged intervention: expanding clinical capacity to recognise and manage heat illness; embedding heat resilience protocols into existing health programs for maternal and child health, noncommunicable diseases, and nutrition; and upgrading health infrastructure to withstand climate shocks.

The Financing Gap

The report's finance chapter puts the global adaptation funding shortfall in sharp relief. Global adaptation finance reached $65 billion in 2023-24, against a developing-country requirement of more than $310 billion annually. Heat receives a disproportionately small share even of that inadequate total, partly because — unlike floods or cyclones — it leaves no visible physical damage trail in government budgets or damage assessments.

Authors Kartikeya Bhatotia, Mihir Bhatt, and Jorge Gastelumendi argue for reframing heat not merely as a public health concern but as a macroeconomic and fiscal risk — one that affects labour productivity, energy stability, agricultural output, and food inflation. They propose integrating heat-related expenditures across departmental budgets using "budget tagging," a system already used in India for gender-responsive budgeting and sustainable development goals spending.

At COP30 in Belém, countries signalled intent to triple adaptation finance by 2035, and India began developing a unified climate finance platform with Green Climate Fund support. The authors argue these developments create a genuine opening — but only if heat resilience is explicitly embedded in the resulting frameworks.

Listening to Those Most Affected

The report closes with a reflection from Harvard Business School professor Tarun Khanna, who attended the New Delhi workshop and was struck by the persistent failure of expert communities to connect their scientific discourse to the lived realities of the most heat-exposed.

He recounts a moment when a SEWA worker from Gujarat raised her hand at a panel on climate science and asked, in Gujarati: "What does all this have to do with me?" The panellists — genuine experts — struggled to respond.

"Those most affected by climate change are not yet at any negotiating table. They are excluded from academic deliberations, geopolitical discourse, as well as financial arrangements," Khanna writes. The conference was, in part, an attempt to begin changing this. But the challenge, he argues, runs deeper — requiring not just better communication but a fundamental rethinking of whose knowledge, whose experience, and whose questions shape the scientific and policy agenda.

Key Recommendations

Across its nine chapters, the report calls for India to:

- Recalibrate heat thresholds used in action plans to reflect local epidemiological data, not global physiological averages derived from non-Indian populations

- Reform Heat Action Plans to prioritise implementability and align with political incentive structures, rather than comprehensiveness on paper

- Extend enforceable worker protections to the informal sector through supply-chain accountability mechanisms and worker-led monitoring

- Treat heat data — meteorological and public health — as open-access public infrastructure, not a commercial product

- Integrate heat resilience into national and subnational fiscal frameworks, including the Finance Commission transfer system and State Disaster Mitigation Funds

- Embed heat resilience into existing health programs rather than treating it as a parallel vertical

- Deploy parametric insurance as one component within a broader system of structural protection, not as a standalone fix