Delhi slum residents document extreme heat survival in groundbreaking heat diaries

Gulshan's evenings follow a ritual born of necessity. She floods the concrete floor of her one-room home multiple times, hoping the moisture will lower the temperature enough for her four children to sleep. Last year, the family scraped together enough money for a desert cooler—a device that cools through evaporation, far cheaper than air conditioning but still a luxury. She runs it sparingly to keep the electricity bill manageable. Even so, she dampens everyone's clothes before bed. The result is predictable: rashes blooming across skin, one child developing an infection from the wet fabric pressed against them through the night. This summer, Gulshan began writing it all down in a garmi khata—a heat registry—documenting the small, grinding strategies her family uses to survive. "I feel relieved that at least somebody might read my family's experiences," she said.

She is one of forty households in Sunder Nagri, a slum in northeast Delhi, now keeping these intimate records of heat survival. The project emerged from a recognition that India's cities have begun drafting heat action plans—formal agreements between municipal authorities on how to prepare for and respond to extreme temperatures. Yet most of these plans rely on meteorological data: satellite readings, air temperature thresholds, abstract numbers. What they lack is the texture of actual life. Aravind Unni, an urban planner and researcher in Delhi, puts it plainly: "Experiences of heat are vastly different depending on geography, income, occupation, gender, caste, class. While we have some meteorological data on heat, what's absolutely missing is people, community—what they feel, what they experience."

The heat diaries were conceived as a corrective. Nibedita Saha, a researcher with Greenpeace India, and her colleagues wanted to move beyond numbers. Aakiz Farooq, a senior campaigner, described the thinking: "What if they become their own storytellers, they write their own evidence, they write their own testimonies?" The diaries ask residents about daily routines, work, home, mood, family—the full architecture of survival. Arshi, nineteen, lives in one room with five others. She is a distance-learning student at Delhi University and works from home making decorative tassels for trucks, earning about 150 rupees—roughly £1.17—per day alongside her mother and sister. She sometimes escapes to the university library just to sit in air conditioning for a few hours, but obligation pulls her back. "I have to come back home so I can help my sister and mother," she says. Her brick house is profoundly humid. The ambient air temperature inside reads 29.3 degrees Celsius, but with humidity at 84.6 percent, the "feels-like" temperature climbs to 36.3 degrees—nearly 97 Fahrenheit.

Raja, twenty-one, sells vegetables from a pushcart and experiences peak summer temperatures of 45 degrees Celsius. The heat spoils his produce quickly, eating into his already thin margins. Fewer people venture onto the streets in such conditions, so his customer count drops along with his income. At night, he returns to a home with minimal ventilation and nothing but a ceiling fan. As Delhi's summers lengthen and the gap between day and night temperatures narrows year after year, there is no respite even after dark. "I started sleeping out on the roof in May so I could feel some air," he said. Unni notes that workers like Raja could be far better protected by public policy if the state understood their experiences at a granular level and established systems for compensation.

When Sunder Nagri residents mapped heat indices within their own neighborhood, they discovered that some streets—including where Raja sells his vegetables—reflected ground temperatures exceeding 54 degrees Celsius, or 129 Fahrenheit. They began identifying pragmatic solutions: shade structures, water sources, increased greenery. Satellite analysis across Delhi revealed stark disparities. The southwest district of Mahipalpur, near the airport, recorded an average land-surface temperature of nearly 44 degrees Celsius, while just two miles away in the leafy, affluent suburb of Vasant Kunj, temperatures averaged about 37 degrees. The geography of heat in Delhi is also the geography of inequality.

The diaries have now been submitted to India's National Human Rights Commission with a request to recognize extreme heat as a human rights issue and recommend protective measures. Farooq and his team plan to share the testimonies with ministries, policymakers, and members of parliament to push for more targeted protections. They are also developing the testimonies into evidence of impacts and injuries that could support lawsuits seeking accountability. This effort gains weight from the Supreme Court's 2024 ruling that protection from the most severe impacts of the climate crisis forms part of the constitutional right to life. On August 4th, India's government added heatwaves to the list of nationally notified disasters, a designation that allows states to access emergency relief funds. Unni and Farooq say it would be ideal if this decision enabled funds to support locally-driven action shaped by community participation. Arshi, for her part, feels a tentative hope. "Even if the government sees something as small as our rising medical and electricity costs and tries to help with that, it would feel like a win for me. At least they would have seen what we are going through," she said.