Extreme heat is imposing a mounting economic and human toll on vulnerable populations worldwide, with poor women workers losing an estimated $57 billion in earnings each year, according to a major new report released at London Climate Action Week.
The report, published by Heat Resilience Action (HERA), identifies extreme heat as a rapidly escalating but under-recognized threat to urban economies, public health systems, and gender equality. Drawing on global data and detailed modeling across cities including Ahmedabad, Bangkok, Monterrey, and Freetown, the analysis shows that heat is already reducing city GDP by between 4 and 8 percent annually, while contributing to more than 1,000 deaths across the case study locations.
Women working in the informal sector—estimated at 740 million globally—are disproportionately affected. In many regions outside Europe and the United States, these workers lose between 4 and 11 percent of their income due to heat-related disruptions. With some earning as little as $3 per day, even small productivity losses have severe consequences for household stability.
“Extreme heat is not a distant climate risk—it is already draining economic growth, damaging health, and deepening inequality,” said Kathy Baughman McLeod, CEO of HERA. “The burden falls heaviest on women who are most exposed and least protected, but the solutions are within reach and highly cost-effective.”
The report highlights that women face higher health risks from extreme heat, accounting for up to 20 percent more heat-related mortality than men. This disparity stems from both physiological differences and social conditions that increase exposure, particularly in informal work settings without adequate protections.
The economic effects extend beyond individuals. Because women tend to reinvest up to 90 percent of their income into their families, income losses translate directly into reduced spending on education, nutrition, and healthcare. In Bangkok, for example, extreme heat cuts women’s annual spending on children by approximately $500.
Citywide impacts are equally significant. In Bangkok, heat-related productivity losses reduce GDP by an average of 4 percent annually—equivalent to the city government’s entire budget—and can reach as high as 8 percent in particularly hot years. In Freetown, rising temperatures are linked to increasing household debt, limiting investments in education and entrepreneurship. Meanwhile, Monterrey is projected to see heat-related preterm births more than triple over the next 25 years.
The report also draws attention to the growing danger of nighttime heat. In many cities, night temperatures are rising faster than daytime highs, preventing the body from recovering. Combined with prolonged heatwaves, these conditions account for up to 85 percent of heat-related deaths, particularly among low-income households living in heat-retaining housing materials.
Despite the scale of the challenge, the report emphasizes that solutions are both available and cost-effective. Measures such as heat response plans, urban greening, cool roofs, labor protections, and targeted insurance schemes could reduce heat-related mortality by more than 36 percent by 2050 in the cities studied.
Some interventions deliver particularly high returns. Heat response plans can generate benefits worth 12 to 90 times their cost, while cool roofs can reduce indoor temperatures by 2 to 7 degrees Celsius immediately after installation. Insurance schemes designed for informal workers could cut income losses among women by over 40 percent by mid-century.
However, the report stresses that effectiveness depends on inclusive design. Many current measures fail to reach the most vulnerable due to barriers such as lack of mobile access, limited literacy, or exclusion from formal labor systems. Tailoring interventions to the realities of informal women workers significantly improves both impact and cost-efficiency.
To support decision-making, HERA has also launched a global heat cost-benefit tool covering more than 11,000 cities across 190 countries. The platform allows policymakers and practitioners to assess heat impacts and compare adaptation strategies through 2050.
The report concludes with four urgent priorities: expanding sustainable financing, strengthening cross-sector partnerships, improving gender-sensitive data, and increasing public awareness of heat risks. With climate change, urbanization, and aging populations expected to intensify the threat, the window for effective action is rapidly narrowing.
