Extreme heat is emerging as one of the biggest threats to economic growth and public health with poor women workers bearing the heaviest burden, according to a new report released by HERA (Climate Resilience for All) during London Climate Action Week.
The report, titled Counting the Cost of Heat: The Case for Urgent Solutions for Cities estimates that nearly 740 million women working in the informal sector lose a combined $57 billion in earnings every year because rising temperatures reduce their ability to work safely. In many developing countries, these women earn only a few dollars a day, making the financial losses even more severe for their families.
The study examined the impacts of extreme heat in Ahmedabad, Bangkok, Monterrey, and Freetown. Researchers found that heat already reduces annual economic output by 4% to 8% of city GDP while contributing to more than 1,000 deaths every year across the four cities. Without stronger adaptation measures, the report warns that heat related health and economic losses could increase three to five times by 2050 as climate change, urbanisation, and ageing populations continue to intensify the crisis.
Women Face Greater Health and Financial Risks
Researchers found that women are especially vulnerable because they are more likely to work in informal jobs such as street vending, agriculture, domestic work, and construction, where access to cooling facilities and labour protections is limited. Heat related mortality among women is estimated to be up to 20% higher than among men in some regions due to a combination of physiological, social and economic factors.
The report notes that reduced income affects entire households because women often spend a significant portion of their earnings on food, healthcare and education. In Bangkok, extreme heat reduces women’s annual spending on their children by around $500. In Freetown, rising temperatures are increasing household debt while reducing investments in education and small businesses.
Researchers also highlighted the growing danger of hot nights, which prevent the human body from recovering after daytime heat exposure. They estimate that hot nights and prolonged heatwaves contribute to nearly 85% of heat related deaths, particularly among people living in poorly insulated homes.
Affordable Solutions Can Deliver Major Benefits
Despite the growing risks, the report says practical and affordable solutions can significantly reduce the impact of extreme heat. Measures such as Heat Response Plans, cool roofs, urban green spaces, labour protections, and heat-income insurance could reduce heat-related deaths by more than 36% by 2050 in the cities studied.
Heat Response Plans were identified as one of the most cost-effective measures, generating returns of between 12 and 90 times their implementation costs. Cool roofs can lower indoor temperatures by 2°C to 7°C, offering immediate relief for low-income households, while specialised income-loss insurance could reduce earnings losses for informal women workers by more than 40%.
The report also introduces a new global tool covering 11,408 cities across 190 countries, allowing governments to assess local heat risks and compare the costs and benefits of different adaptation measures. Researchers conclude that extreme heat is no longer just an environmental challenge but a growing economic and social crisis. They urge governments to invest in climate resilience, improve public awareness, strengthen financing, and design heat action plans that specifically protect women and other vulnerable communities.