The study projects that from June 2026 through the end of February 2027, extreme temperatures exacerbated by El Niño will trigger a surge in mortality, particularly across low-income developing nations in the Global South already grappling with climate change, food insecurity, and elevated energy costs. Co-author and Climate Impact Lab co-founder Michael Greenstone emphasized that the thermal risk will extend into next year's summer, noting that slight temperature increases in already warm, impoverished regions disproportionately endanger human lives due to a lack of air conditioning, clean water, and healthcare infrastructure. The Sahel region in Africa faces the highest burden with nearly 66,800 estimated excess deaths, followed by significant casualties projected across South and Southeast Asia—including India, Indonesia, the Philippines, Thailand, Vietnam, and Latin America. Researchers urged governments to implement early warning systems, cooling centers, and forecast-based emergency funding to mitigate loss of life.