On a weekend when two consecutive days pushed New York City past 100 degrees Fahrenheit, the US Department of Energy deleted approximately 6,000 pages of guidance from its public website — pages that had told Americans, for years, exactly how to keep their homes cooler and their electricity bills lower. The timing was not coincidental. It followed a political storm triggered by New York mayoral candidate Zohran Mamdani, who had asked residents to set their air-conditioning thermostats to 78 degrees in order to reduce strain on an already stretched electrical grid. Republican figures including Senator Ted Cruz, former presidential candidate Nikki Haley, and Representative Nancy Mace of South Carolina condemned Mamdani's request with unusual ferocity, framing it variously as socialism and an assault on women's health.

What was largely absent from their criticism was any acknowledgement that 78 degrees had been the Department of Energy's own official recommendation — and that Greg Abbott, the Republican governor of Texas, had issued nearly identical thermostat guidance during previous heatwaves in his state. The deleted pages, it turned out, covered far more than thermostat settings: water conservation advice, explanations of different types of home insulation, and the department's long-running Solar Decathlon competition all disappeared alongside them. The erasure matters beyond any single political dispute. According to data from the US Centers for Disease Control and Prevention and the National Oceanic and Atmospheric Administration, extreme heat kills more Americans every year than floods, tornadoes, and hurricanes combined.

When grids are overloaded during a heatwave, blackouts can leave the most vulnerable residents — the elderly, the very young, the chronically ill — without the air conditioning that may keep them alive.