Each extra degree adds a heat month as Powell, Mead and Kandersteg hit new limits
A modelling study adds about one extra month of intolerable heat for 1 billion people per added degree. Lake Powell and Lake Mead sit at historic lows, and Kandersteg waits under 15 to 20 million cubic metres of loosening rock.
Science··Evening
Each extra degree adds a month of intolerable heat
A modelling study in The Lancet Planetary Health, led by Qinqin Kong, projects heat beyond human tolerance and adjusts its thresholds for people over 60, who sweat less and have weaker cardiovascular reserve. At 1.5 degrees Celsius of warming, 22 per cent of people over 60 would face unsafe heat for at least a month each year. The projection combines wet-bulb thresholds with population ageing, so the same warming lands harder on an older world. Each additional degree pushes roughly 1 billion more people into about one extra month of intolerable heat a year, and at 3 degrees Celsius older residents of South Asia and the Gulf could face three continuous months. India, Pakistan, Bangladesh, Myanmar and Niger come out highest. These are model outputs under warming scenarios rather than observations, and they depend on how closely laboratory tolerance limits track real exposure.[1]
Powell and Mead sit just above the power cutoff
Lake Powell fell to 3,519.80 feet (1,072.8 metres) above sea level on Sunday and Lake Mead to 1,039.70 feet (316.9 metres) on Friday, on Bureau of Reclamation readings. Both now sit just above the level at which power generation would be affected. The Colorado River supplies about 40 million people across seven states, and Lake Powell now sits just under its previous low of 2023. The report ties the decline to the drought across the Western United States; under the federal drought plan now proposed, California, Arizona and Nevada would cut combined use by up to 3.7 billion cubic metres a year through 2036. Reservoir elevation reflects snowpack, releases and allocation decisions together, so a single historic-low reading does not isolate one driver.[2]
Kandersteg waits under 15 to 20 million cubic metres
Above the village of Kandersteg in the Swiss canton of Bern, the Spitze Stei slope holds an estimated 15 to 20 million cubic metres of unstable rock. Thawing permafrost and retreating ice are loosening it, and the 1,300 residents live under constant monitoring and a prepared evacuation plan. Markus Stoffel of the University of Geneva told the Associated Press that the ice in these slopes had acted like cement and that the slopes grow less stable as it melts. Scientists currently consider a gradual breakdown more likely than a single catastrophic collapse. The precedent residents cite is Blatten, evacuated ahead of the May 2025 collapse that buried much of the valley floor.[3]
