Climate Warming Pushes Northern Hemisphere Snowpack Toward Critical Threshold

Nature, 10 January 2024

This study contained two major findings: first, human-driven fossil fuel emissions have significantly reduced snowpack across the Northern Hemisphere ever since the 1980s. In addition, it found a critical temperature threshold already at -8°C (18°F), above which snowpack becomes very sensitive to warming, entering into dramatic decline. Below an average -8°C winter temperature, snowpack remains fairly insensitive to warming. Each additional 1 °C above that point, however, results in very rapid and accelerated loss. Authors find that many of the world’s most populous river basins are hovering on the precipice of such rapid snow decline, with serious consequences for future meltwater availability. More than one-fourth of major river basins across the Northern Hemisphere have experienced significant snowpack loss over the past four decades. Europe and North America have endured some of the biggest spring snowpack losses, especially the Great Salt Lake, Merrimack, Connecticut, Susquehanna, Hudson, Delaware, Neva, Vistula, Dnieper, Don and Danube river basins. The upper reaches of the Colorado River basin in Wyoming and Colorado have already crossed the -8°C winter temperature threshold: with winter averages now around -5°C, this snowpack has now entered a state of accelerated loss. Today, more than 2 billion people rely on snow from regions where winter temperatures now average between -8°C and 0°C, putting them at risk of severe summer water shortages over coming years unless fossil fuel emissions are curbed.

https://www.nature.com/articles/s41586-023-06794-y