A new study confirms that spring snowpacks across the Northern Hemisphere have shrunk significantly over the past 40 years due to human-driven climate change, putting hundreds of millions of people worldwide at risk of a water crisis. The Southwestern and Northeastern U.S. saw among the steepest declines, with more than 10% of the spring snowpack lost per decade, which the researchers expect will accelerate with further warming. Many heavily populated snow-dependent watersheds are dangerously near what they call a 'snow-loss cliff,' wherein once average winter temperatures exceed 17 degrees Fahrenheit, snow loss accelerates even with only modest increases in temperature.