气温升高和积雪减少威胁着美国西部的水源供应

News Briefing: 14 June 2022

As the western United States endures a multi-year drought exacerbated by decreased seasonal snowpack most years, two major reservoirs have reached dangerously low levels. The Colorado River supplies water to nearly 40 million people in cities from Denver to Los Angeles. Lake Mead near Las Vegas, and Lake Powell on the Utah-Arizona border serve as holding tanks for the outflow from this river. These two major reservoirs have now reached record-low levels: Lake Powell is only one-third full, while Lake Mead has dropped to one-quarter of its full capacity. Rising temperatures increase the amount of precipitation falling as rain rather than snow, accelerate the absorption of water by plants and evaporation of moisture from the ground, and force farmers to increase the amount of water released on their crop fields. These factors all decrease the amount of spring and summer runoff flowing into the Colorado River, and thereby threaten water supplies held in downstream reservoirs. As climate change is projected to further worsen this extreme drought, urgent efforts will be required to reduce water usage and avoid even more devastating water shortages in the future; but mitigation of climate change through reductions in fossil fuel emissions is the only proven solution to reversing current dry conditions, which have long been predicted by multiple climate models.

https://www.latimes.com/environment/story/2022-06-14/big-water-cutbacks-ordered-amid-colorado-river-shortage