NOAA report says declining snowpack means worldwide food disruptions

Human-caused climate change resulting in higher average temperatures has caused a global decline in snowfall, according to a new analysis from NOAA.

That means more precipitation is likely to fall as rain, causing a disruption to food supplies and less water for billions of people, the report said.

The data show that while the long term forecast for snowfall is not good, climate change could mean more erratic weather patterns and increased snowfall events in the near term, as evidenced by recent storms in the U.S. Northeast. But scientists report over time, those events will decline and snowfall will drop off dramatically and noticeably.

"Eventually the laws of thermodynamics mean that as you keep warming you're just going to transition more and more of that snow over to rain," said Brian Brettschneider, a climate scientist with the National Weather Service in Alaska and the author of the data analysis. "You can get away with things for a little bit, and it can hide some trends, but overall the laws of thermodynamics will win out."

The report also shows that snowfall totals won't decline gradually as average temperatures continue to rise. Once temperatures reach a "tipping point," snowfall amounts will plummet.

"We should expect the losses to accelerate,"said Justin Mankin, a climate scientist and associate professor of geography at Dartmouth College.

"It means we can expect a lot of the places that haven't exhibited massive snowfall declines to maybe start to exhibit them with just a little bit more warming," Mankin told CNN.

Brettschneider's analysis of data from the European Union's Copernicus Climate Change Service data show there has been a 2.7% decline in annual global snowfall since 1973.

That decline is especially prominent in the Northern Hemisphere's mid-latitudes, north of the tropics and south of the Arctic, where most of the world's people live.

Beyond less water and disruption to the global food supply, reduced snowfall means higher ground temperatures, too. That's because the sunlight is more direct in lower latitudes, and with less snowpack on the ground, solar rays will not be reflected back into the atmosphere as they have been historically, but instead absorbed by the ground, warming the atmosphere.

A deep and resilient snowpack also acts as a reservoir, storing up water over the winter months, which won't happen when the precipitation instead falls as rain.

California and other parts of the American West will likely be the barometer for the early shift due to their Mediterranean-like climate, subject to more extreme boom-and-bust cycles of precipitation.

"California is the poster child - it does not rain in the summer in California, and so the snow melt runoff, the snow that waits and runs off later in the season, is absolutely essential for all of the ecosystems, all of the agriculture, all of the cities or anyone who wants water during the dry season," University of Washington environmental engineering professor Jessica Lundquist told CNN.

Sno pack provides water to more than 50% of the water supply in the American West, according to a 2017 study, which also predicted snowpack levels in the arid region would continue to decline by more than one-third by 2100, prompted by the combination of an increase in heat trapping gasses and planet-warming pollution.

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