Global warming increases the risk of avalanches

Global warming increases the risk of avalanches

SOURCE: Science Daily DATE: March 14, 2018 SNIP: Avalanches are a natural phenomenon and occur repeatedly in mountain areas; nonetheless, rising temperatures are altering their triggering. This can lead to disasters and serious consequences in mountain areas where they can severely affect the socio-economic development and the destruction of traffic infrastructure, and buildings. This is the case in the Indian state of Himachal Pradesh, where increasing residential numbers and tourism are exerting pressure on land use. The models used for testing the impact of climate change combine the risks of avalanche with local climate data. They were adjusted to include the likely effect on topographical features resulting from earlier avalanches. Since they destroy the plant cover, they are an aggravating risk factor. The results brooked no argument: from the second half of the twentieth century, there has been an increase in the number of avalanches, both in terms of frequency and intensity. The frequency has risen from one event per decade to almost one event every year. Avalanches are bigger, travel greater distances and are triggered earlier in the year. These changes can be attributed clearly to rising temperatures, which have reached 0.2 to 0.4 degrees annually in some parts of the...
New study: Snowpack levels show dramatic decline in western states

New study: Snowpack levels show dramatic decline in western states

SOURCE: AAAS DATE: March 2, 2018 SNIP: CORVALLIS, Ore. – A new study of long-term snow monitoring sites in the western United States found declines in snowpack at more than 90 percent of those sites – and one-third of the declines were deemed significant. Since 1915, the average snowpack in western states has declined by between 15 and 30 percent, the researchers say, and the amount of water lost from that snowpack reduction is comparable in volume to Lake Mead, the West’s largest manmade reservoir. The loss of water storage can have an impact on municipal, industrial and agricultural usage, as well as fish and other animals. “It is a bigger decline than we had expected,” said Philip Mote, director of the Oregon Climate Change Research Institute at Oregon State University and lead author on the study. “In many lower-elevation sites, what used to fall as snow is now rain. Upper elevations have not been affected nearly as much, but most states don’t have that much area at 7,000-plus feet. [S]nowpack levels in most of the western U.S. for 2017-18 thus far are lower than average – a function of continued warming temperatures and the presence of a La Niña event, which typically results in warmer and drier conditions in most southwestern...
Scientists stunned by massive snowfall increases among Alaska’s highest peaks

Scientists stunned by massive snowfall increases among Alaska’s highest peaks

SOURCE: Washington Post DATE: December 19, 2017 SNIP: A team of scientists presented surprising data on Tuesday suggesting that even as the state of Alaska has warmed up extremely rapidly in recent years, snowfall in the iconic Denali National Park has increased dramatically during the era of human-driven global warming. The researchers from Dartmouth College, the University of Maine at Orono and the University of New Hampshire set up a camp at 13,000 feet atop Mount Hunter, within view of Denali, previously known as Mount McKinley, the highest peak in the United States. There, they drilled into the snow to extract lengthy cores of ice that provided a historical record of snowfall patterns going back more than 1,000 years — and found a marked change over the past 150 years or so. “We were shocked, frankly, at just how much snowfall had increased,” said Erich Osterberg, a Dartmouth researcher who was one of the study’s authors. The ice cores showed an enormous upswing in the rates of snowfall beginning around the Industrial Revolution in the 19th century, when humans began burning fossil fuels to produce energy in large quantities. The increase over time represented more than a doubling in the amount of snow. “We can say confidently that the amount of snowfall we see today has never been seen previously during that whole 1,200-year record,” Osterberg said. “That we are way outside the range of what was natural conditions before the Industrial Revolution.” Climate change increases the volume of precipitation, because a warmer atmosphere holds more water vapor. But it isn’t supposed to increase it this...
Why the Last Snow on Earth May Be Red

Why the Last Snow on Earth May Be Red

SOURCE: The New Yorker DATE: September 21, 2017 SNIP: Every spring, in alpine regions around the world, one of Earth’s tiniest migrations takes place. The migrants are single-celled green algae; they are kin to seaweed, but instead of living in the sea they live in snow. (Snow weed, maybe?) They spend the winter deep in the snowpack, atop last summer’s snow, as dormant cysts. In the spring, they wake and swim up through the trickle of snowmelt to the surface, dividing and photosynthesizing as they go. Then, at the top, they turn red. This creates what scientists call pink snow or watermelon snow—drifts and glaciers that look like Slush Puppies and eventually reduce to rivulets of crimson. Watermelon snow is a perfectly natural phenomenon, but in an age of disappearing glaciers it is also problematic. Last year, scientists discovered that the algae had reduced the amount of sunlight reflected by some glaciers in Scandinavia—and increased the amount of sunlight absorbed—by thirteen per cent. The result, as Dial and his colleagues demonstrated in this month’s issue of Nature Geoscience, is faster melting. As in other parts of the warming planet—particularly the Arctic, where scientists fear that thawing permafrost may be triggering a climatic feedback loop—the effect is likely self-perpetuating. Ice sheets are already being darkened by dust, soot, and ash, which hasten melting and add nutrients on which algae can flourish. As the organisms proliferate, they melt even more snow, which allows them to proliferate again. “It spreads more rapidly than people realize, once it gets established,” Dial...