Human-induced climate change impacts the highest reaches of the planet -
- Mount Everest

Date:
February 3, 2022
Source:
University of Maine
Summary:
Melting and sublimation on Mount Everest's highest glacier due to
human- induced climate change have reached the point that several
decades of accumulation are being lost annually now that ice has
been exposed, according to a research team that analyzed data from
the world's highest ice core and highest automatic weather stations.



FULL STORY ========================================================================== Melting and sublimation on Mount Everest's highest glacier due to
human-induced climate change have reached the point that several decades
of accumulation are being lost annually now that ice has been exposed, according to a University of Maine-led international research team that analyzed data from the world's highest ice core and highest automatic
weather stations.


==========================================================================
The extreme sensitivity of the high-altitude Himalayan ice masses in
rapid retreat forewarns of quickly emerging impacts that could range from increased incidence of avalanches and decreased capacity of the glacier
stored water on which more than 1 billion people depend to provide melt
for drinking water and irrigation.

At the rate at which the highest glaciers are disappearing, Mount Everest expeditions could be climbing over more exposed bedrock, potentially
making it more challenging to climb as snow and ice cover continues
to thin in the coming decades, according to UMaine climate scientists
Mariusz Potocki and Paul Mayewski.

The team's findings, published in the journal Nature Portfolio Journal
Climate and Atmospheric Science, are the latest research results
from the 2019 National Geographic and Rolex Perpetual Planet Everest Expedition. The expedition's scientists, including six from UMaine's
Climate Change Institute, studied environmental changes to understand
future impacts for life on Earth as global temperatures rise.

This latest research confirms the heights that human-sourced climate
change reaches, and serves as a bellwether for other high-mountain
glacier systems and the potential impacts as glacier mass declines,
says Mayewski, a glaciologist and director of UMaine's Climate Change
Institute who was the expedition leader and lead scientist for the
Perpetual Planet Everest Expedition.

"It answers one of the big questions posed by our 2019 NGS/Rolex Mount
Everest Expedition -- whether the highest glaciers on the planet are
impacted by human- source climate change. The answer is a resounding yes,
and very significantly since the late 1990s," Mayewski says.



==========================================================================
The study points to the critical balance snow-covered surfaces provide
and the "potential for loss throughout high mountain glacier systems as
snow cover is depleted by changes in sublimation -- passing from a solid
to vapor state - - and surface melt driven by climate trends. Everest's
highest glacier has served as a sentinel for this delicate balance
and has demonstrated that even the roof of the Earth is impacted by anthropogenic source warming," the researchers note in their paper.

In their investigation of the timing and cause of significant mass loss on South Col Glacier, the researchers used data analyzed from a 10-meter-long
ice core and weather stations, as well as photogrammetric and satellite imagery, and other records. They estimated contemporary thinning rates approaching approximately 2 meters of water per year now that the glacier
has turned from snowpack to ice, losing its ability to reflect solar
radiation, resulting in rapid melting and increased sublimation.

Once South Col Glacier ice was regularly exposed, approximately 55 meters
of glacier thinning is estimated to have occurred in a quarter-century
-- thinning over 80 times faster than the nearly 2,000 years it took
to form the ice at the surface. The researchers note that increasing
overall surface ice mass loss in the region -- the transition from
permanent snowpack to majority ice cover - - could have been triggered
by climate change since the 1950s, with sublimation enhanced by rising
air temperatures. The impacts of climate change on the glacier have been
most intense since the late 1990s.

Model simulations found that the region's extreme insolation means
that ablation -- loss of surface mass by melting or vaporization --
can accelerate by a factor of more than 20 if snow cover gives way to
ice. And while warming air temperatures caused most of the sublimation, declining relative humidity and stronger winds also were factors.

"Climate predictions for the Himalaya suggest continued warming and
continued glacier mass loss, and even the top of the Everest is impacted
by anthropogenic source warming," says Potocki, a glaciochemist and
doctoral candidate in the Climate Change Institute who collected the
highest ice core on the planet.

Other co-authors of the paper: Tom Matthews, Loughborough University;
L. Baker Perry, Appalachian State University; Margit Schwikowski, Paul
Scherrer Institut; Alexander M. Tait, National Geographic Society;
Elena Korotkikh, Heather Clifford and Sean Birkel, UMaine; Shichang
Kang, Chinese Academy of Sciences; Tenzing Chogyal Sherpa, International
Centre for Integrated Mountain Development, Kathmandu, Nepal; Praveen
Kumar Singh, Indian Institute of Technology Roorkee; and Inka Koch,
University of Tu"bingen.

They were among the members of the international, multidisciplinary team
of scientists, climbers and storytellers, led by the National Geographic Society and Tribhuvan University, and supported in partnership with Rolex,
that conducted the scientific expedition to Mount Everest, believed to
be the most comprehensive single scientific expedition to the mountain
in history.

The expedition team installed the two highest weather stations in the
world (at 8,430 meters and 7,945 meters), collected the highest-ever ice
core (at 8,020 meters), conducted comprehensive biodiversity surveys at multiple elevations, completed the highest elevation helicopter-based
lidar scan, expanded the elevation records for high-dwelling species and documented the history of the mountain's glaciers. The highest altitude
ice core and highest altitude weather station on land are key to the
latest research paper and recently set two of the expedition's three
Guinness World Records.

========================================================================== Story Source: Materials provided by University_of_Maine. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Mariusz Potocki, Paul Andrew Mayewski, Tom Matthews, L. Baker Perry,
Margit Schwikowski, Alexander M. Tait, Elena Korotkikh, Heather
Clifford, Shichang Kang, Tenzing Chogyal Sherpa, Praveen Kumar
Singh, Inka Koch, Sean Birkel. Mt. Everest's highest glacier is
a sentinel for accelerating ice loss. npj Climate and Atmospheric
Science, 2022; 5 (1) DOI: 10.1038/ s41612-022-00230-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220203083559.htm

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