Climate crisis takes toll on two key glaciers
The South Col glacier, the researchers said, is a sentinel for the accelerating ice loss in the Himalayas, where glaciers feed rivers that flow into the most populated regions in Asia, serving the fresh water need of billions of people.
Two of the world’s most notable glaciers – one is the highest and the other the widest – are rapidly losing ice as the planet warms, two separate studies released in recent weeks have said, spotlighting the near-constant unfolding of the climate crisis around the world.
The first study relates to the Thwaites glacier in Antarctica and the second pertains to the glacier at South Col abutting Mount Everest. As both thin, the potential outcomes capture the two biggest threats from the climate crisis for humanity: sea level rise and the loss of freshwater sources on which billions of people rely.
“The ice shelf is thinning and weakening. When it breaks away, perhaps in as little as 3 to 10 years, the outlet width for Thwaites will widen, and the area of faster flow will expand, accelerating retreat of the glacier. Over the next 50 to 200 years, the rate of ice flow to the ocean, and therefore the contribution to sea level, will increase,” said Ted Scambos, senior research scientist at the Cooperative Institute for Research in Environmental Sciences (CIRES), in an email to HT.
Sitting in west Antarctica, Thwaites is the widest glacier on Earth, spanning about 120 kilometers on the frozen coastline and extending to a depth of about 2,600 to 3,900 feet (800 to 1,200 meters) at its grounding line (the point where land ice begins to float in the sea).
In other words, in 3-10 years, the Thwaites glacier will cross a significant tipping point, which will set off a sequence of events that accelerate its drift into the sea, in a process that will drag several other nearby glaciers into the waters.
Once that happens, the amount of ice that enters the waters will set off a cascade of sea-level rise across the world. Scambos said this could begin happening as soon as in the next 50 years.
Scambos was part of a team of nearly 100 scientists funded by the US National Science Foundation and UK Natural Environment Research Council, which presented its findings at the annual meeting of the American Geophysical Union (AGU) on December 13.
The team estimated the cumulative impact to be as much as 2-10 feet over the coming centuries, which means many low-lying regions across the planet could be inundated.
He told HT a set of factors that worsen the fragility of the Thwaites has increased recently: “retreat of the ice from the ocean (grounding line retreat) and weakening of the ice shelf (increasing flow speed, growth of large fractures) has increased in the past 2-3 years”.
At the heart of the problem is warm water that is directly a consequence of global warming. This water is gradually eroding the ice shelf at the base of the Thwaites. That ice shelf is responsible for anchoring the glacier to an underwater mountain on its eastern side – once that anchor comes unstuck, the speed at which the ice is drifting into the sea will increase, according to an explanation by one of the researchers, Dr Erin Petit, an associate professor at Oregon State University during the AGU meeting.
And roughly 8,000 miles away is the case of the South Col glacier near Mount Everest. In a study published in a Nature Research journal, the npj Climate and Atmospheric Science, on February 3, researchers said the glacier has been thinning at an estimated rate of 2 metres per year.
The South Col glacier, the researchers said, is a sentinel for the accelerating ice loss in the Himalayas, where glaciers feed rivers that flow into the most populated regions in Asia, serving the fresh water need of billions of people.
Standing at nearly 26,000 feet above sea level – the highest in the world – the glacier is losing ice nearly 80 times faster than the rate at which it accumulated, and it may vanish by mid-century.
Like the impact on the Thwaites, this too has been a recent phenomenon. The scientists estimate the thinning picked up pace sometime in the 1990s.
“[This study] answers one of the big questions posed by our [expedition] — whether the highest glaciers on the planet are impacted by human-source climate change,” study co-author Paul Mayewski, a glaciologist at the University of Maine and director of the University’s Climate Change Institute, said in a statement. “The answer is a resounding yes, and very significantly since the late 1990s.”
This study addresses a key question from the 2019 National Geographic and Rolex Perpetual Planet Everest Expedition on whether glaciers at the highest point on earth are experiencing the impacts of climate change.
There could also be more avalanches on Everest, or expose more bedrock that makes the terrain more treacherous for climbers, the authors said.
“This tipping sensitivity and increased mass loss of glaciers, particularly at the world’s highest elevations, where temperatures never rise above zero degree Celsius, is a wake-up call for us all. It also shows the importance of direct measurements on glaciers to increase our understanding of the processes when forecasting how these landforms will respond to changing climate,” said Tenzing Chogyal Sherpa, Remote Sensing and Geoinformation Associate, ICIMOD (International Centre for Integrated Mountain Development), in a statement.
