Antarctica’s Collapse Could Begin Even Sooner Than Anticipated
The article in Scientific American states, “Two expeditions to the Thwaites Ice Shelf have revealed that it could splinter apart in less than a decade, hastening sea-level rise worldwide.
“As Scambos and Wild gazed down from their Twin Otter plane this past January, they spotted several new tears in the shelf—three kilometers long and several hundred meters wide—where it lifts off the seafloor. Ragged cliffs of ice tilted 50 meters up into the air, exposing deep layers that had not seen daylight for thousands of years. “I think it’s losing contact with everything that used to be bracing it,” Scambos says. Not only is the ice shelf separating from its pinning point. As it speeds up, it is also stretching and tearing away from the glacier upstream.
The team was so alarmed that Pettit and Wild decided they will return this December to install a new instrument station: “BOB,” short for Breakup Observer. They hope BOB will survive long enough to record the final throes of the ice shelf as it fractures into shards. It might not take long.”
Greenland Rainfall and Albedo Feedback
The WMO (World Meteorological Organization) released the report State of the Climate in Europe 2021. “Temperatures in Europe have increased at more than twice the global average over the past 30 years — the highest of any continent in the world. As the warming trend continues, exceptional heat, wildfires, floods and other climate change impacts will affect society, economies and ecosystems, according to a new report from the World Meteorological Organization (WMO).”
“Temperatures over Europe have warmed significantly over the 1991-2021 period, at an average rate of about +0.5℃ per decade. As a result, Alpine glaciers lost 30 meters in ice thickness from 1997 to 2021. The Greenland ice sheet is melting and contributing to accelerating sea level rise. In summer 2021, Greenland saw a melt event and the first-ever recorded rainfall at its highest point, Summit station.”
Does the rainfall have a significant impact? Yes; however, it is the Albedo Feedback that is of the most concern.
“It turns out that the rain itself wasn’t the most important factor”, says Prof. Jason Box from GEUS and lead author of the paper Greenland Ice Sheet Rainfall, Heat and Albedo Feedback Impacts From the Mid-August 2021 Atmospheric River reporting their results in Geophysical Research Letters.
“There is an irony. It’s not really the rain that did the damage to the snow and ice, it’s the darkening effect of the meltwater and how the heat from the event erased snow that had overlaid darker ice across the lower third of the ice sheet.”
“Unusually warm atmospheric rivers swept along Greenland in the late summer months, bringing potent melt conditions when the melt season was drawing to a close.”
“The researchers found that, between 19 and 20 August 2021, this melt caused the altitude of the ice sheet’s snowline near Kangerlussuaq to retreat in elevation by a whopping 788 metres, the snowline retreated, exposing a wide area of dark bare ice. Under normal circumstances, snow would cover and insulate this ice, but the snow melted suddenly and exposed the ice to heat, causing even more melting.”
“The authors conclude that the heatwave causing the rain event serves as an excellent example of ‘melt-albedo feedback that amplifies the melt impact of the initial melt perturbation'”.