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What the most recent science says about Antarctica and sea-level rise

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What the latest science says about Antarctica and sea-level rise

Posted on 7 March 2022 by Visitor Writer

This can be a re-post from Yale Climate Connections by Kristen Pope

Because the Earth’s local weather warms, sea ranges are rising, threatening to swallow coastlines and flood low-lying cities. Scientists are working to know how a lot and the way shortly seas might rise in coming a long time – and Antarctica is one wild card.

Listed below are a few of scientists’ most necessary findings from 2021 concerning the adjustments occurring in and around the globe’s coldest continent.

What occurs if Antarctica melts?

More than 97% of Antarctica is roofed in ice. With a depth of as much as three miles, the continent’s 6 million cubic miles of ice include 70% of Earth’s recent water. If all of that ice melted, the world’s oceans would rise by 200 toes (61 meters), sufficient to inundate Tokyo, New York Metropolis, Shanghai, and different cities.

How a lot the Earth’s common temperature rises is likely one of the primary components that can decide how Antarctic melting performs out. The local weather has already warmed by roughly 1 diploma Celsius (1.8 levels Fahrenheit) for the reason that late 1800s.

2021 study printed within the journal Nature discovered that ice loss would probably proceed at a tempo just like present patterns so long as the world doesn’t rise greater than 2 levels Celsius (3.6 F) above pre-industrial ranges.

Nonetheless, if the temperature rises 3 levels Celsius (5.4 F) or extra, the paper’s authors discovered the speed of loss would rise to “an order of magnitude quicker than immediately.”

Scientists use fashions to estimate how a lot the ocean would rise below totally different situations. In 2021, researchers printed a paper in Science Advances noting that earlier estimates of impacts could also be far too low. Earlier research of the huge West Antarctic Ice Sheet had estimated that its collapse would trigger international sea ranges to rise by about 3.2 meters (10.5 toes). However within the new research, researchers mentioned the collapse might really trigger the ocean to rise by an further meter.  

Ice shelf collapse image(Picture credit score: Kelvinsong / CC BY-SA 3.0)

The destiny of Antarctica’s huge ice shelves can even play a job in figuring out future sea-level rise. These cabinets of ice jut out from Antarctica’s shoreline, floating into the ocean. Importantly, they maintain again the large glaciers that circulation from the continent’s huge inside ice sheets towards the ocean. 

If the Earth’s temperature have been to rise to 4 levels Celsius (7.2 F) above pre-industrial ranges, a 3rd of Antarctica’s ice cabinets might develop into destabilized and can be prone to collapse, in line with an April 2021 paper in Geophysical Analysis Letters. About 193,000 sq. miles (500,000 sq. kilometers) of those ice cabinets — an space barely smaller than California and South Carolina mixed — could fail. The impact of ice shelf collapse, the researchers mentioned, can be akin to pulling a cork out of a large bottle, dashing the motion of ice into the ocean.

Some ice cabinets are already melting quickly. The George VI Ice Shelf is the second-largest ice shelf on the Antarctic Peninsula, the northernmost area of mainland Antarctica. Scientists reported that 2019-2020 was a record-breaking melt year, with “probably the most widespread soften” they’d seen there, although they did be aware that they had seen longer melting seasons for the peninsula as a complete earlier than.

Thwaites: the ‘Doomsday Glacier

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NASA Earth Observatory pictures by Lauren Dauphin, utilizing Landsat knowledge from the U.S. Geological Survey.

Maybe probably the most talked-about Antarctic ice story of 2021 was the potential destiny of Thwaites Glacier, popularly dubbed the “Doomsday Glacier.” This huge physique of ice, bigger than the state of Florida, is positioned on the West Antarctic Ice Sheet.

In December 2021, scientists announced that cracks within the Thwaites Japanese Ice Shelf signaled that this ice shelf — which is holding again massive components of the Thwaites Glacier — might fail in as quickly as 5 years. With out the ice shelf to stabilize it, the glacier might pace up its circulation into the ocean. If the whole glacier melted, sea ranges around the globe would ultimately rise about 25 inches (63.5 centimeters).

Pine Island Glacier thins, Getz area loses ice

Pine Island Glacier, which comprises 180 trillion tons of ice, has been thinning for many years. And between the Nineties to 2009, the glacier’s circulation towards the ocean accelerated from round 1.5 miles (2.4 kilometers) per yr to roughly 2.5 miles (4 km) per yr, staying towards the upper finish of that vary for round a decade. And its motion continues to hurry up: Researchers printed a 2021 paper in Science Advances displaying that from 2017 to 2020, the speed of circulation elevated by round 12%. 

The Getz area in West Antarctica can be displaying indicators of dashing up. One study printed in Nature Communications discovered that almost all glaciers within the area have been accelerating. Between 1994 and 2018, the glaciers on this area misplaced about 315 metric gigatons of ice.

Parker Ice Tongue collapsed in 2020

Ice tongues are distinctive options that protrude from a glacier and may stick out far into the ocean. Usually, sea ice that’s hooked up to land helps stabilize them and shield them from the ocean’s waves and currents. Nonetheless, when sea ice disappears, the ice tongues are extra susceptible to break down.

In March 2020, the practically 16-square-mile (41-square-kilometer) Parker Ice Tongue absolutely collapsed into the western Ross Sea. In December 2021, scientists printed a paper in Geophysical Analysis Letters detailing their findings concerning the occasion. Whereas the authors consider that calving probably occurred on and off for a lot of centuries within the area, this loss was huge – and weird. The authors wrote, “A whole ice tongue collapse for these in any other case steady glaciological landmarks alongside the Victoria Land Coast is beforehand unrecorded.”

It might rain extra typically in Antarctica

Antarctica isn’t recognized for wet days. The continent’s excessive plateau very (very!) hardly ever will get rain. The northwestern Antarctica peninsula is the continent’s rainiest area, with round 50 days of rain every year.

However a 2021 study in Geophysical Analysis Letters discovered the continent’s rainfall could increase 240% by the flip of the century. The researchers additionally forecast extra intense storms.

Liquid precipitation might trigger large issues and result in quicker ice soften, particularly because the insulating snow on high of the ice melts, making the ice extra susceptible.

Rain is also a menace to wildlife like penguins. Younger penguin chicks are coated with downy feathers that aren’t rainproof. Moist chicks can freeze, particularly in stormy and windy climate.

And rain is already inflicting issues for penguin colonies. Through the 2013-2014 season, one Adélie penguin colony with about 20,000 breeding pairs failed to provide a single surviving chick. Scientists consider rain was one of the factors concerned.

Melting ice in Antarctica might trigger ecosystem-wide results

Melting ice additionally adjustments the composition of the ocean itself. To review how the water is altering, scientists affixed knowledge loggers to 14 seals close to Pine Island Glacier, utilizing the seals — and different strategies — to assemble knowledge, together with water temperature and salinity. Their results, printed in Communications: Earth and Atmosphere, recommend that when hotter meltwater rises to the highest of the ocean, it could actually make it tougher for sea ice to kind, inflicting areas of open water. Hotter water on the floor may result in different ecosystem impacts.

As scientists proceed to check Antarctic ice, we’ll be taught extra about how this “wild card” could have an effect on life, not solely on the Seventh Continent, however all around the globe.

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