September 29, 2023
Scientists sound alarm as Antarctic sea ice hits report low for second yr working


Antarctic sea ice has reached report low ranges for the second time in two years, with some scientists alarmed that dramatic drops are a sign the local weather disaster could now be extra clearly influencing this huge, advanced and remoted area.

The ocean ice that fringes Antarctica dropped to simply 737,000 sq. miles (1.91 million sq. kilometers) on February 13, based on the Nationwide Snow and Ice Knowledge Middle, or NSIDC, beneath the earlier report of 741,000 sq. miles (1.92 million sq. kilometers) set on February 25 final yr.

Sea ice might nonetheless shrink additional; the bottom stage of the southern summer time will not be reached for greater than per week.

The final two years mark the one time that sea ice ranges have dipped beneath 2 million sq. kilometers since satellites started monitoring it in 1978.

It’s “not simply ‘barely a report low,’” Ted Scambos, a glaciologist on the College of Colorado Boulder, informed CNN. “It’s on a really steep downward pattern.”

Scientists sound alarm as Antarctic sea ice hits report low for second yr working

Not like the Arctic, the place the speed of sea ice loss has adopted a reasonably constant downward trajectory as local weather change accelerates, Antarctic sea ice extent has swung up and down, making it tougher to determine how the continent and its surrounding ocean are responding to international heating.

The 2 polar areas are very completely different. Whereas the Arctic is an ocean surrounded by continents, Antarctica is a continent surrounded by the ocean – this implies its sea ice can develop outward, unconstrained by land. Antarctic ice tends to be thinner than Arctic ice, with higher highs within the winter and steeper declines in the summertime.

Local weather fashions projected declines in Antarctic sea ice that have been much like the Arctic, however till not too long ago the area was behaving fully otherwise than these fashions predicted.

It hit a report excessive for winter sea ice extent in 2014 when it reached 7.76 million sq. miles, which appeared to assist the concept that the Antarctic could also be comparatively insulated from international warming.

However in 2016, one thing modified. Scientists started observing a steep downward pattern.

At first, some put it all the way down to the same old variability of this vastly advanced continent, with its various, intertwined local weather techniques. However after two low sea ice information in a row, scientists have gotten involved.

“The query is, has local weather change reached Antarctica? Is that this the start of the top? Will the ocean ice disappear for good within the coming years in the summertime?” Christian Haas, head of the Sea Ice Physics Analysis Part on the Alfred Wegener Institute in Germany, informed CNN.

03 antarctic ice record low melt climate intl

A number of elements could feed into why sea ice is so low, together with winds, ocean currents and ocean warmth.

Air temperatures have been larger than traditional in components of the Antarctic, round 1.5 levels Celsius above the long run common.

One other vital consideration is the belt of westerly winds which circle Antarctica, often known as the Southern Annular Mode. These winds, which might improve sea ice soften, have been stronger than traditional, based on the NSIDC, and added to climate situations that pump heat air to the area.

The energy of the winds has been linked, partly, to the rise of planet-heating air pollution in addition to the outlet within the ozone layer above the continent.

There are additionally solutions that sea ice could also be melting due to heat trapped slightly below the floor of the ocean, Scambos stated.

“Mainly, you’re getting warmth stirred into the higher layer [of water] across the Antarctic,” he stated. If that idea holds up, and is linked to the overall warming of the oceans, “then that has massive implications for the steadiness of the Antarctic ice sheet.”

The disappearance of sea ice can have cascading results in Antarctica and past.

Whereas it doesn’t instantly have an effect on sea ranges, as a result of it’s already floating within the ocean, the lack of the perimeter of sea ice across the Antarctic leaves coastal ice sheets and glaciers uncovered to waves and heat ocean waters, making them far more susceptible to melting and breaking apart.

An altered Antarctic panorama might have vital impacts on its wildlife, from the microorganisms and algae that prop up the meals chain – meals for krill which, in flip, feed lots of the area’s whales – to the penguins and seals that depend on sea ice for feeding and resting.

Adelie penguins on Paulet Island in the Weddell Sea, near the tip of the Antarctic Peninsula.

Components of Antarctica have been seeing alarming modifications for some time.

The Antarctic Peninsula, a spindly chain of icy mountains which sticks off the west aspect of the continent like a thumb pointing towards South America, is likely one of the quickest warming locations within the Southern Hemisphere.

Carlos Moffat, an oceanographer on the College of Delaware, who has simply returned from a analysis journey to the Antarctic Peninsula, informed CNN that the low sea ice and really heat ocean temperatures they discovered “are dramatically completely different from what we’ve got noticed in the previous few a long time.”

Moffat, who visits the area each summer time as a part of the Palmer Lengthy-Time period Ecological Analysis, stated: “This yr’s situations are in opposition to a backdrop of long-term change on this area of Antarctica.”

Final yr, scientists stated West Antarctica’s huge Thwaites Glacier – also called the “Doomsday Glacier” – was “hanging on by its fingernails” because the planet warms, with speedy retreat doable over the subsequent few years. Scientists have estimated international sea stage rise might improve by round 10 toes if Thwaites collapsed fully, devastating coastal communities all over the world.

It’s too early to say whether or not the report sea ice decline is the brand new regular or whether or not it can bounce again, and Antarctica is understood for its vital swings. The NSIDC factors out that: “Whereas 2022 and 2023 have had report low minimal extent, 4 out of the 5 highest minimums have occurred since 2008.”

“It’s going to take some time to unpack,” Scambos stated. “We’re nonetheless reacting to a comparatively sudden change. Actually the previous few years have been a dramatic exclamation level on a pattern that was simply growing after 2016.”

Scientists will want not less than one other 5 years of knowledge and observations, he estimated, however added: “It does really feel like one thing has modified within the Antarctic and that issues are pretty dramatic.”

Correction: This story has been up to date to right the title of Christian Haas. Moreover, the final two years are solely occasions within the satellite tv for pc period that sea ice extent has fallen beneath 2 million sq. kilometers.