Arctic sea ice summer minimum in 2021 is ‘12th lowest’ on record

It is also 1.50 m km2 smaller sized than the 1981-2010 typical minimum extent, the NSIDC notes– equivalent to two times the size of Texas.

It was an “odd summer” this year, the NSIDC states. They keep in mind that while summertime melt was sluggish due to the mild and rainy conditions, as of 16 September, multi-year ice was at a “record low”– covering roughly one-quarter the location that it did in the 1980s.

The Antarctic tape-recorded its annual minimum on 21 February this year. Following the minimum, there was a 12-day period during which sea ice level increased at the fastest rate in the four-decade record of sea ice degree for the time of year. This was brought on by a rapid refreezing of the western Amundsen Sea and eastern Ross Sea locations..

Arctic sea ice has reached its annual minimum for 2021, clocking in at the 12th lowest on record, according to provisional data from the US National Snow and Ice Data Centre (NSIDC)..

” Even in years like 2021, which do not set brand-new record lows, the Arctic is a dramatically various place than it remained in the 1980s and 1990s.”.

In general, the rate of Arctic sea ice decrease in April was variable– and even increased slightly over 14-19 April. This was triggered by low atmospheric pressure of the Laptev sea, which drew in winds from the north and pressed ice southwards, according to the NSIDC.

Sea ice in both the Arctic and Antarctic goes through an annual cycle, growing in density and coverage over the colder months, and receding and thinning when the temperature level increases. Arctic sea ice generally reaches its “summertime minimum” in September– marking the point when it covers the smallest area.

Dr Zack Labe, a postdoctoral scientist at Colorado State University, stresses that the unexceptional minimum does not mark a long-term healing of Arctic sea ice.

By mid-July, Arctic sea ice extent was tracking just below the record low extent seen in 2012, and “really close” to that of 2020– the two years with the least expensive and second least expensive minimum ice degree in the satellite record. By 13 July, the Laptev Sea area was nearly totally free of sea ice, according to the NSIDC.

The minimum level is not record-breaking, NSIDC director Dr Mark Serrezze keeps in mind that “the quantity of old, thick sea ice is as low as it has ever been in our satellite record”. This means that the boost in overall sea ice level from last years minimum to this years “is thus comprised of first-year ice”, the NSIDC notes.

However, June brought with it a modification of speed, as “unusually strong” low pressure near the north pole and western Europe drove northwesterly winds over the Arctic, raising temperature levels to 2-5C above average. The raised temperatures accelerated ice loss, and one week into July, Arctic sea ice was tracking at a record low for the time of year, the NSIDC states.

Arctic sea ice extent reached its minimum for the year at 4.72 m square kilometers (km2), on 16 September, according to the NSIDC. This is the 12th most affordable in a satellite record extending back 43 years, the NSIDC says, with the past 15 years seeing the 15 tiniest sea ice minima.

Its official– > “The 2021 minimum is the twelfth most affordable in the nearly 43-year satellite record. The last 15 years are the least expensive 15 sea ice degrees in the satellite record.” See @NSIDC release:— Zack Labe (@ZLabe) September 22, 2021.

” Sea ice along the Siberian coast set brand-new records as soon as again. Arctic sea ice in the Laptev Sea melted out several weeks earlier than average. The typical summertime sea ice degree in the Laptev Sea observed new record lows in both 2020 and 2021.”.

However, records have still been set in some parts of the Arctic in recent months. For example, Labe highlights the rapid ice loss in the Laptev sea, which started early in the melt season:.

Last year, the Arctic sea ice minimum clocked in at the 2nd least expensive on record– in part due to an intense heatwave over Siberia. On the other hand, this year has actually been defined by storms and low pressure systems, which have actually kept temperatures low and kept older, multi-year ice moving to fill out spaces in sea ice, limiting the decrease in the level.

At the south pole, Antarctic sea ice extent is tracking “well-above the long-term average”, states the NSIDC, as it grows to its annual maximum, which can be expected in the coming weeks.

Sharelines from this story.

Unremarkable minimum.

Sea ice loss “stalled” over 8-11 August prior to speeding up once again. An “unusually strong” high-pressure system dominated over Siberia during the very first half of August, coupled by low pressure over the Greenland Ice Sheet, promoting strong southwards ice motion from the center of the Arctic Ocean towards the North American and Siberian shorelines.

The 2021 Arctic summer minimum extent, on 16 September 2021. The yellow line reveals the 1981-2010 typical level for that month. Credit: NSIDC.

” We had extremely early ice retreat in the Laptev Sea location, however the multi-year ice that was carried into the Beaufort Sea last winter helped to decrease ice loss because area this summertime– and we have more ice in the Chukchi Sea than weve had for rather some time.”.

Ice loss was slower than average over the May, as stormy weather condition over the eastern Arctic assisted to expand the ice pack and keep temperature levels low, restricting more melting. Average Arctic sea ice level in May ranked as the ninth lowest ice on record.

Earlier this year, Arctic sea ice reached an “uneventful maximum” at the end of March, ranking as the seventh least expensive on record. The months since then have been mainly defined by stormy, cloudy weather which kept temperatures minimal and low sea ice loss, the NSIDC notes.

Antarctic growth.

From the second week of March, Antarctic sea ice growth slowed to a more “normal” rate, and by the end of July, sea ice level was the 8th highest in the satellite record. By the end of August, Antarctic sea ice degree was the fifth highest on record.

” Arctic sea ice extent observes substantial year-to-year irregularity, in spite of a long-lasting trend of reducing ice cover. This is due to modifications in weather patterns and natural variability in the climate system. While not every year is going to set new records, long-term patterns reveal that human-caused environment modification will continue to warm the environment and ocean and reduce the amount of ice cover in the Arctic.

Prof Julienne Stroeve, professor of polar observation and modelling at the NSIDC and University College London, explains how the influx of older, multi-year ice assisted to balance out ice loss in the Laptev sea:.

Throughout the first half of the northern-hemisphere summertime, a pattern of strong low pressure near the north pole continued to dominate, pressing sea ice into an anticlockwise pattern– the opposite of the common motion. Throughout this time, the Arctic Ocean lost a total of 1.73 m km2 of sea ice. This is roughly equivalent in size to the state of Florida, according to the NSIDC:.

While this is the largest summer minimum because 2014, the NSIDC notes that the quantity of multi-year sea ice this year is “among the most affordable levels in the ice age record”.

Serrezze, informs Carbon Brief that this has actually been “a really odd year in the Arctic”, adding that “in regards to level, the Arctic sea ice cover is getting a reprieve this year”.

” Arctic sea ice extent observes significant year-to-year variability, regardless of a long-term pattern of reducing ice cover. Arctic sea ice in the Laptev Sea melted out numerous weeks earlier than average. The average summertime sea ice degree in the Laptev Sea observed brand-new record lows in both 2020 and 2021.”.

Arctic sea ice degree for each decade of the satellite era (dotted lines). Specific years are revealed by the moving lines– 2007 (pink), 2012 (white), 2020 (blue) and 2021 so far (yellow). Chart by Dr Zack Labe utilizing data from the Japan Aerospace Exploration Agency.

As of 15 September, Antarctic sea ice level stays “well-above the long-term average” as it grows to its yearly optimum, which can be expected in the coming weeks, according to the NSIDC.

A rainy and cool summertime.

” At the start of July, sea ice degree was above the levels recorded in 2012, the year that ended up with the lowest September ice extent in the satellite record. Following the minimum, there was a 12-day duration throughout which sea ice level increased at the fastest rate in the four-decade record of sea ice degree for the time of year.

” At the start of July, sea ice extent was above the levels recorded in 2012, the year that wound up with the lowest September ice level in the satellite record. Fairly rapid ice loss during the first week of July brought [ the] degree listed below 2012 levels. From 4-9 July, the 2021 extent was the lowest in the satellite record for that time of the year. The loss rate then slowed, and by late July, 2021 extent was tracking above 2020, 2019, 2011 and 2007.”.