The Arctic sea ice extent 2021 has been among the highest in recent times, due to a cool summer, autumn, especially in the western Arctic Ocean. The Hudson Bay is experiencing a marked negative anomaly. It is now almost completely free of ice and has been delayed for more than a month.
ARCTIC SEA ICE GREEDS FAST IN THIS YEAR
The Arctic sea ice extent has been growing faster than the previous years. By the end of November, its extent was 9.77 million square kilometers (3.77 million square miles) which is just within the interdecile range according to the National Snow & Ice Data Center of Boulder, Colorado (US).
The interdecile range measures statistical dispersion among values in a data set. It is within the normal inter-annual variability of sea-ice, but in the lower portion. The Bering Sea has a much higher average sea ice extent than the average. The ice formed along Siberian coast’s eastern portion relatively early in comparison to recent years.
Many cargo ships that transited the Northern Sea Route were therefore taken by surprise. Many of them were frozen in and are currently waiting for icebreakers. Many could remain stranded for several months while they wait for icebreakers.
Shipowners assumed that this month would be the same as previous years. Infact, warmer weather triggered by global warming allowed ships to cross parts of Russia’s Northern Sea Routes in November without any help from icebreakers.
According to the Barents Sea Observer however, Sea Ice grew rapidly to as high as 30 cm across most of East Siberian and Laptev Seas. The eastern sections of the sea route had their waters ice-covered by October, several weeks earlier that normal.
The present situation originated about October 25th, according to the University’s Center for High North Logistic (CHNL), which has carefully tracked the situation unfold.
24 vessels along the route were stuck in seaice during November 2021. They required icebreaker help. We are not able to determine if this was negligence, as we are not qualified or sufficiently informed to do so.
Therefore, let’s see what’s happening in the Arctic this year and why the ice concentrations and extent are higher than average in some sectors. But first of all, let’s see how sea ice is defined. Below is a video showing the Arctic sea ice extent. The video is updated every 5 Days from half October through the end of November.
WHAT IS SEA ICE?
Sea ice is any type of ice that forms when seawater freezes. Sea ice that isn’t fast ice is called drift ice. If the concentration is greater than 70%, it is known as pack ice. If sea ice concentration falls below 15%, it is considered open water. The boundary between open and ice is known as the ice border.
The Arctic’s sea ice cover increases throughout the winter, peaking in March. The sea ice extension is at its lowest point in September, which is usually only about one-third of the winter maximum. To get a complete picture of the sea-ice state, it is necessary to determine both the extents and the volumes. These numbers include the ice thickness, which is usually linked to the age.
Below is an image of Arctic sea ice climate from 1981 to 2010. It was taken by the Snow and Ice Data Center at the University of Colorado, Boulder.
Sea ice reached its lowest extent this year on September 16th, but it was far from the lowest and was only the 12th lowest in the last decade. The main reason is the colder-than-average weather in the western Arctic Ocean, which slowed sea ice melt in the Canadian/Alaskan regions.
The 2021 minimum sea-ice extent was approximately 4.724 millions square kilometers. This was roughly 1.6 million sq km less than the long term mean. A northern hemisphere’s strong negative height anomaly in the geopotential height in late summer kept the western Arctic cooler and reduced the ice melting.
Last summer, the western Arctic sector saw a drop in air temperature and sea temperatures. This was a positive trigger that contributed to the Arctic sector’s faster and earlier freezing when the fall season began.
This part of the Arctic Ocean has a lot to offer. The Bering Strait is the only outlet through which Arctic Ocean sea ice can exit. The Bering Strait, which divides Alaska from Russia, is shown in the image below. It was taken using data from Terra MODIS.
In fact, even though the sea ice extent anomaly was low in summer 2021, it stopped falling around July 10, then decreased and remained stable in August and September. Then, it dropped rapidly throughout October and November.
Below is a chart showing the Arctic sea ice anomalies for each year between 1979 and 2021 (satellite era, NSIDC; DMSP SSM/I SSMIS). The 5-day running mean of a 1981-2010 climatological baseline is used to calculate anomalies. 2021 is highlighted by a yellow line.
The contribution of the western Arctic sectors (namely the Bering Sea and the Chukchi Sea) to the current situation is the main reason for the present condition. Below is a comparison of the current Arctic sea-ice extents with the red lines. It also shows two standard deviations from 1981-2010.
Other sectors are also running at a lower level than average, such as the Greenland Sea and the Barents Seas, and the Hudson Bay. In contrast to other sectors, sea-ice levels in Hudson Bay are extremely low. The Hudson Bay remained unusually ice free through November. The Hudson Bay freezes up in November and the northern portion of the basin is usually completely iced by the end of November.
Only the Hudson Bay to the north has frozen over by the end of November 2021. The rest of the bay, except for a narrow, long-lasting band of ice that runs along the western coast, is almost entirely ice-free. This is Hudson Bay’s second lowest sea ice extent at this time of the years, according to the NSIDC. It is higher than 2010!
Below is a map showing the detail of the sea ice extent at November 30th, thanks to Multisensor Analyzed Sea Ice extent products from the NSIDC.
WHAT WEATHER PATTERNS ARE ASSOCIATED TO THIS INCREASE IN SEA ICE
To understand the causes of these anomalies, we must also analyze the October weather patterns. The Northern Hemisphere anomaly in October was characterized in part by Arctic regional contrasts, which were primarily controlled by the dominant jetstream configuration.
Low temperatures are a common characteristic of the Arctic Ocean.
Eastern Siberia and part of Alaska were much colder than average with anomalies around -10°C in some areas. Western Siberia, and especially most of Canada, were however relatively warm.
It was much warmer than normal in large areas between Ellesmere Island and Baffin Island, Resolute Island, Victoria Island, Victoria Island, and Iqaluit. This area is very close to the Last Ice Area, where the Arctic’s oldest sea-ice still exists.
The Last Ice Area is the projected summer sea-ice extent for 2040 and beyond. The Last Ice Area has the thickest and most ancient Arctic ice. This is because it is pressed against the northern shores of Ellesmere Island, Greenland, and Greenland by ice circulation.
The oldest sea-ice, which lasted more than four years, is today a small fraction of the total ice. In 1985 the > 4 years old sea-ice represented 35% of all the Arctic ice-pack. However, the majority of the ice-pack today is made up of young ice less than 1 year old. It covers an area of approximately 3.1 Million Square Kilometers (1.2 Million Miles), which is 70% of the total sea ice area.
The Arctic temperature patterns, as of October, led to a rapid recovery of sea ice following the summer minimum. The 2021 situation was definitely better than it was last October.
The situation was reversed at the Last Ice Area.
The extremely warm temperatures led to the melting a lot snow and warmed the ground. This was especially true for the marine surface, which has a lower albedo. This is a classic combination of positive feedback and negative effects.
Below is an image showing diagrams of Arctic sea ice concentration and extent 28 October 2020 (left) compared to 2021 (right), according the Japan Aerospace Exploration Agency. It is also clear that there is less ice than in 2020. In fact, 2020 saw a much lower amount of sea ice than 2021.
The Arctic Air Temperature patterns that were in place in October continued throughout November. As you can see below, the deviation from the Arctic average air temperature (in Celsius) at the 925 hPa levels (source NSIDC) is evident.
This temperature pattern was primarily caused by a low pressure area over the Atlantic side and a high in Beaufort Sea. A strong low pressure over Alaska created a circulation pattern east from the Bering Strait which brought in colder air from the north. This circulation pattern is favorable to ice growth and may account for the positive anomaly.
The essence of the speech is that the current state of sea ice is the most stable in the last 8 year and is consistent with the normal trend in the years 2000-2010. You have to go back to 2008 in order to find a year that has significantly more seaice.
The image below, edited by Zachary Labe, source ads – nipr, captures what has just been said.
Global climate and weather are affected by the Arctic sea ice. Recent research has shown that the Arctic’s decreasing sea ice has a significant impact on northern Europe’s precipitation.
The extraordinary sequence of 6 consecutive, wet summers from 2007 through 2012 was exceptional, even though none of these events were unique in historical records.
Scientist in a dedicated paper published on the Journal Environmental Research letters > state that observed wet summer months in northern Europe tend to occur when the jet stream is displaced to the south of its climatological position. Their simulation shows that Arctic sea ice loss causes a southward shift in the summer jet stream over Europe, and increases northern European precipitation.
The image above shows the average summer precipitation anomalies (% between 1981 and 2010 average) over northern Europe. The inset map shows the precipitation anomalies in the period 2007–2012 relative to the period 1979–2006. (b) Time-series for summer precipitation anomalies (% between 1981 and 2010 average) for England & Wales. The black curves indicate 5-year-long running means.
It will be fascinating to see how sea ice extent changes over the next weeks and months, especially at a time when global heating is moving at a rapid rate. At the moment, the Arctic continues to increase its sea ice extent at a steady pace, and if this trend continues in the coming months, there may be important repercussions for next spring’s synoptic and meteorological conditions.
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Source: Severe Weather