Sea ice at both poles

What’s new about sea-ice data?

The maximum sea-ice extent happens around February in the Arctic. For the year 2022, the maximum extent was recorded at nearly 15 million square kilometres. This maximum is the tenth lowest recorded in the 44-year satellite record. Last end-of-summer minimum extent was reached on 16th September 2021 at 4.72 million square kilometres. While 2012 remains the lowest, the last 15 years have showed us the lowest minimum extents seen in the 44-year satellite era.

Maximum sea-ice extent for the year 2021 happened in September in Antarctica at 18.75 million square kilometres. This was followed by the minimum sea-ice extent occurring in February 2022 at 1.92 square kilometres, the smallest extent recorded. Interestingly, Antarctic sea ice expanded at a slow rate in the first four decades of satellite observations. However, during the austral spring 2016, the sea-ice extent strongly decreased leading to the minimum of 2.07 million square kilometres on 1st March 2017, the lowest record at the time since 1979. This record low arose due to the near total loss of sea ice in Ross Sea and Amundsen Sea, which occurred during January 2017 and continued through February.

Are phenomena at the two Poles linked?

Record low extents of sea ice in the Arctic and Antarctic have led to record lows in global sea-ice extent.

It is sensible to consider the Arctic, which is an ocean surrounded by land, and the Antarctic, which is land surrounded by ocean, as two independent regions of sea-ice change. Both Poles respond to increases in greenhouse gases, but they do so in different ways because the processes that lead to sea-ice loss are not the same in the two regions. Moreover, each region exhibits natural fluctuations in sea ice from year-to-year and decade-to-decade which are distinct from one another. Numerous studies focus on understanding both natural and human-induced fluctuations through observations and modelling applications.

Are we seeing the reversal of a trend in the Antarctic?

Sea ice is highly variable on year-to-year timescales. In 2014, a record maximum extent of Antarctic sea ice was recorded with the five-day average exceeding 20 million square kilometres for the first time in the satellite record. That record maximum and this year’s record minimum could both be the result of short-term fluctuations rather than longer-term trends.

The long-term trend in Antarctic sea-ice extent has been one of small increase since the late 1970s. The 2017’s record minimum followed by the lowest record in 2022 are significant events which may represent a switch away from the previously observed increase. However, the specific circumstances which led to both record minima as well as the present atmospheric/sea-ice/oceanographic conditions need to be thoroughly investigated in order to assess whether we are seeing a new trend in Antarctic sea ice variability.

The IPCC Fifth Assessment projected a decrease in Antarctic sea-ice extent by the end of this century as global mean surface temperature rises, albeit with low confidence due to weaknesses in the representation of Antarctic sea ice in climate models. To improve climate models, scientists need more detailed measurements of the ice, such as its thickness.

What does the record low Arctic maximum imply for weather in UK and further afield?

Much recent research activity has been focused on understanding the impact of Arctic sea-ice loss on weather across Europe, Asia, and North America. While it is clear that changes to the sea-ice coverage have the potential to impact weather patterns, the details remain subject to debate.

When will the Arctic Ocean be ice free in summer?

Arctic sea-ice extent is decreasing rapidly, with September extent for the satellite period of 1979 to 2021 showing a decline of 13.1% per decade. An ‘ice free’ state is often taken to mean a coverage of less than 1 million square kilometres. Sea-ice extent is determined by a combination of natural factors, which lead to fluctuations from year-to-year, decade-to-decade and longer, and a long-term trend as a consequence of warming due to greenhouse gas emissions.

Whether and when an ice-free state is reached will depend on these natural factors and our future emissions. If global emissions reductions consistent with the temperature goals of the Paris Agreement are met, then it might be possible to avert an ice-free Arctic Ocean. On the other hand, if emissions continue on the current trajectory, then an ice-free summertime Arctic is expected within the coming decades.


On this site: Gaelle Veyssiere
30 June, 2022