Impressive Arctic ice recovery continued in December as seen in the animation below:

The month of December 2023 shows Hudson Bay (lower right) starting with some western shore ice and ending 92% ice covered, adding in that basin ~800k km2. Just above Hudson, you can see the Gulf of St. Lawrence icing over, and Baffin Bay adding ice as well, now up to 50% of its annual maximum.

At the extreme and lower left, Okhotsk and Bering Seas also start with little shore ice. Okhotsk grew ice extent from 57k km2 up to 530k, 62% of its max last March.  Bering grew from 48k up to 478k km2, 56% of its max.  At the top Kara freezes over and Barents and Greenland Seas add ice to their margins. The graph below shows the December ice recovery. (Day 365 coming, and may be delayed by holiday.)

Note the average year adds 2M km2 while 2023 added ~2.5M, now 361k km2 above average. SII started 200k km2 lower than MASIE and ended up with the same deficit. Note that the other years are not far from the 17-year average at year end.

The table below shows year-end ice extents in the various Arctic basins compared to the 17-year averages and some recent years.

This year’s ice extent is 361k km2 or 2.8% above average.  Only Baffin Bay and Hudson have deficits to average, more than offset by surpluses elsewhere, espcially Greenland, Bering and Okhotsk seas. Many of the others are already maxed out.

Comparing Arctic Ice at End of Years

At  the bottom is a discussion of statistics on year-end Arctic Sea Ice extents.  The values are averages of the last five days of each year.  End of December is a neutral point in the melting-freezing cycle, midway between September minimum and March maximum extents.

Background from Previous Post Updated to Year-End 2023

Some years ago reading a thread on global warming at WUWT, I was struck by one person’s comment: “I’m an actuary with limited knowledge of climate metrics, but it seems to me if you want to understand temperature changes, you should analyze the changes, not the temperatures.” That rang bells for me, and I applied that insight in a series of Temperature Trend Analysis studies of surface station temperature records. Those posts are available under this heading. Climate Compilation Part I Temperatures

This post seeks to understand Arctic Sea Ice fluctuations using a similar approach: Focusing on the rates of extent changes rather than the usual study of the ice extents themselves. Fortunately, Sea Ice Index (SII) from NOAA provides a suitable dataset for this project. As many know, SII relies on satellite passive microwave sensors to produce charts of Arctic Ice extents going back to 1979.  The current Version 3 has become more closely aligned with MASIE, the modern form of Naval ice charting in support of Arctic navigation. The SII User Guide is here.

There are statistical analyses available, and the one of interest (table below) is called Sea Ice Index Rates of Change (here). As indicated by the title, this spreadsheet consists not of monthly extents, but changes of extents from the previous month. Specifically, a monthly value is calculated by subtracting the average of the last five days of the previous month from this month’s average of final five days. So the value presents the amount of ice gained or lost during the present month.

These monthly rates of change have been compiled into a baseline for the period 1980 to 2010, which shows the fluctuations of Arctic ice extents over the course of a calendar year. Below is a graph of those averages of monthly changes up to and including this year. Those familiar with Arctic Ice studies will not be surprised at the sine wave form. December end is a relatively neutral point in the cycle, midway between the September Minimum and March Maximum.

The graph makes evident the six spring/summer months of melting and the six autumn/winter months of freezing.  Note that June-August produce the bulk of losses, while October-December show the bulk of gains. Also the peak and valley months of March and September show very little change in extent from beginning to end.

The table of monthly data reveals the variability of ice extents over the last 4 decades.

The values in January show changes from the end of the previous December, and by summing twelve consecutive months we can calculate an annual rate of change for the years 1979 to 2023.

As many know, there has been a decline of Arctic ice extent over these 40 years, averaging 70k km2 per year. But year over year, the changes shift constantly between gains and losses, ranging up to +/- 500k km2.  Since 1989 the average yearend gain/loss is nearly zero, -0.033k km2 to be exact.

Moreover, it seems random as to which months are determinative for a given year. For example, much ado was printed about 2023 losing more ice than usual June through September. But then the final 3 months of 2023 more than made up for those summer losses, resulting in a sizeable gain for the year.

As it happens in this dataset, October has the highest rate of adding ice. The table below shows the variety of monthly rates in the record as anomalies from the 1980-2010 baseline. In this exhibit a red cell is a negative anomaly (less than baseline for that month) and blue is positive (higher than baseline).

Note that the  +/ –  rate anomalies are distributed all across the grid, sequences of different months in different years, with gains and losses offsetting one another.  As noted earlier,  in 2023 the outlier negative months were June through September where unusual amounts of ice were lost.  Then unusally strong gains in October and December resulted in a large annual gain, compared to the baseline. The bottom line presents the average anomalies for each month over the period 1979-2021.  Note the rates of gains and losses mostly offset, and the average of all months in the bottom right cell is virtually zero.

A final observation: The graph below shows the Yearend Arctic Ice Extents for the last 34 years.

Year-end Arctic ice extents (last 5 days of December) show three distinct regimes: 1988-1998, 1998-2010, 2010-2022. The average year-end extent 1989-2010 is 13.4M km2. In the last decade, 2011 was 13.0M km2, and six years later, 2017 was 12.3M km2. 2021 rose back to 13.06  2022 slipped back to 12.6M, and 2023 is back up to 13.0M. So for all the the fluctuations, the net is zero, or a gain of half a Wadham (0.5M) from 2010. Talk of an Arctic ice death spiral is fanciful.

These data show a noisy, highly variable natural phenomenon. Clearly, unpredictable factors are in play, principally water structure and circulation, atmospheric circulation regimes, and also incursions and storms. And in the longer view, today’s extents are not unusual.

Illustration by Eleanor Lutz shows Earth’s seasonal climate changes. If played in full screen, the four corners present views from top, bottom and sides. It is a visual representation of scientific datasets measuring Arctic ice extents.

As COP28 began, Arctic ice extrent grew rapidly and by its end the Arctic was completely normal. On lower left, Chukchi sea filled in and below Bering sea started serious freezing. Lower right Hudson Bay more than doubled up to 800k km2, 2/3 of its maximum extent.  Center right Baffin Bay grew to 45% of max.

A Lufthansa aircraft at the snow-covered Munich airport on Saturday. Photograph: Karl-Josef Hildenbrand/AP

Coincidently, COP28 also triggered heavy snow bringing chaos to southern Germany causing Munich to suspend flights to anywhere, including Dubai.

The graph below shows the gains in ice extent mid-November to Mid December for 2023, the 17 year average and some other recent years, as well as SII (Sea Ice Index)

MASIE showed 2023 and 2022 tracking the 17 year average and ending very close together.  2007 fluctuated a lot, well below average in December before rising at the end.  SII tracked ~400k km2 lower most of this period, before rising to match MASIE in the last few days.

The table below shows the distribution of ice in the Arctic Ocean basins.

Note that Arctic ice now exceeds 12M km2, or 80% of last March maximum.  As shown in the table above, the main deficit to average is in Hudson Bay, likely to be overcome with the current rapid growth. Offsetting are surpluses elsewhere, mostly in Greenland sea, along with Barents and Baltic seas.

The animation shows remarkable growth of Arctic ice extent just since COP28 began.  As noted in the previous Arctic ice post, Hudson Bay (lower right) was a lagging region, but freezing accelerated there. At the top, Barents and Greenland sea added ice. As well, both Bering and Okhotsk seas (far left) added fast ice on coastlines. In all, half a Wadham, 517k km2 of ice extent was added in just three days.

A Lufthansa aircraft at the snow-covered Munich airport on Saturday. Photograph: Karl-Josef Hildenbrand/AP

Coincidently, COP28 also triggered heavy snow bringing chaos to southern Germany causing Munich to suspend flights to anywhere, including Dubai.

The graph below shows the gains in ice extent erasing a brief deficit to average.

MASIE shows a gain of ~0.5M km2 from day 334 to 336, now exceeding average after being lower briefly.  SII (Sea Ice Index) also rose but is still estimating ice extent ~500k km2 lower.

The table below shows the distribution of ice in the Arctic Ocean basins.

Note that Arctic ice now exceeds 11M km2, or 74% of last March maximum.  As shown in the table above, the main deficits to average are in Hudson and Baffin Bays, along with less ice in Bering Sea. Offsetting are surpluses elsewhere, especially in Barents and Greenland seas.

The animation shows the continuing growth of Arctic ice extent during November 2023, from day 305 to yesterday, day 334.  For all of the fuss over the September minimum, little is said about Arctic ice growing back rapidly; that’s 4 Wadhams in October, plus another 2,2M in Nov to total 10.6M km2, or 10.6 Wadhams.  The Russian side on the left froze over in October, and now at the center bottom you can see Beaufort sea and Canadian Archipelago icing over completely. At top center Kara and Barents are adding normal ice extents. On the right side are the two lagging basins: Baffin and Hudson Bays, though freezing has started in Hudson bay in the last ten days.  That basin is shallow and likely to freeze over in the next two weeks.

The graph below shows the 30 days of November 2023 compared to the 17 year average (2006 to 2022 inclusive), to SII (Sea Ice Index) and some notable years.

Taking the average extent for the final 5 days of October 2023 compared to same for end of November, the added ice extent is 2.2M km2.  The growth slowed at the end resulting in a 290k km2 deficit to average.  Sea Ice Index (SII) is ~200k km2 lower than MASIE. 

The table below shows the distribution of ice in the Arctic Ocean basins.

As shown in the table above, the deficit is due to lagging growth in Hudson and Baffin Bays, along with less ice in Chukchi and Bering Seas. Typically these basins are among the last to freeze.

The animation shows the rapid growth of Arctic ice extent during November 2023, from day 304 to yesterday, day 319.  For all of the fuss over the September minimum, little is said about Arctic ice growing back rapidly; that’s 4 Wadhams in October, plus another 1.3M in Nov to total 10M km2, or 10 Wadhams.  The Russian side on the left froze over in October, and now at the center bottom you can see Beaufort sea and Canadian Archipelago icing up. Center right is Baffin Bay growing ice as well.

The graph below shows the last 30 days of 2023 compared to the 17 year average (2006 to 2022 inclusive), to SII (Sea Ice Index) and some notable years.

From Mid October to Mid November 2023, MASIE shows NH ice extent growing from 6.3 M km2 to 10M.  That matches 2022 and exceeds the 17 year average by more than 200K km2.   SII (Sea Ice Index) is only slightly lower.

The table below shows the distribution of ice in the Arctic Ocean basins.

Overall ice extent has 212k km2 above average or 2%.  The only sizeable deficit is in Hudson Bay,  more than offset by surpluses elsewhere, especiallly in Greenland and Barents seas, along with the Central Arctic.

The animation shows the rapid growth of Arctic ice extent during October 2023, from day 274 to day 304, yesterday.  For all of the fuss over the September minimum, little is said about Arctic ice growing 4M km2, that’s 4 Wadhams in one month!.  Look on the left (Russian side) at the complete closing of the Northern Sea Route for shipping.

The graph below show 2023 compared to the 17 year average (2006 to 2022 inclusive), to SII (Sea Ice Index) and some notable years.

This year October added 3.95M km2 from end of September compared to an average October increase of 3.45M km2.  As of yesterday NH ice extent is 368k km2 above average and nearly 600k km2 greater than 2007.

The table below shows the distribution of ice in the Arctic Ocean basins.

Overall ice extent has 346k km2 above average or 4%.  Sizeable deficits are in Beaufort Sea and Canadian Archipelago, more than offset by surpluses in Chukchi, East Siberian, Kara and Greenland seas.

The animation above shows the minimum daily extent for 2023 occurred on September 15.  In the next six days ~450k km2 of ice extent was added (nearly half a Wadham). The Arctic ice extent yesterday was 4.53M km2 approaching the 17 year average for the day.

The graph for September shows the first two weeks 2023 was well below the average and tracking with 2007. After hitting bottom day 258, a sharp recovery lifted extents close to average and much higher than 2007.  (SII  has not yet posted a value for day 264).

Note that typically September ends the month slightly higher than it begins, though 2023 is already matching its Sept. 1 value.  If this year’s ice growth continued at the same rate of losses during the first two weeks of September (50k per day), the extent would reach  ~5M km2 at month end.  That would result in a 2023 September monthly average of 4.5M km2.  Such extent would be close to the median prediction, somewhat lower than 2022, but much higher than 2007 or 2020, and 800k km2 higher than 2012 (the year of the great August Cyclone.)

The table for day 264 shows how the ice extent is distributed across the Arctic regions, in comparison to 17 year average and 2007.

The table shows the main deficits are in Beaufort, East Siberian seas and CAA.  Offsetting surpluses are in Laptev, Greenland and Central Arctic seas. The total deficit on this day is 72k km2 or 1.6%.  Note that 2007 did not add more ice as September ended.