2021 Sea ice area and extent data

[gerontocrat]

JAXA ARCTIC SEA ICE EXTENT:  12,453,216 KM2 as at 28-Dec-2021

- Extent gain on this day 103k, 60 k more than the average gain on this day (of the last 10 years) of 43k,
- Extent gain from minimum on this date is 7,840 k, which is 105 k, 1.3% less than the 10 year average of 7,946 k.

- Extent is 15th lowest in the 43 year satellite record

- Extent is  426 k MORE than 2020,
- Extent is  581 k MORE than  2018,
- Extent is  711 k MORE than 2017
- Extent is  155 k MORE than 2012
- Extent is  327 k MORE than the 2010's Average
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On average 79.0% of extent gains  from minimum to maximum done, and 70 days to maximum

Projections. (Table JAXA-Arc1)

Average remaining extent gain (of the last 10 years) would produce a maximum in March 2021 of 14.55 million km2, 0.67 million km2 above the March 2017 record low maximum of 13.88 million km2, which would be 14th lowest in the satellite record
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Some say that when data strays so much from trend values, it can indicate the beginning of system breakdown
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N.B. Click on image to enlarge

[oren]

A couple of posts (FG, coelho) moved to other more appropriate threads.

[gerontocrat]

NSIDC Total AREA as at 28-Dec-2021 (5 day trailing average) 11,344,454 KM2         

Total Area           11,344,454    km2        313,740    km2   >   2010's average.  333,936    km2   >   2020  1,322    km2   >   2019           Total Change    58    k   gain Peripheral Seas    50    k   gain Central Seas___    8    k   gain           Peripheral Regions          Okhotsk______    11    k   gain Bering _______    2    k   gain Hudson Bay___    17    k   gain Baffin  Bay____    10    k   gain St Lawrence___   -3    k   loss Greenland____    5    k   gain Barents ______    8    k   gain           Central Arctic  Ocean Regions          Chukchi______    6    k   gain Beaufort_____   -0    k   loss CAA_________   -0    k   loss East Siberian__    3    k   gain Central Arctic__    4    k   gain Laptev_______    0    k   gain Kara_________   -4    k   loss

         
Sea ice area gain on this day 58 k, 11 k more than the last 10 years average gain of 47 k         
         
- Area is at position #13 in the satellite record.         
- Area is 314 k more than the 2010's average         
- Area is 1064 k more than 2016         
- Area is 1 k more than 2019         
- Area is 334 k more than 2020          
- Area is 480 k more than 2012         
___________________________________________         
NSIDC Total EXTENT as at 28-Dec-2021 (5 day trailing average) 12,798,953 KM2         
         
NSIDC Sea ice EXTENT gain on this day 30 k, 28 k less than the 2010's average gain of 58k         
         
- EXTENT is at position #16 in the satellite record.         
- EXTENT is 355 k more than the 2010's average         
- EXTENT is 776 k more than 2016         
- EXTENT is 337 k more than 2019         
- EXTENT is 355 k more than 2020          
- EXTENT is 253 k more than 2012         
         
click on image to enlarge         

[Juan C. García]

[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

December 29^th, 2021:
     12,499,619 km², an increase of 46,403 km².
     2021 is now 14^th lowest on record.
     In the graph are the 18 lowest years.
     Highlighted 2010's average, 2021 and the 5 years with daily lowest minimum:
          (2012, 2020, 2019, 2016 & 2007)

Source: https://ads.nipr.ac.jp/vishop/#/extent.

[gerontocrat]

JAXA ARCTIC SEA ICE EXTENT:  12,499,619 KM2 as at 29-Dec-2021

- Extent gain on this day 46k, 22 k less than the average gain on this day (of the last 10 years) of 68k,
- Extent gain from minimum on this date is 7,887 k, which is 127 k, 1.6% less than the 10 year average of 8,013 k.

- Extent is 14th lowest in the 43 year satellite record

- Extent is  426 k MORE than 2020,
- Extent is  536 k MORE than  2018,
- Extent is  707 k MORE than 2017
- Extent is  97 k MORE than 2012
- Extent is  302 k MORE than the 2010's Average
_____________________________________________
On average 79.7% of extent gains  from minimum to maximum done, and 69 days to maximum

Projections. (Table JAXA-Arc1)

Average remaining extent gain (of the last 10 years) would produce a maximum in March 2021 of 14.53 million km2, 0.65 million km2 above the March 2017 record low maximum of 13.88 million km2, which would be 14th lowest in the satellite record
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N.B. Click on image to enlarge

[RoxTheGeologist]

[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

December 28^th, 2021:

Another way of visualizing this (highly cherry-picked) date across years.

18^th 2004: 12,627,798 (174,582 above 2021)
17^th 2009: 12,505,826 (52,610 above 2021)
16^th 2005: 12,479,758 (26,542 above 2021)

Just because the year 2007 holds some symbolic weight for me:
I think it's less than 50% likely, but a gain greater than 71,208 km² tomorrow (2010's average: 71,268) would bring 2021 to 17^th place for one day. Above each of the last 16 years (since 2005), but below each of the preceding 27 years.

Great representation!

[Juan C. García]

[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

December 30^th, 2021:
     12,552,646 km², an increase of 53,027 km².
     2021 is 14^th lowest on record.
     In the graph are the 18 lowest years.
     Highlighted 2010's average, 2021 and the 5 years with daily lowest minimum:
          (2012, 2020, 2019, 2016 & 2007)

Source: https://ads.nipr.ac.jp/vishop/#/extent.

[gerontocrat]

JAXA ARCTIC SEA ICE EXTENT:  12,552,646 KM2 as at 30-Dec-2021

- Extent gain on this day 53k, 4 k more than the average gain on this day (of the last 10 years) of 49k,
- Extent gain from minimum on this date is 7,940 k, which is 122 k, 1.5% less than the 10 year average of 8,062 k.

- Extent is 14th lowest in the 43 year satellite record

- Extent is  431 k MORE than 2020,
- Extent is  500 k MORE than  2018,
- Extent is  741 k MORE than 2017
- Extent is  80 k MORE than 2012
- Extent is  302 k MORE than the 2010's Average
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On average 80.2% of extent gains  from minimum to maximum done, and 68 days to maximum

Projections. (Table JAXA-Arc1)

Average remaining extent gain (of the last 10 years) would produce a maximum in March 2021 of 14.54 million km2, 0.66 million km2 above the March 2017 record low maximum of 13.88 million km2, which would be 14th lowest in the satellite record
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N.B. Click on image to enlarge

[Steven]

Below are some regional extent graphs using NSIDC 5-day averages:

- Barents is highest for this date since 2010.
- Bering had a strong start of the freezing season, but slowed down recently due to milder weather.
- Okhotsk is rather high.
- Baffin is lagging.

[oren]

Thanks a lot Steven. We are sorely missing Wipneus' regional graphs.

[gerontocrat]

JAXA ARCTIC SEA ICE EXTENT:  12,626,559 KM2 as at 31-Dec-2021

- Extent gain on this day 74k, 41 k more than the average gain on this day (of the last 10 years) of 33k,
- Extent gain from minimum on this date is 8,014 k, which is 82 k, 1.0% less than the 10 year average of 8,095 k.

- Extent is 16th lowest in the 43 year satellite record

- Extent is  521 k MORE than 2020,
- Extent is  462 k MORE than  2018,
- Extent is  731 k MORE than 2017
- Extent is  198 k MORE than 2012
- Extent is  336 k MORE than the 2010's Average
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On average 80.5% of extent gains  from minimum to maximum done, and 67 days to maximum

Projections. (Table JAXA-Arc1)

Average remaining extent gain (of the last 10 years) would produce a maximum in March 2021 of 14.58 million km2, 0.70 million km2 above the March 2017 record low maximum of 13.88 million km2, which would be 14th lowest in the satellite record
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N.B. Click on image to enlarge

[gerontocrat]

A longer look at 2021 JAXA sea ice extent

Finishing the year with extent at 16th lowest in the satellite record is a fitting end to this year which has bucked the trend for ever decreasing sea ice extent.

The December monthly average extent at 11.61 million km2 is...
- 11th lowest in the satellite record,
- 0.39 million km2 above the long-term linear trend which is the highest amount above trend in December in the satellite record,
- and 0.37 million Km2 above the Dec 2020 average.

The 365 day trailing average on 31 Dec 2021 is 417k greater than that on 31 Dec 2020.

Average daily sea ice extent in 2021 at 10.09 million km2 is 9th lowest in the satellite record, while the average in 2020 was lowest in the satellite record. (see last 2 images)

[Freegrass]

In the financial world, we would put that line on the top of those bars. If you did that, would 2021 still break the trend? 🤔

At first glance, I think it wouldn't...

[Stephan]

I added the monthly extent value for December 2021 into my long-term plot where I calculate the extent anomalies from 1979 up to now.
The average (1979-2021) December extent is now 12.66 M km². December 2021 had an average extent of 12.19 M km², which is 0.47 M km² less than that long-term average.
This month the value is again above the long-term linear trend line. The difference of the actual month from that trend line is +0.62 M km² (calculated from the linear trend line this December should have been at 11.57 M km²).
The slope of the long-term linear trend line went down by two digits (-0.0549 → -0.0547).

See attached graph. Click to enlarge.

[KenB]

The slope of the long-term linear trend line went down by two digits (-0.0549 → -0.0547).

Thanks Stephan,  I think these plots are very informative.  One quibble, though:  wouldn't it be more accurate to say that the slope of the long-term linear trend line went up by two digits?  Since the slope is negative, i.e. downward as time increases, the change is in the direction of bringing the line up, not further down.  Though I suppose there's also a sense in which the absolute value of the slope (what one might call 'steepness') is going down rather than up. Anyway, thanks.

[John_The_Elder]

If the slope of a negative line increases, does this not mean that the line moved "down" from the
x axis? Yes the magnitude has grown to a larger negative number, that is down not up

[Stephan]

The slope of the long-term linear trend line went down by two digits (-0.0549 → -0.0547).

Thanks Stephan,  I think these plots are very informative.  One quibble, though:  wouldn't it be more accurate to say that the slope of the long-term linear trend line went up by two digits?  Since the slope is negative, i.e. downward as time increases, the change is in the direction of bringing the line up, not further down.  Though I suppose there's also a sense in which the absolute value of the slope (what one might call 'steepness') is going down rather than up. Anyway, thanks.

Yes, you are completely right. Next time I'll write "flatter" or "steeper" instead of "up" or "down".
Thanks for this hint.

[KenB]

If the slope of a negative line increases, does this not mean that the line moved "down" from the
x axis? Yes the magnitude has grown to a larger negative number, that is down not up

Maybe it's a matter of perspective.  We crossed below the x axis around 2000 on this plot and I'm focused on points for recent years on the far left.  The most recent addition to the data, while below 0, was still above the trend line and to my way of thinking, that recent addition pulled the trend line up.  But I like using "flatter" and "steeper" as Stephan suggests.  This is very clear since there's no question (unfortunately!) that the slope is negative.

[Stephan]

I take the opportunity to present the anomalies of volume and thickness in the Arctic, because the year 2021 has passed.
The volume graph is much smoother than the thickness graph.