Arctic Ice Abounds at 2021 Minimum

 

The images above come from MASIE showing ice extents on day 260, the lowest daily extent on average the last 14 years.  Note that 2012 was the lowest in this period and 2021 is now the highest, surpassing 2014. The abundance of ice this year contrasts with both 2007 and 2020. Clearly, the location of remaining ice in September varies greatly from year to year.  The marginal seas are open water, including the Pacific basins, Canadian Bays (Hudson and Baffin), and the Atlantic basins for the most part.  As discussed later on, other regions retain considerable ice at the annual minimum, with differences year to year.

The annual competition between ice and water in the Arctic ocean is now at the maximum for water, which typically occurs mid September.  After that, diminishing energy from the slowly setting sun allows oceanic cooling causing ice to regenerate. Those interested in the dynamics of Arctic sea ice can read numerous posts here.  This post provides a look at September from 2007 to yesterday as a context for understanding this year’s annual minimum.  Note that for climate purposes the annual minimum is measured by the September monthly average ice extent, since the daily extents vary and will go briefly lowest on or about day 260. In a typical year the overall ice extent will end September slightly higher than at the beginning.

The melting season in September up to yesterday shows 2021 melted much less than average and so day 260 extents are much higher than average.

2021 ice extents begin September 800k km2 above the 14-year average and on day 260 remained 776k km2 higher.  SII was lower than MASIE by 427k km2.  The table for day 260 shows how large are the 2021 surpluses and how the ice is distributed across the various seas comprising the Arctic Ocean. The surplus this year over 2007 is more than 1 Wadham (1M km2).

Region 2021260 Day 260 Average 2021-Ave. 2007260 2021-2020
 (0) Northern_Hemisphere 5168253 4392025 776228 4045776 1122477
 (1) Beaufort_Sea 715340 463613 251727 481384 233956
 (2) Chukchi_Sea 493208 132989 360219 22527 470681
 (3) East_Siberian_Sea 338189 248694 89495 311 337878
 (4) Laptev_Sea 32974 114492 -81518 235869 -202895
 (5) Kara_Sea 95956 17336 78619 44067 51888
 (6) Barents_Sea 18 18201 -18183 7420 -7402
 (7) Greenland_Sea 50718 192388 -141670 333181 -282463
 (8) Baffin_Bay_Gulf_of_St._Lawrence 35493 28885 6609 26703 8791
 (9) Canadian_Archipelago 452857 270948 181909 225526 227331
 (10) Hudson_Bay 4504 5318 -814 2270 2233
 (11) Central_Arctic 2948362 2898150 50213 2665244 283118

The main deficits to average are in Laptev and Greenland Seas, overwhelmed by surpluses almost everywhere, especially in BCE (Beaufort, Chukchi, East Siberian seas), Kara and Canadian Archipelago.  And as discussed below, the marginal basins have little ice left to lose.

The Bigger Picture 

We are close to the annual Arctic ice extent minimum, which typically occurs on or about day 260 (mid September). Some take any year’s slightly lower minimum as proof that Arctic ice is dying, but the image above shows the Arctic heart is beating clear and strong.

Over this decade, the Arctic ice minimum has not declined, but since 2007 looks like fluctuations around a plateau. By mid-September, all the peripheral seas have turned to water, and the residual ice shows up in a few places. The table below indicates where ice is found in September. Numbers are area units of Mkm2 (millions of square kilometers).

Day 260 14 year
Arctic Regions 2007 2010 2012 2014 2015 2017 2018 2019 2020 2021 Average
Central Arctic Sea 2.67 3.16 2.64 2.98 2.93 3.07 2.91 2.97 2.50 2.95 2.90
BCE 0.50 1.08 0.31 1.38 0.89 0.84 1.16 0.46 0.65 1.55 0.89
LKB 0.29 0.24 0.02 0.19 0.05 0.26 0.02 0.11 0.01 0.13 0.16
Greenland & CAA 0.56 0.41 0.41 0.55 0.46 0.52 0.41 0.36 0.59 0.50 0.46
B&H Bays 0.03 0.03 0.02 0.02 0.10 0.07 0.05 0.01 0.02 0.04 0.04
NH Total 4.05 4.91 3.40 5.13 4.44 4.76 4.56 3.91 3.77 5.17 4.48

The table includes some early years of note along with the last 5 years compared to the 14 year average for five contiguous arctic regions. BCE (Beaufort, Chukchi and East Siberian) on the Asian side are quite variable as the largest source of ice other than the Central Arctic itself.   Greenland Sea and CAA (Canadian Arctic Archipelago) together hold almost 0.5M km2 of ice at annual minimum, fairly consistently.  LKB are the European seas of Laptev, Kara and Barents, a smaller source of ice, but a difference maker some years, as Laptev was in 2016.  Baffin and Hudson Bays are inconsequential as of day 260.

2021 stands out from lower ice years by the higher extents in Central Arctic, BCE and LKB, especially Kara Sea this year.

Resources:  Climate Compilation II Arctic Sea Ice

Resilient Arctic Ice September 2021

The animation shows Arctic ice extents on day 248 in 2007 (matching 14 year average), then the same day in 2019, 2020, and yesterday in 2021.  Note that Hudson Bay upper left is open water, and below that Baffin Bay next to Greenland is also ice-free.  In the center Canadian Archipelago holds a lot of ice, especially this year.  Also unusual in 2021 is ice covering Svalbard lower right all the way to Europe mainland.  Also upper right 2021 shows ice in Chukchi touching Russian coastline.

The graph above shows mid-August to mid-Sept daily ice extents for 2021 compared to 14 year averages, and some years of note.  During the 17 days from August 18 to yesterday, the black  line shows Arctic Ice extent declined on average by 1M km2 (1 Wadham).  Meanwhile the cyan line shows MASIE 2021 ice extents lost only 171k km2, and Sea Ice Index (SII) in orange lost 317k km2. Note on day 230 all three lines started at the same value.

Why is this important?  All the claims of global climate emergency depend on dangerously higher temperatures, lower sea ice, and rising sea levels.  The lack of additional warming is documented in a post Adios, Global Warming

The lack of acceleration in sea levels along coastlines has been discussed also.  See USCS Warnings of Coastal Flooding

Also, a longer term perspective is informative:

post-glacial_sea_levelThe table below shows the distribution of Sea Ice across the Arctic Regions, on average, this year and 2007.

Region 2021248 Day 248 Average 2021-Ave. 2007248 2021-2020
 (0) Northern_Hemisphere 5464375 4672631 791744 4751076 713299
 (1) Beaufort_Sea 798213 522472 275741 665051 133162
 (2) Chukchi_Sea 524060 202259 321800 116358 407702
 (3) East_Siberian_Sea 408523 310662 97862 6329 402195
 (4) Laptev_Sea 51574 143286 -91712 280600 -229026
 (5) Kara_Sea 122087 30192 91896 103072 19015
 (6) Barents_Sea 18 15631 -15612 10766 -10748
 (7) Greenland_Sea 98270 176374 -78104 334524 -236254
 (8) Baffin_Bay_Gulf_of_St._Lawrence 16983 23131 -6148 31787 -14804
 (9) Canadian_Archipelago 440366 288302 152064 270755 169612
 (10) Hudson_Bay 39285 15338 23947 29961 9324
 (11) Central_Arctic 2963852 2944150 19702 2900617 63235

The overall surplus to average is 792k km2, (+17%).  Note large surpluses of ice in BCE (Beaufort, Chukchi and East Siberian seas).  Meanwhile Laptev on the Russian coast melted out early, as has Greenland Sea.  Kara and CAA (Canadian Arctic Archipelago) are holding considerable ice.  We are about 12 days away from the annual minimum mid September, but at this point it appears that extents will be much greater than the last two years.

See also Abundant August Arctic Ice with 2021 Minimum Outlook

bathymetric_map_arctic_ocean

 

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.

Abundant August Arctic Ice with 2021 Minimum Outlook

The images above come from AARI (Arctic and Antarctic Research Institute) St. Petersburg, Russia. Note how the location of remaining ice at end of August varies greatly from year to year.  The marginal seas are open water, including the Pacific basins, Canadian Bays (Hudson and Baffin), and the Atlantic basins for the most part.  As discussed later on, other regions retain considerable ice at the annual minimum, with differences year to year.

The annual competition between ice and water in the Arctic ocean is approaching the maximum for water, which typically occurs mid September.  After that, diminishing energy from the slowly setting sun allows oceanic cooling causing ice to regenerate. Those interested in the dynamics of Arctic sea ice can read numerous posts here.  This post provides a look at end of August from 2007 to yesterday as a context for anticipating this year’s annual minimum.  Note that for climate purposes the annual minimum is measured by the September monthly average ice extent, since the daily extents vary and will go briefly lowest on or about day 260. In a typical year the overall ice extent will end September slightly higher than at the beginning.

The melting season in August up to yesterday shows 2021 melted slower than average and the month end extents were much higher than average.  I have added a hockey stick to dramatize the abundance of August Arctic ice this year.

 

Firstly note that on average August ice declines 205k km2 but in 2021 only 112k km2 was lost. The decline in Sea Ice Index in orange  was only slightly more, 130k km2.  The table for day 243 show how large are the 2021 surpluses and how the ice is distributed across the various seas comprising the Arctic Ocean. Since 2007 was the same as average, 2020 day 243 is shown for comparison.  The surplus this year over last is more than 1 Wadham.

Region 2021243 Day 243 Average 2021-Ave. 2020243 2021-2020
 (0) Northern_Hemisphere 5489976 4823907 666069 4345398 1144577
 (1) Beaufort_Sea 855409 543972 311437 763281 92128
 (2) Chukchi_Sea 573897 221139 352758 212438 361459
 (3) East_Siberian_Sea 454688 337359 117328 176996 277692
 (4) Laptev_Sea 24500 164608 -140107 1029 23471
 (5) Kara_Sea 120346 41181 79165 23958 96387
 (6) Barents_Sea 598 20645 -20047 0 598
 (7) Greenland_Sea 63956 172538 -108583 192361 -128406
 (8) Baffin_Bay_Gulf_of_St._Lawrence 16313 26222 -9909 5016 11297
 (9) Canadian_Archipelago 431968 300878 131089 273116 158852
 (10) Hudson_Bay 44909 23291 21618 23611 21298
 (11) Central_Arctic 2902324 2971236 -68912 2672904 229421

The main deficits to average are in Laptev and Greenland Seas, overcome by surpluses almost everywhere, especially in BCE (Beaufort, Chukchi, East Siberian seas), Kara and Canadian Archipelago.  And as discussed below, the marginal basins have little ice left to lose.

The Bigger Picture 

We are close to the annual Arctic ice extent minimum, which typically occurs on or about day 260 (mid September). Some take any year’s slightly lower minimum as proof that Arctic ice is dying, but the image above shows the Arctic heart is beating clear and strong.

Over this decade, the Arctic ice minimum has not declined, but since 2007 looks like fluctuations around a plateau. By mid-September, all the peripheral seas have turned to water, and the residual ice shows up in a few places. The table below indicates where we can expect to find ice this September. Numbers are area units of Mkm2 (millions of square kilometers).

Day 260 14 year
Arctic Regions 2007 2010 2014 2015 2016 2017 2018 2019 2020 Average
Central Arctic Sea 2.67 3.16 2.98 2.93 2.92 3.07 2.91 2.97 2.50 2.90
BCE 0.50 1.08 1.38 0.89 0.52 0.84 1.16 0.46 0.65 0.89
LKB 0.29 0.24 0.19 0.05 0.28 0.26 0.02 0.11 0.01 0.16
Greenland & CAA 0.56 0.41 0.55 0.46 0.45 0.52 0.41 0.36 0.59 0.46
B&H Bays 0.03 0.03 0.02 0.10 0.03 0.07 0.05 0.01 0.02 0.04
NH Total 4.05 4.91 5.13 4.44 4.20 4.76 4.56 3.91 3.77 4.39

The table includes two early years of note along with the last 7 years compared to the 14 year average for five contiguous arctic regions. BCE (Beaufort, Chukchi and East Siberian) on the Asian side are quite variable as the largest source of ice other than the Central Arctic itself.   Greenland Sea and CAA (Canadian Arctic Archipelago) together hold almost 0.5M km2 of ice at annual minimum, fairly consistently.  LKB are the European seas of Laptev, Kara and Barents, a smaller source of ice, but a difference maker some years, as Laptev was in 2016.  Baffin and Hudson Bays are inconsequential as of day 260.

For context, note that the average maximum has been 15M, so on average the extent shrinks to 30% of the March high before growing back the following winter.  In this context, it is foolhardy to project any summer minimum forward to proclaim the end of Arctic ice.

Resources:  Climate Compilation II Arctic Sea Ice

Arctic Ice Hockey Stick August 2021

Arctic2021235 w HS

The graph above shows August daily ice extents for 2021 compared to 14 year averages, and some years of note.

The black line shows during this period on average Arctic ice extents decline ~2M km2 from ~6.8M km2 down to ~4.8M km2.  The Hockey Stick shape refers to the 2021 cyan MASIE line starting ~227k km2 below average but matching average by day 230, and in the last five days produced a surplus of 414k km2.  The Sea Ice Index in orange (SII from NOAA) started with the same deficit and also matched MASIE average day 230, but tracking the downward average since.  2019 and 2020 were well below average at this stage of the summer melt.

Why is this important?  All the claims of global climate emergency depend on dangerously higher temperatures, lower sea ice, and rising sea levels.  The lack of additional warming is documented in a post Adios, Global Warming

The lack of acceleration in sea levels along coastlines has been discussed also.  See USCS Warnings of Coastal Flooding

Also, a longer term perspective is informative:

post-glacial_sea_levelThe table below shows the distribution of Sea Ice across the Arctic Regions, on average, this year and 2007.

Region 2021235 Day 235 Average 2021-Ave. 2007235 2021-2007
 (0) Northern_Hemisphere 5745634 5331499 414135 5309870 435765
 (1) Beaufort_Sea 872981 605537 267444 730813 142168
 (2) Chukchi_Sea 539676 329819 209856 178493 361182
 (3) East_Siberian_Sea 508990 445221 63769 63523 445468
 (4) Laptev_Sea 61548 205077 -143529 295384 -233836
 (5) Kara_Sea 136181 58898 77283 155754 -19573
 (6) Barents_Sea 6047 24071 -18025 17998 -11951
 (7) Greenland_Sea 84815 202922 -118108 334622 -249808
 (8) Baffin_Bay_Gulf_of_St._Lawrence 40877 33602 7275 50303 -9426
 (9) Canadian_Archipelago 465781 354257 111524 323329 142452
 (10) Hudson_Bay 64148 35761 28387 61078 3070
 (11) Central_Arctic 2964500 3035379 -70879 3097316 -132816

The overall surplus to average is 414k km2, (8%).  Note large surpluses of ice in BCE (Beaufort, Chukchi and East Siberian seas).  Meanwhile Laptev on the Russian coast melted out early, as has Greenland Sea.  Kara and CAA (Canadian Arctic Archipelago) are holding considerable ice.  We are about a month away from the annual minimum mid September, but at this point it appears that extents will be greater than the last two years.

bathymetric_map_arctic_ocean

 

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.

Fear Not for Arctic Ice Mid August 2021

Arctic2021226

The graph above shows mid July to mid August daily ice extents for 2021 compared to 14 year averages, and some years of note.

The black line shows during this period on average Arctic ice extents decline from ~8.3M km2 down to ~5.9M km2.  The 2021 cyan MASIE line started ~400k km2 below average but as of yesterday was slightly surplus.  The Sea Ice Index in orange (SII from NOAA) started with a deficit to MASIE (in cyan) of ~300M km2.  August 14 saw the two indices mid August close together, close to average and surplus to 2007.

Why is this important?  All the claims of global climate emergency depend on dangerously higher temperatures, lower sea ice, and rising sea levels.  The lack of additional warming is documented in a post Adios, Global Warming

The lack of acceleration in sea levels along coastlines has been discussed also.  See USCS Warnings of Coastal Flooding

Also, a longer term perspective is informative:

post-glacial_sea_levelThe table below shows the distribution of Sea Ice across the Arctic Regions, on average, this year and 2007.

Region 2021226 Day 226 Average 2021-Ave. 2007226 2021-2007
 (0) Northern_Hemisphere 6066634 5889687 176947 5727937 338697
 (1) Beaufort_Sea 915133 688804 226329 777766 137366
 (2) Chukchi_Sea 572339 404505 167834 260048 312290
 (3) East_Siberian_Sea 624917 556990 67927 196982 427934
 (4) Laptev_Sea 52213 252434 -200221 316363 -264150
 (5) Kara_Sea 173342 88626 84716 201115 -27772
 (6) Barents_Sea 5256 29027 -23771 17324 -12068
 (7) Greenland_Sea 118995 224977 -105982 316155 -197160
 (8) Baffin_Bay_Gulf_of_St._Lawrence 23528 59670 -36142 86165 -62637
 (9) Canadian_Archipelago 465880 420722 45157 375241 90638
 (10) Hudson_Bay 83051 74370 8681 91653 -8603
 (11) Central_Arctic 3031058 3088557 -57499 3087868 -56810

The overall surplus to average is 177k km2, (3%).  Note large surpluses of ice in BCE (Beaufort, Chukchi and East Siberian seas).  Meanwhile Laptev on the Russian coast melted out early, as has Greenland Sea.  Kara and CAA (Canadian Arctic Archipelago) are holding considerable ice.  We are about a month away from the annual minimum mid September, but at this point it does not appear it will be out of the ordinary.

bathymetric_map_arctic_ocean

 

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.

Routine Melting of Arctic Ice in July

The animation shows Arctic ice extents on Day 212 (end of July) for the years 2007 to 2021 (yesterday).  Evidently, there is considerable variation year over year both on the total amount and where the ice is to be found.  The images are from MASIE (Multisensor Analyzed Sea Ice Extent) platform operated by the US National Ice Center (NIC).  More on MASIE can be read at previous post NOAA Loses 1M km2 of Arctic Ice in July

Note that in all years, some regions are open water by day 212:  Sea of Okhotsk (lower left), Bering Sea (lower center). Mostly ice free are Hudson Bay (lower right) and Barents Sea (top left).  Center left along the Russian coastline runs the Northern Sea Route for summertime shipping from Kara Sea (top left) down through the Bering Strait.  As you can see, some years the ice is still plentiful along this route, and other years are almost ice free.  This year, Laptev is largely open water, while Kara (above) and Chukchi (below) still have much ice to challenge the ice breakers.

Of interest also is the Canadian Arctic Archipelago (center right, below Greenland).  Here is found the Northwest Passage by which intrepid sailors seek transit from the Atlantic (right) through to the Pacific by way of Bering Sea.  Again, some years it is open and simple, and other years closed completely.  On day 212, 2021, CAA has more ice than average, so this year could be more challenging than in other recent years.

The graph below shows July daily ice extents for 2021 compared to 14 year averages, and some years of note.

On average, July Arctic ice declines from ~9.7M km2 down to 6.9M km2.  This year Sea Ice Index in orange (SII from NOAA) lost ice rapidly and opened up a deficit to MASIE (in cyan) of ~700M km2.  The last three weeks saw the two indices ending the month close together, slightly below average and matching 2007.  Note that both 2019 and 2020 had much lower extents at end of July.

Why is this important?  All the claims of global climate emergency depend on dangerously higher temperatures, lower sea ice, and rising sea levels.  The lack of additional warming is documented in a post Adios, Global Warming

The lack of acceleration in sea levels along coastlines has been discussed also.  See USCS Warnings of Coastal Flooding

Also, a longer term perspective is informative:

post-glacial_sea_levelThe table below shows the distribution of Sea Ice across the Arctic Regions, on average, this year and 2007.

Region 2021212 Day 212 Average 2021-Ave. 2007212 2021-2007
 (0) Northern_Hemisphere 6621487 6903677  -282190  6344860 276627 
 (1) Beaufort_Sea 899718 776180  123539  760576 139143 
 (2) Chukchi_Sea 563418 526326  37091  382350 181068 
 (3) East_Siberian_Sea 652192 745174  -92982  445385 206807 
 (4) Laptev_Sea 97962 389632  -291669  314382 -216420 
 (5) Kara_Sea 230155 159737  70418  239232 -9077 
 (6) Barents_Sea 37818 32484  5334  23703 14115 
 (7) Greenland_Sea 149142 298586  -149444  324737 -175595 
 (8) Baffin_Bay_Gulf_of_St._Lawrence 143110 136724  6387  94179 48931 
 (9) Canadian_Archipelago 594031 547883  46148  510063 83968 
 (10) Hudson_Bay 113973 151424  -37452  93655 20318 
 (11) Central_Arctic 3139007 3137899  1108  3154837 -15830 

The overall deficit to average is 282k km2, (4%) which matches the deficit in Laptev.  Other places with less than average extents are East Siberian, Greenland Sea and Hudson Bay.  Offsetting these are surpluses in Beaufort, Chukchi, Kara and CAA.  

 

NOAA Loses 1M km2 of Arctic Ice in July

Arctic2021185

NOAA’s Sea Ice Index (shown in orange above) dramatically lost 1M km2 of Arctic sea ice extent in just the last four days.  Meanwhile MASIE from the National Ice Center (NIC) (cyan color) declined much less, ~400k km2, a more typical decline since the two datasets were nearly the same on June 30, 2021.  Note that extreme drops in ice extents can happen in July, as seen last year (purple line after day 190), so the issue bears watching. There is history of satellite difficulties discriminating between open water and surface melt water during both the melting and refreezing seasons.  A background post below explains differences between the two datasets.

Background from previous post Support MASIE Arctic Ice Dataset

MASIE: “high-resolution, accurate charts of ice conditions”
Walt Meier, NSIDC, October 2015 article in Annals of Glaciology.

Update February 4, 2017 Below

The home page for MASIE (here) invites visitors to show their interest in the dataset and analysis tools since continued funding is not assured. The page says:
NSIDC has received support to develop MASIE but not to maintain MASIE. We are actively seeking support to maintain the Web site and products over the long term. If you find MASIE helpful, please let us know with a quick message to NSIDC User Services.

For the reasons below, I hope people will go there and express their support.

1. MASIE is Rigorous.

Note on Sea Ice Resolution:

Northern Hemisphere Spatial Coverage

Sea Ice Index (SII) from NOAA is based on 25 km cells and 15% ice coverage. That means if a grid cell 25X25, or 625 km2 is estimated to have at least 15% ice, then 625 km2 is added to the total extent. In the mapping details, grid cells vary between 382 to 664 km2 with latitudes.  And the satellites’ Field of View (FOV) is actually an ellipsoid ranging from 486 to 3330 km2 depending on the channel and frequency.  More info is here.

MASIE is based on 4 km cells and 40% ice coverage. Thus, for MASIE estimates, if a grid cell is deemed to have at least 40% ice, then 16 km2 is added to the total extent.

The significantly higher resolution in MASIE means that any error in detecting ice cover at the threshold level affects only 16 km2 in the MASIE total, compared to at least 600 km2 variation in SII.  A few dozen SII cells falling below the 15% threshold is reported as a sizable loss of ice in the Arctic.

2. MASIE is Reliable.

2017029google

MASIE is an operational ice product developed from multiple sources to provide the most accurate possible description of Arctic ice for the sake of ships operating in the region.

Operational analyses combine a variety of remote-sensing inputs and other sources via manual integration to create high-resolution, accurate charts of ice conditions in support of navigation and operational forecast models. One such product is the daily Multisensor Analyzed Sea Ice Extent (MASIE). The higher spatial resolution along with multiple input data and manual analysis potentially provide more precise mapping of the ice edge than passive microwave estimates.  From Meier et al., link below.

Some people have latched onto a line from the NSIDC background page:
Use the Sea Ice Index when comparing trends in sea ice over time or when consistency is important. Even then, the monthly, not the daily, Sea Ice Index views should be used to look at trends in sea ice. The Sea Ice Index documentation explains how linear regression is used to say something about trends in ice extent, and what the limitations of that method are. Use MASIE when you want the most accurate view possible of Arctic-wide ice on a given day or through the week.

That statement was not updated to reflect recent developments:
“In June 2014, we decided to make the MASIE product available back to 2006. This was done in response to user requests, and because the IMS product output, upon which MASIE is based, appeared to be reasonably consistent.”

The fact that MASIE employs human judgment is discomforting to climatologists as a potential source of error, so Meier and others prefer that the analysis be done by computer algorithms. Yet, as we shall see, the computer programs are themselves human inventions and when applied uncritically by machines produce errors of their own.

3. MASIE serves as Calibration for satellite products.

The NSIDC Background cites as support a study by Partington et al (2003).  Reading that study, one finds that the authors preferred the MASIE data and said this:

“Passive microwave sensors from the U.S. Defense Meteorological Satellite Program have long provided a key source of information on Arctic-wide sea ice conditions, but suffer from some known deficiencies, notably a tendency to underestimate ice concentrations in summer. With the recent release of digital and quality controlled ice charts extending back to 1972 from the U.S. National Ice Center (NIC), there is now an alternative record of late twentieth century Northern Hemisphere sea ice conditions to compare with the valuable, but imperfect, passive microwave sea ice record.”

“This analysis has been based on ice chart data rather than the more commonly analyzed passive microwave derived ice concentrations. Differences between the NIC ice chart sea ice record and the passive microwave sea ice record are highly significant despite the fact that the NIC charts are semi-dependent on the passive microwave data, and it is worth noting these differences. . .In summer, the difference between the two sources of data rises to a maximum of 23% peaking in early August, equivalent to ice coverage the size of Greenland. (my bold)  For clarity: the ice chart data show higher extents than passive microwave data.

The differences are even greater for Canadian regions.

“More than 1380 regional Canadian weekly sea-ice charts for four Canadian regions and 839 hemispheric U.S. weekly sea-ice charts from 1979 to 1996 are compared with passive microwave sea-ice concentration estimates using the National Aeronautics and Space Administration (NASA) Team algorithm. Compared with the Canadian regional ice charts, the NASA Team algorithm underestimates the total ice-covered area by 20.4% to 33.5% during ice melt in the summer and by 7.6% to 43.5% during ice growth in the late fall.”

From: The Use of Operational Ice Charts for Evaluating Passive Microwave Ice Concentration Data, Agnew and Howell  http://www.tandfonline.com/doi/pdf/10.3137/ao.410405

More recently Walter Meier, who is in charge of SII, and several colleagues compared SII and MASIE and published their findings October 2015 (here).  The purpose of the analysis was stated thus:
Our comparison is not meant to be an extensive validation of either product, but to illustrate as guidance for future use how the two products behave in different regimes.

The abstract concludes:
Comparisons indicate that MASIE shows higher Arctic-wide extent values throughout most of the year, largely because of the limitations of passive microwave sensors in some conditions (e.g. surface melt). However, during some parts of the year, MASIE tends to indicate less ice than estimated by passive microwave sensors. These comparisons yield a better understanding of operational and research sea-ice data products; this in turn has important implications for their use in climate and weather models.

A more extensive comparison of MASIE from NIC and SII from NOAA is here.

4. MASIE continues a long history of Arctic Ice Charts.

Naval authorities have for centuries prepared ice charts for the safety of ships operating in the Arctic.  There are Russian, Danish, Norwegian, and Canadian charts, in addition to MASIE, the US version.  These estimates rely on multiple sources of data, including the NASA reports.  Charts are made with no climate ax to grind, only to get accurate locations and extents of Arctic ice each day.

Figure 16-3: Time series of April sea-ice extent in Nordic Sea (1864-1998) given by 2-year running mean and second-order polynomial curves. Top: Nordic Sea; middle: eastern area; bottom: western area (after Vinje, 2000). IPCC Third Assessment Report

Figure 16-3: Time series of April sea-ice extent in Nordic Sea (1864-1998) given by 2-year running mean and second-order polynomial curves. Top: Nordic Sea; middle: eastern area; bottom: western area (after Vinje, 2000). IPCC Third Assessment Report

Since these long-term records show a quasi-60 year cycle in ice extents, it is vital to have a modern dataset based on the same methodology, albeit with sophisticated modern tools.

Summary

Measuring anything in the Arctic is difficult, and especially sea ice that is constantly moving around.  It is a good thing to have independent measures using different methodologies, since any estimate is prone to error.

Please take the time to express your appreciation for NIC’s contribution and your support for their products at MASIE  home page.

Update February 4, 2017

In the comments Neven said MASIE was unusable because it was biased low before 2010 and high afterward.  I have looked into that and he is mistaken.  Below is the pattern that is observed most months.  March is the annual maximum and coming up soon.

march-masie-sii

As the graph shows, the two datasets were aligned through 2010, and then SII began underestimating ice extent, resulting in a negative 11-year trend.  MASIE shows the same fluctuations, but with higher extents and a slightly positive trend for March extents.  The satellite sensors have a hard time with mixed ice/water conditions (well-documented).

More on the two datasets NOAA has been Losing Arctic Ice

Typical Arctic Ice Extents in June

 

 

Arctic2021181

Previous posts reported that Arctic Sea Ice has persisted this year despite a wavy Polar Vortex this spring, bringing cold down to mid-latitudes, and warming air into Arctic regions.  Then in May and now again in June,  the sea ice extent matched or exceeded the 14-year average several times during the month, tracking alongside until month end.  Surprisingly  SII (Sea Ice Index) showed much more ice the first week, similar extents mid- June, and then SII lost ice more rapidly the final week.  Yesterday both SII and MASIE day 181 were close to the same day in 2007.

Note that on the 14-year average, June loses ~2M km2 of ice extent, which 2021 matched, as did 2007.  Both 2020 and 2019 finished lower than average, by 500k and 400k respectively.  

Why is this important?  All the claims of global climate emergency depend on dangerously higher temperatures, lower sea ice, and rising sea levels.  The lack of additional warming is documented in a post Adios, Global Warming

The lack of acceleration in sea levels along coastlines has been discussed also.  See USCS Warnings of Coastal Floodings

Also, a longer term perspective is informative:

post-glacial_sea_level
The table below shows the distribution of Sea Ice across the Arctic Regions, on average, this year and 2007.

Region 2021181 Day 181 Average 2021-Ave. 2007181 2021-2007
 (0) Northern_Hemisphere 9644967 9741628  -96661  9672969 -28002 
 (1) Beaufort_Sea 999085 905769  93316  939209 59876 
 (2) Chukchi_Sea 760235 715065  45170  670088 90146 
 (3) East_Siberian_Sea 924474 1010406  -85932  901963 22511 
 (4) Laptev_Sea 578894 703006  -124112  658742 -79848 
 (5) Kara_Sea 527080 545919  -18839  657478 -130398 
 (6) Barents_Sea 129619 123601  6018  130101 -482 
 (7) Greenland_Sea 461815 501479  -39664  548399 -86584 
 (8) Baffin_Bay_Gulf_of_St._Lawrence 497237 504688  -7451  450461 46777 
 (9) Canadian_Archipelago 761843 778224  -16381  773611 -11768 
 (10) Hudson_Bay 736119 728550  7569  718441 17678 
 (11) Central_Arctic 3239262 3205301  33960  3218999 20262 
 (12) Bering_Sea 15316 4566  10750  981 14336 
 (13) Baltic_Sea 0 3 -3  0
 (14) Sea_of_Okhotsk 12919 13765  -847  2983 9936 

The overall deficit to average happened yesterday, being an extent 1% lower, and one day earlier than average.  The largest deficits to average are in East Siberian and Laptev Seas, along with Greenland Sea.  These are partly offset by surpluses elsewhere, mostly in Beaufort, Chukchi, and Central Artic seas.

 

 

June Arctic Ice Returns to Mean

 

Arctic2021159

A previous post reported that Arctic Sea Ice has persisted this year despite a wavy Polar Vortex this spring, bringing cold down to mid-latitudes, and warming air into Arctic regions.  Now in June, after tracking in deficit the sea ice extent is matching the 14-year average on day 159.  Note that SII (Sea Ice Index) since mid-May has been showing 200 to 400k km2 more ice than MASIE, and currently the two datasets have converged on a value of ~11.25 M km2.

Note that on the 14-year average, during this period ~1.7M km2 of ice extent is lost, which 2021 is matching, as did 2007.  Both 2020 and 2019 were much lower than average at this date, by ~600k and ~700k respectively.  

Why is this important?  All the claims of global climate emergency depend on dangerously higher temperatures, lower sea ice, and rising sea levels.  The lack of additional warming is documented in a post Adios, Global Warming

The lack of acceleration in sea levels along coastlines has been discussed also.  See USCS Warnings of Coastal Floodings

Also, a longer term perspective is informative:

post-glacial_sea_level
The table below shows the distribution of Sea Ice across the Arctic Regions, on average, this year and 2007.

Region 2021159 Day 159 Average 2021-Ave. 2007159 2021-2007
 (0) Northern_Hemisphere 11240999 11259536  -18538  11316498 -75500 
 (1) Beaufort_Sea 1019264 964689  54575  1000434 18830 
 (2) Chukchi_Sea 849650 820007  29642  828275 21375 
 (3) East_Siberian_Sea 1018939 1060847  -41907  1065467 -46528 
 (4) Laptev_Sea 719152 797804  -78652  750975 -31824 
 (5) Kara_Sea 786077 768820  17257  805583 -19506 
 (6) Barents_Sea 253238 260182  -6944  312729 -59491 
 (7) Greenland_Sea 664297 581528  82769  579724 84573 
 (8) Baffin_Bay_Gulf_of_St._Lawrence 755645 803058  -47412  811860 -56215 
 (9) Canadian_Archipelago 802846 802905  -60  783908 18938 
 (10) Hudson_Bay 1022997 1058859  -35862  1027039 -4042 
 (11) Central_Arctic 3233401 3215315  18085  3235047 -1646 
 (12) Bering_Sea 59415 70145  -10729  62751 -3336 
 (13) Baltic_Sea 0 8 -8  0
 (14) Sea_of_Okhotsk 54471 53989  482  51031 3440 

The main deficits are in Laptev and East Siberian Seas, Baffin and Hudson Bays, offset by surpluses in Beaufort, Chukchi and Greenland Seas.

 

Ordinary Arctic Ice Extents in May

Arctic2021151

A previous post reported that Arctic Sea Ice has persisted this year despite a wavy Polar Vortex this spring, bringing cold down to mid-latitudes, and warming air into Arctic regions.  Now in May, the sea ice extent matched the 14-year average on day 144, tracking alongside until month end.  Surprisingly  SII (Sea Ice Index) is showing ~400k km2 more ice, which is also ~70k km2 higher than the 14-year average for SII on day 151 (not shown in chart).

Note that on the 14-year average, May loses ~2M km2 of ice extent, which 2021 matched, as did 2007.  Both 2020 and 2019 finished lower than average, by 300k and 400k respectively.  In contrast SII shows a May loss of only 1.3M km2.

Why is this important?  All the claims of global climate emergency depend on dangerously higher temperatures, lower sea ice, and rising sea levels.  The lack of additional warming is documented in a post Adios, Global Warming

The lack of acceleration in sea levels along coastlines has been discussed also.  See USCS Warnings of Coastal Floodings

Also, a longer term perspective is informative:

post-glacial_sea_level
The table below shows the distribution of Sea Ice across the Arctic Regions, on average, this year and 2007.

Region 2021151 Day 151 Average 2021-Ave. 2007151 2021-2007
 (0) Northern_Hemisphere 11605537 11733260  -127723  11846659 -241122 
 (1) Beaufort_Sea 1034779 992955  41825  1059461 -24682 
 (2) Chukchi_Sea 900868 861978  38891  894617 6251 
 (3) East_Siberian_Sea 1051959 1065828  -13869  1069198 -17239 
 (4) Laptev_Sea 738294 831217  -92923  754651 -16357 
 (5) Kara_Sea 824068 831440  -7373  895678 -71610 
 (6) Barents_Sea 325745 322981  2765  323801 1944 
 (7) Greenland_Sea 615174 567365  47810  591919 23255 
 (8) Baffin_Bay_Gulf_of_St._Lawrence 812548 908759  -96211  934257 -121709 
 (9) Canadian_Archipelago 811040 811378  -338  818055 -7015 
 (10) Hudson_Bay 1084892 1098368  -13476  1077744 7148 
 (11) Central_Arctic 3232324 3219180  13144  3230109 2215 
 (12) Bering_Sea 89124 122512  -33388  112353 -23228 
 (13) Baltic_Sea 0 161 -161  0
 (14) Sea_of_Okhotsk 83572 97612  -14040  83076 495 

The overall deficit to average happened yesterday, being an extent 1% lower, and two days earlier than average.  The largest deficits to average are in Baffin Bay and Laptev Sea, along with Bering and Okhotsk.  These are partly offset by surpluses elsewhere, mostly in Beaufort, Chukchi, and Greenland Seas.