Arctic Ice Hockey Stick

Update July 18, 2018

Arctic day 198 hockey

No one knows how long this divergence of surplus ice will persist, but for now 2018 Arctic ice extent resembles a hockey stick.  Presently the ice is 525k km2 above 11 year average (2007 to 2017 inclusive) and  ~1M km2 greater than 2007.  More detailed report from July 14 below.

ims1952007to2018

In June 2018, Arctic ice extent held up against previous years despite the Pacific basins of Bering and Okhotsk being ice-free.  The Arctic core is showing little change, perhaps due to increased thickness (volume) as reported by DMI.

The image above shows ice extents on day 195 (July 14) for years 2007, 2012, 2017 and 2018. Note this year ice is strong on both Russian and N. American sides.  Beaufort Sea and Canadian Archipelago are solid. E. Siberian and Chukchi Seas are also solid, despite early melting in Bering Sea.  Hudson and Baffin bays still have considerable ice compared to other years.

The graph below shows how the Arctic extent has faired in July compared to the 11 year average and to some years of interest.
Arctic day 195
Note that 2018 started July well above the 11 year average and other recent years.  As of day 195 (yesterday) ice extent is still greater than average and the years 2007 and 2017.  SII 2018 is tracking well below MASIE this month, a gap of 500k km2 at this point.

The table below shows ice extents by regions comparing 2018 with 11-year average (2007 to 2017 inclusive) and 2017.

Region 2018195 Day 195 
Average
2018-Ave. 2007195 2018-2007
 (0) Northern_Hemisphere 8828959 8549517 279442 8355280 473679
 (1) Beaufort_Sea 993219 826109 167110 845973 147246
 (2) Chukchi_Sea 644989 636401 8588 576079 68911
 (3) East_Siberian_Sea 1024284 950636 73648 788128 236156
 (4) Laptev_Sea 492172 633149 -140977 575520 -83347
 (5) Kara_Sea 438240 399007 39233 483785 -45545
 (6) Barents_Sea 30629 64124 -33495 75731 -45101
 (7) Greenland_Sea 285428 443318 -157890 472890 -187462
 (8) Baffin_Bay_Gulf_of_St._Lawrence 489193 305230 183963 343396 145797
 (9) Canadian_Archipelago 747737 719112 28626 730629 17109
 (10) Hudson_Bay 619471 381783 237688 248785 370686
 (11) Central_Arctic 3062425 3185383 -122959 3211275 -148850

2018 is 280k km2 above average, mostly due to Hudson and Baffin bays having surplus ice.   Laptev, Greenland Sea and Central Arctic are down, more than offset by surpluses elsewhere.  Since the two bays will melt out soon, the eventual annual minimum remains to be seen.

 

 

 

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Arctic Ice Beats Odds July 14

ims1952007to2018

In June 2018, Arctic ice extent held up against previous years despite the Pacific basins of Bering and Okhotsk being ice-free.  The Arctic core is showing little change, perhaps due to increased thickness (volume) as reported by DMI.

The image above shows ice extents on day 195 (July 14) for years 2007, 2012, 2017 and 2018. Note this year ice is strong on both Russian and N. American sides.  Beaufort Sea and Canadian Archipelago are solid. E. Siberian and Chukchi Seas are also solid, despite early melting in Bering Sea.  Hudson and Baffin bays still have considerable ice compared to other years.

The graph below shows how the Arctic extent has faired in July compared to the 11 year average and to some years of interest.
Arctic day 195
Note that 2018 started July well above the 11 year average and other recent years.  As of day 195 (yesterday) ice extent is still greater than average and the years 2007 and 2017.  SII 2018 is tracking well below MASIE this month, a gap of 500k km2 at this point.

The table below shows ice extents by regions comparing 2018 with 11-year average (2007 to 2017 inclusive) and 2017.

Region 2018195 Day 195 
Average
2018-Ave. 2007195 2018-2007
 (0) Northern_Hemisphere 8828959 8549517 279442 8355280 473679
 (1) Beaufort_Sea 993219 826109 167110 845973 147246
 (2) Chukchi_Sea 644989 636401 8588 576079 68911
 (3) East_Siberian_Sea 1024284 950636 73648 788128 236156
 (4) Laptev_Sea 492172 633149 -140977 575520 -83347
 (5) Kara_Sea 438240 399007 39233 483785 -45545
 (6) Barents_Sea 30629 64124 -33495 75731 -45101
 (7) Greenland_Sea 285428 443318 -157890 472890 -187462
 (8) Baffin_Bay_Gulf_of_St._Lawrence 489193 305230 183963 343396 145797
 (9) Canadian_Archipelago 747737 719112 28626 730629 17109
 (10) Hudson_Bay 619471 381783 237688 248785 370686
 (11) Central_Arctic 3062425 3185383 -122959 3211275 -148850

2018 is 280k km2 above average, mostly due to Hudson and Baffin bays having surplus ice.   Laptev, Greenland Sea and Central Arctic are down, more than offset by surpluses elsewhere.  Since the two bays will melt out soon, the eventual annual minimum remains to be seen.

 

 

 

Arctic Ice Persisting in July

AARI072008to2018

In June 2018, Arctic ice extent held up against previous years despite the Pacific basins of Bering and Okhotsk being ice-free.  Now in July when ice extent typically declines, 2018 extents were flat, and now declining slowly.  The Arctic core is showing little change, perhaps due to increased thickness (volume) as reported by DMI.  The image above from AARI shows ice extents first week of July for years 2008 through 2018. (Image format was different for previous years.  In 2018, water is showing typically in Chukchi in July, a bit more than usual in Laptev and less in Beaufort.

The graph below shows how the Arctic extent has faired from mid June to July 7 (yesterday) compared to the 11 year average and to some years of interest.
Arctic day 188Note that 2018  was on average and comparable to other years from Mid June on.  Then recently ice extents have held steady just below 10M km2, while averages and other years declined.  2018 is now 288k km2 above the 11 year average,  400k km2 higher than 2017, and 624k km2 greater than 2007 at this date.   SII 2018 was tracking the same as MASIE in June but is now showing 335k km2 lower.

The table below shows ice extents by regions comparing 2018 with 11-year average (2007 to 2017 inclusive) and 2017 as of day 179.

Region 2018188 Day 179 
Average
2018-Ave. 2007188 2018-2007
 (0) Northern_Hemisphere 9465018 9181173 283844 8841116 623902
 (1) Beaufort_Sea 977561 863028 114533 871601 105960
 (2) Chukchi_Sea 635350 682991 -47641 622583 12767
 (3) East_Siberian_Sea 1037340 996766 40574 855273 182067
 (4) Laptev_Sea 545304 684244 -138941 644539 -99236
 (5) Kara_Sea 568399 477164 91236 523575 44824
 (6) Barents_Sea 54547 88754 -34206 91567 -37020
 (7) Greenland_Sea 353292 477433 -124141 506546 -153254
 (8) Baffin_Bay_Gulf_of_St._Lawrence 592755 393419 199336 411743 181013
 (9) Canadian_Archipelago 778940 756496 22444 752103 26837
 (10) Hudson_Bay 791754 543956 247798 354253 437502
 (11) Central_Arctic 3128568 3203921 -75353 3202400 -73832

2018 is above the 11 year average,  with BCE (Beaufort, Chukchi, East Siberian) higher, Laptev and Kara offsetting.  Barents and Greenland Sea are down, but Baffin and Hudson Bays have larger surpluses.

Footnote: 

Arctic extents are shaped by the three Ws: Water, Wind and Weather.  This video shows how a massive cyclone in 2012 broke up the ice, moved it around and flushed much of it out through the Fram strait.The ice has recovered since then and is now quite thick.

 

 

 

Arctic Ice Resilient in July

IMSSandIce07to18day179

In June 2018, Arctic ice extent held up against previous years despite the Pacific basins of Bering and Okhotsk being ice-free.  Now in July when ice extent typically declines, 2018 extents are essentially flat.  The Arctic core is showing little change, perhaps due to increased thickness (volume) as reported by DMI.  The image above shows ice extents on day 179 for years 2007 through 2018.

The graph below shows how the Arctic extent has faired from mid June to July 3 (yesterday) compared to the 11 year average and to some years of interest.
NH arctic ice day 184Note that 2018  was on average and comparable to other years from Mid June on.  Then recently ice extents have held steady just below 10M km2, while averages and other years declined.  2018 is now 370k km2 above the 11 year average,  535k km2 higher than 2017, and 660k km2 greater than 2007 at this date.   SII 2018 was tracking the same as MASIE in June but has now dropped 360k km2 lower.

The table below shows ice extents by regions comparing 2018 with 11-year average (2007 to 2017 inclusive) and 2017 as of day 179.

Region 2018179 Day 179
Average
2018-Ave. 2007179 2018-2007
 (0) Northern_Hemisphere 10029935 10054734 -24798 10034293 -4358
 (1) Beaufort_Sea 1015808 919074 96734 948463 67345
 (2) Chukchi_Sea 711178 732616 -21437 680534 30645
 (3) East_Siberian_Sea 1053171 1032249 20923 963850 89321
 (4) Laptev_Sea 647574 745700 -98126 663276 -15702
 (5) Kara_Sea 726226 598140 128086 665920 60307
 (6) Barents_Sea 60948 134229 -73281 177419 -116471
 (7) Greenland_Sea 356614 552157 -195543 627602 -270989
 (8) Baffin_Bay_Gulf_of_St._Lawrence 714402 552083 162319 531706 182696
 (9) Canadian_Archipelago 794355 783057 11298 775033 19322
 (10) Hudson_Bay 900609 761919 138690 777550 123058
 (11) Central_Arctic 3047677 3217803 -170125 3216654 -168977
 (12) Bering_Sea 185 6350 -6165 1080 -895
 (13) Baltic_Sea 0 4 -4 0 0
 (14) Sea_of_Okhotsk 0 17972 -17972 3531 -3531

2018 is 25k km2 below average, entirely due to Okhotsk plus Bering being ice-free.  Greenland Sea and Barents are down, offset by surpluses in Beaufort, Kara, Baffin and Hudson Bays.

Footnote: 

Arctic extents are shaped by the three Ws: Water, Wind and Weather.  This video shows how a massive cyclone in 2012 broke up the ice, moved it around and flushed much of it out through the Fram strait.The ice has recovered since then and is now quite thick.

 

 

 

Arctic Ice Holding Up June 29

IMSSandIce07to18day179

In June 2018, Arctic ice extent held up against previous years despite the Pacific basins of Bering and Okhotsk being ice-free.  The Arctic core is showing little change, perhaps due to increased thickness (volume) as reported by DMI.  The image above shows ice extents on day 179 for years 2007 through 2018.

The graph below shows how the Arctic extent has faired in June compared to the 11 year average and to some years of interest.
NHday179Note that 2018 started June well below the 11 year average and below other recent years.  As of day 179 (yesterday) ice extent is matching average and 2007, and slightly above 2017, with further losses to come in previous years.  SII 2018 is tracking the same as MASIE this month.

The table below shows ice extents by regions comparing 2018 with 11-year average (2007 to 2017 inclusive) and 2017.

Region 2018179 Day 179
Average
2018-Ave. 2007179 2018-2007
 (0) Northern_Hemisphere 10029935 10054734 -24798 10034293 -4358
 (1) Beaufort_Sea 1015808 919074 96734 948463 67345
 (2) Chukchi_Sea 711178 732616 -21437 680534 30645
 (3) East_Siberian_Sea 1053171 1032249 20923 963850 89321
 (4) Laptev_Sea 647574 745700 -98126 663276 -15702
 (5) Kara_Sea 726226 598140 128086 665920 60307
 (6) Barents_Sea 60948 134229 -73281 177419 -116471
 (7) Greenland_Sea 356614 552157 -195543 627602 -270989
 (8) Baffin_Bay_Gulf_of_St._Lawrence 714402 552083 162319 531706 182696
 (9) Canadian_Archipelago 794355 783057 11298 775033 19322
 (10) Hudson_Bay 900609 761919 138690 777550 123058
 (11) Central_Arctic 3047677 3217803 -170125 3216654 -168977
 (12) Bering_Sea 185 6350 -6165 1080 -895
 (13) Baltic_Sea 0 4 -4 0 0
 (14) Sea_of_Okhotsk 0 17972 -17972 3531 -3531

2018 is 25k km2 below average, entirely due to Okhotsk plus Bering being ice-free.  Greenland Sea and Barents are down, offset by surpluses in Beaufort, Kara, Baffin and Hudson Bays.

 

 

 

Persistent Arctic Ice Mid June

cice_combine_thick_sm_en_20180614
In June, ice extents are declining as usual, except for the early melting in Bering and Okhotsk Seas.  The image above from DMI shows widespread thick ice across the Arctic core, likely to melt more slowly.  The graph above shows how much volume was added since March 2018, bringing it close to 2014, a particularly icy year.

The graph below shows how the Arctic extent from MASIE has faired the first two weeks of June up to yesterday, compared to the 11 year average and to some years of interest.
MASIE2018165
Note that 2018 is now matching the 11-year average, as well as 2017 and 2007.  SII 2018 is tracking MASIE 2018 closely.

The table shows regional ice extents compared to average and 2007.

Region 2018165 Day 165
Average
2018-Ave. 2007165 2018-2007
 (0) Northern_Hemisphere 10915601 10987296 -71695 10959202 -43601
 (1) Beaufort_Sea 1029988 964246 65742 952869 77119
 (2) Chukchi_Sea 756185 803037 -46852 770182 -13997
 (3) East_Siberian_Sea 1067948 1051979 15968 1040890 27058
 (4) Laptev_Sea 722052 786204 -64152 755629 -33577
 (5) Kara_Sea 870277 716595 153682 770755 99522
 (6) Barents_Sea 201802 222598 -20796 264253 -62451
 (7) Greenland_Sea 444260 578046 -133786 574726 -130465
 (8) Baffin_Bay_Gulf_of_St._Lawrence 763976 741257 22719 778469 -14493
 (9) Canadian_Archipelago 808464 798083 10381 781578 26886
 (10) Hudson_Bay 1063014 1014784 48230 997061 65953
 (11) Central_Arctic 3165771 3224235 -58464 3224700 -58929
 (12) Bering_Sea 8803 42373 -33570 15285 -6482
 (13) Baltic_Sea 0 7 -7 0 0
 (14) Sea_of_Okhotsk 11757 42495 -30738 31131 -19373

Note that Bering and Okhotsk account for the 2018 deficit to average.  Chukchi, Laptev and Greenland Seas are down somewhat, but offset by surpluses in Kara Sea, Beaufort Sea and Hudson Bay. The differences from 2007 are similar.

The Pacific basins of Bering and Okhotsk are the first to lose ice, and it will be interesting to see how the core Arctic Seas holds up this summer.  Chukchi is down, perhaps influenced by the early melting in Bering, but is offset by surpluses in Beaufort and East Siberian.

Ice Alive: Uncovering the secrets of Earth’s Ice

You have to respect glaciologists whose curiosity takes them to the most extreme places, in this case the Arctic.  Joseph Cook received the Rolex award for Science in Extremis and he provides at his blog a wonderful 20 minute video explaining his work.  From Ice Alive: Uncovering the secrets of Earth’s Ice by Joseph Cook and Chris Hadfield.  Excerpts from below in italics.

In collaboration with Rolex Awards for Enterprise, Proudfoot Media and I have produced a documentary film explaining the latest research into the surprising hidden biology shaping Earth’s ice. The story is told by young UK Arctic scientists with contributions from guests including astronaut Chris Hadfield and biologist Jim Al-Khalili. We went to great lengths to make this a visually striking film that we hope is a pleasure to watch and communicates the otherwordly beauty and incredible complexity of the Arctic glacial landscape. We aim to educate, entertain and inspire others into exploring and protecting this most sensitive part of our planet in their own ways.

We think the film is equally suited to the general public as school and university students, and we are delighted to make this a free-to-all teaching resource. Please watch, share and use!

Albedo is the survival probability of a photon entering a medium. Light incident upon a material partly reflects from the upper surface, the remainder enters the medium and can scatter anywhere there is a change in the refractive index (e.g. a boundary between air and ice, or ice and water, etc). Where there are opportunities for scattering, light bounces around in the medium, sometimes preferentially in a certain direction depending upon the optical properties of the medium (ice is forward-scattering) but always changing direction to some extent each time it scatters, until it is either absorbed or it escapes back out of the medium travelling in a skywards direction.

The albedo of the material is the likelihood that the down-welling light entering the medium exits again later as up-welling light. The more strongly absorbing the material, the more likely the light is to be absorbed before exiting. Ice is very weakly absorbing in blue wavelengths (~400 nm), becoming generally more strongly absorbing at longer wavelengths into the near infra-red (hence ice often appearing blue). Solar energy is mostly concentrated within the wavelength range 300 – 5000 nm and the term albedo concerns the survival probability of all photons with wavelengths within this range either at a particular wavelength (spectral albedo) or integrated over the entire solar spectrum (broadband albedo).

For a single material, its absorbing and scattering efficiencies are described using the scattering and absorption coefficients. The ratio of these two coefficients is known as the single scattering albedo (SSA), which is a crucial term for radiative transfer. A higher SSA is associated with a greater likelihood of a particle scattering a photon rather than absorbing it. a particle with SSA = 1 is non-absorbing.

Algal cells are strongly absorbing and their effect on snow and ice albedo is to increase the likelihood of a photon being absorbed rather than scattered back out of the medium. For this reason, the better term to use would be bio-co-albedo, where co-albedo describes the fraction of incident energy absorbed by the particles (i.e. 1-SSA).

Albedo is a primary driver of snow melt. For clean snow and snow with black carbon, radiative transfer models to an excellent job of simulating albedo, yet there remain aspects of snow albedo that are poorly understood. In particular current models do not take into account algal cells that grow and dramatically discolour ice in some places (except our 1-D BioSNICAR model) and few take into account changes in albedo over space and time.

This led me to wonder about using cellular automata as a mechanism for distributing albedo modelling using radiative transfer over three spatial dimensions and time, and also enabling a degree of stochasticity to be introduced to the modelling (which is certainly present in natural systems).

As an Arctic scientist I am privileged to be able to explore the coldest parts of our planet, making observations and measurements and helping others to understand how these areas function by writing papers and giving talks, lectures and writing for magazines and newspapers. But to truly understand an environment, we must also explore the intangible and immeasurable. To communicate it to diverse audiences, we must use not only facts and observations, but aesthetics and emotion. The piece above is a bridge connecting music and science – an effort to understand and communicate the hidden beauty, complexity and sensitivity of the Greenland Ice Sheet through sound. I hope that projects like this will bring new audiences to Arctic science, using music, art and aesthetics to pique their curiosity.

Footnote:

The video mentions algae as a positive feedback:  more warming>more algae>less albedo>more warming.  However, there are also negative feedbacks operating in summertime.  More warming>more open water>more evaporation>more clouds>less sunshine on the surface.  Also, more evaporation>more snowfall>whiter surface>higher albedo>less solar absorption.

More on sea ice dynamics: Climate on Ice: Ocean-Ice Dynamics

 

Bering Sea Blues

“Freedom’s Just Another Word for Nothing Left to Lose.” (Kris Kristofferson)

In May, Arctic ice extent declined as usual with the notable exception of Bering Sea, now almost ice free.  Bering still has some ice to lose, but at 23k km2 it is only 5% of the ice there March 17 at annual Bering maximum, just two months ago.  It is unusual since the Bering ice is only 10% of the 11 year average for this date.  Nearby Chukchi Sea is showing open water, somewhat ahead of schedule.  Okhotsk also in the Pacific is melting and now below average for this date.

Elsewhere things are mostly typical.   Russian and Canadian basins are frozen with high extents and Barents is now matching average.

The graph below shows how the Arctic extent has faired in May compared to the 11 year average with and without the Pacific basins of Bering and Okhotsk.  2018 (brown line lacks B&O) is tracking the orange line with some divergence lately.
NHday141less BO

The graph below shows May 2018 compared to average and some years of interest.
NHday141

Note that 2017 tracks above the 11-year average.  2018 is tracking 2007, which will match average by end of May.  The table below shows ice extents by regions comparing 2018 with 11-year average (2007 to 2017 inclusive) and 2007.

Region 2018141 Day 141 
Average
2018-Ave. 2007141 2018-2007
 (0) Northern_Hemisphere 11963940 12493152 -529212 12114407 -150467
 (1) Beaufort_Sea 1046328 1025787 20541 1063324 -16996
 (2) Chukchi_Sea 790287 916151 -125864 936237 -145949
 (3) East_Siberian_Sea 1076816 1074527 2289 1067808 9008
 (4) Laptev_Sea 893794 866784 27009 793551 100243
 (5) Kara_Sea 934453 881645 52808 885543 48909
 (6) Barents_Sea 401369 396306 5063 327568 73801
 (7) Greenland_Sea 441882 606737 -164856 576791 -134909
 (8) Baffin_Bay_Gulf_of_St._Lawrence 1125388 1062146 63242 968062 157325
 (9) Canadian_Archipelago 839235 833381 5854 837658 1577
 (10) Hudson_Bay 1153411 1158944 -5533 1097706 55705
 (11) Central_Arctic 3132441 3231803 -99361 3235644 -103203
 (12) Bering_Sea 23001 268930 -245929 213547 -190547
 (13) Baltic_Sea 788 2344 -1556 2146 -1358
 (14) Sea_of_Okhotsk 103188 165353 -62165 106753 -3565

As indicated Bering supplies almost half of the deficit to average, along with Chukchi and Okhotsk deficits.  Lack of ice in Greenland Sea may signify a reduced flow of drift ice out of the Arctic through Fram Strait.

20180522

Current ice chart from AARI St. Petersburg Russia. Old sea ice is in brown.

 

 

 

 

Arctic Ice May 11

cice_combine_thick_sm_en_20180511

Sea Ice Thickness and Volume from DMI. H/T NoTricksZone

In May, ice extents are declining as usual, except for the early melting in Bering Sea.  The image above from DMI shows widespread thick ice across the Arctic core, likely to melt more slowly.  The graph above shows how much volume was added since March 2018, bringing it close to 2014, a particularly icy year.

The graph below shows how the Arctic extent from MASIE has faired the last 26 days up to yesterday, compared to the 11 year average and to some years of interest.
NHday131
Note that 2017 is now matching the 11-year average, while 2018 and 2007 are tied ~360k km2 below average.  SII 2018 is tracking ~250k km2 lower at this point.  The graph below shows 2018 ice extents are matching the 11 year average once Bering and Okhotsk are excluded from the calculations.
NHday131less BO

The table shows regional ice extents compared to average and 2017.

Region 2018131 Day 131 
Average
2018-Ave. 2017131 2018-2017
 (0) Northern_Hemisphere 12701360 13058129 -356769 13075378 -374017
 (1) Beaufort_Sea 1070445 1047690 22755 1059451 10994
 (2) Chukchi_Sea 890598 950844 -60246 938716 -48117
 (3) East_Siberian_Sea 1087048 1083143 3906 1073762 13286
 (4) Laptev_Sea 896588 889502 7087 897845 -1256
 (5) Kara_Sea 925975 903277 22698 929156 -3182
 (6) Barents_Sea 530424 452492 77931 505439 24984
 (7) Greenland_Sea 460748 638101 -177353 710167 -249419
 (8) Baffin_Bay_Gulf_of_St._Lawrence 1264692 1146815 117877 1312382 -47690
 (9) Canadian_Archipelago 853109 844456 8653 851119 1990
 (10) Hudson_Bay 1255514 1207449 48065 1247480 8034
 (11) Central_Arctic 3173427 3233754 -60327 3248013 -74586
 (12) Bering_Sea 37974 412141 -374167 136049 -98075
 (13) Baltic_Sea 16848 9483 7365 11830 5018
 (14) Sea_of_Okhotsk 236246 236354 -108 152156 84090

Note the Bering accounts for the 2018 deficit to average.  Chukchi and Greenland Seas are down somewhat, but offset by  surpluses in Baffin Bay, Barents and Hudson Bay.  Compared to last year, the Bering deficit is much less, but Greenland Sea difference is much greater.

The Pacific basins of Bering and Okhotsk are the first to lose ice, and it will be interesting to see how the core Arctic Seas hold up this summer.  Barents is still up, but less dramatically than in April.  Chukchi is starting to open up, perhaps influenced by Bering.

Persisting Arctic Ice April 30

 


In April, Arctic ice extent showed typical losses, with two exceptions.  Bering Sea has melted out ahead of schedule, while Barents Sea Ice is remarkably high this Spring. The image above shows Barents ice extents on day 120 from 2012 to 2018 (yesterday).  Note how both shelf ice and central ice are greater this year and last.  The graph below shows 2018 exceeds even 2014, the previous decadal high, stubbornly holding onto 700k km2.

The graph below shows how the Arctic extent has faired in April compared to the 11 year average and to some years of interest.
Note that 2018 is close to 2017 and slightly below the 11-year average.  SII 2018 tracks about 200k km2 lower, while 2007 is another 200k behind.   The table below shows ice extents by regions comparing 2018 with 11-year average (2007 to 2017 inclusive) and 2017.

Region 2018120 Day 120 
Average
2018-Ave. 2017120 2018-2017
 (0) Northern_Hemisphere 13360026 13650051 -290025 13519865 -159839
 (1) Beaufort_Sea 1069887 1067233 2654 1070445 -558
 (2) Chukchi_Sea 897588 962679 -65091 960509 -62921
 (3) East_Siberian_Sea 1084975 1085634 -659 1083984 991
 (4) Laptev_Sea 895710 891029 4680 897556 -1846
 (5) Kara_Sea 934470 908342 26128 933484 986
 (6) Barents_Sea 710238 526176 184062 570066 140172
 (7) Greenland_Sea 589041 657057 -68015 678737 -89696
 (8) Baffin_Bay_Gulf_of_St._Lawrence 1249752 1242545 7206 1452133 -202382
 (9) Canadian_Archipelago 853109 845536 7573 853214 -106
 (10) Hudson_Bay 1258712 1239854 18857 1260903 -2192
 (11) Central_Arctic 3219128 3237929 -18801 3248013 -28885
 (12) Bering_Sea 58432 556317 -497885 256470 -198037
 (13) Baltic_Sea 35281 21596 13685 18836 16446
 (14) Sea_of_Okhotsk 501401 404448 96953 232763 268638

2018 is 290k km2 below average (2%) and 160k below last year.  The deficits are entirely due to Bering Sea, which is down 500k km2 to average and 200k to 2017.  OTOH both Okhotsk and Barents are showing large surpluses.  The graph below show April 2018 is on average once Bering and Okhotsk are removed form the calculations

The latest diesel-electric Ilya Muromets icebreaker of the Northern fleet began trials in the ice of the eastern Barents Sea. It approached the ice edge of average thickness, the Northern fleet said.  “The ice is from 50 to 100 centimeters thick in the area. Ice compaction is 9-10 points. Thus, trial conditions are favorable and correspond to the technical capabilities of the icebreaker. The trials are to continue until the end of the month and the icebreaker will return to Murmansk after them,” it said.  From http://www.navyrecognition.com