Arctic Sea Ice

Freezing season has started, or has it?

We tend to focus on the end of the melting season, also known as the minimum, because that's when the ice covers the least amount of water. That's all fine and dandy, but of course, it's just an arbitrary measuring point. For instance, this year's minimum for the JAXA sea ice extent data set was 6th lowest on record, but flash forward to the first week of October and this year's trend line is third lowest on record and could soon be second lowest on record:

This, as always, had to do with the weather, which has been pretty crazy the past two weeks. First, fierce winds pushed back against the ice edge in most of the Arctic Ocean, delaying the ice pack's expansion, while at the same time continuing to melt that last, stubborn sliver of ice extending towards the East Siberian Sea. The result has been a continuing decline of sea ice extent in the Arctic Basin, and to a lesser extent in the East Siberian Sea, where, normally, the trend line should have been going up already (image courtesy of Wipneus, ASIG Regional graphs):

Another factor that has come into play these past few days, is heat. It's mostly coming from the Pacific, where sea surface temperatures are running quite hot again, as can be seen on these DMI sea surface temperature anomaly maps, comparing this year's start of October with those of 2016 and 2017:

As we approach the final stretch...

For years we've talked about one of the most fascinating phenomena of Arctic sea ice loss as it progresses from year to year: The moment when the ice disappears regardless of the weather. We've seen some of that, back in July 2012, when extent and area numbers kept going down steadily, even though weather conditions weren't conducive to melt and should have caused a marked slowdown on the graphs (like they did in the preceding years). Some time later I concluded that this had to do with what I now call melting momentum.

The idea is that if during May and July the ice gets hit by lot of sunshine, lots of melt ponds form and they soak up a lot of heat. This doesn't immediately cause the ice to melt, but starts to make itself felt towards the later stage of the melting season. The built-up momentum keeps the melting going. For this reason I've been focusing on things like compactness, that tells us something about the amount of water within the ice pack, whether open water or melt ponds (satellite sensors can't see the difference).

But does this still hold true? Will there be a moment when the ice disappears regardless of melting momentum as well? We saw in 2016 that there wasn't much melting momentum built up during May and June, but despite the cloudiness, a record warm winter and persistent high air temperatures were enough to make the ice vulnerable enough for a big cyclone and massive dipole to have 2016 come in second on almost all graphs (see this overview). Yes, melting momentum is important, but there are other things at play as well, of course.

NSIDC Compactness (are divided by extent) as of July 29th

Now, this year has been extremely interesting so far. For the third time in a row, the winter preceding the melting season was relatively mild, the maximum was low (second lowest on record), and the trend line on many a graph went low from the get-go. Not as low as 2016, but low. However, as in previous years, clouds moved in and things slowed down to a crawl, taking the trend line as high up as 11th lowest on record on the JAXA sea ice extent chart last week. But then this happened in the last couple of days, suggesting spectacular melting on the Pacific side of the Arctic:

So, what's going on?

The 2018 melting season has started

For a while it looked like the record for lowest maximum was going to be broken for the third year in a row, especially after an extreme warm event shook the Arctic. But this anomalous heat was followed by anomalous cold, which was just enough to nudge JAXA sea ice extent above last year's record low maximum. By 13 thousand km2, to be precise, which is around 0.1% of total sea ice this time of year.

I don't mind, as I correctly guessed both this maximum's date as well as the final number on Arctic Sea Ice Forum polls, probably for the first (and last) time in my life as an Arctic observer, as the maximum is incredibly difficult to pinpoint.

Here's the best visual representation of maximums throughout the years, produced by ASIF member Hautbois, as it shows when the maximum of a given year was reached, as well as how high it got:

Not a record low maximum, but the fourth maximum in a row that has ended up (well) below 14 million km2. That's for JAXA sea ice extent data (formerly known as IJIS, now provided by ADS-NIPR).  The NSIDC has just reported that for their SIE product this year's maximum was also second lowest on record.

Looking at how much sea ice extent was created since the last minimum (total freeze), this past winter ended up fourth lowest since 2006. Of course, back in the day, minimums were higher than they are now, which meant there was less 'room' for re-freezing:

Here's the spectacular drop from anomalously warm to anomalously cold on the DMI 80N temperature graph, which normally isn't all that representative for the Arctic as a whole, but in this case it is:

Global sea ice records broken (yet again)

This is starting to become an annual tradition, here on the Arctic Sea Ice Blog. Just like last year and the year before that, the record for lowest global sea ice minimum has been broken. The lowest global sea ice extent minimum on record (NSIDC and JAXA) was reached two weeks ago. I wanted to wait a bit and see whether the record for NSIDC global sea ice area would be broken too, but it wasn't, although the minimum came in at a solid second place, practically on a par with last year.

Here's the graph, as provided by Wipneus:

And here you see the anomaly of all those trend lines in chronological order, having hovered between 2 and 4 σ (standard deviations) since the 2016 crash:

Not enough Antarctic sea ice melted to clinch the lowest Antarctic sea ice minimum record (coming in second lowest 'only'), and so the decisive nudge was given by the sea ice in the Arctic, refusing to freeze along some of the edges, most notably in the Bering Sea. Here's how the graph for that region looks as of today, with some of the open water even spilling into the adjacent Chukchi Sea, which is highly unusual for this time of year:

PIOMAS January 2018

Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

Volume increases for December in the last 10 years aren't all that far apart, ranging from 3500 to 4000 km3 (rounded off). This year was on the lower side of that range, with 3547 km3. Only 2010 and 2014 were lower than that, just barely. This means that 2017 ends the year in third spot. The gap with 2012 has been reduced some more, from 733 to 497 km3, and the quickly widening gap with 2016 has stopped widening for now, going from 1482 to 1340 km3.

Here's how the differences with previous years have evolved from last month:

On Wipneus' version of the PIOMAS graph you can see how that difference with 2012 has become smaller again since September (red is 2017, purple is 2012):

Lowest maximum on record (again)

After a drop of almost 262 thousand km2 in just three days, it looks highly likely that the maximum for sea ice extent was reached two weeks ago, according to the data provided by JAXA, the Japan Aerospace Exploration Agency (via ADS-NiPR ; it used to be provided by IJIS).

It's a new lowest maximum record, and the third time in a row that extent stayed below the 14 million km2 mark. The previous lowest max on record was reached in 2015 (13.942 million km2), almost beaten last year (13.959 million km2), but this year SIE went lower still and peaked at 13.878 million km2.

This graph by commenter Deeenngee, posted on the Arctic Sea Ice Forum, visualizes maximums from the past and the trajectory to this year's max:

It looks highly likely that the max has been reached for NSIDC daily SIE as well (graph provided by Jim Hunt from the Great White Con blog), a third record low in a row if my eyes don't deceive me:

The drops are mostly driven by sea ice reductions in the Bering and Okhotsk Seas, but will soon be joined by drops on the Atlantic side of the Arctic as well, as the ice is pretty thin there, according to the Uni Bremen SMOS thin sea ice map.

Given the wind forecast, I also expect further sea ice retreat from the southern shores of Novaya Zemlya (similar to what happened in 2011 and 2012):

Global sea ice records broken (again)

Sabbatical or not, records must be reported (like I did last year, here and here, albeit a month later).

According to NSIDC data, the Global sea ice area record for lowest minimum has just been broken, as shown on this Wipneus graph (world famous now because of what happened after September last year; see the dark red line on the right side of the graph which should be fairly easily to spot):

The extent version is about to break the record as well:

For those who still think that man-made global warming poses no risk whatsoever, that it is a hoax, I'm just going to repeat what I wrote last year:

PIOMAS November 2016

Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

Do you see that 2016 trend line simply refusing to go up, ending at the lowest level on record for this time of year? That's because of this:

The Arctic has stubbornly refused to refreeze before, but this is another event we can add to the unprecedented list. After ending second/third lowest on record around minimum time, there was a rapid refreeze that was traditionally touted as the End of Global Warming, but for the past weeks things have been at a figurative standstill. Whatever the respective roles of natural variability and AGW, these wild swings do not inspire confidence in a semi-stable system (and the same goes, unfortunately, for the Antarctic).

The slow refreeze inevitably has an effect on sea ice volume, as modelled by PIOMAS. As of November 1st, sea ice volume is lowest on record, but this post covers the month of October only, and at the end of that month, 2016 was just marginally behind 2012. But with an increase of just 1648 km3 during October (only 2007 managed to have an increase below 2 million in the past decade) 2016 has left all other years in the dust.

Here's how the differences with previous years have evolved from last month:

The 'flatline' can also clearly be seen on Wipneus' version of the PIOMAS volume graph:

ASI 2016 update 7: minimum time

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Because of issues with data based on the SSMIS sensor aboard DMSP satellites, I mainly focus on higher-resolution AMSR2 data from the Japan Aerospace Exploration Agency (JAXA), as reported on the Arctic Data archive System website. I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.

The animation on the right consists of NSIDC
sea ice concentration maps, one for each ASI update.

Check out the Arctic Sea Ice Graphs website (ASIG)
for daily updated graphs, maps, live webcam images, and
the Arctic Sea Ice Forum (ASIF) for detailed discussions.

September 10th 2016

It's that time of year when the melting season is drawing to a close and the Arctic sea ice pack is reaching its lowest size of the year, also known as the minimum.

This melting season was a strange one. After the mildest winter on record, a spectacular opening up of the Beaufort and Chukchi Seas made trend lines on graphs go extremely low even before the melting season had properly started. But then clouds moved in during the period when the Sun is at its peak, and solar radiation causes melt ponds to form on the ice pack, building up so-called melting momentum.

June and July were really cloudy, as cloudy as in rebound years 2013 and 2014, but this time around atmospheric conditions weren't accompanied by low temperatures on the ground and in the water. The warm winter, early opening up of the ice pack and the rapid melting of land snow cover, caused another kind of momentum, one of heat, that kept the melting going throughout.

And then in August, a massive storm that kept on re-intensifying (or maybe they were two separate storms), followed by a Dipole with a massive pressure gradient, battered the ice pack. Again, as in 2012, we've witnessed the detachment of one large piece of ice from the main pack. And now the 2016 melting season has reached 2nd place on almost all extent and area graphs out there.

You read it right, a melting season that saw mostly cloudy conditions during the sunniest period of the year (June-July-August) has beaten the 2007 melting season which went astonishingly low after weeks of ceaseless sunshine and a massive Beaufort Gyre, continuously compacting the ice pack, well into September.

But it looks rather unlikely that the 2016 melting season will end that late. The past few weeks have promoted massive ice dispersal, with large zones of low concentration near the Pole, and so there's a lot of compaction potential. But for compaction to happen, winds need to blow towards Greenland and the Canadian Arctic Archipelago, or else freezing temperatures start to dominate and all that open water within the ice pack and on its fringes starts to fill up with ice. The reverse is the case.

We can see that happen on this animation of Uni Bremen sea ice concentration maps of the past week:

The remnants of the now fully detached Wrangel Arm are still melting, compensating the ice growth elsewhere, but I'm pretty sure the minimum has been reached.

I will have a blog post with more images characterizing this melting season up later this week.

2016 Mega-Dipole

As reported in the last ASI update, the forecast Dipole has now set up. Yesterday's last analysis chart provided by Environment Canada, at 18Z, showed the high pressure moving in via the Bering Strait at 1037 hPa, while a rapidly weakening storm that had moved in from Siberia (lowest central pressure was 967 hPa, two days ago) was still at 974 hPa on the other side of the Arctic. This then evolved to a massive 1041 hPa on one side of the Dipole, and 977 hPa on the other:

That's a humongous pressure gradient of 63-64 hPa! You don't see that often around this time in the Arctic, a not so nice story for the grandkids. Right now, the high is still at 1041 hPa, but the low has weakened further to 980 hPa. That's still a pressure gradient of 61 hPa.

It means very strong winds are blowing over the ice pack, from Siberia to Canada, compacting the ice pack and further pushing open water towards the pole, as can be seen on this animation of Uni Bremen sea ice concentration maps:

If one looks carefully at the ice in the so-called Wrangel Arm, you can clearly see the ice flash in and out of existence. There comes a point where the ice no longer flashes back, but in the meantime it makes for wild swings on the CT sea ice area graph, as calculated by Wipneus: