Arctic Sea Ice

PIOMAS November 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:

October has seen a continuation of the trend that set in right after the September minimum (see last month's update), where 2018 went from 6th lowest at the minimum to 5th lowest at the end of the September, and now it's 4th at the end of October, practically on a par with 2011. The increase of 2115 km3, well below the 2367 km3 average, was actually 3rd lowest in the 2007-2018 record, with only 2007 and 2016 having an even lower increase (1637 and 1648 km3 respectively). That means that 2018 has crept closer to the years below it, and moved away further from the years above it, overtaking 2017 for the first time this year.

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

Wipneus' version of the PIOMAS graph shows how this year's trend line blocks out that of 2011, that's how close together they have been for a couple of weeks now:

PIOMAS September 2018

I've waited an extra week with this post because I was on a holiday and because the minimum is about to get hit. More on that below, but first a short discussion of the PIOMAS August data.

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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:

Just like last month, I had expected perhaps a larger drop. But whereas last month the volume loss was still above average, this month's isn't. The 2007-2017 average volume decrease for August is 2578 km3, and this year it was 2347 km3, more than 200 km3 lower. This means that 2018 is back in 6th position again, as the difference with lower years (except last year) has grown again.

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

On Wipneus' version of the PIOMAS graph we can see how the trend line made a slight drop towards the end of the month, veering away from 2013:

PIOMAS August 2018

PIOMAS data came in a bit later this month, and I'm a bit later still, but this gives us an opportunity to look at what may happen during the second half of the month.

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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:

Given the heat on the Siberian side of the Arctic and extensive melting in the Kara and Laptev Seas I had expected a larger drop. Nevertheless, a loss of 6229 km3 of sea ice volume is well above the 2007-2017 average of 6020 km3. This essentially means that 2018 has caught up some more with the years in front of it, and even slipped below 2016 (the difference is a mere 17 km3), which means it's in 5th position as of July 31. The difference with 2012 has been reduced with 610 km3, and is now 907 km3.

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

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?

PIOMAS July 2018

What a coincidence. Just like last month, I will have to precede the PIOMAS update with a short news flash that a very strong cyclone is barreling through the Arctic. But this time too, the cyclone will be short-lived, and so it's not entirely clear whether, on the whole, it will be damaging or beneficial. It has gone further into the Arctic this time.

Either way, the cyclone' has bottomed out at 968 hPa according to Environment Canada, which is just 2 millibar more than last month's cyclone:

With their sub-970 hPa pressures these cyclones come close to the Great Arctic Cyclone of 2012 (963 hPa), but I think they lack in other parameters such as longevity to really deserve the GAC epithet. Nevertheless, to see two of these monsters in June and July in what hasn't otherwise been a very noteworthy melting season so far, is quite noteworthy. We might even see another one before the melting season is over, which could be a sign of some yet to be identified change going on in the Arctic, causing these extremely warm winters, followed by relatively cold and cloudy summers.

But that's all speculation. Let's look at the updated PIOMAS volume numbers.

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PIOMAS June 2018

Before kicking off this latest PIOMAS update, there's a little piece of information I'd like to share: A massive cyclone is passing through the Arctic right now. The cyclone has bottomed out about half a day ago at 966 hPa, which is slightly lower than the 968 hPa storm we saw at the end of August 2016, and slightly higher than the Great Arctic Cyclone of 2012 (963 hPa). Even though pressure levels are similar, this current storm can't match the other big ones when it comes to longevity. But at the same time, bear in mind it's only June, and not August.

And also remember what IARC chief scientist John Walsh said back in 2012:

This past week’s storm was exceptional, and the occurrence of Arctic storms of extreme intensity is a topic deserving closer investigation. With reduced ice cover and warmer sea surfaces, the occurrence of more intense storms is certainly a plausible scenario. The limitation at present is the small sample size of exceptional events, but that may change in the future.

I think it's safe to say it's changing.

Here's an image of the moment this current cyclone reached its lowest pressure, according to Environment Canada:

I will soon discuss the consequences of this storm for the ice pack, and apologize for not having started writing regular ASI updates yet (too busy).

Okay, now for the PIOMAS update.

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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:

According to the PIOMAS model, volume decrease for May 2018 has been below average: 2285 vs 2650 km3. This means that 2018 is 5th lowest right now, and the difference with last year has grown to a massive 1915 km3, which is 299 km3 more than last month. It has also been overtaken by 2012, which saw a huge volume reduction in May. Likewise for 2016 and 2011, with 2010 not far behind now either.

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

PIOMAS May 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:

The maximum for sea ice volume was reached during April. According to the PIOMAS model, it peaked on April 16th at 22,376 km3, which is the second lowest maximum on record, 1594 km3 above last year's stunning record low maximum, and 301 km3 below 2011's maximum. The total freeze during the 2017/2018 freezing season was the highest since 2013, but not all that much above the 2006-2017 average. This bar graph shows total freeze for the 2006-2018 period:

So, that's the maximum. After the maximum was reached, the trend line flattened, with sea ice volume going down by a meagre 91 km3 from the 16th to the end of the month, which can clearly be seen on Wipneus' version of the PIOMAS graph:

PIOMAS April 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:

March 2018 turned out to be quite cold, relatively speaking (more on that below). And thus, as expected, volume increased by a lot, especially given that it was relatively low at the end of last month. In fact, with 2278 km3, sea ice volume growth during March was the largest in the 2007-2018 period, well above the average of 1832 km3. This means that the gap with 2017 has widened again, whereas the difference with all other years has become smaller. 2011 is now hot on this year's tail, being just 217 km3 behind. I expect this year to end up having the second lowest maximum on record, but you never know.

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

The 2018 trend line can clearly be seen moving back towards the pack on Wipneus' version of the PIOMAS graph:

Naturally, the trend line on the PIOMAS sea ice volume anomaly graph has shot up, moving away from the linear trend line again, meaning volume loss is slightly less than expected, if one were to extrapolate the data average into the future:

PIOMAS March 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:

During February Arctic sea ice volume increased by 2075 km3, according to the PIOMAS model, which is well below the 2007-2017 average of 2437 km3. Only 2014 and 2016 managed to score lower, at 1930 and 2047 km3 respectively. This means that 2018 has consolidated its second place in the ranking, creeping somewhat closer to 2017. Especially the gap with 2013 has widened spectacularly from 166 to 1261 km3. Closest follower is now 2011 at 817 km3. 

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

Wipneus' version of the PIOMAS graph clearly shows how the 2018 trend line strongly deviates from all the other trend lines during February:

PIOMAS February 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:

A new year, a new trend line, and if you watch the above graph closely, you'll see how it dips right under the 2013 trend line at the end of January. This means that 2018 now has the second lowest sea ice volume on record, according to the PIOMAS model. A monthly total of 3005 km3 was well below the 2007-2017 average of 3195 km3, which means 2018 also extended its lead over most other years. Last year, however, January volume was 50 km3 lower still and so that gap has grown slightly bigger again. Given how volume fared during the first few months of 2017, it doesn't look like that 1407 km3 gap is going to be bridged any time soon.

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

Wipneus' version of the PIOMAS graph more clearly shows how the 2017 trend line (light red) goes off even further on a tangent: