Arctic Sea Ice

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:

Beaufort under early pressure

A high-pressure area has been moving in over the Beaufort Sea lately. It's quite big and quite high in pressure. Environment Canada has the current pressure there at 1042 hPa:

I've coloured the land masses to make it easier to orient. I've also put in the red arrows to show which way the winds blow along the so-called isobars.

This is the second notable high of this year, following another big one in February that produced strong winds that pushed the ice away from the coast. This phenomenon called the Beaufort Gyre resulted in what we call a cracking event around here (see this blog post). Of course, the Arctic was plenty cold around that time and so the leads froze over again, but the marks are still visible on this AVHHR image (provided again by Environment Canada):

On the one hand those leads let heat escape from the ocean water, on the other hand the thin ice between the enormous floes will melt out easily as soon as sunlight and higher temperatures start taking over, possibly making the entire zone more vulnerable early in the melting season.

The reason I've decided to dedicate a blog post to this, has to do with the current ECMWF forecast for the coming 6 days:

Global sea ice area record minimum?

This post is about global sea ice area, the simple addition of Arctic and Antarctic sea ice area.
As a statistic it's somewhat interesting, but it doesn't convey all that much information about the individual health of both polar regions,
let alone their sub-regions.

Despite this fact, or probably because of it, it's often being touted by climate risk deniers as proof that global warming is a scam and all is well, because Arctic sea ice loss is compensated by a growth in Antarctic sea ice. Even if this were true - it isn't, as this Skeptical Science article explains - it's like saying there is no hunger in the world because there are so many obese people.

But anyway, we're approaching that time of year when global sea ice area as calculated by and presented at Cryosphere Today is going to hit its minimum, or lowest amount of sea ice cover. And currently the number is quite low, as can be seen on this graph from Piotr Djaków's Pogoda i Klimat website:

According to the data 2016 is already 4th lowest at 14.73 million km2, just behind 2007's minimum, and almost 350K behind 2011 and record holder 2006 (14.39 million km2, the grey trend line just below the 2011 green trend line). Below I'll discuss the factors that will determine whether a new record is in the books.

An absolute prerequisite for a new record is for Antarctic sea ice area to go low. Whereas it's freezing in the Arctic right now, it's summer in the Southern Hemisphere and so the Antarctic melting season is slowly moving towards its apogee. If we look at the NSIDC sea ice extent graph for March, for instance, we can see some fairly large swings, with record years 2006 and 2011 standing out with their distinct dips:

ASI 2015 update 5: late momentum

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2014 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). 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.

July 30th 2015

My apologies for being a week late with this update. In my defence: things have been remarkably stable in the past three weeks, or all month really, both weather conditions and trend lines on graphs. To make up, here's a guest blog I've written, that was posted by John Abraham on the Guardian website today.

The article describes the melting season so far, starting out with more sea ice volume than previous years, because of the rebound in volume after the 2012 mega-record melting season. This year the ice pack underwent little preconditioning during May and June, perhaps slightly more than 2013 and 2014, but much less than big melt years such as 2007 and 2012.

This order of play led to the early conclusion that 2015 wouldn't break any records, and could very well end up near the previous two rebound years. However, subsequent weather conditions during all of July have broadened the range of possibilities (see the previous ASI update). I'll be going into the details in the July analysis that will be posted in 10 days or so, but I can tell you that July 2015 was exceptionally sunny and warm.

And that brings us to this melting season's main theme: Will the rebound remain intact, or will it be reversed, and perhaps even wiped out?

Let's first have a look at what has happened in these past 3 weeks.

Sea ice area (SIA)

Here's the latest Cryosphere Today SIA chart, to which I've added preliminary data as calculated by Wipneus:

ASI 2015 update 4: massive heat

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2014 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). 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.

July 7th 2015

I wanted to wait for the latest PIOMAS update and do another melt pond analysis for June, but given the current circumstances and the forecast I've decided to squeeze this ASI update in first.

As we've seen in previous ASI updates this melting season hasn't had a flying start, but it hasn't been as slow as 2013 and 2014 either. With extent going low real fast, but area lagging behind, the compactness numbers indicated little melt pond formation and no divergence to speak of. Melt ponds - and to a lesser extent openings within the ice pack - are important because they lower the ice pack's albedo and soak up a lot of sunlight, preconditioning the ice for further melting. This melting momentum, as I call it, can play a decisive role in the latter half of the melting season, trumping weather conditions.

Of course, weather still plays a very significant role in the final outcome of a melting season. This year hasn't seen any substantial preconditioning and is more similar to rebound years 2013 and 2014 than record years 2012, 2007 and 2011. In fact, this year has been very much like last year, in the sense that there is hardly any movement. Very little ice is transported through Fram Strait to the North Atlantic ice graveyard, and there is no compaction or divergence to speak of because of a lack of strong winds. Most of the extent/area decrease is caused by so-called in situ melting, or melting on the spot.

However, there is one big difference compared to last year and that's heat. Despite a very cold start, there have been several outbreaks of warm air over the ice, slowly but radically shifting the balance between extent and area data. The impact is felt on the surface of the ice pack, but doesn't translate directly into a decrease. Not yet. In theory, it should percolate through after a while, especially if the heat persists. And right now the Arctic sea ice pack is undergoing a massive heat wave which shows no signs of letting up.

More on what has happened and what is going to happen below.

Sea ice area (SIA)

Here's the latest Cryosphere Today SIA chart, to which I've added preliminary data as calculated by Wipneus:

Big drops have been alternating with small upticks, keeping the trend line near the upper half of the pack, but below that of 2013 and 2014.

ASI 2013 update 1: a slow start

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2012 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.

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.

May 26th 2013

This is a slow start in two ways.

I wanted to begin posting ASI updates a couple of weeks earlier, but had the idea to try and make video versions of them to save time, as it took me an average 3-4 hours last year to write an update (gazing at graphs and satellite images not included). But I've never made videos before, and it takes me a while to get over the psychological barrier to do new things. So after fiddling with settings for a while and trying stuff out, I realized a couple of things, leading to this video:

Luckily, my slow start wasn't a problem, as the Arctic melting season has a slow start itself, just like last year. At least, when it comes to area and extent numbers.

We know, based on the latest PIOMAS update and the 2012/2013 Winter Analysis I did a couple of weeks back, that 2013 so far looks pretty similar to 2012, except perhaps for the initial configuration, with thicker ice on the Siberian side of the Arctic instead of in the Beaufort Sea.

I can repeat one part of the Winter Analysis, as my opinion hasn't changed:

Despite a couple of differences, this melting season looks similar to last year's melting season and so it will probably beat the 2007 records. Whether it will also beat last year's records is too early to tell, as weather is still an important factor. We used to see rebounds in the Arctic whenever a record low was hit (also known as 'recovery! recovery!' on fake skeptic blogs), but I'm not sure how bouncy the Arctic is anymore.

The start is slow, just like last year. The why and whereto is explained below.