Arctic Sea Ice

Poll Results 2

Here's an update on the poll widget in the right side bar. A few weeks back I started a new poll to see whether expectations had shifted since the first poll. I have put up a third and final poll for these last few weeks that ends September 1st (so don't wait too long).

This is the result of the second poll:

According to my calculations the average is 4.28 million km2, which is slightly up from the 4.20 million km2 from the last poll. This is probably too low, considering the recent slowdown in extent decrease. But it's still possible.

What isn't possible, is that the minimum extent will be over 5.5 million km2, as IJIS extent currently stands at 5.34 million km2. So some people were wrong, three to be precise. One of them was from downtown Los Angeles, the other one lives real close to Deception Bay, and the third one lives close to Stepaside, which I find pretty funny:

I'm just teasing a bit. There's nothing wrong with being wrong. In fact it's very healthy. I'm wrong at least once a day, or so my wife tells me.

To balance things out a bit I'm showing an area with a high concentration of people who think/thought the IJIS minimum extent will go below 3.5 million km2. Isn't that area part of what they call Tornado Alley? Are people seeing some kind of correlation between sea ice extent and tornado activity?

SIE 2011 update 17: unfulfilled potential

During the melting season I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2005-2010. NSIDC has a good explanation of what sea ice extent is in their FAQ. I also look at other things like sea ice area, concentration, volume, temperature and weather forecasts, anything that can be of particular interest. Check out the Arctic sea ice graphs webpage for daily updated graphs, maps and live webcam images.

August 20th 2011

Switching weather patterns slowed down the sea ice decrease, as they often do. I must admit I was expecting a bit more after the massive drop in sea ice extent of 127K (the second highest daily drop IJIS recorded during August) last week. I was also expecting CAPIE to go up again (after it hit a record low percentage on August 12th), but because extent would catch up, not because area would shoot up by more than 100K in two days.

On the other hand, despite adverse weather patterns, this year has managed to nibble away at 2007's lead and halved it in 10 days time. This of course says something about the state of the ice, which is so weak it melts anyhow or easily gets compacted in specific areas (see the latest animation). Perhaps not this year, but we are approaching a time when weather patterns will no longer be able to prevent extent and area numbers to drop through the floor.

To repeat what I wrote on August 9th: "If 2011 manages to get within 150K of 2007 by August 20th, the race is on again." I don't think this will become about, as the difference is 250K with only one day to go. It's now very probable that the 2007 minimum extent will remain the record. At the same time the combination of slush puppie ice and relatively high sea surface temperatures make it difficult to rule anything out, as we enter the final weeks of the melting season.

Nothing in the Arctic is a dead certainty.

Sea ice extent (SIE)

Here's the current IJIS SIE graph:

As said, 2007's lead has been almost halved from 470K to 251K from August 9th to 19th. Except for 2008 which had a very big extent decrease in August, 2011 has managed to increase its lead over other years. Barring a really early end to the melting season, this year is bound to end up somewhere in the top 3.

The current difference between 2011 and the other years is as follows:

2011 Slush Puppie Animation

If last year was characterized by holes in the middle of the ice pack, this year is the year of rotten ice. A term I like even better is Slush Puppie, because it's ice that's not only very fragile, but keeps getting churned around as well. This ice is becoming a more and more dominant factor when it comes to setting records. Can it spread out and hold out long enough until the sun goes down and freezing temperatures end the melting season (like it did last year)? Or will it suddenly just fall apart and disappear?

On the LANCE-MODIS satellite images we can see that large areas at the edge of the ice pack are covered with this weak ice, especially in the East Siberian, Chukchi and Beaufort Seas. But as clouds don't allow me to make a decent animation, I've returned yet again to the University of Bremen's excellent archive of sea ice concentration maps.

Do not be distracted too much by the rapidly changing colours, and instead concentrate on the edges of the ice pack or focus on one point. Also check out how the warm water from the Laptev Sea is eating its way into the pack:

I will try and update this animation on a daily basis. Don't forget: you have easy access to this and all other animations by clicking on Animations in the upper menu bar.

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Update September 8th: Added images from the previous 2 days. Some of the ice in the Laptev Bite has re-appeared, as it is being pushed together again.

Update September 6th: Added images from the previous 3 days (and removed a couple). There was some more flash melting in the Laptev Bite.

Update September 2nd: Added images from the previous 3 days. The ice is still slowly disappearing.

Update August 31st: Added yesterday's image. More ice vanishing.

Update August 30th: Added images from the previous two days. Some of that ice on the Pacific side is disappearing again.

Update August 28th: Deleted a couple of images (up to the 20th) and added a couple of images. Some of the 'melted' ice seems to be flashing back to life.

Update August 23rd: Added yesterday's image. More flash melting in the Beaufort sea. Could be a fluke. See this post.

Update August 22nd: Added yesterday's image. Lot of flash melting in the Beaufort sea, apparently.

Update August 21st: Added yesterday's image.

NSIDC Arctic sea ice news mid-August 2011

It's been out for a couple of days already - and I'm a bit slow - but I want to give it some attention nevertheless: Another mid-month analysis from the National Snow and Ice Data Center. A few snippets, starting with the last bit which I found particularly interesting (Rob Dekker already told us about this buoy site a while back):

 

Summer melt and sea ice thickness
Data indicate that the Arctic ice cover continues to thin. Sea ice thickness is also an indicator of the health of the ice cover; thick ice is resistant to melt. Specialized buoys managed by the U.S. Army Cold Regions Research and Engineering Laboratory help supplement limited satellite measurements of sea ice thickness. The buoys provide accurate data at specific locations, and can tell us whether thickness changes are due to surface melt, melt at the bottom of the ice floe, or ice growth. These buoys are deployed on thick multiyear ice, which provide long-lasting, stable platforms.

Data from six of these buoys through July 20 show that this year, the ice surface is melting faster than the underside of the ice. As the sun starts to sink on the horizon, surface melt will slow. However, ocean waters warmed during the summer will continue to melt the ice from below, reducing ice thickness and extent into September.

Polar ice caps can recover

More news from Arctic sea ice GCMs, scientifically interesting though perhaps less stimulating than the recent Funder et al and Kay et al studies (hat-tip Bob Wallace). From Science Daily:

Polar Ice Caps Can Recover from Warmer Climate-Induced Melting, Study Shows

A growing body of recent research indicates that, in Earth's warming climate, there is no "tipping point," or threshold warm temperature, beyond which polar sea ice cannot recover if temperatures come back down. New University of Washington research indicates that even if Earth warmed enough to melt all polar sea ice, the ice could recover if the planet cooled again.

In recent years scientists have closely monitored the shrinking area of the Arctic covered by sea ice in warmer summer months, a development that has created new shipping lanes but also raised concerns about humans living in the region and the survival of species such as polar bears.

In the new research, scientists used one of two computer-generated global climate models that accurately reflect the rate of sea-ice loss under current climate conditions, a model so sensitive to warming that it projects the complete loss of September Arctic sea ice by the middle of this century.

However, the model takes several more centuries of warming to completely lose winter sea ice, and doing so required carbon dioxide levels to be gradually raised to a level nearly nine times greater than today. When the model's carbon dioxide levels then were gradually reduced, temperatures slowly came down and the sea ice eventually returned.

DMI SST maps back up

And the maps have undergone some visual changes (no more pink):

Get your desktop wallpaper now

It could be discerned through the clouds for a few days already, a huge algal bloom off the coast of Norway, and yesterday it finally came into full view. I've made a couple of wallpapers out of it for my laptop monitor (1366 x 768 resolution). I liked these two best:

Go get it while it's still there over at LANCE-MODIS, splice the two images together (250m resolution) and copy part of it in your monitor's resolution. It's an awesome background.

CAPIE hits record low

CAPIE stands for Cryospheretoday Area Per IJIS Extent (another more scientific term is 'compactness'), the index which we collectively created last year and that is regularly mentioned in the weekly SIE updates. I'll quote from last year's blog post that saw the birth of CAPIE, called Area vs Extent, to explain what CAPIE means and what it is useful for:

It tells us something about how much the ice pack is spread out. When the pack gets compacted area and extent will come closer together. But in the melting season the gap gets greater. This is because ice is melting, gets spread out and melt ponds start to form.

If you look at the ice pack as a whole, the holes that form away from the edges are not counted as sea ice area, but they do get counted as sea ice extent. That's because for extent every grid cell that contains more than 15% ice is counted as 100% ice. In consequence area will always be lower than extent.

Because of the difference between the ways area and extent are calculated, we can divide the first by the second and this gives us a percentage that, especially in comparison to other years, tells us something about how much the ice pack is compacted or spreading out. If the ice spreads out, there will be more holes, area will drop faster than extent, and thus the area/extent ratio will drop. If the ice gets compacted by winds, holes will disappear, the difference between area and extent becomes smaller and the percentage goes up.

Well, due to a huge drop in CT sea ice area CAPIE has hit an all-time low: 57.39%. As can clearly be seen on our CAPIE graph:

This is the yearly record low in previous years:

• Aug. 16th 2005: 69.53%
• Sept. 26th 2006: 67.69%
• Aug. 19th 2007: 60.01%
• Aug. 13th 2008: 59.57%
• Aug. 16th 2009: 63.91%
• Sept. 3rd 2010: 60.28%
• Aug. 12th 2011: 57.39%

But I don't think this is just the ice pack spreading a lot. I think that in a significant part of the Arctic - the Pacific side to be exact (the Beaufort, Chukchi and East Siberian Seas) - the ice is, to quote Professor Peter Wadhams from this BBC interview a few years back, "just melt[ing] away quite suddenly". Or to link back to the title of the last SIE update: flash melting. And it's showing up in area numbers first.

SIE 2011 update 16: flash melting

During the melting season I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2005-2010. NSIDC has a good explanation of what sea ice extent is in their FAQ. I also look at other things like sea ice area, concentration, volume, temperature and weather forecasts, anything that can be of particular interest. Check out the Arctic sea ice graph webpage for daily updated graphs, maps and live webcam images.

August 13th 2011

I took my eyes off the ice for two days, which was a grave mistake. Just like life, the melting season goes slow, but lightning fast at the same time. No time for distraction. I've been catching up today, had an intense look and read to get that gut feeling back, and as always it is difficult to express how fascinating the Arctic and its ice are.

I had essentially ruled out a new record minimum extent last week, stating that 2011 would only have a chance left if by August 10th sea ice extent would be within 200K square km of 2007. Even though this didn't come about, I left the door ajar, as the weather seemed to be shaping up for increased declines. I'll quote myself from a comment on August 9th: "If 2011 manages to get within 150K of 2007 by August 20th, the race is on again."

I still stand behind that. At the same time must admit I had expected extent to go down a bit faster. Not that things were going slow for this time of year, but I'd (wishfully) thought we'd see a century break or two. There's still 7 days to go until August 20th, and the difference between 2007 and 2011 is somewhat smaller, but still significant. At the same time 2011 hasn't budged when it comes to sea ice area, and our CAPIE graph is signalling major divergence of the ice pack.

This divergence is taking place on the Pacific side of the Arctic and can be seen on sea ice concentration maps and on satellite images (through the many clouds). Where holes in the ice pack were the most striking feature of last year's melting season, I would say this year is increasingly characterized by a sea of slush puppy ice in the Beaufort and East Siberian Seas.

Greyish, brown, spread out like butter on warm toast. Despite high SSTs, high air temperature, battering winds, waves and sun, this rotten ice is still somehow managing to keep the extent from dropping through the floor. For how much longer, I wonder.

If 2011 is to set new records, it'll have to do so on this battlefield where the Arm of multiyear ice held out till the very end. That Arm is not there this year, or at least it's not as muscular. We'll see what the arm-wrestling brings this year.

Sea ice extent (SIE)

Here's the current IJIS SIE graph:

Not much has changed really since the last SIE update, except that - as I expected last week - the 6 million mark has been passed. 2011 has nibbled a bit at 2007's lead, but is still more than 400K behind. It has however maintained and even increased its lead over the other years. 2007's extent decrease is leveling off in the coming week, so perhaps 2011 can creep a little bit closer. Like I said, depending on the slush puppy and weather patterns (more on that below).

The current difference between 2011 and the other years is as follows:

SEARCH 2011 Sea Ice Outlook: August report

SEARCH (Study of Environmental Arctic Change) has released its third Sea Ice Outlook report for August.

Here's their summary:

We received 21 responses for the Pan-Arctic report (Figure 1), with estimates in the range of just below 4.0 million square kilometers to as high as 5.4 million square kilometers for the September arctic mean sea ice extent. As in the July Outlook, the median value was 4.6 million square kilometers with quartile values of 4.3 and 4.6 million square kilometers, a rather narrow range. All contributions are well below the 1979-2007 climatological mean of 6.7 million square kilometers, and also below all values seen prior to 2007. Thus, the low values observed the last four summers are expected to continue again this September. On a regional level, the long-term downward trend is expected to continue in all regions except the Greenland Sea.

And here's the figure showing all the projections (click for a larger version):

So the median is 'stuck' at 4.6 million square km. Jinlun Zhang's projection - based on the PIOMAS sea ice thickness model - has gone up from 4.3 to 4.6 million square km. We see Lucia Liljegren from the Blackboard blog make a contribution, and of course our very own Chris Randles and Larry Hamilton have submitted their projections again. The WUWT poll went from a 5.1 to a 5.0 million square km prediction. NSIDC's Walt Meier's group started with a 4.7 million square km prediction, now 4.5 million square km.

Just for reference, these are the September average extents as calculated by NSIDC for the period 2005-2010 (in million square km):

2005 5.57
2006 5.92
2007 4.30
2008 4.68
2009 5.36
2010 4.90