Over the past few days, Arctic sea ice extent has braked dramatically in the daily loss rate and now has made a sharp right turn, which is rather unusual. Here’s the JAXA extent:
And here is a close up view, note the 2011 red line:
That turn is unique to the record since 2002. Note that in 2007, there was also a turn, though brief, and then melt accelerated.
It is also showing up in the NSIDC plot:
But what is really most interesting is the plot from DMI, which show not only a turn, but a reversal:
What does this mean? The short answer is, probably nothing. When we approach the minimum, and the ice pack becomes more fractured and scattered, it also becomes more susceptible to the vagaries of local and regional wind and weather.
WUWT regular and contributor “Just the facts” suggested in comments that:
One factor appears to be the Greenland Sea, where sea ice began to grow on July 15th and has been trending above average since then.
Source: ftp://sidads.colorado.edu/DATASETS/NOAA/G02186/plots/r07_Greenland_Sea_ts.png
On the other hand, looking at the most recent comparison with 2007, the Arctic ice cover looks a bit more soupy in 2011:
Air temperature is above freezing throughout the Arctic….
…as is fairly normal for this time of year:
Clearly, at present, air temperature in the Arctic is not in any way climatologically abnormal, so the reasons for the current extent being low and making erratic turns must lie elsewhere. Wind, soot deposition/albedo, ocean currents, etc. all factor in.
So, while we may have temporarily avoided a new record minimum (as many in the “Serreze death spiral” camp said we are headed to) there’s still the possibility that the plots will turn to the left again, and resume or even accelerate. It all depends on the weather, and the outcome could go either way at this point. Historically, we have about 7 more weeks before the turn upwards as the Arctic begins the slow re-freeze.
Still, it makes for interesting observation and discussion. The WUWT sea ice page has all the latest stats, updated as soon as they are made available.
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UPDATE: Bill Illis runs his own database, and offers this interesting view in comments.
The last 21 days are the lowest melt since 1973 in my database over the same period. The total ice extent is still well-below average but there are very few periods in the record where the trend is so different than normal for an extended period of time like the current period is.
Matching up a few different datasets back to 1972.
UPDATE2: In the meantime, while extent loss slows, the NSIDC “death spiral team” tries to make a case for a record low average for July, while at the same time admitting that On July 31, 2011 Arctic sea ice extent was 6.79 million square kilometers (2.62 million square miles). This was slightly higher than the previous record low for the same day of the year, set in 2007.
Arctic sea ice at record low for July
Arctic sea ice extent averaged for July 2011 reached the lowest level for the month in the 1979 to 2011 satellite record, even though the pace of ice loss slowed substantially during the last two weeks of July. Shipping routes in the Arctic have less ice than usual for this time of year, and new data indicate that more of the Arctic’s store of its oldest ice disappeared.
Figure 1. Arctic sea ice extent for July 2011 was 7.92 million square kilometers (3.06 million square miles). The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data.
—Credit: National Snow and Ice Data CenterHigh-resolution image
Overview of conditions
Average ice extent for July 2011 was 7.92 million square kilometers (3.06 million square miles). This is 210,000 square kilometers (81,000 square miles) below the previous record low for the month, set in July 2007, and 2.18 million square kilometers (842,000 square miles) below the average for 1979 to 2000.
On July 31, 2011 Arctic sea ice extent was 6.79 million square kilometers (2.62 million square miles). This was slightly higher than the previous record low for the same day of the year, set in 2007. Sea ice coverage remained below normal everywhere except the East Greenland Sea.
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An “unusual” sharp right turn.
Sharp turns are undoubtedly going to be more common due to global climate disruption. /sarc
R. Gates says:
Ice melt is now being driven more by water temps than air temps…
…as opposed to times when water temps are not the primary driving force? If you want to be taken seriously, you should acknowledge that water temps are always a greater driver than air temps, regardless of whether you meant it relatively speaking, The greatest factor that the atmosphere has going for it is the wind effect, which you might mention, as that is “driven” by air temps.
Daniel M says:
August 4, 2011 at 11:44 am
R. Gates says:
Ice melt is now being driven more by water temps than air temps…
…as opposed to times when water temps are not the primary driving force? If you want to be taken seriously, you should acknowledge that water temps are always a greater driver than air temps, regardless of whether you meant it relatively speaking, The greatest factor that the atmosphere has going for it is the wind effect, which you might mention, as that is “driven” by air temps.
______
Don’t know what you mean “greatest factor the atmosphere has going for it”. Certianly, wind can be viewed in some regards as a “macro” temperature effect, if one views temperature from a statistical thermodynamics perspective as being a measurement of average kinetic energy of the molecules. When masses of air rush around, that’s a lot of kinetic energy, which can move ice and melt ice, and of course wind in general is yet another form of the net energy budget of the earth, and therefore wind is of course at least partially another form of solar energy.
And yes, since most of the volume of sea ice is under water, most of the melting by volume also must occur there as well, but there are times when air temps play a greater role relatively speaking.
Dave Springer says:
August 4, 2011 at 11:32 am
An “unusual” sharp right turn.
Sharp turns are undoubtedly going to be more common due to global climate disruption. /sarc
____
Though of course you are being sarcastic, you probably are more accurate than you know. As Arctic sea ice thins in general, it should see many seasons of rapid swings up and down. We saw this after the 2007 low, when the extent grew rapidly again in the fall, and then again in 2008, when it plunged from a higher level very rapidly, though didn’t get to the 2007 low.
As sea ice volume declines, it will be much more subject to sharp turns, especially later in the melt season as the “soupy” ice can get pushed around by the wind and currents far more readily, leading to divergence or compactification, depending on the wind directions.
This up-turn is actually very unusual. Over a two week period, the melt rate in 2011 is by far the lowest in the record going back to 1972 (a sensor glitch shouldn’t be ruled out).
We have just passed the peak per day melt period and 2011 is now only 50% of the average 2 week melt rate.
http://img838.imageshack.us/img838/351/nhseaice2weekchange.png
If some of the Alarmists keep wish-casting the ice below 2007, then it might actually come true eventually.
In all seriousness, its been hilarious to watch their reactions as the ice loss flattens out the last week. Until the pattern shifts dramatically up there, the ice will continue a general slower than average melt.
Dennis Wingo and R Gates – you both draw a link between Arctic temperatures and temperatures further south. DW http://wattsupwiththat.com/2011/08/03/sea-ice-news-arctic-sea-ice-extent-making-a-sharp-right-turn/#comment-712036 expects the cold Arctic to lead to cold further south, RG http://wattsupwiththat.com/2011/08/03/sea-ice-news-arctic-sea-ice-extent-making-a-sharp-right-turn/#comment-712055 thinks that cold further south tends to be associated with a warmer Arctic not cooler. I have no idea if either of you is right, but is there any evidence to support one view vs the other?
Sort of appropriate
http://www.canada.com/technology/Arctic+loss+been+much+worse+historically+Study/5206595/story.html
After looking at whats transpired over the past 2 weeks and reviewing the sea ice concentration 30 day animation on Cryosphere Today, as much as it pains me, I have to agree with R Gates on what we might expect for the remainder of the melt period.
Dispersion of the ice is very clearly behind the current low rate of extent loss. This has left a massive area of ice with concentrations below 60% which will be exceedingly vulnerable to melt over the next 30 days.
I think we should expect to see a number of days where the extent loss is well in excess of 100,000km2 per day and a minimum in the 4.5-4.7 million km2 range.
I don’t want to get into the game of guessing what might happen next. Except to say that the ice sheets are demonstrating an ability to spring surprises and the ensuing discussion reveals a lot about doom and gloom predictions.
For those who expect a sudden loss of ice because it may be thin, why is it that ice albedo effects are being ignored? Surely some of the AGW rhetoric would acknowledge that the extended ice cover will deprive the water of sunlight and therefore the heating that is argued to amplify ice loss. Doesn’t the same argument indicate amplification of ice gain?
Kelvin Vaughan says:
August 4, 2011 at 3:32 am
cannot disagree with you there – the interesting point being that if summer melt is generally consistent (by the surface air temps being similar) then the ice pack extent and thickness must be dependent on some other factor…obviously if air temps are above freezing, ice cannot form (except perhaps by wind chill factor?) so during subzero temps, other effects must play a major role – ergo, ice formation cannot be primarily affected by surface air temp?
I would suspect that ice albedo arguments are a more long term effect. If water temp is more of a driver than air temps (in combination with wind and ocean currents) then it stands to reason there would be a lag in seeing impacts from any albedo effects.
Interesting Danish study on Arctic sea ice extent going back 5,000 years:
http://www.bbc.co.uk/news/science-environment-14408930
Notice this bit of science wasn’t written up by Richard Black.
No, air temperatures during the Arctic “summer melt season” – up where the ice actually is! above 80 north – are very steady at +1.0 degree C. Very seldom the past 60 years do temp’s go above +1.5 degrees, very seldom do the air temp’s go below -1.0 C.
Melting of the sea ice is most strong from below, from the water – at +2 to +4 degrees C melting out the ice. (Obviously, if the sea ice breaks up, individual floes and areas go further by wind and current drift much further south into warmer air, warmer water, and more solar insolation. ALL of those three melt out the ice even faster.)
Right at mid-Sept, Arctic air temps drop below freezing, and stay there at -25 degrees until the next June. That period – when the very cold Arctic air IS freezing the sea water into sea ice – is when the ice extents begin recovering and return to their maximum extents the next Feb-March. So, right now, right between mid-July and early August do the “highest” water temperatures AND highest air temperatures AND highest amount of solar insolation combine that ice melt rates are the greatest. So, since every day now, the sun is lower in the sky, and since day further more energy will be absorbed by the atmosphere before it reaches the surface, and since every further day now more energy will reflect off the ice and water surface, there is little reason to suspect loss rates will increase substantially. Losses will continue most certainly, but the physical effects causing those losses to occur are decreasing now, and will continue to decrease.
R. Gates says:
August 4, 2011 at 12:19 pm
Directtions: Shake contents vigorously before spraying can of CO2 Barbecue Red.
Warning – contents under pressure.
Flammable – keep away from ignition sources.
Toxic – Use only in well ventilated area.
Keep away from pets and children.
35 years ago, the can was labeled Cyrogenic Blue.
RACookPE1978 says:
August 4, 2011 at 4:21 pm
agreed – which begs the question – is arctic sea ice loss a direct consequence of global warming (even more specifically CO2 related warming) – based on the knowledge of historical NW passage travel, etc – surely, the variation of arctic sea ice is far more ‘natural’ than the warmists would have use believe?
“Kev-in-UK says:
August 4, 2011 at 3:58 pm
obviously if air temps are above freezing, ice cannot form (except perhaps by wind chill factor?)”
When the temperatures are above freezing, such as 2 C, humans experience a wind chill factor during high winds since our body temperature is 37 C. However ice experiences the opposite effect during high winds and 2 C. If the temperature is 2 C, the ice melts much faster the windier it is. However despite this, I think that the sun shining down, especially if there is a lot of soot on the ice surface, causes far more surface ice to melt than the slightly warmer air temperature.
To attach any meaningful importances to sunshine in the Arctic at this time of the year, you need W/M^2 at each latitude, starting at 65N.
Sort of: Every year, all the sea ice melts in most areas of the Arctic: Sea ice extents basically drops from 14 million km^2 to between 5 to 6 millon, now trending towards 4+ million. Regardless of anything anybody wanted to believe above earlier years, sea ice will always melt each summer, then always re-freeze as temperatures begin to drop down towards -20 degrees C (or less) beginning the first week in October as the sun drops lower and lower.
However, you can very closely approximate that 4.0 million square km of ice as a circular cap centered on the pole, extending south to 79.8 degrees latitude. Use 80 north latitude. (80 north latitude skims across a little bit of north Greenland – and that isn’t sea ice, and the actual center of the “real sea ice” is centered about 83 north latitude at 180 longitude 180 west.) There is almost no sea ice below 65 south at any times of the year, and none significantly measurable during any part of the summer melting season when the sun is up for substantial parts of the day at substantial elevations.
Well, according to NSIDC (I know), ice loss for July set a new record, beating out `07. And they are claiming old ice is still declining.
“On the other hand, looking at the most recent comparison with 2007, the Arctic ice cover looks a bit more soupy in 2011:”
Thats cause for concern. That soupy ice could disappear in a hurry, and area and extent could start dropping like an elevator.
“It’s great fun anyway you look at it. Over at Real Climate, they were wetting themselves over the prospect of a new summer minimum.”
Nothing would please them more than an ice free Arctic.
DMI (Aug. 4) shows extent declining again.
Here’s a serious question : Why are we watching Arctic ice extent so avidly? We know that over each Northern summer it’s driven primarily by winds and ocean currents, so one season’s about as irrelevant as it can get to global warming.
Now I’ll answer the question : Because it makes headlines. As Dave said earlier of RC, they were wetting themselves over the prospect of a new summer minimum, ie, a figure they can blast into the headlines.
It seems that every time you think the wacky world of climate science just can’t possibly sink any lower, it proves you wrong.
RACookPE1978 says:
August 4, 2011 at 4:21 pm
“….and since every further day now more energy will reflect off the ice and water surface, there is little reason to suspect loss rates will increase substantially.”
I don’t think this takes into acount extent measurement which is a combination of ice melt and dispersion. I think this season differs to previous seasons for which we have JAXA data in. In previous seasons there was still a degree of compaction in the remaining ice to limit the impact of ice melt on extent loss. 100% sea ice concentrations will not display as much extent loss for the same rate of ice melt as 50% sea ice concentrations
Certainly the extent loss for 4th August has jumped back up to over 80,000km2 demonstarting that in terms of the extent minimum we may still have a way to go.