When we last checked in to the Nansen Sea Ice Graphs, it looked like they were heading towards the “normal” line in a hurry. Ice area seems to still be on that trend, while extent seems to be leveling off it’s growth rate. Area appears to be within about 200,000 square kilometers of the 1979-2007 monthly average and still climbing.
Of course the fact that the 2007 data is included in the average line, means the average is a lower than usual target than one might expect. If we compare to ice area over at Cryopshere today, they use a 1979-2000 mean, which is higher. Still the rebound we are seeing is impressive.
Sea ice extent looks like this:
These graphs will automatically update, so check back often.
For those of you wondering, here is the difference between area and extent, as described in the NSIDC FAQ’s page:
What is the difference between sea ice area and extent? Why does NSIDC use extent measurements?
Area and extent are different measures and give scientists slightly different information. Some organizations, including Cryosphere Today, report ice area; NSIDC primarily reports ice extent. Extent is always a larger number than area, and there are pros and cons associated with each method.
A simplified way to think of extent versus area is to imagine a slice of swiss cheese. Extent would be a measure of the edges of the slice of cheese and all of the space inside it. Area would be the measure of where there’s cheese only, not including the holes. That’s why if you compare extent and area in the same time period, extent is always bigger. A more precise explanation of extent versus area gets more complicated.
Extent defines a region as “ice-covered” or “not ice-covered.” For each satellite data cell, the cell is said to either have ice or to have no ice, based on a threshold. The most common threshold (and the one NSIDC uses) is 15 percent, meaning that if the data cell has greater than 15 percent ice concentration, the cell is considered ice covered; less than that and it is said to be ice free. Example: Let’s say you have three 25 kilometer (km) x 25 km (16 miles x 16 miles) grid cells covered by 16% ice, 2% ice, and 90% ice. Two of the three cells would be considered “ice covered,” or 100% ice. Multiply the grid cell area by 100% sea ice and you would get a total extent of 1,250 square km (482 square miles).
Area takes the percentages of sea ice within data cells and adds them up to report how much of the Arctic is covered by ice; area typically uses a threshold of 15%. So in the same example, with three 25 km x 25 km (16 miles x 16 miles) grid cells of 16% ice, 2% ice, and 90% ice, multiply the grid cell area by the percent of sea ice and add it up. You’d have a total area of 675 square km (261 square miles).
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Headline in the Guardian, UK:
“Arctic Ice Normal” It’s on the presses right now and is coming in 5..4..3..
October CET half a degree down! http://hadobs.metoffice.com/hadcet/cet_info_mean.html
M White. Please bear in mind the intelligence level of our MPs.
The earth has always gone through cycles of global cooling and warming in it’s history even before cars were invented…The Arctic Ice going back to normal will certainly not make very many headlines in the global warming scare…But it’s good to see it posted elsewhere!
Mike Bryant,
Is this what you’re looking for?
Sea ice extent before and after “adjustment”: click
Thank you Smokey,
Looks like Arctic sea ice area is back to normal. Who’da thunk it?
Ozone depletion is an incredibly important topic when it comes to the melting of the ice in our polar regions. NASA is absolutely phenomenal in their learning of what happens with ozone depletion and is already asserting the changes via the polar vortexes, firstly, to reduce the rate of depletion, and secondly, to restore the integrity of ozone concentrations that were once there. Please acknowledge their efforts as carbon dioxide dominates the media and very few people ever talk about ozone depletion when it comes to global warming.
Has anyone explained yet how we could have two Septembers in a row now with sea ice betweeen 3 and 4 standard deviations from the mean? The odds of this are around a million to one against. Is the STD calcualtion reliable?
M White,
I have emailed Jeremy Hunt MP pointing out the stupidity of his comment and pointing him in the direction of where he can find the evidence (although he probably doesn’t want to be confused with facts). I hope many others do the same.
Braddles,
I am a plumber but I’ll take a stab at it. Here is a quorte from NASA:
Nghiem said the rapid decline in winter perennial ice the past two years was caused by unusual winds. “Unusual atmospheric conditions set up wind patterns that compressed the sea ice, loaded it into the Transpolar Drift Stream and then sped its flow out of the Arctic,” he said. When that sea ice reached lower latitudes, it rapidly melted in the warmer waters.
“The winds causing this trend in ice reduction were set up by an unusual pattern of atmospheric pressure that began at the beginning of this century,”
Nghiem said.
The ice refroze quickly and in the 2008 summer melt there was more first year ice. The first year ice was expected to completely melt and leave the Arctic Ocean with even less sea ice area/extent than 2007. That is not what happened. Instead, there was a minor comeback which I expect to continue in the years ahead.
This type of ice melt is not unprecedented. If you have read this blog, you have seen many historic references to low ice levels. With the advent of satellite monitoring, people have begun to believe that the thirty year record somehow proves that the ice has been uniform for millenia. It hasn’t.
The short answer, it’s weather. Ice melts every summer, different weather conditions cause differing melts and melt patterns. Our parents were too smart to ever try to do anything about the weather. We, however, for some reason, think it is within our sphere of influence to change it. It isn’t. We can enjoy it. We can curse it. We can even prepare for it. We cannot change it. When we comes to this simple realization he will be happier.
Look at the latest sea ice graph here [from Anthony’s link on the right side of this page; updated twice daily].
If the current trend continues for only a few more days, 2008 sea ice levels will exceed those of 2002 – 2007.
How will the globaloney bovine fecal purveyance specialists spin that inconvenient fact?
Smokey:
“How will the globaloney bovine fecal purveyance specialists spin that inconvenient fact?”
We may find they are too busy trying to stay warm to have enough time to spin it.
Jim
Well, I’d have to say hold the applause on the Arctic freeze – the “Anti-Deniers” have switched their focus to the West Antartic Peninsula as apparently it’s now melting after decades of growth. It seems that we need a constant fix of concern or hysteria.
(Why does this sound like the methodology of a dictator who must maintain the constant external threat in order to maintain internal controls?)
Cryosphere Today Area anomaly shows an increase of 1 million square kilometres since early spring. (That is the ice has increased by 1 million square kilometres more than the average for same time during years 79-00)
How often have increases of 1 million square kilometres for arctic ice anomaly occurred during the past trend of ice decrease to 2007?
Almost once a year.
The most impressive previous recovery in sea ice was close to 2 million square kilometres during 1996, followed by an equal anomaly loss in a matter of weeks to a month or two.
Also compare the late 2007 recovery – an increase in sea ice anomaly of 2.5 million square k, followed by the early 2008 anomaly reduction of 1.5 million square kilometres.
Michael Hauber (16:15:56) :
Cryosphere Today Area anomaly shows an increase of 1 million square kilometres since early spring. (That is the ice has increased by 1 million square kilometres more than the average for same time during years 79-00)
Which graph are you looking at, that’s only true if you’re an Aussie?
There is a major difference in Arctic ice behavior this year compared to 2007. This military buoy shows ice thickness of 1.6 meters and increasing rapidly. In 2007 the minimum summer ice thickness was the same (1.1m,) but thickness didn’t reach 1.6 meters until the end of January.
http://www.crrel.usace.army.mil/sid/IMB/buoy_plots/ice2006C.gif
Location is here:
Lat: 85.652 N
Long: 111.676 W
Not only is ice extent and area increasing well ahead of last year, but so is the third dimension. As our friends always love to rebuke us, ice is not two dimensional.
Hi Steven,
So the red line equates to ice thickness? Or have I mis-interpreted?
What does the green line signify?
Thanks
Steven Goddard (19:37:26) :
There is a major difference in Arctic ice behavior this year compared to 2007. This military buoy shows ice thickness of 1.6 meters and increasing rapidly. In 2007 the minimum summer ice thickness was the same (1.1m,) but thickness didn’t reach 1.6 meters until the end of January.
Trouble is that buoy depth meter is malfunctioning.
REPLY: How do you know that? Where is that referenced from?- Anthony
Phil (18:35:32)
Which graph are you looking at, that’s only true if you’re an Aussie?
The ‘tale of the tape’
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg
The buoy ice data is fine. The temperature profile shows freezing (< -2C) temperatures down to 180cm, which is consistent with the ice depth graph. It also shows much colder ice temperatures than at the end of October, 2007.
http://www.crrel.usace.army.mil/sid/IMB/buoy_plots/2006C.gif
http://www.crrel.usace.army.mil/sid/IMB/2006C.htm
Additionally, the low ice temperatures are consistent with other military buoys. They all show ice temperatures ranging from -20 to -35C in the top meter.
Graeme,
The red line represents depth of the bottom of the ice below sea level. The green line is supposed to show snow depth above sea level, though that line appears incorrect on most of the buoys.
It should be noted that as of 31Oct 2008 the ice extent as measured by IJIS is the largest of all of the plotted data for that date (2003-2008) and is rising faster than any year recorded on that plot. (sort on column A, B and D for the data link and look for 31Oct). 2008 took the lead on 30Oct.
All the fanfare is fantastic but the mean amount of none walkable water included in the “extent” measure for October was about 2.2 million km square.
And the little reality check for self deception is that, though “extent” stalled a bit due whatever, hitting the coast, gyre effects, winds, you name it, there’s what I reckon still 1.75 million km square water inside “extent”. That said IJIS-IARC-JAXA has no update for 2 days, so it’s a slight guess.
As for AREA, the real stuff, 2008 over 2007 improvement is day on day per Nov. 1 around 600,000 km^2 better, but still 1 million km2 behind the 79-00 mean. Watch this for your daily dose:
http://arctic.atmos.uiuc.edu/cryosphere/iphone/iphone.currentarea.series.html
Looking at GDAS, enormous areas of very very thin ice. Let’s call it a parchment thick improvement. What’s important is if it’s going to live through the 2009 spring, summer melt. http://seaice.bplaced.net/thickness/
Phil. (20:40:54) :
Steven Goddard (19:37:26) :
There is a major difference in Arctic ice behavior this year compared to 2007. This military buoy shows ice thickness of 1.6 meters and increasing rapidly. In 2007 the minimum summer ice thickness was the same (1.1m,) but thickness didn’t reach 1.6 meters until the end of January.
Trouble is that buoy depth meter is malfunctioning.
REPLY: How do you know that? Where is that referenced from?- Anthony
A couple of reasons: that meter has been behaving strangely for a couple of years, at the maximum the signal flattened out last year at ~1.1, even the noise was truncated, this year it flattened in the same way at exactly the same value. Earlier this fall that buoy stopped updating for ~1 month and then recently started down in a noise free straight line (similar behaviour to that seen in some buoys on rapidly melting ice in the Beaufort sea (http://www.crrel.usace.army.mil/sid/IMB/buoy_plots/ice2007E.gif)
Contrary to Goddard’s statement the air temperature history is similar to last year’s, if anything early October was warmer this year (bear in mind the buoy’s not in the same location as last year).
http://www.crrel.usace.army.mil/sid/IMB/buoy_plots/met2006C.gif
All of the above leads me to think that the ice-depth meter on that buoy has not been performing properly for some time (I’ve posted about it here before). One possibility is that the buoy has drifted towards the coast which may result in folding but that wouldn’t explain the ‘flatness’.
Michael Hauber (21:30:35) :
Phil (18:35:32)
Which graph are you looking at, that’s only true if you’re an Aussie?
The ‘tale of the tape’
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg
Unless by spring you mean September (i.e. you’re an Aussie) then I don’t know where you see this:
Cryosphere Today Area anomaly shows an increase of 1 million square kilometres since early spring.