# Arctic sea ice continues rebound

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.

Sea Ice Area - red line is current value, shaded area represents 1 standard deviation

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:

Sea Ice Extent - red is current value, shaded area is 1 standard deviation

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).

## 68 thoughts on “Arctic sea ice continues rebound”

1. fred says:

I see the 1 std shading , do you happen to have the 2 std /95% Confidence interval?

Isn’t that the defacto most common test if you assume a normal distribution?

REPLY: Not my graph, it’s Nansen’s so no I don’t have that data. – Anthony

2. Leon Brozyna says:

For a couple days it looked like the spread of the ice extent north of the Bering Strait slowed, perhaps as a result of wind or storm. But it looks that while the increase in ice extent slowed, the area of ice within that extent increased as open water continued to freeze.

Now let’s see how far the extent expands through the winter in the Bering and Barent Seas.

3. hyonmin says:

Way to go ice! Incredible given the ever increasing reported temperatures in the Arctic.

4. BarryW says:

It’s frustrating that these sites provide the graphs but not the values behind the graphs (except for JAXA and they don’t provide areal data). The extent here looks higher than JAXA’s (~8.8).

5. Smokey says:

I check Anthony’s Sea Ice link on the upper right of the page every day. It compares current sea ice area to the average from 2002 – 2008.

To some folks, though, more sea ice = global warming.

6. Steven Goddard says:

Dr. Meier tells me that the early 1980s had abnormally large amounts of ice. If those years are included in the average, then we also need to include more recent years with abnormally low amounts. The argument to exclude recent years reminds me of Dr. Hansen’s tendency to verbally emphasize the importance of El Nino years while discounting La Nina years.

Another important parameter is polar drift, which will largely determine the thickness and age of the ice next year. Polar drift has been minimal this summer, and if that trend continues the ice will be thicker and older going in to next year’s melt season than it was this year.

Also, the Arctic Oscillation is forecast to go deeply negative in the next few days.

7. Anthony,
While arctic sea ice doesn’t have impact on sea level, snow falling elsewhere might have impact on it. Jason’s altimetry data seems to be lacking for some time at http://sealevel.colorado.edu/ Are there other online ways to check it out?
EcoTretas

8. Leon Brozyna says:

In case anyone may have missed it, it appears that the IARC-JAXA is updated twice a day. The first update seems to occur around midnight Eastern Time (US), with another update in the afternoon. With the audience here being more refreshingly skeptical, perhaps it’s been missed so far. But remember this detail when in five or six months the melting kicks in again.

9. Bill Illis says:

Sea level data from Jason 1 and Jason 2 is going to be released by AVISO from now on. Jason 2 is still being calibrated and no data is available from the new satellite yet.

http://www.aviso.oceanobs.com/en/home/index.html

Earlier this year, there was an error discovered in the Jason 1 data so they said they would not be updating the data until the error was resolved probably at the end of 2008. They did say that sea level rise has been adjusted downwards to 2.4 mms per year (from 3.2 mms per year) as a result of this error.

They also started releasing data very recently from Jason 1 up to August 2008

This one does not remove the seasonal signal and shows there is no real sea level increase since 2006.

When the seasonal signal is removed, however, there is a large increase in 2008r but it certainly seems there is an error in the algorithm for removing the seasonal signal since there is no rationale for this kind of adjustment.

10. Bill Illis says:

Oops, I pasted the wrong link for Jason 1, seasonal signal not removed. Here is the right one.

11. Hi Anthony,

Thanks for the update!
Grant

12. I ran across a couple of studies that had determined there is a 1.8 to 2.1 year lag between El Nino/La Nina events and Arctic ice response. If anyone’s interested I can try to find them again.

13. An Inquirer says:

In pre-2004 pictures of Arctic ice cover, snow is not part of the picture on igloo.atmos.uiuc.edu/cgi-bin, and we see ice area extending into fjords and rivers. In the pictures of the the last few years, we do not see this ice cover, rather the area shows up as snow. Did previous years’ ice area (and extent) get credited with ice-covered fjords while current year’s ice area (and extent) not get credited for this ice cover? Or has this issue been taken care of? Perhaps this is a question for Dr. Meier.

14. anna v says:

And trees were growing in Antarctica some millions of years ago, but the mantra is still there:

http://www.sciencenews.org/view/generic/id/37267/title/When_trees_grew_in_Antarctica

” Trees that lived about 237 million years ago, during the Triassic, have growth rings as wide as 6.8 millimeters, Ryberg and University of Kansas colleague Edith L. Taylor found.

At each of these times, large amounts of planet-warming greenhouse gases boosted global temperatures, giving even Antarctica a temperate climate.”

! ! !

15. Dodgy Geezer says:

Don’t worry, Global Warming fright figures are still safe.

I understand that Sea Ice Extent or Area are not figures which may be quoted any longer. The new requirement is for Sea Ice Volume. So long as we use earlier estimates of very thick ice in the 70s, it will still show today as endangering Polar Bears, etc….

16. Manfred says:

Bill Illis said:

“Earlier this year, there was an error discovered in the Jason 1 data so they said they would not be updating the data until the error was resolved probably at the end of 2008. They did say that sea level rise has been adjusted downwards to 2.4 mms per year (from 3.2 mms per year) as a result of this error. ”

that would bring it closer to the average rate of 1.8mm/year of last century and with the falling sea-level recently even more down.

sadly on wikipedia, the average sea-level rise of 1.8 mm/year is not attributed to the recovery from the low sea-level during the little ice age but “a result of human induced global warming”.

this view doesn’t hold much water, because 100 years ago the trend was already going up, and even agw advocats usually do not deny the dominance of natural factors for at least the first half of the 20th century.

http://en.wikipedia.org/wiki/Sea_level_rise

17. Alan the Brit says:

Bill Illis:-)

IPCC Sea-level rises have been the subject of much discussion since early 2007.

Nils Axel Morner, the worlds former leading expert on sea-level rises has always said there is no increase in the rate of rise unless the satellite data is played with (nothing unusual three).

However, the old agreed sea-level rise rate used to be 2.3mm/year average over the last 80 years. IPCC AR4 2007 gave 1961-1993 rate rise of 1.8mm/yr+ or – 0.5mm/yr error, & from 1993 to 2003 of 3.1mm/yr + or – 0.7mm/yr error. Being a very simple structural engineer, 1.8 + 0.5 = 2.3mm/yr, & 3.1 – 0.7 = 2.4mm/yr. Now it just may be a coincidence. However, if I was monitoring a similar range of house crack movement over the same period I would have concluded long ago that the numbers were exactly the same!

When an organisation is acclaimed to be a local, national, or international expert/authority on a subject, by those who know & use it then it is probably true. However, when the organisation proclaims itself to be the local, national, international expert/authority on a matter, then it probably is not the case! When independent internationally renowned “climate” experts claim the IPCC is the best then OK, but when so many of the aforementioned claim otherwise then one has to ask questions.

The BBC has not covered sea-ice extent for a very long time, but has regurgitated & recycled old stories over again with a different slant, linked to so called recent new studies (Sun has no effect on climate, etc). We in the UK are starved of real news.

18. Alan the Brit says:

Manfred:-)

Does that mean the sea level is increasing becasue of the water has to go somewhere?

19. Steve Keohane says:

anna v (22:51:34) Antartica did not exist at that time, 237Ma, but was still part of Pangea. It occupied the SE region of Pangea from approx 50 deg. S to 80 deg. S, with what was to become India at the north and Australia attached to the east. Just some minor details left out of the article, geographic placement might have some effect on climate. /sarc off

20. Mike Bryant says:

Does anyone here remember the animated GIF that shows the retroactive adjustment in sea ice area? Please post it if you will.
Thanks,
Mike

21. M White says:

BBC radio 4’s Question time has been on today. One of the questions to a panel of elected politicians asked them to highlight incidents waiting to happen.
JEREMY HUNT MP a member of the opposition conservatives shadow cabinet in his answer said “with the arctic melting in the winter as well as the summer”

http://www.bbc.co.uk/iplayer/console/b00f4swz

It was stated as a matter of fact, nobody questioned the statement so I assume they all believe it to be true.
I don’t believe any of the politicians who recently voted for the climate change bill will change their minds unless mother nature upsets the voters.

22. JimB says:

“…unless mother nature upsets the voters.”

or more likely when mother nature upsets the voter’s pocketbooks.

Jim

23. Any intelegent comments of the Ant-Arctic situation. It appears to be going in the other direction – shrinking.

Never mind, it appears that in the last month, it has also seen a rapid “growth” when comparing to the average. In fact, normaly it is shrinking by now, but this year it is currently flat.

24. Robert Wood says:

“Arctic Ice Normal” It’s on the presses right now and is coming in 5..4..3..

25. Steve Berry says:

M White. Please bear in mind the intelligence level of our MPs.

26. 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!

27. Smokey says:

Mike Bryant,

Is this what you’re looking for?

Sea ice extent before and after “adjustment”: click

28. Mike Bryant says:

Thank you Smokey,

29. Mike Bryant says:

Looks like Arctic sea ice area is back to normal. Who’da thunk it?

30. Craig says:

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?

32. Phillip Bratby says:

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.

33. Mike Bryant says:

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.

34. Smokey says:

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?

35. JimB says:

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

36. Mongo says:

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?)

37. Michael Hauber says:

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.

38. 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?

39. Steven Goddard says:

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.

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.

40. Graeme Rodaughan says:

Hi Steven,

So the red line equates to ice thickness? Or have I mis-interpreted?

What does the green line signify?

Thanks

41. 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

42. Michael Hauber says:

Phil (18:35:32)

Which graph are you looking at, that’s only true if you’re an Aussie?

The ‘tale of the tape’

43. Steven Goddard says:

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/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.

44. freespeech says:

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.

45. Sekerob says:

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/

46. 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).

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’.

47. 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.

48. Steven Goddard says:

Phil,

I said nothing about air temperatures. The ice thickness data is consistent with the temperature/depth data. Ice temperatures are colder than last year. There is no indication that the buoy is misbehaving. Ice is growing in all three dimensions must faster than last year.

Stop the FUD. You are just generating needless CO2 and other noxious greenhouse gases.

49. Steven Goddard (11:40:00) :
Phil,

I said nothing about air temperatures. The ice thickness data is consistent with the temperature/depth data. Ice temperatures are colder than last year. There is no indication that the buoy is misbehaving. Ice is growing in all three dimensions must faster than last year.

Indeed, I misread your remark on temperature, however the ice temperature shown at that site is significantly colder than its near neighbours which only adds to the suspicions about that buoy. Contrary to your assertion there is reason to believe that that buoy is misbehaving.

I take it that Anthony will take the usual counter-measures against your abusive remarks?

There is nearly no chance of it going asymptotic to the mean value. It will shoot past it, unless something really weird happens.

I’m referring to area, not extent. Although, once the area fills in, extent will want to increase in areas outside the immediate Arctic Basin.

52. Michael Hauber says:

Apologies Phil, I meant spring as September and forgot to turn the seasons ‘right way up’ from my Aussie version, and should have said 1 million square k increase since Autumn

53. One way of looking at Ice extent is to look at when we got to this area of ice in recent years. In 2006 it look till the end November and in 2007 the 20th November to reach the current 2008( 1st November) area.

Does this means that the 2008 one year ice will have a longer period to thicken and will therefore take longer to melt in summer 2009 I wonder?

54. Sekerob says:

Whatever Extent is meant to be, take out the magnifier and align with binoculars to see but a fingernail thickness of difference these last few days, BUT 2007, and only data from 2002-2008. Visit NSIDC NOAA to see how the state is comparing to 1979-2000 and how far away from the mean.

http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

Depends on the “weather” in the coming months and what heat comes up from below. Salinity was up puting the average freezing point of sea water at -1.77C

55. An Inquirer says:

It now looks like as of November 5th that the Antarctica positive ice anomaly offsets the Arctic negative anomaly so that total world ice should be back to the 1979-2000 mean — which I think an honest appraisal would say has an upwardly biased mean.

56. Pamela Gray says:

I have been looking at the color coding regarding ice concentrations on Cryosphere Today and it appears to me that the Arctic is filling up with ice that is quite a bit thicker than has been the case for a few years. Or am I misinterpreting the data?

57. Pamela, I think Cryosphere gives density, as in 100% ice, no open water, or 80% ice, 20% open water. Thickness is not given in the color graphic.

58. Dale says:

Man can NOT change the weather ONLY GOD can!! This Global warming is a bunch of crap !!!!!!!!!!!!!!!

59. Curious says:

On the AMSR-E Sea Ice Extent graphic on the sidebar of the main page, there is a “blip” that occurs every June. What is it?

60. MikeP says:

I know that this is likely to be buried, but with no more recent ice topics … Does anyone know what is going on over at NSIDC? They not only show that the “ice extent” has stopped growing, but they show such things as the Kara Sea being largely ice free (< 15%). This is in complete contradiction, both to what one would expect for this season and regional images such as at Cryosphere Today. It’s also in apparent contradiction with the Nansen Sea Ice graphs (although they haven’t been updated in a few days). Has NSDIC gotten stuck?

61. MikeP says:

Interesting that after I posted here, the 11/13 daily ice image changed. The daily graph on the right still looks the same though.

62. Karl says:

I’ve been checking back in on this graphical representation of data since I first came across this post. This morning, the message below instead of graphs.

Forbidden
You don’t have permission to access /vhost/arctic-roos.org/doc/observations/images/ssmi1_ice_area.png on this server.

Looks like the WUWT auto-update runs into the same roadblock. Hopefully a temporary circumstance?