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).
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[…] Sea ice area approaching the edge of normal standard deviation 22 10 2008 10/31 NEWS: See updated graphs here […]
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
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.
Way to go ice! Incredible given the ever increasing reported temperatures in the Arctic.
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).
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.
here is a website that shows the sea ice extent and prediction for the next week. It is updated ones a day. http://retro.met.no/kyst_og_hav/northern_anim.html
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.
http://psc.apl.washington.edu/northpole/gifs/DriftMap.gif
Also, the Arctic Oscillation is forecast to go deeply negative in the next few days.
http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif
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
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.
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.
http://www.aviso.oceanobs.com/fileadmin/images/news/indic/msl/MSL_Serie_MERGED_Global_IB_RWT_PGR_NoAdjust.png
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.
http://www.aviso.oceanobs.com/fileadmin/images/news/indic/msl/MSL_Serie_J1_Global_IB_RWT_PGR_Adjust.png
Oops, I pasted the wrong link for Jason 1, seasonal signal not removed. Here is the right one.
http://www.aviso.oceanobs.com/fileadmin/images/news/indic/msl/MSL_Serie_J1_Global_IB_RWT_PGR_NoAdjust.png
Hi Anthony,
Thanks for the update!
Grant
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.
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.
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.”
! ! !
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….
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
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.
Manfred:-)
Does that mean the sea level is increasing becasue of the water has to go somewhere?
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
Does anyone here remember the animated GIF that shows the retroactive adjustment in sea ice area? Please post it if you will.
Thanks,
Mike
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
About 38 minutes into the broadcast.
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.
“…unless mother nature upsets the voters.”
or more likely when mother nature upsets the voter’s pocketbooks.
Jim
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.