From NSIDC Sea Ice News:
Cold snap causes late-season growth spurt
Arctic sea ice reached its maximum extent for the year on March 31 at 15.25 million square kilometers (5.89 million square miles). This was the latest date for the maximum Arctic sea ice extent since the start of the satellite record in 1979.
Early in March, Arctic sea ice appeared to reach a maximum extent. However, after a short decline, the ice continued to grow. By the end of March, total extent approached 1979 to 2000 average levels for this time of year. The late-season growth was driven mainly by cold weather and winds from the north over the Bering and Barents Seas. Meanwhile, temperatures over the central Arctic Ocean remained above normal and the winter ice cover remained young and thin compared to earlier years.
Figure 1. Arctic sea ice extent for March 2010 was 15.10 million square kilometers (5.83 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 Center
Overview of conditions
Arctic sea ice extent averaged for March 2010 was 15.10 million square kilometers (5.83 million square miles). This was 650,000 square kilometers (250,000 square miles) below the 1979 to 2000 average for March, but 670,000 square kilometers (260,000 square miles) above the record low for the month, which occurred in March 2006.
Ice extent was above normal in the Bering Sea and Baltic Sea, but remained below normal over much of the Atlantic sector of the Arctic, including the Baffin Bay, and the Canadian Maritime Provinces seaboard. Extent in other regions was near average.
Figure 2. The graph above shows daily sea ice extent as of April 4, 2010. The solid light blue line indicates 2010; green shows 2007; dark blue indicates 1999, the year with the previous latest maximum extent, which occurred on March 29, 1999; and solid gray indicates average extent from 1979 to 2000. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.
—Credit: National Snow and Ice Data Center
Conditions in context
Sea ice reached its maximum extent for the year on March 31, the latest maximum date in the satellite record. The previous latest date was on March 29, 1999. The maximum extent was 15.25 million square kilometers (5.89 million square miles). This was 670,000 square kilometers (260,000 square miles) above the record low maximum extent, which occurred in 2006.
Sea ice extent seemed to reach a maximum during the early part of the month, but after a brief decline, ice extent increased slowly and steadily through the end of the month. By the end of the month, extent had approached the 1979 to 2000 average. During March 2010, ice extent grew at an average of 13,200 square kilometers (5100 square miles) per day. Usually there is a net loss of ice through the month.
Figure 3. Monthly March ice extent for 1979 to 2010 shows a decline of 2.6% per decade.
—Credit: National Snow and Ice Data Center
March 2010 compared to past yearsThe average ice extent for March 2010 was 670,000 square kilometers (260,000 square miles) higher than the record low for March, observed in 2006. The linear rate of decline for March over the 1978 to 2010 period is 2.6% per decade.
Figure 4. The map of sea level pressure (in millibars) for March 2010 shows high pressure over the central Arctic (areas in yellow and orange) and areas of low pressure over the Bering and Barents seas (areas in blue and purple). The low pressure systems over the Bering and Barents seas have helped to push the ice edge southward.
—Credit: National Snow and Ice Data Center courtesy NOAA/ESRL Physical Sciences Division
Late-season growth spurt
The maximum Arctic sea ice extent may occur as early as mid-February to as late as the last week of March. As sea ice extent approaches the seasonal maximum, extent can vary quite a bit from day to day because the thin, new ice at the edge of the pack is sensitive to local wind and temperature patterns. This March, low atmospheric pressure systems persisted over the Gulf of Alaska and north of Scandinavia. These pressure patterns led to unusually cold conditions and persistent northerly winds in the Bering and Barents Seas, which pushed the ice edge southward in these two regions.
Figure 5. This map of air temperature anomalies for March 2010, at the 925 millibar level (roughly 1,000 meters or 3,000 feet above the surface), shows warmer than usual temperatures over most of the Arctic Ocean, but colder than usual temperatures in the Bering and Barents seas, where sea ice extent is above normal. Areas in orange and red correspond to positive (warm) anomalies. Areas in blue and purple correspond to negative (cool) anomalies.
—Credit: National Snow and Ice Data Center courtesy NOAA/ESRL Physical Sciences Division
Meanwhile, elsewhere in the Arctic
This winter’s strong negative mode of the Arctic Oscillation was moderated through the month of March. Average air temperatures for the month nevertheless remained above average over the Arctic Ocean region. Overall for the winter, temperatures over most of the Arctic were above average, while northern Europe and Siberia were colder than usual.
Figure 6. These images show the change in ice age from fall 2009 to spring 2010. The negative Arctic Oscillation this winter slowed the export of older ice out of the Arctic. As a result, the percentage of ice older than two years was greater at the end of March 2010 than over the past few years.
—Credit: National Snow and Ice Data Center courtesy J. Maslanik and C. Fowler, CU Boulder
Ice age and thickness
The late date of the maximum extent, though of special interest this year, is unlikely to have an impact on summer ice extent. The ice that formed late in the season is thin, and will melt quickly when temperatures rise.
Scientists often use ice age data as a way to infer ice thickness—one of the most important factors influencing end-of-summer ice extent. Although the Arctic has much less thick, multiyear ice than it did during the 1980s and 1990s, this winter has seen some replenishment: the Arctic lost less ice the past two summers compared to 2007, and the strong negative Arctic Oscillation this winter prevented as much ice from moving out of the Arctic. The larger amount of multiyear ice could help more ice to survive the summer melt season. However, this replenishment consists primarily of younger, two- to three-year-old multiyear ice; the oldest, and thickest multiyear ice has continued to decline. Although thickness plays an important role in ice melt, summer ice conditions will also depend strongly on weather patterns through the melt season.
At the moment there are no Arctic-wide satellite measurements of ice thickness, because of the end of the NASA Ice, Cloud, and Land Elevation Satellite (ICESat) mission last October. NASA has mounted an airborne sensor campaign called IceBridge to fill this observational gap.
More Information
For more information, including animations and satellite images, visit the NASA Arctic 2010 Sea Ice Maximum Web page.
Looking at graphs of ice extent whether annually or covering thousands of years, there are no horizontal lines anywhere. Ice is either growing or in retreat, all the time.
“”” jorgekafkazar (14:39:52) :
Norm Milliard (07:58:32) : “In terms of global warming, it seems the primary concern is ref(l)ectivity of the ice and I can’t believe that light knows the difference between old ice and new ice or between thick ice and thin ice.” “””
Well that could be a risky wager.
The Infra-Red Handbook, has graphs of snow reflectance versus wavelength for various times after first fall; and it is pretty illuminating.
In the near IR from 1.0-2.5 microns, snow reflectandce changes quite rapidly with time. At 1.1 microns where snow reflectance is a maximum, 14 hour old snow has a reflectance of 90%. That drops to 65% after 44 hours, and to 45% after 70 hours.
At 1.3 microns, another local maximum, those numbers are 55%, 40% and 20%.
Even more dramatic at 1.8 microns, giving 20, 15, and 3% respectively.
That is with source and detector each 5 deg off zenith angle (specular reflection), for source and detector at 0deg and 30 deg (diffuse reflection), over that whole o.7 to 2.5 micorn range, fresh snow exhibits typically double the reflectance of 2 day old snow.
The snow density in that time went from 0.137 to 0.216.
Beyond 1.5 microns in the near IR, even fresh snow, never gets above 20% reflectance, and after a couple of days it is well under 5%.
Ice specially on a small scale, and maybe wet, behaves like a refractive solid, and most of the incident radiation is refracted into the solid, and at long wavelenghts absorbed by the high absorption coefficient in the LWIR.
So I’m not impressed by polar ice contributions to earth albedo. The reflectance isn’t high, and the irradiance isn’t either.
After taking up the actual measurements of sea ice area and plotting them out, I’m not particulary surprised to see an entirely different story than the ‘infilled hole’ extent.
Disparity exists between the two data sets.
The hole in the satellite coverage has been the playground of imaginations running wild.
Clearly, the Arctic experienced an extended melt season, it wasn’t anything near what it was puffed up to be.
Steve W. (14:00:24) :
By the way, something has happened to Arctic ROOS. http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
They are still showing 3/30.
They had problems with their satellite about a year ago since then they’ve been the odd-man out among the data sets, maybe having more problems?
George E. Smith (16:12:39) :
So I’m not impressed by polar ice contributions to earth albedo. The reflectance isn’t high, and the irradiance isn’t either.
You might be more impressed when you realize the albedo doesn’t just apply to the infrared. And that after “thin ice’ melts in the summer, we are dealing with open ocean.
http://nsidc.org/seaice/processes/albedo.html
Sea ice has a much higher albedo compared to other earth surfaces, such as the surrounding ocean. A typical ocean albedo is approximately 0.06, while bare sea ice varies from approximately 0.5 to 0.7. This means that the ocean reflects only 6 percent of the incoming solar radiation and absorbs the rest, while sea ice reflects 50 to 70 percent of the incoming energy. The sea ice absorbs less solar energy and keeps the surface cooler.
As they suggest:
You understand the concept of low albedo intuitively when you avoid walking barefoot on blacktop on a hot summer day. Blacktop has a much lower albedo than concrete because the black surface absorbs more energy and reflects very little energy.
In any event, the changing climate has no need to impress anybody.
“…Ice extent was above normal in the Bering Sea and Baltic Sea, but remained below normal over much of the Atlantic sector of the Arctic…”
And this has always been one of the problems – those that gather, process and chart the data get to say what “normal” is.
The chart in fig 2 shows a “normal” for years 1979-2000, and they show traces for only a couple of years outside that range. The trace for 1999, is naturally, within the normal range.
At the end of 2010, will they re-chart to include the latest years? Will they really want to be forced to re-define “normal” as a lower value?
As it is now, they can point to each year after 2000 and call it as below normal. If the “normal” lowers, they’ll lose that edge – the ice will, for a couple of years, fall in the “normal” range. No alarm there, right?
@ur momisugly terry46 (06:00:16) :
“From what all the global warming crowd was telling us I thought all the ice was supposed to be gone by now. If it is so warm why has the ice grown?”
No Terry, you’re wrong. What the global warming crowd was telling us was that all the ice at the summer minimum might be gone by 2050 at the earliest, possibly well after 2100 (as per IPCC predictions).
What you are looking at now is the winter maximum in 2010.
In short:
1. Summer is not the same thing as winter.
2. A minimum is not the same thing as a maximum.
3. 2010 is not the same thing as 2050.
John Egan (06:46:57) :
Eye of the Gyre
As I posted at Climate Progress – the Beaufort Gyre is back….
…..In addition, NSIDC says that the new ice is “thin” –
Yet this map from Canadian Climate shows that first year ice in the Western Arctic is thick.
http://ice-glaces.ec.gc.ca/prods/WIS56SD/20100329180000_WIS56SD_0004895913.gif
REPLY:
I noticed on the chart are a lot of numbers without labels. can you tell me what the labels are? Location, Feet or Meters or CM of Ice???
Thanks, Great information by the way. Post it to American thinker and elsewhere
http://www.americanthinker.com/2010/04/was_the_arctic_ice_cap_adjuste.html
Larus (04:16:05),
Since ice cover is increasing compared with recent years, what’s your fallback position?
click
Alexander Feht (10:36:44) :
“…. don’t understand the rather rude and unthoughtful attitude toward Mr. Pawełczyk by the moderators…”
REPLY:
Anthony was the one who answered the question. His temper is rather short right now because he is having to deal with a Global Warming Stalker.
Given the bad economy and politicians determined to ram economy crippling regulations and taxes down our collective throats, many of us are short tempered these days, especially those who have spent years trying to shove information into closed minds.
I have noticed as Cap and Trade type law becomes more likely to become and after the Health Care bill was passed despite the majority of Americans being opposed to it, tempers around here are much shorter. Yes I know many are not US citizens but if Obama gives the UN sovereignty of the USA it affects everyone. He already is doing so:
at the G20 summit last year in April Obama agreed to sign off on International control over our US financial institutions to the Financial Stability Board. They want control over every detail, not surprisingly right down to setting pay and compensation levels. http://www.investorsinsight.com/blogs/forecasts_trends/archive/2009/04/28/the-end-of-america-s-financial-independence.aspx
@Smokey
I will be prepared to reconsider my position on the decrease of Arctic ice coverage as soon as the trend reverses itself. So far we are seeing a very clear downward trend over decades of observation.
The loss of Arctic ice coverage is characterised by a statistically significant long-term trend that involves a good deal of short-term variation.
In other words, new record years have followed one another relentlessly every few years. In between the record years people like you occupy themselves with trumpeting the trend’s supposed reversal.
BTW, it’s exactly the same story with global temperatures.
Europe’s ice measurement satellite Cryosat-2 – now launched.
http://news.bbc.co.uk/1/hi/sci/tech/8606303.stm
arctic-roos.org has updated its ice extent graph to April 6th. It seems to show only very slight loss of extent since March 31st. It looks significantly less than the loss shown on the NSIDC graph. Has any one else noticed that?
Gail Combs (05:09:29) :
REPLY:
Anthony was the one who answered the question. His temper is rather short right now because he is having to deal with a Global Warming Stalker.
(…)
Wow, that sounds unfortunate.
Running through the sub-thread, I found the reply in Przemysław Pawełczyk (01:00:12) to be in the classic “short but polite” format, I didn’t think about it when I first read it. Someone is complaining about work that wasn’t Mr. Watts, and this was summarily pointed out. Same format used in Przemysław Pawełczyk (01:13:06) when it was decided to be “irked” by the previous reply.
But then came that beautiful declaration in Alexander Feht (10:36:44) :
Heh. The vet we’ve used for over a decade now has a long Polish last name, his main staff have worked closely with him for many years, and when asked they can provide a few “close enough” vocalizations. Take that as you will.
Hate to spoil the party but should we really get excited about a one month blip when there are 30 years of decline in end of season ice extent to compare that with? In fact there are Norwegian observational records that suggest declines going back to the 1960’s.
Anu (14:44:55) :
Well, that was nice – the early Spring ice almost reached the recent “average” extent line. Brings back memories.
Now, off to the Summer melt:
http://nsidc.org/images/arcticseaicenews/20091005_Figure3.png
Will it be right around the longterm melting trendline ?
http://nsidc.org/images/arcticseaicenews/20091005_Figure2.png
Somewhere between 2007 and 2009 ?
Or is the Death Spiral speeding up the trendline, with another plunge even worse than 2007 in store ? Hard to say – the ice is thinner than this time 2007, the ocean slightly warmer, the global temperature slightly warmer, the sun (with sunspots picking up) slightly brighter – given the right winds and cloudless days, these underlying trends could combine for a massive ice loss.
But it might not be till 2013, or 2015. You can’t rush the slow train wreck of climate change.
————
REPLY: Actually, I’m still marveling at the sudden train wreck of what used to be called the “scientific consensus” for climate change!
Lots of “mights”…by 2015, we might all be dead of a mutant, recombined influenza virus or bioweapon released by a rogue state.
There is no climate emergency, just natural processes at work. If you are going to be glued to your Windows 98 tower until 2015, waiting for the Arctic to become permanently ice-free, I feel sorry for you.
Why is the current year ice extant compared to the average from 1979 to 2000 instead of the average from 1979 to 2009? There is such a small data set it seems wrong to cut 1/3 in any analysis. Is there no estimate of arctic sea ice over a longer period? I read a book about the rescue of the “Orca” a Whaling ship trapped in arctic ice back in 1897. The implication is that there was a detailed (but flawed) understanding of sea ice patterns more than 100 years ago.
Thanks – Craig
George E. Smith (16:12:39) :
“”” jorgekafkazar (14:39:52) : [You omitted my reply to Norm, George. Why not just quote Norm directly?]
Norm Milliard (07:58:32) : “In terms of global warming, it seems the primary concern is ref(l)ectivity of the ice and I can’t believe that light knows the difference between old ice and new ice or between thick ice and thin ice.”
“Well that could be a risky wager. [Norm didn’t propose a wager, merely disbelief–jk.] The Infra-Red Handbook, has graphs of snow reflectance versus wavelength for various times after first fall; and it is pretty illuminating.”–George
George, the comment was about ice, not snow. Ice has different properties.
“That is with source and detector each 5 deg off zenith angle (specular reflection), for source and detector at 0deg and 30 deg (diffuse reflection), over that whole o.7 to 2.5 micorn range, fresh snow exhibits typically double the reflectance of 2 day old snow.” –George
Probably so, but if you’d read my comment, which you evidently didn’t, zenith angle is more important than ice or water surface condition at the poles. Zero to thirty degrees zenith angle doesn’t occur at the poles.
“Ice specially on a small scale, and maybe wet, behaves like a refractive solid, and most of the incident radiation is refracted into the solid, and at long wavelenghts absorbed by the high absorption coefficient in the LWIR.”
True, but, again, less so at polar zenith angles. Norm and Smokey were wrong and so are you, though you got it a lot closer than Norm did.
Alexander Feht (10:36:44) : “…Those who call Mr. Pawełczyk “Mr. Unpronounceable” should think again. His name is very pronounceable and simple to those who know the rules of the Polish language…”
…and who can utter consonants that require pointing your tongue at your uvula.
@ur momisugly There is no climate emergency, just natural processes at work.
Why should that be a question of either-or? In a way, there is nothing “unnatural” about the effects of human-generated greenhouse gases or their related feedback processes. We are simply prodding climate to go a certain way, and it obliges in its lumbering way – there is nothing supernatural about it. And (naturally) the long-term effect of that is likely to be a dire climate emergency.
Larus (14:07:58):
“We are simply prodding climate to go a certain way, and it obliges in its lumbering way – there is nothing supernatural about it. And (naturally) the long-term effect of that is likely to be a dire climate emergency.”
How frightening! A ‘dire climate emergency.’
Where’s your evidence?
Smokey, there’s a ton of evidence of all sorts, and you know it. But I’m genuinely intrigued by your refusal to be frightened. Do you refuse to be afraid because you actually reject the evidence, or is there a different reason? (like, you just don’t care, or are the kind of person who fears nothing?) I’d really like to know.
We’re aware that there’s been a 30-year downtrend. Prior to that there was — from what we can gather from pre-satellite information — a 30-year uptrend. Etc. This fits in with the (roughly) 60-year cycle of the Pacific Decadal Oscillation. Here’s a link to prof. Akasofu’s paper (a long but neat PDF) on the matter, “Two Natural Components of Recent Climate Change,” here:
http://people.iarc.uaf.edu/~sakasofu/little_ice_age.php
Except for the past seven years. Or maybe even since 1995. The long-term uptrend started over 150 years ago.
Smokey has indefatigably & repeatedly expounded the climate-contrarian position on this site, as have others. Check the archives. (But brew up a gallon of coffee first.)
“”” Anu (19:11:35) :
George E. Smith (16:12:39) :
So I’m not impressed by polar ice contributions to earth albedo. The reflectance isn’t high, and the irradiance isn’t either.
You might be more impressed when you realize the albedo doesn’t just apply to the infrared. “””
Well I’m not aware that I ever said that albedo only applies to the Infra-red; and certainly not in regard to that long wave IR that comprises the roughly 288 K thermal radiation from earth.
In fact albedo applies ONLY to solar spectrum reflectance. If we aren’t talking about surface reflections of “sunlight”; meaning surface of land sea and air (clouds) it isn’t albedo; it’s simply reflectance. Any reflection of atmospheric LWIR off the ground or oceans (or ice) is not a contribution to albedo. Albedo represents the fraction of the incident TSI radiation, that is reflected back into space without contributing any energy to this planet.