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.
“”” 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.”
Some weathered ice does show a reduction in albedo, but it’s not directly related to age. Zenith angle is more important than ice or water surface condition. “””
“”” jorgekafkazar (11:25:56) :
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. “””
“”” Zenith angle is more important than ice or water surface condition. “””
“”” Zero to thirty degrees zenith angle doesn’t occur at the poles. “””
Well it seems I didn’t explain myself very well.
I was citing snow reflectance data from the Infra-red handbook. The first numbers I cited, were for specular reflectance off the surface, so the illumination and detection were optically disposed according to the normal laws of reflection, so only reflected light with the same magnitude angle off the (surface) zenith was measured. In the second set of numbers the illumination was at zero (surface) zenith angle, but the detected reflected light was at 30 deg (surface) zenith angle, so could only be scattered light; not specular reflectance.
So I used the term “zenith angle” rather than the more scientifically accurate “angle of incidence measured from the normal to the surface”.
Excuse me for choosing brevity over pedantry.
The reason that fresh snow turns into old snow in a few hours with lower reflectance, is that the “snow” turns into “ice”.
Single hexagonal “ice” crystals that make up “snow” melt and refreeze as a much more amorphous mass, that behaves on a macro scale, more like an optical surface, rather than a nano-particle with a size not too differnt from the wavelength of the light.
So to get back to your “zenith angle”, I concur, that when the surface consists of optically flat ice that is perpendicular to the earth’s radius, then at the pole you would not get zenith angles in the zero to 30 deg range.
But if that surface should buckle from stress, and form piled up ice masses that might have any possible surface orientation, from zero to 90 degrees relative to the mean earth surface; then regardless (or irregardless) of the sun’s altitude angle above the horizon, sunlight could impinge on arctic sea ice at any possible incidence angle from zero to 90 degrees.
And I WAS responding to Norm directly; and included YOUR shingle, ONLY to show exactly where it was that I found NORM’S statement. Since I was reading the thread from the bottom up; since the responding window is at the bottom, I naturally came upon your cut and paste before Norm’s original statement.
And finally: “”” “Well that could be a risky wager. [Norm didn’t propose a wager, merely disbelief–jk.] “””
For the following words:- ““Well that could be a risky wager.”” please substitute these:- “”Well that could be a difficult position to defend.””
Please forgive me for using figures of speech and thereby impugning Norm’s respectability; by suggesting he might be a gambling wastrel.”
“”” 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. “””
Is it permissable for one to read that statement of yours, as implying that Norm’s position ‘might be a difficult one to defend’ ?
Larus (22:54:49) :
It’s not that I would refuse to be afraid, if there was solid, empirical evidence showing that the climate was acting abnormally. But there isn’t, and it isn’t.
Simply saying that “there’s a ton of evidence of all sorts” doesn’t make it so.
True, there are a ton of opinions out there, and there are computer climate models, and there are carefully selected tree rings, and there are retreating [and advancing] glaciers, and there are predictions that the oceans will become acid, and that the polar ice caps will melt, and claims that the sea level is rising abnormally fast, and that hurricanes will increase in intensity, and that CO2 is bleaching the corals, and so on.
All of those claims and more have been deconstructed, most of them right here on WUWT.
If you look at the situation through the eyes of a scientific skeptic, the first thing you will ask yourself is this: Is the climate outside of its long term parameters? That is the null hypothesis which must be disproved, rejected or nullified.
In other words, is there anything that can be verified with empirical [real world] evidence, based on raw data and methodologies made available to skeptics, that shows the climate is acting abnormally? Or, are the current climate fluctuations within normal historical parameters?
At first glance it might appear that each new piece of “evidence” proves AGW. But upon closer scrutiny, all the claims fall apart. Every one of them. The climate is well within its normal long term parameters. The MWP was warmer than today. The LIA was colder than today. CO2 has been many times higher in the past without triggering a catastrophe, and so on.
If the public panics at every report of a receding glacier, or discovery of a three-headed frog, or birds flying into cliffs, then it’s easy to convince worried people to open their wallets. And that’s what this scare is all about. $Billions every year, and the prospect of $Trillions, is a big incentive to sound the alarm.
I get scared about real problems, like an asteroid that will sooner or later impact the Earth: click
We’re overdue, but the funds for preparing against that emergency, like the funds drained from other areas of science, have been sucked up by the global warming scare. If an asteroid like this hits [and this was a fairly small one], it will be too late for pointing fingers.
jorgekafkazar,
You were right about the ice melt, and I was wrong. I was assuming Norm meant the annual summer/winter change in the 15% ice cover. That’s what I get for assuming. Thanks for pointing it out.
In some haste – you don’t have to look for “whole of climate” things for evidence. IMHO you need to look for the things that have the potential to distinguish between natural and AGW.
CO2 traps one wavelength – does this particular wavelength show a decline in the outgoing radiation? Roy Spencer recently reported as saying No.
IPCC says warming originates in tropical troposphere (AR4 fir 9.1(c),(f)), do satellites show it happening? No, the surface has warmed more.
Until those two problems are overcome, AGW is refuted by the evidence.
Smokey, thanks for replying.
Mike Jonas (18:29:33) :
CO2 traps one wavelength – does this particular wavelength show a decline in the outgoing radiation? Roy Spencer recently reported as saying No.
Well Spencer’s wrong, see for example:
http://www.nature.com/nature/journal/v410/n6826/abs/410355a0.html
http://www.eumetsat.int/Home/Main/Publications/Conference_and_Workshop_Proceedings/groups/cps/documents/document/pdf_conf_p50_s9_01_harries_v.pdf
Phil – the body of the paper does not appear to support the abstract, and hence also does not support the associated article, at least wrt CO2 (the paper seems to concentrate mainly on methane). Average CO2 at Mauna Loa in 2006 was 381.84ppm, in 1970 I don’t have the figure but it would probably have been around 325ppm (1980 was 338.69). So, on a logarithmic scale, the increase in CO2 over the 36 years was about 2.8%. The TES and IRIS measurement graphs (black lines) for 1970 and 2006 are virtually identical in the CO2 absorption band. Also, in the CO2 band, IRIS is noticeably further below the model in 1970 than TES was in 2006 – in other words the absorption did not increase as predicted by the model.
Having said all that, I would also have to say that I doubt that any of this is all that reliable, with very small differences being examined between two measurements made in different ways. ie, maybe it hasn’t been possible to properly distinguish trend from noise and measurement variation.
OTOH, I would have thought that over 36 years, if AGW is correct, the trend (we are after all talking about 2.8% or over half of all the industrial-era CO2 increase) should have been simply obvious.
HR (08:56:38) :
“In fact there are Norwegian observational records that suggest declines going back to the 1960’s.”
In fact there are Norwegian observational records suggesting decline going much further back to the 1860’s. See:
http://www.climate4you.com/
(Click on “Sea Ice”, then “Sea Ice in a longer time perspective” and scroll down to the chart labeled “April Ice Extent”.)
This chart shows clearly the long term decline in ice extent since 1864 for 3 Arctic areas; NS – Nordic Seas (Atlantic area), ES – Eastern Seas (Siberian area), and WS – Western Seas (N. Canada & Alaska). From the caption: “Apparently, much of the sea ice reduction in this region occurs in concert with the termination of the Little Ice Age and the following warming during the 20th century.”
Interestingly, most reduction has taken place in the Atlantic area, and also that the reduction was faster during 19th century than during the 20th century, for all areas. Also interesting to note that there is strong covariation among the 3 areas, and that the minimums in the 1920’s, 1930’s and even late 1950’s were not much different from the 1990’s. This chart also places the satellite records from 1979 to 2000 into perspective, showing how the starting point was on the highest peak for the period since 1970.
Scrolling further down to the next graph, there is a chart showing April sea ice exent for the Atlantic sector since 1769. Here we can see that the sea ice extent in 1769 is recorded to be quite similar to that of 1995, and indeed much less than in 1866. Assuming covariation with other Arctic sectors, as shown in first graph, most likely the sea ice extent in 1769 was not much different from that seen in the 1990’s.
All this points to the fact that the sea ice extents in recent decades have not been outside of normal for previous centuries. The negative anomaly in 2007 was due to “weather”, not AGW.
Grumpy Old Man has it right. Across short runs the noise (variability due to randomness) overwhelms the signal (purported trend(s) due to AGW). Sensible conclusions cannot be drawn over a few years of data in such circumstances. Early declarations (by non-scientists) that arctic ice would be lost in a few years post 2007 have not been supported to date. Declarations that arctic ice has ‘recovered’ in the last few years in light of the downward trend line of Average Monthly Arctic Sea Ice Extent are not that meaningful either.
Recent studies suggest that both Greenland glaciers and Antartic ice sheets are being eaten from below by increasingly warm ocean waters. This systemic attack does not bode well for arctic ice in summers to come…