What Is Normal Arctic Ice Extent?

Blatant lies:
http://www.guardian.co.uk/environment/2009/apr/28/climate-change-poles
“In the past four years, air temperatures have increased, sea ice has declined sharply, surface waters in the Arctic ocean have warmed and permafrost is in some areas rapidly thawing.”
Note the use of alarmist language “sharply” and “rapidly”

Also,
I wonder if Dr. Meier would comment on why these side by side graphs are using different comparison years… 2007 in Arctic vs. 2008 in Antarctic?
http://nsidc.org/data/seaice_index/daily.html

“nearly large enough to place California inside”
YIKES !!!
Ring the alrm bells !!!!
Has any one told Mr Waxman that CA was moved North and then apparently melted ? Or did it evaporate ? I always have trouble keeping those two in order.

Why would you accept just 15% coverage as full coverage. Maybe 85% sea ice would classify as coverage; but 15% ice coverage is open water to me.
George

It seems weird that given those factors it’s still below the average.
Do you mean “it seems weird that it hasn’t immediately rebounded to above normal conditions in just 1 year“?
Sounds a little weird, actually, when you put it in this context.
Mark

Following years will have to take into account the area covered with ice over Canada..:)

Off topic but I just saw on Fox news where Antarctic ice is starting to break up and they don’t know why it’s happening but for sure of course it’s due to the warming.I didn’t think Antarctic mattered any mores???

I’m sure the choice of 1979 to some recent year as the span to average for comparison is based mostly on the fact that we don’t have any satellite-based coverage or extent measurements from any earlier than 1979. But what is the basis for assuming that this particular 20+ year period is long enough to cover all of the natural variation in the ice pack?
Isn’t it possible that recent low excursions are simply part of the natural variation and not an issue at all?
If we don’t know if the reference period is “normal”, it isn’t particularly honest to call excursions from it “abnormal” after all.

That is peculiar that the NANSEN mean is higher than the NSIDC mean.
Makes no sense.
It’s good to have Dr. Meier accessible and so responsive.
Perhaps he stops in here on occasion.
So I have a few questions for him.
1) Why couldn’t, and hasn’t, the NSIDC adapted it’s mean from their current 1979-2000 mean to a 1979-2007 mean?
2) Will the Dr. acknowledge that in doing so would reduce the NSIDC mean?
3) With 30 years of record why are none of the most recent 9 years included in computing the mean?
4) Wouldn’t removing any 9 year period from calculating the mean make that mean a poor representation and basis for comparison?

Adolfo,
Good questions. In winter the Arctic is dark; covered with clouds, and the ice is fractured and interspersed with open water. Visible wavelength photography is out of the question, so satellites use microwave data and organisations like NSIDC calculate the extent (area of the sea with greater than 15% ice concentration.)

O/T, but couldn’t resist this from my RSS feed:
http://briefingroom.typepad.com/the_briefing_room/2009/04/bill-mckibben-pulls-out-of-global-warming-tv-debate.html

In addition to the cracks in the antarctic ice, there are now cracks in the Australia governments stand on climate change.
http://www.theaustralian.news.com.au/story/0,25197,25406747-11949,00.html

” But something odd happened with the NANSEN data on December 13, 2008 ”
Does anyone know the whereabouts of James Hansen on the date in question? 😉 jk

Looking at the Sea ice graphs that Anthony kindly displays on the RHS of his webpage can anyone provide a reason behind the persistent annual small “blip” in June? This appears to suggest a small regular annual increase at a time when ice is melting fastest. Quite strange.

Another thing that seems odd… CT has the SH Sea Ice Area at 1,227,000 sq. km. ABOVE the 1979-2000 mean, while NSIDC has the SH Sea Ice EXTENT just barely meeting the 1979-2000 average. Now I know that area and extent are different but isn’t that a pretty big difference?
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.south.jpg
http://nsidc.org/data/seaice_index/daily.html
On the Arctic Roos, I know it’s the Arctic and not the Antarctic… however even though the area and extent ARE very different numbers, they are still each about the same distance from the mean…
http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
Mike

From a statistical standpoint, I don’t see a real problem with -2000 instead of -2007. The data in that region is fairly consistent with little variation. Since the point of contention is the recent history (the last decade), it’s nice to have a control signal outside the area in question.
In addition, if you move the end points for the 79-00 readings, the average stays fairly consistent (and flat). ‘choosing’ end points close to the 2007 minimum (or even specifically choosing a certain point) can distort the results drastically. Whenever a signal is comparing specific results to itself, you have to be very skeptical of the results and examine the comparison very carefully.
I’ve seen quite a few graphs of this ice coverage data [media bias supporting the ‘polar bears are dying’ standpoint] which don’t go much beyond 2007 – even though we have quite up-to-date daily data – disingenuous to say the least.
It’s pitiful that whenever the facts don’t fit the premise they are summarily dismissed (as the antarctic data has) on a whim. It wouldn’t surprise me to see that the sea ice coverage doesn’t matter; it’s now the volume that’s monumentally important (data which can be distorted or massaged and thrown out with a “don’t bother with the boring details, you wouldn’t understand it: our top scientists have assured us we are all going to die”)

Heat or no heat the maximum winter ice extent has no real significance in my opinion as the arctic is constrained by landmass. An increase in the ice extent/area as opposed to the last few years at maximum melt in mid september is what we want to see. In view of the reported increase in ice thickness and changed weather/circulation patterns in the arctic as opposed to the 2007 season this looks increasingly likely in my view.
Saying that ( fingers crossed ) we dont want to see too much of a dip in temperatures in the coming years – not good for nature in general and certainly not for us human saps. The alarmists are not worth dying for just to make a point – not that we have any control over anything anyhow.

Moving the goalposts. That’s what the media does and their information is provided by, or filtered through various so-called science organizations.
This past year we’ve been hearing about how Arctic ice is on a steady decline which will inevitably lead to an ice-free summer in the very near future. In fact, the decline in relation to recent years ended in 2007. It has been coming back rapidly this past winter and spring. So what does the media do now?
They either continue to report on the 2007 ice year, or, if they have been told by a flood of e-mails pointing to the current data which has the ice on this date above the previsous high for this date back to 2003, the previous highest in this time frame. (In fact, yesterday, Apr 28th, the extent of Arctic ice as reported by JAXA was 245,000 km² above 2003 and getting very close to the 1979-2000 mean).
So does the AGW crowd concede? You’ve got to be kidding! They simply move the goalposts. Now they say that it is the ice volume that counts and most of the present ice is 1-year ice and the Polar ice sheet is much thinner than normal. Thus the ice volume is a lot lower.
But now we have the real measurements obtained this month by the Alfred Wegener Institute for Polar and Marine Research (featured in an article on WUWT a day or two ago) that measured the ice thickness with a sophisticated electromagnetic sensing device attached to a revamped C54 (DC3) and towed about 20m above the ice. Their route crossed the Pole and they ran several legs in various directions from the Pole. (I know, all of the routes ran southward, but at different longitudes). What did they find?
The first reports said that the ice thickness at the North Pole was about twice the amount they expected to find. Since the volume varies as the cube of the thickness, what do the AGWers do now. They’ve already backed the goalposts up to the grandstands.
The answer is bait and switch. They’ll probably shift their reportage to the Catlin expedition. This is a highly publicized trek by 3 grossly unprepared publicity seekers whose equipment failed early-on and any data they may have collected will be of little, if any scientific value. Nevertheless, they will be lionized by the media, especially the BBC a co-sponsor, for their daring and acumen as they dutifully report in regard to the ice situation that “It’s worse than we thought”.
As a matter of fact, if the AGW community had an emblem, their motto would be “It’s worse than we thought”.
Reply: Small point of correction. If you vary only one axis of a solid, ie the thickness and not the width or length, (just z, not x or y) the volume change would be directly proportional or simply double, not proportional to the cube of the variance. ~ charles the moderator.

OceanTwo (16:57:38) said “From a statistical standpoint, I don’t see a real problem with -2000 instead of -2007.”
Although this argument may be correct and there may not be a “real problem”, the more words required to explain the data the more the data should be questioned.

Hey Anthony,
I know this is completely off topic but I had a discussion a while ago with a guy called Foinavon (I think) about climate’s sensitivity to CO2. I think it was to do with Hansen having nailed the sensitivity/gain, g, to 3.
One of the papers I referenced was by John Christy and was, at the time, not published, hence Foinavon was not interested. Apparently this has now been published and is available to view at http://www.nsstc.uah.edu/atmos/christy_pubs.html.
It seems quite interesting as it purports to show that CO2’s forcing has no feedback. I.e. a doubling of CO2 leads to at most 1 degree C rise in temperature or that if there is a positive feedback mechanism it must be balanced currently by an existing negative feedback. The negative feedback cannot be due to aerosols, as the IPCC claims, because of Chylek(2007)
These results puts CO2’s forcing well below all existing models and well below any disaster scenario.
Cheers
Steve

Notice that if you look at the values of the averages for now, they both are 14 million square kilometers. But the current values are quite different. If one value is presently larger, the average should also be larger unless what they’re measuring happens to be currently affected by the differences.

Re the rapidity of ice melt. First, at this time of year, the ice melts from below.
The rate of melt depends on two major components. The temperature of the water and the speed of the ocean current across the base of the ice.
For the most part, the temperature itself is related to the rate of flow of the ocean beneath the ice which determines the advection of warmer waters either horizonatlly or is some cases vertically especially near the boundary layer. When the ocean current is high the melt rate increases, when the current subsides to near calm, the water adjacent to the base of the ice quickly comes to equibrium with the ice and melting proceeds very slowly. If the current increases, the surface layer of near freezing temperatures is mixed both horizontally and vertically and the rate of ice melt increases.
It’s all about the conditions of the ocean near and in contact with the ice.
As for the presence and extent of open water, there is nothing new about that. Open water near the Pole, even right at the Pole has been observed frequently in the past. Submarines have surfaced on many occasions at the Pole going back to the first such incidence back in 1958 with the first atomic submarine, the Nautilus. Wide leads and polynyas have been observed frequently near the North Pole even in the Winter.
Most importantly, historic records of undersea as well as surface vessels show that there is nothing unusual about the character of Arctic ice conditions for more than half a century.

Here’s an item from today’s “best of the web today” by the Wall Street Journal’s Jim Taranto:
<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>
Global Warming on the Rocks
Al Gore said Tuesday the world must act quickly to slow the melting of the world’s polar ice packs and glaciers before it reaches a critical rate for global warming.
But it turns out the world acted very quickly indeed, as Germany’s Radio Bremen reports (translation here):
The research aircraft “Polar 5” today concluded its Arctic expedition in Canada. During the flight, researchers measured the current ice thickness at the North Pole and in areas that have never before been surveyed. The result: The sea-ice in the surveyed areas is apparently thicker than scientists had suspected.
Normally, newly formed ice measures some two meters in thickness after two years. “Here, we measured ice thickness up to four meters,” said a spokesperson for Bremerhaven’s Alfred Wegener Institute for Polar and Marine Research.
Is it possible that global warming is neither a catastrophe waiting to happen nor a fraud but merely the result of confusion induced by the metric system?
Question– did they mean the “feet” thickness instead of “meters”? Looks like it’s getting thicker, anyhow.
Pag

I think they continue to use the 1979 to 2000 average because that period was chosen the last time they went through all the data thoroughly and checked each day.
In addition, there is some stability overall in this time period, some ups, some downs but reasonably close to an average. Starting in 2000, the extent started to go down and since they wanted to measure a decline due to global warming, they stayed with this average period.
The final, perhaps unfair, potential explanation is they don’t have enough time to thoroughly go through every day again and verify the data and they don’t have time to extend the data back to 1972 which is when the actual satellite data begins. Yes, I am not a fan.
Fortunately, it can be done.
So here is today’s Northern Hemisphere Sea Ice Extent versus the average from 1972 to 2009.
April 28th, 2009 – day 188 (due to the leap years) – is the 12th lowest sea ice extent (out of the 26 years).
It is 438,000 km^2 below the average for this date (but rapidly gaining).
http://img411.imageshack.us/img411/5084/april28sei.png
Here is what the complete daily series since 1972 looks like.
http://img411.imageshack.us/img411/4302/nhdailysei.png

George E. Smith (14:19:31) :
Why would you accept just 15% coverage as full coverage. Maybe 85% sea ice would classify as coverage; but 15% ice coverage is open water to me.
George

George, I have often wondered the same thing, but then it dawned on me, if they use 15% now, they can adjust that to 25% later and paint a worse picture, then 35%, 45%, 50%, … ratchet it up as they need to in order to keep the hysteria flowing, move them thar goal posts again. In 10-15 year time, they will be able to say that sea ice extent has disappeared completely, as they will then be using 125% coverage as a meter.

Why don´t you send some of those Global Warmers/Changers to preach and reeducate Al-Qaida people. Their persuasive and pervasive speech will make change their minds or convince them it is useless to make any harm to America after they realize than their wildest terrorist goals have been already achieved and surpassed by them.

Report from the Arctic Council,
“I am deeply grateful to Nobel Peace Prize Laureate Al Gore for reporting to the Arctic Council today from yesterday’s conference on melting ice. His intervention and the presentations by leading scientists yesterday confirm that the ice is melting even faster than previously imagined, both in the Arctic and in other regions of the world. This makes it all the more urgent that we address the issue of climate change, and we will convey our sense of urgency to the UN Climate Change Conference in Copenhagen in December 2009,” said Mr Støre.”
Nice to see that they listen to a former politician with vested AGW interests rather than the scientific results. I think that Copenhagen 2009 will be a lovefest of AGW alarm – get committments and grants before the big freeze sets in.

Any one want to Bet that the 2009 line never passes the average line?
I bet it will do the magical drop like it did 12/11/2008?

Um…y’all are missing the basic point. Someone needs to print-out a nice poster-size plot of the global ice exceeding the average for the last 30 years…I don’t care whose average (mean) you use…and ship a copy to the EPA, Al Gore and the IPCC and say: “..’splain this …how can the climate be warming if the ice keeps growing?”

Bill Illis (19:00:43) :
great data sets, thanks, Bill, for all that diligent work!

NANSEN’s Dr. Meier says, “The important thing to remember is that there is a good consistent record from the passive microwave data as long as you consistently use the same algorithm and the same processing.”
This responce doesn’t really address Mr Goddard’s central point.
If both organisations have been consistent they may well have different averages from different algorithms ( I will never hear that word in the same way again – Yuk!) but the NANSEN current figure should still be closer to their average than NSIDC is to theirs.
Or am I missing something?

Bill, at a time of computers and significant data searching capabilities including good old summer students grind, chosing the 1979-2000 average is simply an undefendable position for a serious scientific department, especially when on other datasets, they are willing to use the climatology widely accepted arbitrary 30 y average. The fact that they do it on this particular dataset and it suits their well publicized bias – Mark Serreze at least is unapologetic about it- is even more unacceptable. If you could do it, they could and should. Period.

Using the 1979 to 2000 period doesn’t make much of a difference – its just an average to compare against.
Is a 30 year period better? I would think that would only be true if it encompassed whatever the period is that encompasses a full cycle of arctic ice variability. Since we don’t know what that period is, 1979 to 2000, arbitrary as is clearly is, is as good any other.
For all we actually know, the cycle could be 40 years, or 20, or 60. My guess would be 60, based on the PDO. But that’s still a guess and irrelevant since we don’t have 60 years of data.

Yes, as Dr. Meier points out, it is poor science to “mix and match products” in making a graph. However, it is good science to check a variety of sources and approaches to see if your trend is robust over a number of analyses.

Paul (14:16:49) : Just out of curiosity, why doesn’t NSIDC use the 1979-2007 average?
An international agreement has most countries reporting “normals” or averages using 30 years of data with the final year ending in “0”, such as 1990, 2000, 2010.

Before someone says that I’m rejecting correlation graphs, I must say that correlation graphs are useful instruments for identifying and interpreting variables because graphs are visual representations of real data. Unfortunately, if the databases or the algorithms have been flawed, the correlation graphs will be flawed also. The latter has been demonstrated many times here, in WUWT.

Has anyone ever wondered about the choice of years for averages or normals of climatic variables? In case you have but haven’t found the answer, here is one:
“Climatologists define a climatic normal as the arithmetic average of a climate element such as temperature over a prescribed 30-year interval. The 30 year interval was selected by international agreement, based on the recommendations of the International Meteorological Conference in Warsaw in 1933. The 30 year interval is sufficiently long to filter out many of the short-term interannual fluctuations and anomalies, but sufficiently short so as to be used to reflect longer term climatic trends. Currently, the 30-year interval for calculating normals extends from 1971 to 2000.”
http://www.aos.wisc.edu/~sco/normals.html
Also, here: http://ams.confex.com/ams/pdfpapers/26747.pdf

If you go north of the Arctic Circle during the NH winter there is very little sunlight and for much of it none. So whether or not the Sun is in a “lull” would seem to make no difference. This lack of sunlight within the Arctic extends back in time for each and every year – so the average is not going to be directly effected. The Arctic basin is like a gigantic toilet bowl with rotation, tides, currents, and wind. When these things combine in certain ways the flush is on and the ice clears out and melts at lower latitudes. When rotation, tides and so on do not effectively clear the ice out, it stays and thickens and grows older. Just because Gore and Waxman and others think the ice melts/evaporates and exposes the tundra doesn’t mean we skeptics should.
An average is easily skewed by a few extreme values. Example, the average wealth of folks in King County, Washington State – Bill Gates and other Microsoft billionaires live there. Most folks are well below the average and have no hope of getting close. That’s why some things are better compared to a mode or a median. If you like playing with numbers look at each of the years of ice extent and see if some were not quite large. That would explain why the current year is still below average.

[snip, while there are few limits on what you can say about Hansen, please be more respectful of Dr. Meier who contributes his time to posting here]. ~ charles the moderator

Sorry Charles the moderator but you should have just snipped out the Mx#!?r part and not the whole post. These Hansen/Gore alarmists are scaring people to gain power. Consider editing my post removing my mention of the nice guy Mx#!?r. It’s obvious with this Ice Extent manipulation that these groups are working the answer backwards to a conclusion that fits the story that CO2 the problem.
Reply: I considered that, but it would have required an editorial rewriting of your post to make sense and that is not really an option. ~ charles the moderator.