While Joe Romm and Mark Serreze bloviate about the current Arctic sea ice being “lowest in history”, science that doesn’t have an agenda (or paying thinktank) attached says otherwise:
“More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.”
From the Hockey Schtck: Paper: Current Arctic Sea Ice is More Extensive than Most of the past 9000 Years
A peer-reviewed paper published in the Canadian Journal of Earth Sciences finds that Arctic sea ice extent at the end of the 20th century was more extensive than most of the past 9000 years. The paper also finds that Arctic sea ice extent was on a declining trend over the past 9000 years, but recovered beginning sometime over the past 1000 years and has been relatively stable and extensive since.
Although it seems like a day doesn’t go by without an alarmist headline or blog posting obsessing over the daily Arctic sea ice statistics (and never about Antarctic sea ice extent which reached a record high this year), this paleo-climate perspective takes all the wind out of alarmist sails. Satellite assessment of sea ice conditions is only available beginning in 1979 (around the time the global cooling scare ended), with only sparse data available prior to 1979. The alarmists at the NRDC fraudulently claim in a new video that due to “climate destruction,” Arctic sea ice reached the lowest in history in 2010 (actually the low since 1979 was in 2007 and 2010 was the 3rd or 4th lowest depending on the source). Probably wouldn’t bring in many donations if they mentioned the truth: the 21st century has some of the highest annual Arctic sea ice extents over the past 9000 years.
The figure below comes from the paper, but has been modified with the red notations and rotated clockwise. The number of months the sea ice extent is greater than 50% is shown on the y axis. Time is on the x axis starting over 9000 years ago up to the present. Warming periods are shown in gray with the Roman and Medieval warming periods (RWP/MWP) notated, a spike for the Minoan Warming Period about 5000 years ago, and two other older & unnamed warming periods. The last dot on the graph is the end of the 20th century and represents one of the highest annual sea ice extents.
Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the eastern Chukchi Sea Canadian Journal of Earth Sciences, 45: 1377-1397
Authors: J.L. McKay, A. de Vernal, C. Hillaire-Marcel, C. Not, L. Polyak, and D. Darby
Abstract: Cores from site HLY0501-05 on the Alaskan margin in the eastern Chukchi Sea were analyzed for their geochemical (organic carbon, d13Corg, Corg/N, and CaCO3) and palynological (dinocyst, pollen, and spores) content to document oceanographic changes during the Holocene. The chronology of the cores was established from 210Pb dating of near- surface sediments and 14C dating of bivalve shells. The sediments span the last 9000 years, possibly more, but with a gap between the base of the trigger core and top of the piston core. Sedimentation rates are very high (*156 cm/ka), allowing analyses with a decadal to centennial resolution. The data suggest a shift from a dominantly terrigenous to marine input from the early to late Holocene. Dinocyst assemblages are characterized by relatively high concentrations (600–7200 cysts/cm3) and high species diversity, allowing the use of the modern analogue technique for the reconstruction of sea-ice cover, summer temperature, and salinity. Results indicate a decrease in sea-ice cover and a corresponding, albeit much smaller, increase in summer sea-surface temperature over the past 9000 years. Superimposed on these long-term trends are millennial-scale fluctuations characterized by periods of low sea-ice and high sea-surface temperature and salinity that appear quasi-cyclic with a frequency of about one every 2500–3000 years. The results of this study clearly show that sea-ice cover in the western Arctic Ocean has varied throughout the Holocene. More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.
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| Arctic summer sea surface temperatures are also currently lower than much of the past 9000 years |
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So we’re leaving everything as is, do we?
Well, in that case all I can hope is that people see what is happening here. And perhaps they’ll notice a trend and conclude how trustworthy this blog is as a source.
REPLY: Maybe I’ll get lucky and you start citing Joe Romm then. -A
@ur momisugly savethesharks
Correct The paper does not consider Arctic-wide sea ice cover over the Holocene, just a 10% area of it.
You say;
The graph is derived from data taken from the “Alaskan margin in the eastern Chukchi Sea.” The paper is about sea ice cover during the Holocene is assessing an area in the West Arctic ocean that is 10% of the Arctic ocean. The paper also notes that for much of the period, the opposite is occurring in the East arctic.
It’s there in black and white in the paper. I can understand the frustration with blind opposition to what’s clear to see for anyone with a neutral pair of eyes. I’m not fond of the term ‘denialism’, but I am struggling to come up with something else that fits the latter comments in the thread here. ‘Blind rejectionism’?
I have to agree with Günther.
Maybe I’ll get lucky and you start citing Joe Romm then. -A
How nice of you to react. Do you believe the title of your post accurately describes the conclusions of the paper?
REPLY: Actually Gunther (or is it Neven?) I’ve learned that no matter what title I put down, somebody won’t like it. Tough noogies for you then. And no, I’m not interested in a discussion about changing it to something you like. Your points are not significant. The title is derived from the source, argue it there. If they change it, then I’ll be happy to follow.
From the Hockey Schtick: Paper: Current Arctic Sea Ice is More Extensive than Most of the past 9000 Years -A
barry says:
September 23, 2010 at 10:12 pm
The Chukchi Sea, the area considered in the study, is 10% of the Arctic ocean. The top post here refers to the entire Arctic ocean. That is an error of 90%.
Other proxies such as ice cores represent only a few square cm (or inches if you prefer). This gives you an “error” of almost 100%. Why does anyone take them seriously? (/sarc off)
When the Chukchi sea temperatures and ice melt are above normal, the Chukchi sea is a cause celebre for the AGWer – but find an inconvenient proxy result in the Chukchi sea and suddenly its “only 10% of the Arctic”.
This is completely and utterly fictitious. A straw man pulled from the contrary air.
As this has come down to a stand-off between reason and rhetoric, it’s time to move on. Hopefully there will be fewer pins and less dancing in the next thread.
Looks a bit like a hockeystick again: long stick of slow decline followed by a very sharp uptick.
richard telford says:
September 23, 2010 at 9:13 pm (Edit)
Thank you for finding this paper – I hadn’t seen it previously. Dinocysts for sea ice, temperature and salinity are my least favourite proxy. I have published a couple of papers describing some of the statistical problems with them (mainly spatial autocorrelation in the modern training set leading to over optimistic estimates of model performance and encouraging inappropriate model choice), and have shown they have little if any skill, at least for reconstructing salinity, and probably the other variables. Barry Dale at Oslo also has several papers discussing the ecological problems with them.
##########################
Thanks for that. I looked at this paper and asked myself. “if it was a tree ring study from Mann, what issues would I look for”
1. quality of the proxy
2. the temporal resolution
3. the spatial area actually reconstructed.
4. the reconstruction method
5. the length of the training period.
Let’s just say 2,3,5 looked suspect. I couldnt find 4 ( the reference to MAT was vague) and I didnt have time to look at 1.
thanks for the pointers on number one.
I remain singularly unimpressed with reconstructions, both those that show warmer past periods and those that don’t.
Smokey
” No one has falsified the hypothesis that the observed temperatures changes are the result of natural variability.”
that’s because its NOT a properly formulated hypothesis. “natural variability” is NOT a cause. It is the admission that we dont know the cause.
If you double C02, you will see a 3C increase in temperature, IS a hypothesis.
it makes a prediction, it attaches numbers. it tells you what to measure.
your hypothesis does none of these. its unfalsibiable IN PRINCIPLE. that can be fixed, sugesst that you put your hypothesis in a quantified form. otherwise its religion
Günther Kirschbaum says:
September 23, 2010 at 11:04 pm
So we’re leaving everything as is, do we?
To make things easier I have put a red line across the graph and we can compare the past with the present:
https://docs.google.com/fileview?id=0B9p_cojT-pflNmMzMjQzZDYtNWIzNS00ZDViLWI3ZGYtZjI5NTVjMzZlYTdm&hl=en_GB
How much of the last 9000 years proxy curve is above the red line?
i.e. For how much of the last 9000 years has there been less Arctic ice at the Chukchi sea than today?
Is it more than half? (Yes, it is.)
If so, then this could be described as “most” of the last 9000 years.
So yes, lets leave it as it is.
Steven Mosher says:
September 24, 2010 at 1:21 am
Smokey
” No one has falsified the hypothesis that the observed temperatures changes are the result of natural variability.”
that’s because its NOT a properly formulated hypothesis. “natural variability” is NOT a cause. It is the admission that we dont know the cause.
We’ve been through this before. Rejecting “natural variation” because we dont understand all the sources of variation, is “argumentun ad ignorantium” i.e. bad epistemology and logic.
Natural variation is a valid null hypothesis.
( the reference to MAT was vague)
Outside of the palaeo community, MAT is better known as k-nearest neighbours (knn; http://en.wikipedia.org/wiki/K-nearest_neighbor_algorithm ). In principle it is a good method, but is problematic because it generates local solutions. It is a method widely used by the palaeoceanographic community, perhaps because it typically appears to have the best performance statistics, however this is an artefact of the strong spatial autocorrelation in most marine training sets. For training sets with no spatial autocorrelation, MAT performs about as well as most other transfer function methods.
I remain singularly unimpressed with reconstructions, both those that show warmer past periods and those that don’t.
That would be to throw the baby out with the bathwater. Many reconstructions from biological assemblage data are reliable, reconstructing important environmental variables in ecologically sensitive sites. Unfortunately, the techniques are easily used to generate reconstructions that make no ecological sense, especially of spatial autocorrelated environmental fields. Trying to identify which reconstructions are useful and which are not requires further effort, but expect several relevant papers (and a comment on one egregious paper if we ever get hold of the data) in the next year.
Oooooohh! That must have hurt!
Payback is such a female canine.
/dr.bill
@ur momisugly Günther
“More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.”
Does that sound to you like ‘many times’ or even worse: ‘most of the time’, like it says in the blog post title
————————-
It just say that the number of times is unknown. There may be a few times, or many times.
I don’t see anything so surprising about the paper. Eyeballing the second graph, which gives data from approximately 9500 to 1250 years ago, we see the following:
A general decline peaking at about 5000 years ago – representing the remains of the transition from the last glacial maximum to what is known as the Holocene Climate Optimum. Then about a thousand years of strong recovery suggesting colder conditions – certainly in the UK a deterioration in climate is thought to have occurred during the Bronze age – then a decline again through into Roman times – known to have been marked by warmer conditions. The data then stops at 750 AD.
Someone mentioned the previous Interglacial – the Eemian. About 2C warmer than today and sea levels a good 5m higher. Food for thought!
Cheers – John
“Hey George!” If George E. Smith is on this thread, a question on solar reflectivity / absorption at the polar ice cap has come up that I think you can answer in this thread over at my place:
http://chiefio.wordpress.com/2010/09/23/saving-good-ideas/
If you could pop over and clarify, that would be great…
Oh, and on the topic of this article, the world was much warmer not too long ago. The wet savanna like Sahara in that period of time says so. I’d expect there was less ice then too…
http://chiefio.wordpress.com/2010/08/10/cold-dry-sahara-hot-wet-savanna/
Various people in this thread have attempted to interpret what the authors of the paper in question were actually saying (or not saying). Unfortunately, mind reading is just one of the many skill areas in which I am lamentably deficient.
Consequently, I have taken the radical step of contacting the editorial office of the CJES and asking if any of the original authors might care to share their thoughts with us.
It does not matter what the original authors thought. The paper says a number of things, and you can use any angle you want really with regard to the title. I don’t think Gunther’s suggestion is wrong as a title either, but no one has proven that it should be changed “because it is wrong”. Its not, its an interpretation of the study.
Let me put it more simply, if people who did not like the title were respectful, I can think of a few in this discussion….I have no problems with them arguing that the study does not say that. This is a scientific blog, so discussing the issues with the research is not an issue with me, but saying that “something is wrong” and not proving it is not really something I like to hear.
and I must repeat this:
Because Barry just made my weekly email for the funny comment of the week. Hope you were trying to be funny, because otherwise what should I think? lolol
Lets be serious for a minute, that 90% error was actually more scientific than Mann!
barry says:
September 23, 2010 at 10:12 pm
The Chukchi Sea, the area considered in the study, is 10% of the Arctic ocean. The top post here refers to the entire Arctic ocean. That is an error of 90%.
Other proxies such as ice cores represent only a few square cm (or inches if you prefer). This gives you an “error” of almost 100%. Why does anyone take them seriously? (/sarc off)
When the Chukchi sea temperatures and ice melt are above normal, the Chukchi sea is a cause celebre for the AGWer – but find an inconvenient proxy result in the Chukchi sea and suddenly its “only 10% of the Arctic”.
Günther Kirschbaum says:
September 23, 2010 at 11:04 pm
At least on this blog everyone is allowed to express their views, as long as they are polite.
Even when moderators snip, there is a record of the snipping with the reason the comment has been snipped.
Not so at other places.
wial says:
September 23, 2010 at 4:22 pm
I’ve got an even better idea.
Why don’t we discuss this in 30 years, to really give the AGW hypothesis to prove itself?
Once again, I have to ask, what possible difference does it make to the average member of the human race if the Arctic ice cap just goes away?
The paper cited shows there was much lower ice levels in the past and everything seems to have worked out. Polars bears survived. So did those crazy walruses who seem to like to herd up and trample each other.
Just like people. Maybe the walruses were attending a rock concert or soccer game.
http://firegeezer.com/2010/07/25/crowd-panics-stampede-kills-19/
http://www.thefreelibrary.com/120+killed+as+soccer+crowd+panics+in+tear+gas+attack-a074879458
In any event, the grand experiment continues.
China and India, as well as others, will not curtail their production of CO2 to make AGWr’s happy. CO2 will go up, no matter what the US and other western economies do about their emissions.
I personally take exception to this “we” stuff.
First off, the null hypothesis regarding CO2 and the climate, has not been falsified. As this paper demonstrates, along with everything else I have read about the history of climate, natural variability does account for the 20th century warming.
Second, the “we” is all inclusive. I have no control over what China does. I certainly have no control over the climate. Neither do you.
The climate is doing what it has always done – change. Just like the weather.
My personal observations, subjective of course, indicate we seem to be going back to the climate we had in the early seventies here in Colorado. A little cooler and wetter.
One thing we can all be thankful for is that nearly 50% of the political and economic changes the world will need for another Ice Age have already been proposed by the AGW mob. These guys is real smart.
John F. Hultquist says:
September 23, 2010 at 5:16 pm
John,
Thank you very much for the detailed explanation of how one goes about collecting core samples.
barry says:
September 23, 2010 at 10:12 pm
“The Chukchi Sea, the area considered in the study, is 10% of the Arctic ocean. The top post here refers to the entire Arctic ocean. That is an error of 90%.”
So, we should infer that while the Chukchi sea ice was less than present, the rest of the arctic, of which Chukchi is a part, was showing more ice?
Hmmm!
Steven Mosher,
“If you double C02, you will see a 3C increase in temperature, IS a hypothesis.”
Agreed, but what if the prediction is that temperatures will increase by between 1.5C and 6C. Is it still a hypothesis then? You may wish for a hypothesis to be contained within AGW, but wishing does not make it so. The nearest thing to a hypothesis that I have come across has been the prediction that GCM’s have made for a tropical mid troposphere hotspot. Hows that one working out?
I am not terribly impressed by this paper. It seems that their dates all came up wrong, so they “corrected” them by assuming that someone had managed to lose 1m from the top of the cores! This means that there is no overlap between the proxies and any real data. Why then did they not go back and get a core sample to cover the last few thousand years? Because of this I have no confidence that the calibration of the absolute level from these proxies is correct, or that they can be usefully compared with the recent actual observations. That the extent has historically expanded and contracted in the way their graph shows seems a reasonable conclusion, but whether at any given epoch it was greater or less than now is not, in my judgement, and in the absence of proxy-and-direct-observation overlap, sustainable with any certainty.