Thursday
Sep122013
by 
Bishop Hill
Bishop Hill Long-term trends in sea ice
Sep 12, 2013 Climate: Surface The BBC has a big article reporting a new low in Arctic sea ice last winter, based on volume measurements from the European Cryosat programme.
Prof Andy Shepherd, from Leeds University, said: "Now that we have three years of data, we can see that some parts of the ice pack have thinned more rapidly than others. At the end of winter, the ice was thinner than usual. Although this summer's extent will not get near its all-time satellite-era minimum set last year, the very thin winter floes going into the melt season could mean that the summer volume still gets very close to its record low," he told BBC News.
I'm not sure talk of record lows can be seen as anything other than propaganda, for a data series that is so short.
Reader Comments (41)
So three years of data confirms a long term trend? I love the way we've gone from ice area to volume to confirm the bias in getting the right answer. And I love the use of the scientific word "perhaps" to tell us how much ice volume there was 30 years ago.
Yup, the machine seems to be in full "floe" awaiting the expected grant securing capabilities of the AR5 tablets of stone.
Final thrashings of a mortally wounded beast?
Just a pre-emptive PR strike a couple of days before the dramatically high Arctic ice minimum is confessed.
Bob Ward was on the ball like a rat up a drainpipe of course.
Climate science as usual.
I thought "fast fingers" was a rat up a drainpipe.
"could mean that the summer volume still gets very close to its record low"
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Untrue. Sea ice volume increased by about 1600 km3.so far.
http://neven1.typepad.com/blog/2013/09/piomas-september-2013.html#more
http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/
Eyeballing from the picture, I would say we'll end up with an increase of 50% in volume.
http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2_CY.png
Notice how effortlessly the pea was slipped under the cup labelled volume when it became apparent that area wasn't playing the game.
Pre-emptive strike
Anybody else noticed Auntie doesn't allow commenting on any environmental issues any more? Kind of makes you wish Richard Black was still there - OK, not really, but you know what I mean
I see it is Jonathan Amos again, author of the 2007 BBC news story telling us that the arctic ice was all going to disappear by 2013. He does not seem to have learnt from his mistakes.
mango: Yes, the BBC no longer want their audience to know the science isn't settled.
@Phillip Bratby: Did they ever?
mango: We did have some fun commenting on Richard Black's propaganda pieces and upsetting his supporters.
I couldn't help but chuckle when I saw this post hot on the heels of the excitement over David Rose's article!
Bishop - your dislike of 'propaganda' based on too few data points is shared by many, but doesn't the argument cut both ways?
I was interested in the stats seminar you posted yesterday. They wanted "some knowledge of eg standard deviation" as a pre-requisite.
There is a more important pre-requisite which seems to be missing entirely. The missing trait is an honest effort to understand the physical world. An honest effort to forget prior prejudices and forget what you expect to find or hope to find and instead just try to collect some meaningful raw data and then interpret it using honest methods.
But they fail to account for the volume of water ice on the sea floor which has been growing in response to the deep heat locked up there and must be quite undetectable from satellites. This conjecture is admittedly hard to prove with available data but where else could it be? I can’t think of anywhere else. It should be simple enough to modify robot vacuum cleaners for sea floor applications. Allowing for existing software a provisional estimate is that a low budget £100m effort should be ample ... Anyone here any good at securing piffling funding amounts?
So, that could as easily read: ""Now that we have three years of data, we can see that some parts of the ice pack have not thinned [so much]..."
Mind you, once Astronomer Royal, Lord Rees (DT this morning) gets his way 'hacking' the climate, the ice sheet will reach all the way to Scotland and the climate will be perfect.
So the scene is set for a biannual wailing and gnashing of teeth by the doomsayers. Now they will feel free to broadcast their scare tactics twice a year! First instalment - Beware the Ides of March 2014!
Please pardon my lack of reading scope, but what method is being used to calculate volume instead of extent? Someone here in Oz commented elsewhere during the week that it was Grace altimetry, but Grace is not that accurate. Can a reader please assist with a couple of reliable references? Thanks, Geoff.
Geoff Sherrington
Sea ice thickness is estimated from observations by submarines and satellite laser altimetry - see the bottom of the page at the National Snow and Ice Data Center website, which gives references.
@Richard Betts
Is it not possible that ice breakers contribute, perhaps significantly to ice melt? Why isn't this mentioned on the page you link to?
I'm just wondering what the story will be this time next year. A lot of first year ice has survived the summer, that will all be two year ice next year and presumably thicker. Unless there are unusual or extreme conditions rather than a repeat of this year in the Arctic next summer then the ice volume will presumably be the highest yet measured by Cyrostat?
If the volume is the highest or at least higher than this year then I guess they'll have to divert attention somewhere else. My suggestion would be that they look in
The AntarcticorHimalayan GlaciersorAustralian droughtor2013 Hurricane CountorNorthern Hemisphere Snow Coveror Andean Glaciers?Richard Betts
Are there a lot of submarine measurements made public and used it the estimate? In terms of accuracy isn't submarine acquired data chocolate teapot territory?
SandyS
If you are interested in sea ice volume data look at PIOMASS here
http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/
There are issues with the reported Arctic ice estimates during the summer.
As discussed before, passive microwave sensors understate the amount of sea ice during the melting season, due to difficulties discerning melt water on top of ice. I am more trusting of the NIC (National Ice Center) reports as they also include analyses of satellite imagery and reports from vessels in Arctic waters.
As of yesterday, Sept 11, the ice extent continued its normal decline, reported by NIC at 5.6 M Sq. Km, with the packed ice portion (>8/10ths) at 4.7. In 2012 the extent at this date was. 4.6 M, and the 8/10ths part was 3.1 M. The difference is significant. Note how much higher is the packed ice this year.
Over the past several years, the minimum has occurred on day 265 +/- 1 day (Sept. 21 to 23). For example, last year on Sept. 21, NIC showed ice extent at 4.2 M. Sq. Km., with the 8/10ths portion at 3.3 M.
This data is from the BBC's favourite, the EU.
Complete rubbish aince thee is an area 60% greater of ice cover compared to the same date last year. Do these people think the ice refreezes at 4m thick immediately? No, of course it is a slow process to build thickness but the latest area build is impressive and bodes badly for a mild winter.
Ice area has been the Warmist bugaboo for many years, based on albedo concerns and the [non]fact that it could in all probability possibly perhaps constitute part of a positive feedback, maybe. There are major problems with this:
(1) the albedo of sea water at high (polar) zenith angles overlaps that of ice.
(2) much of the loss of sea ice area and volume is related to removal by winds and by sublimation due to low humidity, not by air temperature. Variations in ocean current temperatures unrelated to radiative "greenhouse" heat gain are another factor.
(3) ice insulates the polar oceans from the sky, which has a blackbody temperature of about 4° Kelvin. The more ice lost, the faster the system refreezes due to radiative heat loss. There will always be ice at the poles in winter.
(4) polar ice cover has been less in previous eras without creating a catastrophe.
The Warmist kazatsky has accelerated as they try to dance their way around the "inconvenient" facts.
This is a long running saga:
http://news.bbc.co.uk/1/hi/sci/tech/1058353.stm
Thursday, 7 December, 2000, "Arctic sea ice 'thins by almost half'", By environment correspondent Alex Kirby
"Two UK scientists say they have found evidence to show that sea ice is thinning across the Arctic.
The two, Dr Peter Wadhams and Dr Norman Davis, are from the Scott Polar Research Institute in Cambridge. They say their work shows that the ice in the Fram Strait, between Svalbard and Greenland, thinned by nearly half in two decades. And they say the findings have serious implications for climates at high latitudes. Dr Wadhams told BBC News Online: "Between summer 1976 and summer 1996 there was a 43% thinning of sea ice over a large area of the Arctic Ocean between Fram Strait and the North Pole."
But it wasn't so.....
Ice and Climate News, No. 1, September 2001
"Is Arctic Sea Ice Rapidly Thinning?"
Greg Holloway and Tessa Sou, Institute of Ocean Sciences, Sidney BC, Canada
"Everywhere the environment always changes, and ability to sample those changes is limited. Inferences from limited observations can be misleading. Numerical ice-ocean modelling together with re-analyses of atmospheric forcing can help refine inferences. In the case of submarine-inferred rapid loss of Arctic sea ice, combined modelling and data argue that a more physically plausible inference is that the ice was not "lost" but only shifted within the Arctic. The pattern of submarine sampling happened to miss the shift. Observations to date, together with model physics, imply only that the loss of sea ice volume is not inconsistent with the 3% per decade loss of ice area, a modest rate itself not inconsistent with multi-decadal natural variability."
Surprisingly, Jonathan Amos did report on the Holloway paper: http://news.bbc.co.uk/1/hi/sci/tech/1311007.stm
Friday, 4 May, 2001, 17:21 GMT 18:21 UK
"Arctic's big melt challenged"
"I believe we have been a little bit overly stampeded into the idea that there is a terribly alarming melting taking place, (says) Dr Greg Holloway"
His ideas were supported in 2004: http://www.sciencedaily.com/releases/2004/12/041220010410.htm
"Winds, Ice Motion Root Cause Of Decline In Sea Ice, Not Warmer Temperatures", ScienceDaily (Dec. 29, 2004)
And in 2007,
http://global-warming.accuweather.com/2007/10/recent_rapid_decline_in_sea_ic.html
"Recent Rapid Decline in Sea Ice caused by Unusual Winds", says NASA
And there was this in 2008:
http://www.sciencedaily.com/releases/2008/10/081020095850.htm
"Less Ice In Arctic Ocean 6000-7000 Years Ago"
ScienceDaily (Oct. 20, 2008) — Recent mapping of a number of raised beach ridges on the north coast of Greenland suggests that the ice cover in the Arctic Ocean was greatly reduced some 6000-7000 years ago. The Arctic Ocean may have been periodically ice free.
”The climate in the northern regions has never been milder since the last Ice Age than it was about 6000-7000 years ago. We still don’t know whether the Arctic Ocean was completely ice free, but there was more open water in the area north of Greenland than there is today,” says Astrid Lyså, a geologist and researcher at the Geological Survey of Norway (NGU)."
My opinion is that the Cryosat measurements are nonsense. NASA tried to do the same thing with Icesat and failed utterly (this is obvious from the published papers, though they never admitted it openly). Now there is talk of an Icesat 2 in 2016, perhaps, maybe…
Consider this:
To measure the ice freeboard you must know
A. The altitude of the satellite
B. The altitude of the ice surface
C. The altitude of the sea surface
The altitude of the satellite can be determined within a few centimeters, but no better than that (NASA is seeking appropriations for a new series of satellites to improve the reference system for position measurements to a level where measurements of ice thickness and sea level can be done reliably at millimeter levels, one wonders why since this has supposedly already been done for many years).
The altitude of the ice surface is measured by radar, optimistically with a precision of a few centimeters (this does not factor in the problem of also measuring the depth of snow on the ice, which was one of the killer problems for Icesat).
The altitude of the sea surface is the really BIG problem. We have very little information on the actual level of the sea surface in the Arctic ocean. Icesat worked OK as long as there was a large area of open water nearby to compare with (if this wasn’t a melt pool of course). If there wasn’t any they seem to have assumed that the lowest point they had in the radar footprint was the sea level (which of course violently underestimates ice thickness if there isn’t any open water).
Actually estimating the sea level is extremely difficult. There are geoid models of course, but nobody knows how good they really are, and sea levels of course constantly vary due to winds, barometric pressure, tides and temperature/density of the seawater all of which are very imperfectly known, particularly for the central Arctic ocean. How many tidal measurements have ever been done out in the Arctic Ocean one wonders (remember there is no land nearby so the levels must be measured by GPS)?
And so the final problem: since 90% of the ice is below water any error in the freeboard measurement is automatically multiplied by 10 when calculating ice thickness.
Entropic man
Did you see my question vis a vis the current sea level data on unthreaded - assuming that it was you who raised the question about accelerating increases two three months ago?
As sea ice area is pretty much a rough figure and therefore multiplying a rough area by a guess at the thickness is going to give nonsense as a result so I rarely look at Piomass thanks all the same. This was the point I was trying to make to Richard Betts, still chocolate teapot territory I'm afraid.
Sep 12, 2013 at 8:34 PM | tty
but obviously the data must have been ground truthed in hundreds of locations to verify the accuracy?? Or am I being optimistic in this would mean actually moving away from your computer desk for a few months (still dirt cheap in comparison to getting a satellite up there)
But volume is of all but no importance to the climate change issue, so why the obsession with it (apart from the fact that areal extent is not at an all time minima).?
First, there is no increase in sea levels caused by the volume of ice that is melting since this is all sea ice. So no useful link beween volume and the 'dreaded' consequence of sea level rise.
Second, it is area not volume that is important to albedo in the region.
Third, it is area not volume that acts as a cap and inhibits direct heat loss from the ocean to the atmosphere and thence into space.
Fourth, the recent speculation that the recent blocking highs seen over northern europe/the UK these past few winters (changes in jet stream locations etc), is postulated on a decrease in the areal extent of Arctic ice, not the volume of that ice.
Because it has no significant relevance, the claims pertaining to volume of ice do have the air of desperation about them.
Richard Betts (Sep 12, 2013 at 11:52 AM) states:
Geoff Sherrington
Sea ice thickness is estimated from observations by submarines and satellite laser altimetry - see the bottom of the page at the National Snow and Ice Data Center website, which gives references.
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There probably was not that much volume of ice back in the late 1950s (1958/59) when the US nuclear submaries (the Skate and Nautilus) surfaced at the north pole. Of course, that is conveniently over looked when discussing recent trends in Arctic ice.
The media is doing its usual job of managing the message. There is much scientific evidence that black carbon is one of the main issues and an international committee with substantial funding is paying for projects to reduce BC emissions. For example, replacing Soviet era diesel engines.
The reason for the disproportionate melt of older ice and hence the decline in ice volume is embedded BC which concentrates on the ice surface reducing albedo and increasing melt.
Arctic BC levels have steadily decline since 2000, mostly due to the shutdown of Soviet era industry on the Kola peninsula. Hence newer ice has less embedded BC, and is more resistant to albedo driven melt.
Incidentally, I predicted this year's recovery based on the fact that most of the older multi-year ice has already melted out. From memory, its down to 10% of what it was a decade ago.
Richard Betts,
Thank you for the reference. In emails to the authors, I find "Here, we use multiple precise geodetic data sets and a simultaneous global estimation platform to determine that the ITRF2008 origin is consistent with the mean CM at the level of 0.5 mm yr−1, and the mean radius of the Earth is not changing to within 1sigma measurement uncertainty of 0.2 mm yr−1."
Accuracy of the International Terrestrial Reference Frame origin and Earth expansion
X. Wu,1 X. Collilieux,2 Z. Altamimi,2 B. L. A. Vermeersen,3 R. S. Gross,1 and I. Fukumori1
(Published 2011).
While these figures do not deal with ice altimetry, they do give possible performance estimates, for a more or less ideal case.
Ice is far from an ideal case. A point on the ice is likely to have moved before another satellite pass. Precision would be hard to improve by averaging multiple measurements if ice moved in the meantime. Measurement of the thickness of ice requires a knowledge of both the top of the ice but more importantly the bottom, which I understand to be poorly mapped. Hence there seems to be a need to know what is yet unknown.
The URL that you referred to me gives this "NSIDC is closed today because of severe weather and flooding. We are sorry for any inconvenience this may cause you." I'm not sure if this is a spoof. One would have thought that such an august body would have predicted the weather to avoid such problems.
So, I guess I'm asking you directly if you could put typical one sigma figures on the measurement uncertainty of both the top and bottom if Arctic ice. Thanks Geoff.
Philip Bradley (Sep 13, 2013 at 12:10 AM) - I am not sure Black carbon is that significant; the average temperature in the high Arctic is well below double figures (Celcius) for most of the year, and I don't think a few black spots of carbon in a white expanse will make much difference considering what little heat comes from the Sun even in the short Arctic summer. Much if not most of the sea ice melt is from below, and the considerable input of milder waters coming from the North Atlantic Drift which Nansen and others have measured, does get far into the Arctic Ocean, and have a significant effect. And in any case, I should add that much of the sea ice loss is not from melting, but from transport out of the Arctic Ocean down the Fram Strait and to a lesser extent down the Kennedy Strait. So wind patterns are predominant, as was shown by time-lapse video of satellite images in 2007. Rather than focus on the sea ice minima each year, I would much rather see the cryologists try to quantitatively attribute how much ice-loss was due to air temps, sea temperatures, transport by wind and breakup by storms (and ice-breakers?). I'd also like to see a quantitative analysis of the feedbacks, i.e. how significant is the positive from increased albedo feedback (when in practice the Arctic is covered with clouds most of the time) and whether this is offset by the negative feedback from reduced ice cover (the oceans lose much less heat when they are covered with insulating snow and ice). I have never seen this obvious negative feedback mentioned by the alarmists, yet it is likely just as significant. Odd that as Arctic sea ice September minima has seen a decline in the last few years, and yet the northern hemisphere has had a run of cold and even severe winters. I wonder if this is related? (where else does the cold come from?) And I am not suggesting it is due to the alleged jet stream blocking bollocks they made up because they could not think of anything else.
lapogus
We have little to do with ice in Australia. Some years ago I started asking a question for which I have seen no answer. In the tropics, if a cloud passes between you and the sun, you immediately feel cooler.
What is the perceived reaction if you below zero near a Pole?
In the meantime, I note that the Sea Ice graphs are turning the corner towards re-freezing...
No doubt someone will say: 'Ah, but the VOLUME is not what it used to be...'
Yeah, right...
Whose records on Arctic ice are reliable?
"Ice charts are more accurate and detailed at the ice edge than passive microwave data because they are often made using higher resolution data. Also, analysts pay particular attention to regions near the ice edge because the characteristics and extent of ice in the marginal ice zone are important for operations taking place within or near that region. (Conversely, analysts generally do not characterize the central Arctic with as much attention to detail, because most of the time there are no supported operations there.)"
http://nsidc.org/data/docs/noaa/g02172_nic_charts_climo_grid/
"Differences between the NIC ice chart sea ice record and the passive microwave sea ice record are highly significant . . . We find a baseline difference in integrated ice
concentration coverage north of 45N of 3.85% ± 0.73% during November to May (ice chart concentrations are larger). In summer, the difference between the two sources of data rises to a maximum of 23% peaking in early August, equivalent to ice coverage the size of Greenland."
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1058&context=usdeptcommercepub
Lapogus says:
"I don't think a few black spots of carbon in a white expanse will make much difference considering what little heat comes from the Sun even in the short Arctic summer."
From which I predict that You have had limited experience of actual ice and snow melting at high latitudes.
Geoff Sherrington says:
"In the tropics, if a cloud passes between you and the sun, you immediately feel cooler.
What is the perceived reaction if you below zero near a Pole?"
The same of course (with the reservation that my personel experience does not extend much beyond 80 degrees latitude) .
tty - apart from a brief stop over in Iceland you are correct that I have not spent much time in Arctic latitudes. But I have plenty of experience of snow and ice melt in similar conditions. The highest the midday sun in a Highland winter is about 33 degrees above the horizon, so much the same as how high the Sun gets in an Arctic summer. Indeed, the average January temperatures here in recent winters has been below or on a par with the average Arctic summer temperatures above 80 degrees north. So I have experienced many ice days in recent winters and more distant winters, when the warmth of the sun has not been enough to melt snow flakes let alone solid ice, even when this has been inadvertently covered with some homemade black carbon (wood ash) which I have to transport to the bottom of the garden most days.
As I said, I don't think the black carbon is a significant contributory factor in sea ice melt, which is primarily lost through transport and melting from below. I do accept that black carbon could exacerbate melt ponds on the fringes of the Greenland Ice sheet however. But these are only in existence from May to August, at the lower altitudes and are fairly insignificant in terms of the total areal extent of the GIS.
Why is the Norwegian Ice Data Service - 'Nansen', 'Norsex', or 'Arctic ROOS', been off-line for over a week? Is it because the info on their graphs could give rise to doubt among the faithful?