Monday, May 31, 2010

Ups and downs

Although Eli really likes the AMSR-E sea ice maps from the Uni-Bremen, he gotta admit that their web access ain't as reliable as it might be and there are, sure enough, a lot of other sea ice maps and graphs that are of interest. Today's comes from Cryosphere Today at the University of Illinois, the sea ice anomaly, and we here at Bunny Labs may work on it a bit later, but the publication rate is down, so let's start from here. The bottom line jumps out at you



In the last few years, the annual cycle is appearing in the anomaly. Since the anomaly contains the mean annual cycle, this means that the formation of new ice is dominating the winter season freeze over much more than it used to before ~2006 and Eli would say that this is a pretty good elevator graphic. Oh yeah, the graph is a pretty good reason to use 1979-1999 as the period for computing the mean. Something different started happening ~2000.

25 comments:

Anonymous said...

Luminousbeauty posted a video at Deltoid of Dr David Barber , U of Manitoba, explaining what he saw with the latest sea ice, how it's very different to what he normally sees, and how the satellite readings are missing the very different composition of the sea ice. He suspects that multi-year sea ice will be gone from the NH very soon.

-J Bowers

Anonymous said...

you know... all of them are a bunch of warmist-alarmists trying to cheat the average citizen of the world [ModeIrony: Off]

MickyMinniMouseJon

dko said...

Maybe someone can clarify this for me. Looking at the PIOMAS site, they are showing an Arctic sea ice volume anomaly of about -9500 km3 at present. (http://psc.apl.washington.edu/ArcticSeaiceVolume/images/BPIOMASIceVolumeAnomalyCurrent.png) I believe they use NSIDC data but your UIUC Cryosphere Today anomaly data should be close and it uses the same 1979-2009 baseline as PIOMAS. So dividing a volume anomaly of -9500 km3 by an extent anomaly of -967,000 km2 means the ice is thinner by 9.8 m?

Jon said...

dko,

I'll try to clarify that. If you want to determine the average thinning over the whole ice extent (pretending the whole area is 100% ice covered rather than somewhat less uniformly ice covered), you need to divide the volume anomaly by the whole remaining ice extent, not just by the current anomaly in ice extent. Your calculation implicitly assumes that ice volume has decreased only through decreases in ice extent.

Did that help?

TimChase said...

J Bowers wrote in the first comment, "Luminousbeauty posted a video at Deltoid of Dr David Barber, U of Manitoba, explaining what he saw with the latest sea ice, how it's very different to what he normally sees, and how the satellite readings are missing the very different composition of the sea ice. He suspects that multi-year sea ice will be gone from the NH very soon."

That was:

Comment 1726 of "The empirical evidence for man-made global warming"
Category: Global Warming
Posted on: March 1, 2010 8:30 PM, by Tim Lambert
http://scienceblogs.com/deltoid/2010/03/the_empirical_evidence_for_man.php#c2555153

... where the video itself is at:

Arctic sea ice vanishing faster than imagined
http://www.youtube.com/watch?v=LjaVp6AS5XU

Anonymous said...

Eli, you are a very observant bunny!

As it happens I had also recently noticed the rather odd oscillations in ice anomalies that appeared in the last three years-- I even commented to my wife that to me it was a signal that the system may becoming "unstable".

What you say makes sense. Does not look promising does it?

MapleLeaf

Anonymous said...

OT, but a clan of dedicated denialists have set up camp over at Bart Verheggen's blog.

Their latest claim assaulting the body of understanding of climate science is that the radiative forcing from doubling CO2 is much, much less than that found by Myhre et al. (1998).

There are some eager bunnies who are trying very hard to set the record straight, but to no avail.

Maybe Eli (or other informed minds) could hop over there and explain the science? Tks.

Frustrated bunny

Gareth said...

I noted that change in the trajectory of the anomaly in this post a couple of months ago, suggesting I might discuss it "another day". Has that day come, I wonder? Looking back at that post, it's sobering to note that in the last 6 weeks the CT anomaly has increased from 0.3 to just under 1m km2, and the PIOMAS ice volume has plummeted...

Steve Bloom said...

That's all very well for you, Gareth, but over at WTF Goddard has found a new method for cooking things to look like the ice is just fine. This is using US Navy thickness data of some sort. I thought about taking the time to identify the fly in the ointment but then thought better of it, me not having a blog and all.

Anonymous said...

@Steve Bloom

It's the same old tried and true method of cherry-picking a couple of data points a year or two apart.

The Navy 'data' is a forecast of sea ice based on the previous day's data. No one appears to have any problem with Steve and Anthony asserting values derived from a forecast MODEL (or with deriving values strictly from graphs).

bob-tail barry

Anonymous said...

I've been following WUWT on sea-ice, and it smells of desperation.

toby

Anonymous said...

One explanation of the pattern in the last 3 years could be, that Winter ice is a current and Sepetember ice a lagging indicator.

Winter ice is depending on current parameters, such as temperature.

September ice depends a lot on what is left from previous years, particularly the volume.

So, if the overall conditions indicate a turning point to the upside, Winter ice turns up instantly, while September ice still battles with historical leftover.

dhogaza said...

"I've been following WUWT on sea-ice, and it smells of desperation."

Apparently Watts and Goddard managed to convince themselves that one prediction that the arctic *might* be ice-free in summer by 2013 is actually a consensus scientific position that the arctic *will* be ice-free in summer starting in 2013.

So they set forth a post in which they predicted that the arctic will become ice-free by 2060.

It was cheerfully pointed out to them that they're more pessimistic than IPCC AR4, which suggests a 2050-2100 timeframe. Watts and Goddard, warmistas!

I think the recent nonsensical spam-quality "there's actually more ice than before" crap is a desperate attempt to undo the damage done by their 2060 prediction.

Aaron said...

But, when is the ice “gone”?
30 years ago, sea ice was still a highway for dog sleds. Now there are too many breaks in the ice. 30years ago the sea ice locked water vapor from the sea away from the atmosphere and served as a condensation surface keeping the atmosphere dry. Now, the ice is porous and perforated, thereby contributing to moisture in the atmosphere. That moisture in the atmosphere is another feedback in the warming of the Arctic. Likewise, due to the film of water on the surface of the remaining ice, its albedo during the summer melt season has decreased. 30 years ago if you wanted to take a ship through the heavier Arctic Sea Ice you needed a 400 foot long, 60,000 horsepower, icebreaker. Now, Dr. Barber is able to view the thickest ice from the deck of a little 94 foot, research vessel. Both polar bears and walrus have lost young due to early melt of the ice. By any practical standard, this is not the “the Arctic Sea Ice” of our fathers. When do we admit that the Arctic Sea Ice is gone? We do not need the current numbers so much as we need a decision criteria.

Are we going to pick up a bergy-bit and put it in a freezer case at Smithsonian so we can point at it and say, “See the Arctic Sea Ice is not gone!”?

Phil Clarke said...

Where Eli leads, others follow. At some distance and with faltering gait.

Over at WattsUpWithArcticIce Willis 'Conehead' Eschenberg has noticed the same thing and thrown open the floor for explanations. The obvious suggestion of 'hop over to Rabett Run' was dismissed. I was forgetting that you two have 'history'. Apparently even a financial inducement would not pursuade Willis to visit the website of one who hides behind anonymity like a 'common criminal'.

[Of course I enquired after a CV for 'Steve Goddard' but the comment ended up in tbe bit bucket]

Willis then got a bit shirty when the explanations were advanced, annoyed that what was now presented as evidence of AGW had been predicted by precisely nobody. So Tom P pulled out ...

“Sea ice evolution over the 20th and 21st centuries as simulated by current AOGCMs” Olivier Arzel, , Thierry Fichefet and Hugues Goosse, Ocean Modelling
Volume 12, Issues 3-4, 2006, Pages 401-415

From the abstract:

“We show that the amplitude of the seasonal cycle of sea ice extent increases in both hemispheres in a warming climate, with a larger magnitude in the Northern Hemisphere. Furthermore, it appears that the seasonal cycle of ice extent is more affected than the one of ice volume.”


At which point my supply of popcorn ran out.

Phil Clarke said...

Steve Bloom: This is using US Navy thickness data of some sort. I thought about taking the time to identify the fly in the ointment but then thought better of it, me not having a blog and all.

Anatomy of a Cherry-Pick.

OK, let us imagine that you had predicted that a key climate metric, say arctic ice extent, would 'continue to recover' over the year, but a few weeks after you make this forecast, the observed value actually plummets more than two standard deviations....

http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png

Some misdirection urgently needed; easy - let us arrange for the ice volume to grow. Here's the drill:

1. All a trend really requires is two datapoints, so we need to find a low start point. Now in 2007 the summer ice extent did this

http://nsidc.org/news/images/20081002_Figure3.png

so it should be the case that in the following winter refreeze, MOST of the ice would be be first year and therefore thinner than average. Here is what the NSIDC wrote in April 2008

Despite strong growth of new ice over the winter, sea ice is still in a general state of decline. The ice that grew over the past winter is relatively thin, first-year ice that is susceptible to melting away during the summer. In fact over 70% was first year ice (FYI) here's the graph:http://nsidc.org/images/arcticseaicenews/200804_Figure5.png

So the thin ice of Spring 2008 gives us our low volume starting point. Excellent.

2. Publish percentages, not absolute values. Analyse the percentage of ice of various thicknesses now and then, ignoring the fact that the ice has shrunk in extent since May 2008. Its only about 3% but every little helps. It's not like we're doing science here.

3. Devise a novel methodology. Fortunately there are no long term observations of ice volume/thickness. What we do have is the US Navy Polar Ice Prediction model. PIPS 2.0 (superceded by v3.0 in 2005 but that is classified, presuambly it is sufficiently accurate to assist an enemy...). PIPS 2.0 gives us a colour coded map of thickness for any given day. So we can reverse-engineer this by counting pixels of different colours and devise a nonsense algorithm to get to volume. The advantage being that nobody reading the blog is likely to go to similar lengths to check our figures or choose different dates....

[As an aside, last time Steven Goddard had a go at pixel-counting, it didn't end well - scroll down to the Editor's Note http://www.theregister.co.uk/2008/08/15/goddard_arctic_ice_mystery/ ]


And we're done, by careful choice of start date, by using percentages and rolling our own algorithm we can announce

Arctic Ice Volume increases by 25% http://wattsupwiththat.com/2010/05/29/arctic-ice-volume-has-increased-25-since-may-2008/

Which we can quote any time the inconvenient decline in extent comes up. Cool. Just hope nobody digs up the figures published by the University of Washington http://psc.apl.washington.edu/ArcticSeaiceVolume/images/BPIOMASIceVolumeAnomalyCurrent.png or reads the associated analysis Total Arctic Ice Volume for March 2010 is 20,300 km^3, the lowest over the 1979-2009 period and 38% below the 1979 maximum.

If there is a less reliable climate science science blog than WUWT I am not aware of it.

Phil.

Cthulhu said...

what is that weird oscillation in recent years. I can understand the bottom falling out, but why does it peak so much higher? Maybe it's just chance - what else could it be?

EliRabett said...

Truth be told, Eli has more or less ignored Willis, but he must have been touched by the Rabett's pointing out a major flim flam of his.

It's the old victim bully trick. Roger is also putting on the whine about how mean others are to him.

EliRabett said...

Phil, you will be happy to know that RR got several hundred hits from WUWT today. Pearls before swine.

Marco said...

Ah, but Eli, those hits were because Watts added a bit of personal vendetta to his post about Memorial Day. Apparently, you and Tamino should show your patriotism by flying a flag, because your snarkiness makes him believe you may not be proper patriots...

Phil Clarke said...

Hang on a minute - According to NothingUpWithArcticIce Eli and Tamino are 'anonymous cowards'.

So how does he know they're even American?

Either he knows their identities [course he does, both have recently published under thier own names, both have been 'outed' on CA], in which case the anonymity charge fails, or he doesn't in which case he has no business implying they're less than patriotic.

Or there's a third option involving a bag of hammers.....

Pangolin said...

So, if I'm following this correctly......
Sometime on or around May 25 we all looked at the sea ice extent graphs at NSIDC. We noticed that the current years line and the 2007 line crossing. This is presumably a bad thing.

Being curious folk we then popped over to WhatsUpWattsApple and took a look at what he had to say about this following his notorious "sea ice is recovering" statement of several months ago. There we found the inexplicable statement that somehow sea ice volume has grown massively. This is in contradiction to all published data coming from legitimate scientific bodies.

Is it fair to say he's just pulling these statements out of his..... donkey? Can we look forward to Anthony Watts announcing that there are vast plumes of undersea sea ice come October 1st.? Or, perhaps, one really tall skyscraper of ice keeping the total volume up?

Tell me I'm wrong.

Gareth said...

Geography, it's all about geography. I knew it would come in useful one day...

carrot eater said...

"This is presumably a bad thing. "

That, I don't know about. Just because May had a particularly high rate doesn't mean June or July will.

S said...

Howdy, if there's more freshwater around (due to melting of thick ice and/or due to more precipitation) and it's sitting on the surface of the Arctic Ocean, spreading out, when it gets cold maybe you see a quick freezing of a thin layer with great extent. Is this too simplistic? If it's correct, then why isn't the freshwater entrained and mixed (I would expect the open water up there to facilitate mixing).

I understand that the Antarctic has its own reasons for showing increased sea ice extent recently (isolation from warming Southern Ocean, ozone hole allowing escape of IR), but maybe the same thing is happening there as continental ice melts --> more freshwater on the surface that freezes quickly.