Loss of Arctic sea ice '70% man-made'

Greenland has had its day in the Sun. Now it's back to the Arctic sea ice.

The Guardian has more for me to copypaste today:

Loss of Arctic sea ice '70% man-made'

Study finds only 30% of radical loss of summer sea ice is due to natural variability in Atlantic – and it will probably get worse

Since the 1970s, there has been a 40% decrease in the extent of summer sea ice. Photograph: AlaskaStock/Corbis

The radical decline in sea ice around the Arctic is at least 70% due to human-induced climate change, according to a new study, and may even be up to 95% down to humans – rather higher than scientists had previously thought.

The loss of ice around the Arctic has adverse effects on wildlife and also opens up new northern sea routes and opportunities to drill for oil and gas under the newly accessible sea bed.

The reduction has been accelerating since the 1990s and many scientists believe the Arctic may become ice-free in the summers later this century, possibly as early as the late 2020s.

"Since the 1970s, there's been a 40% decrease in the summer sea ice extent," said Jonny Day, a climate scientist at the National Centre for Atmospheric Science at the University of Reading, who led the latest study.

"We were trying to determine how much of this was due to natural variability and therefore imply what aspect is due to man-made climate change as well."

To test the ideas, Day carried out several computer-based simulations of how the climate around the Arctic might have fluctuated since 1979 without the input of greenhouse gases from human activity.

He found that a climate system called the Atlantic multi-decadal oscillation (AMO) was a dominant source of variability in ice extent. The AMO is a cycle of warming and cooling in the North Atlantic that repeats every 65 to 80 years – it has been in a warming phase since the mid-1970s.

Comparing the models with actual observations, Day was able to work out what contribution the natural systems had made to what researchers have observed from satellite data.

"We could only attribute as much as 30% [of the Arctic ice loss] to the AMO," he said. "Which implies that the rest is due to something else, and this is most likely going to be man-made global change."

Read the rest of the article here. Paper is here (via James Annan).

Not too long ago there was another paper by Notz and Marotzke about the Arctic sea ice loss and the role of AGW. They focussed mainly on the influence of the PDO and AO (see Chris Reynolds' blog post on the paper and his PS on the AMO).

This possible connection between AGW/CO2 and Arctic sea ice loss reminds me a bit of the connection between smoking and lung cancer. It's pretty obvious from the data that one causes the other, but how to prove it? Well, we have more and more data coming in, and it seems more and more researchers are taking up the challenge to prove the connection.

We have a canary, we see it asphyxiating, we have a very strong suspicion it has to do with the coal mine. How long until we can be sure?

Comments

[Bob Wallace]

At least 70% is due to human activity, possibly up to 95%.

That would make natural variability 5% to 30%.

But the Guardian editor who wrote the headline states "Study finds only 30% of radical loss of summer sea ice is due to natural variability in Atlantic".

[EverythingIsPeeerfectlyOkey]

"many scientists believe the Arctic may become ice-free in the summers later this century, possibly as early as the late 2020s."

As early as the late 2020s? According to the PIOMAS numbers, the September ice will be long gone in 2020. Sometimes I wonder whether these socalled "many scientists" actually have heard about exponential growth.

[Climate Changes]

By looking at one of the graphs the arctic sea ice extent is even enough with that of 2007 at the moment. In the CT comparison the ice this year doesn't look very 'solid' next to 2007. Could we potentially lose that much area (area below 60/50%)? I'm aware that the ice will move around and compact but still... http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=07&fd=25&fy=2007&sm=07&sd=24&sy=2012

[Mark Hadf]

I am sure Greenland will have many more days in the sun this summer.

[Anthonywobrien]

Any bets that in time will be held responsible for more than 100% of the ice loss? That we will work out that without an anthropogenic influence the ice would have grown.

[Steve Bloom]

That's absolutely the case, Anthony, given that the cooling-inducing Milankovitch forcing that dominated the long-term global temp trend up until 1850 or so, when our forcing began to dominate, has continued through the present, and IIRC will continue for some centuries if not thousands of years.

[Rob Dekker]

I am surprised that Anthony Watts did not yet jump on this paper.
After all, in the realm of 'attribution', a claim that 70 % of Arctic sea ice loss is man-made is quite significant.
Moreover, there is plenty of opportunity to misinterpret the paper and the statements made by Day in the Guardian interview.

Since Watts did not do it, let me give it a shot :

--- FOIA requests no longer needed to show that CAGW alarmists are fudging data -----

From the what are they smoking department of the CAGW cabal comes yet more evidence how "CAGW alarmism" and "climate science" are mutually exclusive terms. Johnny Day tells the Guardian that 70 % of Arctic sea ice loss is man-made, but he is disproven by his own research :

Using sensitivity statistics derived from the models, assuming a linear relationship, we attribute 0.5-3.1%/decade of the 10.1%/decade decline in September SIE (1979-2010) to AMO driven variability.

As our commenters will readily point out :
(1) The models are shown to be significantly off in their forecasts, and hopeless in their hind-casts without actual climate data input. Models are useless when it comes to the complexities of climate systems.
(2) To base statistics on such models that are is futile : garbage in, garbage out.
(3) Even if you believe that 30 % of the ice decline is caused by the AMO, that does not mean that 70 % is man-made. For example, other papers suggested that 30 % is caused by changes in ice export, and Key et al 2011 suggests that at least 50 % is caused by short-term natural variability.

That means 110 % decline is of identifiable natural causes, which does not even include other causes of Arctic sea ice decline, such as the increased icebreaker activity that poster "(a)justthefacts" asserts. So CO2 influence over Arctic sea ice must have been one of a 'cooling' of at least 10 %, as this-and-that 'skeptic' has already shown to be in agreement with scientific observations.

Needless to say that Day is an alarmist who makes non-scientific claims in the press while hiding the decline in the case of man-made warming. Day is part of the Team that does uses pal-review to forward their CAGW agenda, and has just put the final nail in the coffin of Anthropogenic Global Warming.

How about them cookies, huh ?

[Jim_pettit]

I attribute the wishy-washiness of the Notz-Marotzke paper to what NASA's James Hansen called "scientific reticence" back in 2007.

I suggest that 'scientific reticence', in some cases, hinders communication with the public about dangers of global warming. If I am right, it is important that policy-makers recognize the potential influence of this phenomenon.

Scientific reticence may be a consequence of the scientific method. Success in science depends on objective skepticism. Caution, if not reticence, has its merits. However, in a case such as ice sheet instability and sea level rise, there is a danger in excessive caution. We may rue reticence, if it serves to lock in future disasters.

One thing I find most amusing/disturbing about the release of results of studies such as Day's is that most everyone will talk only about the 70% man-made figure. Denialists, because that's the least damning (though it's pretty darn damning even at that number), and members of the scientific community, because they'll wish as always to avoid appearing alarmist. I understand caution, but, as Bob Wallace hinted at, why can't everyone just call a spade a spade?

Ah, well...

[Jim_pettit]

Rob Dekker wrote: Since Watts did not do it, let me give it a shot...

That's spot-on scary, Rob. You've clearly spent too much time perusing WUWT... ;)

[Bannor Haruchai]

Watts is up to something - no details yet but I suspect a marshaling of the Denialist Brigades.
Somehow I don't think he'll be posting about the London Olympics

http://wattsupwiththat.com/2012/07/27/wuwt-publishing-suspended-major-announcement-coming/

The ridiculously warm spring and the horrendous hot weather in the US and other places along with the Arctic news have the Cooling Cohort playing a lot of defense.

[Espen Olsen]

Is he out for a drink?

[Kevin McKinney]

Hmm. Interesting.

Well, he sure knows how to puff stuff...

[Artful Dodger]

WUddaWaistaTime Speculation Thread

[Steve Bloom]

Curse you, Lodger, I had to click on that. Goodness, they're excited.

I posted a comment to the effect that noon Sunday is a really stupid time for a press event. Tony, OTOH, isn't the brightest bulb around, so maybe could think it was a good idea even after "Climategate II" flopped so badly.

[Neven]

If it isn't something that drives the final nail into the AGW coffin, I'm going to be disappointed.

[idunno]

re WUWT, Rabbett Run speculates that it's the latest from BEST:

http://rabett.blogspot.co.uk/2012/07/rumor-has-it-that-climate-change-is-real.html

[cynicus]

I guess you better leave the speculating to the speculators...

[cynicus]

... and the science to the scientists.

[Kevin McKinney]

Off-topic--but I'm hoping for a little help with a literature search. I'm looking for anything that sheds light on the *effects* of an ice-free Arctic. Certainly we can reasonably predict some things, like further increases in Arctic coastal erosion, or polar bear population crashes, without straining too hard.

But what does the literature say about things like, say, general atmospheric circulation changes, or marine ecological changes? Any leads for me out there?

[AmbiValent]

Scientific reports and well-reasoned educated projections? Maybe Nature, Scientific American or others. Or do you mean a popularised book that basically states the author's opinion? Or do you mean fiction set in the world after the arctic ice has melted?

[idunno]

Hi Kevin,

This link to a searchable database of 100k documents...

http://www.alaskadispatch.com/article/free-access-thousands-high-north-research-documents

...may help.

[Seke Rob]

But what does the literature say about things like, say, general atmospheric circulation changes, or marine ecological changes? Any leads for me out there?

The evapo-transportation [generally associated with plant respiration **]and increase in winter precipitation would be my estimated most major change... possibly a negative feedback [temporarily]. Read somewhere that 80% of the recent decades SLR potential was actually mitigated such as by snow on Antarctica [Grace will tell us soon what's up with Greenland on that front]. Snow on the NH... hope in heck to survive spring/summer. It just melts out as it currently is already doing. Whiter winters, more river/lake overflows... not at all sure, but deeply concerned over agricultural land flooding. Will winter wheats show up in spring? Seen enough in the recent week of crops that were far behind in their growth development... expect world food price explosion, second run.

** something undesirable happening to plant stomata as CO2 rises further. The in-famous Dutch bloat tomato might bloat more.

[Seke Rob]

A easy crowd level document by the USGS recently updated and available in 60 languages: http://ga.water.usgs.gov/edu/watercycleevapotranspiration.html ... no word on CO2 [so good for plants, the FS's so hopefully repeat] and the stomata.

[Kevin McKinney]

Ambivalent, I'm looking primarily for work in the professional literature. I'm working on a little essay, and for that purpose would like to know what is (so far) known about what is likely to follow an ice-free Arctic. Opinion (unless well-supported) and imagination aren't really helpful.

My sense is that perhaps there isn't so much on this yet--I sure haven't seen too much. But I'm sure there's something.

idunno, thanks--I'll check that out!

SR, thanks--I'll look for stuff on projected snow cover. Certainly the paper I linked earlier today would suggest strongly that a cloudier Arctic is likely.

Speaking of articles, for those who haven't had the time to read Michael Mann's "Hockey Stick" book yet can get the gist (at some length) here:

http://doc-snow.hubpages.com/hub/Michael-Manns-The-Hockey-Stick-And-The-Climate-Wars-A-Summary-Review

Unfortunately, I had to scrimp on the scientific side of the story--which leaves many reasons to buy or borrow the book; his explanations of paleoclimate issues are very substantial and (considering the level of detail) quite easy to read and understand.

[Neven]

Looking forward to your essay, Kevin. I'm also planning to write a piece on potential consequences of disappearing sea ice, pulling all the effects together into an overview. Working title: "Why the Arctic sea ice shouldn't leave anyone cold".

[Kevin McKinney]

Thanks, SR!

Thanks, Neven--"great minds think alike" (and "fools seldom differ," of course!) I'll look forward to that as well.

[idunno]

Further to the the Watts Watts Up To speculation...

http://reason.com/blog/2012/07/28/new-global-temperature-data-reanlysis-co

[Kevin McKinney]

Hmm. So the leaks begin, apparently! No wonder Mr. Watts is dropping everything to figure out how to respond.

[Artful Dodger]

Kevin,

Try something like this...

http://scholar.google.com/scholar?q=related:vITocgtRkdIJ:scholar.google.com/&hl=en&as_sdt=1,5

[Rob Dekker]

I seriously hope that this is the Watts versus Muller dispute, and that it has nothing to do with my little prank here which I posted just hours before WUWT's shut-down...:o)

[Espen Olsen]

Rob,

Or he may become a re convert?

[idunno]

Joe Romm on Muller:

http://thinkprogress.org/climate/2012/07/28/602151/bombshell-koch-funded-study-finds-global-warming-is-real-on-the-high-end-and-essentially-all-due-to-carbon-pollution/

[Bob Wallace]

Watts has authored a paper which claims, apparently, that the Earth is not warming. It's a measurement error.

"A reanalysis of U.S. surface station temperatures has been performed using the recently WMO-approved Siting Classification System devised by METEO-France’s Michel Leroy. The new siting classification more accurately characterizes the quality of the location in terms of monitoring long-term spatially representative surface temperature trends. The new analysis demonstrates that reported 1979-2008 U.S. temperature trends are spuriously doubled, with 92% of that over-estimation resulting from erroneous NOAA adjustments of well-sited stations upward. The paper is the first to use the updated siting system which addresses USHCN siting issues and data adjustments.

The new improved assessment, for the years 1979 to 2008, yields a trend of +0.155C per decade from the high quality sites, a +0.248 C per decade trend for poorly sited locations, and a trend of +0.309 C per decade after NOAA adjusts the data. This issue of station siting quality is expected to be an issue with respect to the monitoring of land surface temperature throughout the Global Historical Climate Network and in the BEST network."

more at...

http://wattsupwiththat.com/2012/07/29/press-release-2/#more-68286

[Daniel Bailey]

And for their next "paper", they will prove the world is actually flat after all.
http://instantrimshot.com/classic/?sound=rimshot

[DrTskoul]

Yeah!! He found it..."Measurement Error". The genius ex. meteorologist has discovered why the global ice is melting. Apparently it is a "measurement error". I new there was something fishy going on...

[Steve Bloom]

Not too exciting, Bob. The whole thing is built on a misapplication of Leroy's standards. There are a number of related considerations, one being that if we suspect that a given station has a bias, we would expect to see it reflected in the station record. Another is that USHCN tracks pretty well with CRN, which has been around for long enough now for that fact to be highly significant.

All of this can be seen as Pielke Sr.'s revenge for his mesoclimate model being defunded years ago.

[Steve Bloom]

Another thought: I haven't checked the numbers, but do these results suggest that the CONUS is warming less rapidly than the adjacent oceans? That would be a good trick if so, although a bit unphysical.

[Twemoran]

This may be an extreme case of American Exceptionalism. As the rest of the world swelters, America is found to be saved, probably through Divine Providence,from the ravages of AGW Hell experienced by other, less spiritually pure countries.

Amen
Terry

[Llosmith57]

Amen, I assure you that we are being saved by living daily with the atmosphere from Hell. The thermometers referred to above are probably those inside air conditioned spaces. I do feel a certain kinship with my ancestors from 1889. Twenty days out of the last thirty above 38. Twelve days above 40.6. A normal year here in the Midwest along the banks of the now shriveled Mississippi yields 3 days of 38 or above. We are thankful, however, for the 2mm rainfall here today. First rain at my house in 45 days. Of course, normally we would have received 100+ in the same time period. I do not see any end in sight. The transition to El Nino has paused and the atmosphere seems stuck. Another year like this in MidAmerica and we may all become UFO's (Unidentified Frying Objects).

[Daniel Bailey]

Steve, Dana gives a pretty succinct read on AW's gaffes (comparing uncorrected Time of OBservation data to corrected data, for example). Even the reviewers at E&E can't give this one a free pass. Major "own goal".

[Daniel Bailey]

Steve, Dana gives a pretty succinct read on AW's gaffes (comparing uncorrected Time of OBservation data to corrected data, for example). Even the reviewers at E&E can't give this one a free pass. Major "own goal".

[Daniel Bailey]

How nice, posted twice! (Typepad is fubar)

[Steve Bloom]

And yet, Daniel, you were able to recognize it. :)

I didn't mean to imply any sort of comprehensive treatment of the paper. The Leroy misuse is just the first of many errors, and that's without being able to check on what sort of a job Tony, Steve, "Rev" Jones and their minions did with the classification.

An amusing irony is that the paper admits that the 1998 Leroy standards were inappropriate for use on existing stations (i.e. they were just for siting purposes), when Watts has spent years arguing the contrary position.

I'll check out Dana's piece, thanks.

[Daniel Bailey]

Meh. Me mouse is double-clicking things instead of single-clicking. MS POS.