I suggest removing the “captcha” requirement for submitting comments. It’s sometimes damn difficult to read what the !@#& those words are — even for a human. And since all comments are moderated, I don’t see how it will reduce spam.
[Response: There is a lot of spam that gets through the filter that we need to clean up as moderators - none since yesterday though. Plus it's for a good cause! - gavin]
Comment by David B. Benson — 12 Jul 2008 @ 5:41 PM
Re: Wilkins ice shelf
Today, I was looking at a NOAA animation of surface temperature anomalies, and I was amazed to see that there were several anomalies during the past 30 days of more than 20 C over Antarctica. Is this right?
Is there any scientific analysis on why the Wilkins Ice sheet is breaking up in winter? Surface meltwater is not likely a factor right now … how about tidal forces?
According to Ted Scambos basal melting seems to be at work here. Warming water from below.
Ted Scambos, an expert with the U.S. National Snow and Ice Data Center, said warm sea water appears to be “reaching the underside of the Wilkins Ice Shelf and thinning it rapidly — and perhaps reaching the surface, or at least mixing with surface waters.”
The following piece, which is considerably more technical, concurs, but goes into more depth, particularly with respect to the growth of fault lines since the 1990s which are being subject to bending stresses due to differential buoyency forces that result from differences in ice thickness. Heat is playing a role largely in terms of causing different pieces of ice to melt to different thicknesses, then weakening the ice so that it is less able to withstand the stresses. Surface melt is not an issue. Interestingly, the author also argues that pinning points where the ice is welded to rock and would normally increase the stability of the shelf are at this point acting to amplify the breakup events.
Apparently the blind already have difficulty accessing the site. Won’t the reCaptcha requirement make it impossible for them to comment? Won’t it make it inordinately difficult for the visually impaired? Isn’t helping them a “good cause”?
I’m against making it harder for people to comment.
[Response: Agreed. If we can make the site more accessible, we will. But you need to deal with the spam - for the time being, the captcha seems to be the least worst option, but we will assess this periodically. - gavin]
How about increasing frequency of katabatic winds for the Wilkins breakup. I read one article saying a 1% increase in frequency can cause an increase in temperature of 1 deg C in winter. That could explain the heating in winter sufficient to cause melting.
tamino we can only begin to guess the amount of goo moderators of a high profile site like RC have to wade through. Well, perhaps you can begin to guess :-)
BTW be amazed at how much more sensible the whole Internet looks in a text-only browser :-)
I have been following the sagas of political interference in the communication of climate science from early in year 2000 until recent. It’s unfortunate that the UCS excluded and ignored years of interference by federal and state agencies in their graphic summary.
The current hypothesis is that it is the expanding ice pack on the Antarctic Continent that is causing the collapse of the marine ice sheets. The expanding ice pack is causing stress to the ice dam that keeps the ice sheet in place. As the stress increases the ice dam fractures and the ice sheet starts to collapse.
It would appear that, ironically it is the cold weather (June 2008 is one of the coldest Junes in the last 30 years) that is to blame for the ice sheet collapse.
[Response: I don't think this has much validity. Ice sheets don't pay much (if any) attention to sea ice. The continuing collapse is far more likely to be due to internal stresses and the lack of buttressing from the segments that have already disappeared. - gavin]
Yes there’s plenty of spam at my blog, but the spam filter does an outstanding job. Nonetheless, I still have to scan the spam queue periodically because it’s also possible for genuine messages to be misidentified as spam. Which is another advantage of the reCaptcha system. And of course, RC gets a lot more traffic (and therefore spam) than I do.
I seem to be the only objector to the new system. My opinion is unchanged, but I’ve had my say and I’ll leave it at that.
Quite soon, today or tomorrow, RealClimate will have had
visits! The last million didn’t take long.
Comment by David B. Benson — 13 Jul 2008 @ 2:32 PM
I’ve read at several other sites set up for collecting consumer complaints about vendors and for identifying junk fax and phone caller numbers, that they’ve seen a huge increase in superficially convincing postings. People trying to fake reputations are searching out sites mentioning them and directing botnets to post fake comments applauding them. This sort of chaff is getting very sophisticated and automated.
And it’s an election year in the USA.
PS, I do agree with Martin about Lynx. A text browser makes the whole world seem a much saner place to visit than most graphics browsers. If not for Firefox plus constant work with NoScript, AdBlock, Greasemonkey and Killfile, I’d stay with Lynx all the time myself.
Regarding the Captcha issue, I have read of an alternative method that seems to make more sense. It works like this:
Add another field to your contact form, but set ‘display’ to ‘none’ in the CSS. This makes it invisible to a human visitor, but will not be distinguished by spambots. You can then write a php script which checks if the invisible field has been filled in. If it has, you know that the correspondent is not human, and can stop their comment getting through.
Feel free to drop me an email if you want any help or further information about this. Your site is an invaluable source of information for non-scientists like myself, and I would be happy to help out in any way I can.
Off topic….anyone seen Christopher Monckton’s recent foray into climate sensitivity? I’m a palaeo person and could see that his grasp of this was ropey. I assume that he made mistakes in the atmospheric physics too. Doesn’t he assume (wrongly) a continuous and equal S-B realtion throughout the atmosphere?
[Response: I had a glance and may do a post - the fundamental errors are a) an arbitrary reduction in the forcing term based on no actual radiative calculations, b) the addition of CO2 feedback term to the forcing at fixed CO2 (think about it) and c) a bunch of confused manipulations of a definition of feedback. He adds in some simple untruths ("the SPM does not define radiative forcing" - umm.. try page 2), some standard disinformation and finishes with a flourish that declares that regardless of the quality science or its results the only policy is to do nothing (quel surprise!). The last is a very clear demonstration of the futility in treating Monckton seriously. - gavin]
There is a considerable presence within the scientific community of people who do not agree with the IPCC conclusion that anthropogenic CO2 emissions are very probably likely to be primarily responsible for the global warming that has occurred since the Industrial Revolution. Since the correctness or fallacy of that conclusion has immense implications for public policy and for the future of the biosphere, we thought it appropriate to present a debate within the pages of P&S concerning that conclusion. This editor (JJM) invited several people to contribute articles that were either pro or con. Christopher Monckton responded with this issue’s article that argues against the correctness of the IPCC conclusion…
Well, to be fair, the committee may have been wise to draw a line: rule that they are only addressing _scientific_misconduct_ and rule outside of their ambit any decision on the press release the author “allowed” to be “crafted” (did they identify by whom the misleading PR was “crafted” anywhere?).
The USA at least has long established that advertising and PR is “puffery” — defined legally as language that no reasonable adult will rely on. That’s why there are slightly tighter rules about advertising to children, they’re legally presumed easier to fool.
Puffery is, reasonably, not part of the scientific record.
I’m not arguing in favor of deceit. I’m just saying:
1) Much public discourse is known to be deceptive by intent and by effect.
2) Much known effective deceit is considered fair and proper business practice by legal decisions such as the Fox News/Monsanto Florida Supreme Court decision.
2) keeping the scientific record limited by ruling out all news/press/PR writing, anything not in the actual journal article, as per the bubble fusion paper mentioned above, seems to me a wise choice that accepts actual limits on what this group can address. Look only to the scientific record, make that expectation clear and limited — and make clear different rules apply in the scientific record than anywhere else.
There are other areas (a few) where lying, lying by omission, and misleading are ruled out. Congress but only when sworn testimony is taken (not usual); the SEC’s rules for selling stock; for example.
Each rulemaking group is wise to draw a very clear perimeter within which they can have any hope of functioning.
Of course that leaves us ordinary citizens in the usual course of our lives buried up to our shoelaces in lies, and we went in headfirst; a lifetime spent mistrusting everything does wear one out eventually.
Someone could do a very interesting study documenting the areas and targets for legally approved and effective deceit.
Over at Liberal Conspiracy, http://tinyurl.com/5n5wct, someone has raised questions over this data. Their link is here: http://preview.tinyurl.com/56ye2e . What they are claiming is that the spike in the graph circa 1961 is most likely down to a move of the weather station. Is this something that’s in the peer reviewed (read firewalled) literature?
The glacier retreat appeared throughout the entire observed time period and has shown an accelerated tendency during the last 20 years, particularly after 1995. In addition to summer temperature increase, other two reasons may also be responsible for the acceleration of glacier melting: one is the glacial temperature rise, which reduced the cold reserve in the glacier and thus increased the sensitivity of the glacier to air temperature rise; the other is the decrease of albedo on the glacier surface, which evidently enhanced absorption of radiation.
As a non scientist, I’d appreciate any comments you’d care to make on this, or suggestions for further reading.
Thanks for the site, by the way. It is an excellent resource.
[Response: This isn't anything I know much about, but I very much doubt that the Chinese scientists are relying on the GISTEMP website to determine local temperature rise. Looking at the temperatures without any context (i.e. what are regional temperatures doing), and simply assuming that any short term change is due to a move without any evidence for it, is foolish. I looked at some of the other records closest to this station, and in fact a bunch of them show a very similar change in 1960-1963 so I wouldn't automatically assume that there is a problem in that Station. But on the face of it, if the glacier is retreating at 9 meters per year, that is prima-facie evidence that you've had some local warming. Pollution dirtying the ice is also conceivable but most local pollution is lower down in the atmosphere, and the dominant winds take pollution to the east - but you'd have to look more closely. If this was just one glacier then you'd probably leave it at that, but mountain glaciers are receding almost everywhere and that can't be because of one towns industrial output. - gavin]
So, the Wilkins Ice Sheet is breaking up because of global warming? Just a month or two ago, I was reading on this site a rebuttal to those skeptics who were trotting out the claim that Antarctic cooling disproved AGW. The rebuttal was subtitled “Yeah, We Knew That”, and claimed that all the global warming models, in fact, predicted a cooling Antarctic.
So, which is it? Is Antarctica warming or cooling? And, which one is in agreement with major AGW theories? You can’t say both cooling and heating are evidence of AGW. You have to choose one or the other.
What are you talking about, Jim? We are talking ocean here. The entry on 2/12/08 clearly says the Southern oceans are supposed to be colder due to Global Warming.
[Response: No it doesn't. It says the Southern Oceans take longer to warm up, There is a difference. But as for the Wilkins Ice shelf it is responding to local ocean conditions (not the whole Southern ocean), and locally (on the west side of the Peninsula), ocean temperatures have significantly and sea ice is way down. This spatial pattern is likely related to the changes in the wind patterns around the pole (possibly related to the ozone hole and greenhouse gases (see Thompson and Solomon, 2001 or Miller et al, 2006). - gavin]
‘Bottom line: A cold Antarctica and Southern Ocean do not contradict our models of global warming. For a long time the models have predicted just that.’
That’s a direct quote, Gavin. So is this:
‘In the Southern Ocean around Antarctica the mixing of water went deeper than in Northern waters, so more volumes of water were brought into play earlier. In their model, around Antarctica “there is no warming at the sea surface, and even a slight cooling over the 50-year duration of the experiment.” (4) In the twenty years since, computer models have improved by orders of magnitude, but they continue to show that Antarctica cannot be expected to warm up very significantly until long after the rest of the world’s climate is radically changed.’
“Polar ice experts from the U.S. and U.K. met at UT Austin in March 2007 to draft a consensus statement about the future of the West Antarctic Ice Sheet.”
“The surface of Antarctica is so cold and the ice so thick that raising the region’s air temperature a few degrees is not enough to cause significant melting. Instead, scientists have long suspected that warm water in the Amundsen Sea is flowing up under ice shelves—platforms of floating ice attached to the grounded ice sheet—and melting them from below. This increased melting speeds the flow of grounded ice sheet into the water.
But it’s unlikely these warmer waters result directly from recent climate change. By measuring oxygen content, oceanographers have discovered that the warm water welling up below the glaciers has not been near the sea surface in the past few centuries. In oceanographer’s terms, the water is “old.” It is part of a mass known as Circumpolar Deep Water connected to the North Atlantic through the globetrotting ocean conveyor belt. This water has been at depth for too long, scientists believe, for its temperature to reflect recent global warming.
Polar scientists meeting at the three-day WALSE Workshop knew that explaining this upwelling could go a long way towards predicting the future of the WAIS. Fortunately, the workshop brought together experts in atmosphere, oceans, and ice—all critical players in this story.
New Hypothesis on Atmospheric Currents
Adrian Jenkins, a polar researcher from the British Antarctic Survey and WALSE participant, developed a computer model that showed a possible solution. …”
This is a comment about the arctic rather than antarctic: Some well-reported climatologists were predicting that the North Pole would be ice free this summer for the first time, yet here we are on August 1 and the arctic actually has far more ice than historical averages, according to satellite data. Can you do a piece on this please?
[Response: Where did you get this from? 2008 is running significantly below the long term average and will certainly end up as one of the three lowest years recorded. 2007 was really extraordinary - well below the long term trend in declining sea ice. - gavin]
[Response: Its not that hard to find the actual real-time data. This graphic from the National Snow and Ice Data Center is updated daily. Its show the current year against the modern (1979-2000) average. While its unlikely we'll reach the record low of last summer, we're running well below the modern average. - mike]