Some excerpts from the paper (my paras, bold and italics):
Currently, ice loss from the Amundsen Sea sector of the West Antarctic Ice Sheet (WAIS) contributes ~7% of the global sea-level rise. The WAIS is potentially dynamically unstable, with a capacity to raise global sea level by several meters (1). Pine Island Glacier (PIG) is a principal outlet of the WAIS that has rapidly thinned, retreated, and accelerated (2–6). The spatial pattern of thinning suggests that the glacier drawdown is the direct result of increased basal melting of the ice shelf that has reduced its buttressing effect.
The restraint offered by the PIG ice shelf is dependent on its basal melt rate, which in turn is controlled by heat transport in the underlying ocean cavity. Therefore, how an ice shelf interacts with the ocean and melts now and into the future can alter the mass discharge from the Antarctic Ice Sheet in general and the WAIS in particular, affecting global sea level...
...The continuity of the channels seen in satellite imagery and the airborne radar survey, in conjunction with the vigorous melt rates here described, indicate that basal melting is active from the grounding line to at least the mid-shelf location of the observations. In addition to our observations, a recent idealized numerical simulation of an ice shelf base and ocean boundary layer has suggested that channelization is of fundamental importance, because a channelized base actually melts much less vigorously than a nonchannelized one (14). The remarkable ice/ocean coupling evident in our observations points to the need to represent channelized ice/ocean interaction in models of PIG and similar outlet glaciers in global climate simulations of sea-level change.In other words (as I understand it), the degree of "channelisation" will determine the rate at which melting takes place. The scientists are looking at the detail of how the water moves in under the ice shelf to try to determine where, how and how quickly the ice will melt.
Deniers scoff while the ice melts
Anthony Watts posted an item (archived here) about this, with the normal scoffing headline starting with the word "claim": Claim: atmosphere heats the oceans, melts Antarctic ice shelf.
Showing his usual form, Anthony doesn't even link directly to the Penn State news item he posts, let alone the published paper. Going by his headline, Anthony also seems to (wrongly) think that it's a new idea that the ice is melting from below, even though he's written about warm water melting ice in Antarctica before. (Anthony Watts keeps demonstrating that he has a very bad memory - and here too.) Here is an excerpt from the website of the British Antarctic Survey, which was part of the research team:
Given the flow of warm sea water below the glacier, scientists have long known that Pine Island Glacier was melting from below — the accelerated flow of Western Antarctic Ice Shelf glacial ice into the Amundsen Sea has been a concern of scientists since the late ‘80s. An exhaustive expedition to the 50km-long floating ice shelf at the outer reaches of the glacier field, and 500 meters down into it, reveal the first measurements detailing ice-shelf melting rates and processes within melt channels bore into the shelf underbelly.The research is difficult because while Antartica itself is a remote and dangerous continent, Pine Island glacier is remote even by Antarctic standards. The news item at Penn State says in part:
"It has taken years and years to do the logistics because it is so remote from established permanent bases," said Anandakrishnan....
...The ice shelf is melting more rapidly from below for a number of reasons. The oceans are warmer than they have been in the past and water can transfer more heat than air. More importantly, the terrain beneath the ice shelf is a series of channels. The floating ice in the channel has ample room beneath it for ocean water to flow in. The water melts some of the ice beneath and cools. If the water remained in the channel, the water would eventually cool to a point where it was not melting much ice, but the channels allow the water to flow out to the open ocean and warmer water to flow in, again melting the ice shelf from beneath.
"The way the ocean water is melting the ice shelf is a deeply non-uniform way," said Anandakrishnan. "That's going to be more effective in breaking these ice shelves apart."
The breaking apart of the ice shelf in the channels is similar to removing an ice jam from a river. The shelf was plugging the channel, but once it is gone, the glacier moves more rapidly toward the sea, forming more ice shelf, but removing large amounts of ice from the glacier.
From the WUWT comments
I have nothing but contempt for the crowd at WUWT. They are a pack of utter nutters. Anthony Watts writes for the genuine illiterati who are completely ignorant of the dangers of the West Antarctic ice sheet. Most of them are scornful of the researchers who braved goodness knows what unknown dangers to take in situ measurements at remote Pine Island. (WUWT article and comments are archived here.)
Mickey Reno doesn't have a clue about the article and seems to be talking about something else completely. He says:
September 14, 2013 at 5:14 am
Here we see a large calving event in an area that has probably seem hundreds of similar events over the past couple of millenia. Most people would see this as an awesome display of nature’s power and grandeur. The alarmist sees an opportunity that must not be wasted.
September 14, 2013 at 2:14 am
In life it is always best to give people the benefit of the doubt? I doubt if this paper has any merit whatsoever. When a scientists uses perjorative words such as dumping then they must be talking crap. (No pun intended)
Julian in Wales says:
September 14, 2013 at 2:09 am
“The researchers looked at the remote Pine Island Glacier, a major outlet of the West Antarctic Ice Sheet because it has rapidly thinned and accelerated in the recent past.”
Maybe that should read the researchers cherry picked the remote Pine Island Glacier……..past………and then worked out how to link this to alarmist stories for warmist propaganda
DJ says "it's volcanos":
September 13, 2013 at 11:26 pm
Uh… Did I miss the part about the volcanoes at Pine Island and all along the sea floor in that region that could, possibly, maybe, provide a small amount of heat???
Caleb says "it's not warming":
September 13, 2013 at 11:02 pm
Pine Island is the silver lining on the dark cloud Alarmists are increasingly facing. It is the microcosm that defies the macrocosm. It is the exception that proves the rule, the rule being: “Global Warming is not happening.”
johanna, who can't possibly have read the paper, says:
September 13, 2013 at 10:53 pm
What rubbish! This paper highlights what is wrong with much of contemporary science. In observing and analysing the natural world, you need benchmarks, history, geography and a bunch of other things. This paper could have been a useful addition to the sum of knowledge if it had just stuck to the facts. There is a lot to learn about the Antarctic, glaciers and so on. Instead, it debased itself and destroyed its own credibility with outright partisanship.
A.D. Everard says:
September 13, 2013 at 10:17 pm
They are going to keep making stuff up – anything, everything – until every last person on the planet stares at them blankly and there is not a drop of funding left. And then they’ll probably Just Keep On Making Stuff Up. I wish some of them would actually do some science.
Eyal Porat has never been for a swim in a body of water and says:
September 13, 2013 at 10:13 pm
This is amazing:
These people make assumptions about mechanisms they do not refer to or explain (i.e. the warming of the oceans by the atmosphere), then build their theory upon it. And voilla! we have a solution!
The simplest first grade test will tell them this is wrong. You cannot heat the oceans from above.
This is bad science and it really makes me saddened. And to see the degrees of these people… All professors… sigh.
a jones is another denier who thinks there is a bunch of new volcanoes says, with kindest regards:
September 13, 2013 at 10:08 pm
Some years ago when there was last excitement about the Pine Island glacier I wrote to the Times of London, which for a wonder published my letter, pointing out that if you have a glacier above a volcanically active region, as in this case, the geothermal heat below tends to melt the ice above. As happens all along the Antarctic peninsula.
September 13, 2013 at 9:54 pm
It’s all about the money. The politicians want a crisis to capitalizes on, and they pay government money to obtain studies claiming crisis. The pseudo-scientists who want the money produce studies that claim crisis. It’s that simple.
Okay - I'll stop there. All the other comments are at least as abysmal. I don't think there is a single comment that makes any sense. It's even worse than usual. Anthony has given up any pretence at being a "science" blog. He's pandering to the scientific illiterati. If those comments don't demonstrate to lurkers the intent and "quality" of WUWT and the type of people that Anthony Watts caters to, then I don't know what will.
You can't help but contrast the above disbelief of actual scientific observations published in a top ranking journal with WUWT-ers unquestioning acceptance of the denialist guff from Matt "CO2 is plant food" Ridley, who is not a scientist at all.
Stanton et al Channelized Ice Melting in the Ocean Boundary Layer Beneath Pine Island Glacier, Antarctica; Science 13 September 2013: Vol. 341 no. 6151 pp. 1236-1239, DOI: 10.1126/science.1239373