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Tenney Naumer at 15:27 PM on 15 July 2010Monckton tries to censor John Abraham
Someone should also start a facebook community. -
scaddenp at 13:09 PM on 15 July 2010Part One: How do ice sheets lose ice?
HR - surely the really simple way to look at this is that IN GENERAL glaciers respond to temperature, especially in the ablation zone, and obviously irrespective of the cause of the temperature change. (Though surely you are not trying to resuscitate the "recovering from the LIA" saw). In particular, glaciers also respond to changes in precipitation in the neve area and to changes things like grounding line and seaice buttressing but generally these changes are ultimately due to temperature change anyway. The take-home message to me was that no matter how cold the neve area in greenland or antartica, you are going to lose ice if warming margins and rising sealevels affect the ablation zone. But yes, nothing to do with CAUSE of warming - just further evidence that it is happening. -
Jeff Freymueller at 13:01 PM on 15 July 2010Part One: How do ice sheets lose ice?
Great post. I'm looking forward to the next two parts. #29 HumanityRules (1) Yes, of course these processes operate all the time, but what can change over time are the rates. For example, if temperature is held constant over a few years, but the ice shelf buttressing a glacier breaks up, the glacier will speed up, moving toward a negative mass balance. Or, increased precipitation could result in a positive mass balance even if flow increases. (4) As pointed out in the main post, surface melt is only one of the components, and not the most important one for Antarctica. To complete the circle and address Goddard's argument: that fact means that Goddard's argument that significant ice loss is impossible because the average surface temp remains sub-zero (C) is totally wrong. -
gallopingcamel at 13:01 PM on 15 July 2010Hotties vs Frosties?
Good to see scaddenp and BP getting along. They realise that today's nuclear waste is fuel for future generations. Forget glassification; just burn it! When BP talks about U233 or U232 he is making a subtle pitch for Thorium cycle reactors (e.g LFTR). Uranium reactors are dominant because they produce fissile Plutonium that is great for making weapons. Thorium reactors produce fissile materials but only tiny amounts of Plutonium. The fissile materials they do produce (e.g. U233) are useless for weapons productions but excellent for power generation. Don't forget Rubbia's ADRs (Accelerator Driven Reactors) that can process waste even when k<1. "Sub-critical" reactors have many potential uses in dry reprocessing of nuclear waste. Take a look at GEM*STAR at Virginia Tech: http://csis.org/files/attachments/091007_chang_virginia_tech.pdf -
John Brookes at 12:36 PM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
Chemware @6: "Einstein himself said in 1920: This world is a strange madhouse. Currently, every coachman and every waiter is debating whether relativity theory is correct. Belief in this matter depends on political party affiliation." I tutored 1st year uni physics students about 25 years ago. Special Relativity used to really bother them. Many of them were convinced it was wrong. There seemed to be two reasons for this: 1) It didn't fit with their common sense (which is hardly surprising because it only matters at speeds thousands of times faster than those of everyday life). 2) They hated the idea that they couldn't travel faster than the speed of light. They wanted to believe that they could quickly pop over to Alpha Centauri for lunch, and be back for dinner, and here was this silly theory telling them that it was simply not possible (or even if it was, everyone back on earth would have aged 8 years in a day). Both these reasons apply to the desire to ignore global warming. Firstly, CO2 is a colourless, odourless gas, present in the atmosphere in minute quantities - how can that do anything? Secondly, the cure is to stop pumping CO2 into the air - limiting our personal freedom and our right to do whatever we like. So battles over issues like this have been fought in the past, relativity, smoking etc. I wonder if there were people in London at the time of cholera who fought for the Thames not to be cleaned up, and who argued that water wasn't the cause? Did anyone rail against the huge expense and change in lifestyle involved in fixing the drinking water problem? It would be interesting to know.Response: LOL re the rejection of special relativity. Re point 2, you could always tell them that the sequel to special relativity, general relativity, may still give them a loophole (or should that be wormhole) to get them to Alpha Centauri quickly by warping the space-time continuum. Of course you run again into point 1. -
HumanityRules at 11:53 AM on 15 July 2010Part One: How do ice sheets lose ice?
That was great Robert, I suspect the measurement part won't be boring I'm on the edge of my seat already :) I have few questions and observations. 1) I thought this was nice largely because it doesn't actually mention AGW. I suspect that all these processes you describe are true at all times irrespective of whether humans are pumping CO2 into the sky or not. For example since the end of the Little Ice Age one could argue that velocities have been constantly changing, mainly increasing to give us an interrupted 200 or 300 years of mass loss to global land ice, at least the first half of that time period had absolutely nothing to do with AGW. 2) I read the Bell review. There's a lot of "ifs" and "maybes" and "possiblies" and "mights". I might (probably will) get blasted along the lines of the previous post about partial science but I just wondered to what extent we actually know what's going on at the base of a glacier? These are hypothesizes or proven theories? 3) Again I get from the Bell review that glacier velocity can be affected by a multitude of things some of which have absolutely nothing to do with whats going on on the surface or AGW. And it is not necessarily possible to tease out the impact from all these different processes. I wonder why we always seem to return to AGW for the explanation of mass loss? He also suggests there isn't necessarily a direct relationship between incresed 4) Although you mention the flawed arguments of WUWT and Goddard at the start you don't seem to actually address them. Surely if we are looking at the impact of AGW on glaciers then that still requires increased surface melt to affect velocities. Melt is dependant on air temperature which at least suggests on Goddard is looking in the right area? maybe this is all in part 3 in which case save it for then. -
Joe Blog at 11:15 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
muoncounter at 10:45 That quote on the T's is a bit disconcerting.... 4C a decade? In the tropics?(i think i dislocated an eye brow) http://en.wikipedia.org/wiki/Lohachara_Island This wiki on Lohachara i think is relevant. But this is getting a bit away from the topic at hand. There is unquestionably a trend in rising sea levels. -
muoncounter at 10:45 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
#30: I note Wikipedia mentions that the island was a "sandbar"; I have no firsthand knowledge of the geology of the area. Google Earth shows a circular patch, part of a more extensive submerged shoal. Maybe the delta is sinking due to subsidence, as in Louisiana. Don't know if there are any COE levees on the Hariabhanga River. Here are additional quotes from the Sunday Times Online. He noted that temperatures in the region had been rising at an annual rate of 0.4C (0.8F). Until 2000, the sea level rose about 3mm (0.12 inches) a year, but over the last decade it had been rising about 5mm annually, he said. He warned that another ten islands could be at risk. A nearby island, Lohachara, was submerged in 1996, forcing its inhabitants to move to the mainland, while almost half of another island, called Ghoramara, was now under water. “We will have ever larger numbers of people displaced… as more island areas come under water,” Professor Hazra said. One island, two islands, three islands ... pretty soon you've got a trend. -
Glenn Tamblyn at 10:41 AM on 15 July 2010Part One: How do ice sheets lose ice?
Great post Robert. I have been reading some of the posts over at WUWT with a kind of fascinated horror. Slightly off topic but still interesting wrt to what is happening in the Antarctic is an absolute howler by Steve Goddard at the end of "AGW Mathematics", the second post you link to. After showing how the main body of Antarctica hasn't really warmed, he says 'Must be the Ozone? I’m curious how one gets to be a “climate expert.”'. Presumably sarcastically. Obviously Steve doesn't keep up with the science enough (or if he does he chooses not to mention it). Because recent research suggests it is the Ozone. Or rather the lack of it. Antarctica is surrounded by a westerly air flow called the Southern Hemisphere Annular Mode (SAM). And the SAM has reportedly been stronger during summer for the last 30-40 years, tending to isolate Antarctica from outside weather systems. And research released last year suggests that this is being caused by the Ozone Hole. With less UV being absorbed in the stratosphere, more reaches the lower atmosphere, more energy. And this has had the effect of strengthening the SAM during Summer. Hence the warming such as it is in Antarctica has tended to be more in Winter & Spring. So the Ozone hole really does cause it Steve! Here is a link to a discussion about this over at RC. http://www.realclimate.org/index.php/archives/2009/10/putting-the-recent-antarctic-snowmelt-minimum-into-context/ -
muoncounter at 10:27 AM on 15 July 2010What's in a trend?
Here's a comparison of UAH and RSS for what would be considered the global LT temperature anomaly.
Despite UAH appearing to be noisier, there doesn't seem to be lots of difference. The slope of the straight line shown equates to 0.16 deg/decade, as Marcus states above (#15). Linear trend of RSS' North polar data (actually N60-N82.5 lat) gives a slope of 0.34 deg/decade.
Like it or not, in the data the deniers often cite, the North pole is getting hotter faster. To state otherwise is to ignore the evidence. Not an interpretation of the evidence, but the actual evidence. No hype, no hysteria. "Just the facts, ma'am."
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robert way at 10:01 AM on 15 July 2010Part One: How do ice sheets lose ice?
Peter Hogarth, it would be nice then to at some point see if the authors had came across any of that or if they were working on it at all. -
michael sweet at 09:43 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
BP: If you read the density/temperature graph in the link you supplied, you will see that the expansion of sea water is temperature dependent. This means that the expansion of surface water at 20C when it absorbs 1E22 joules of energy is greater than the expansion of bottom water at 1C when it absorbs the same amount of energy. This is the basic physics that Chris is referring to. Since deep water is colder then surface water, the graph you copied with constant temperature is not relevant to the discussion. -
Sense Seeker at 08:46 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
Thanks for the explanations of Fig. 2. It makes perfect sense to me now. -
Joe Blog at 08:13 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
muoncounter at 07:50 AM Ummmm, are you aware that, that "island" was a sand bar(not a rock island).... and only existed for 30 years... I dunno if i would be using it as an example, without having a long hard look at its history. Maybe more an example of storm erosion/change in currents, than anything else. Humans have been effecting climate im sure since we first started clear felling land for agriculture. And no doubt co2 will cause a rise in radiative forcing... But attribution of individual effects, is a bit more o a messy business. -
muoncounter at 07:50 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
Here's what happens when you wait until all the science is settled before acting: Disputed isle in Bay of Bengal disappears into sea by Nirmala George, Associated Press Writer Wednesday, March 24, 2010 For nearly 30 years, India and Bangladesh have argued over control of a tiny rock island in the Bay of Bengal. Now, it's gone. Rising sea levels in the bay have plunged New Moore Island in the Sunderbans completely underwater, said oceanographer Sugata Hazra, a professor at Jadavpur University in Calcutta. Its disappearance has been confirmed by satellite imagery and sea patrols, he said. "What these two countries could not achieve from years of talking, has been resolved by global warming," said Hazra. -
muoncounter at 07:44 AM on 15 July 2010What's in a trend?
#16 "conveniently dropped the anomalies" answers #15 "why the Denialists rely so heavily on UAH" And Dr. Spencer? He can look at this graph
and not conclude that the 30 trend is up. But then, he uses a 13 month average, despite being a self-proclaimed 'climatologist.'
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scaddenp at 07:31 AM on 15 July 2010Hotties vs Frosties?
BP - I agree Fast Breeder is best for waste - just have to solve the other little issue. I'd like to see more research in Thorium cycle too. I am not opponent of nuclear power - just not a good match to NZ energy issues. I think it is likely the only way forward for Europe. "I dont see why the land use is such an issue" To clarify - I dont see this is an issue because windmill allow multi land use. The contribution to land loss per person for tower footprint and access road is way below the other land use cost for each extra person on the planet. It feels to me like you are clutching any kind of argument against renewables which I find hard to understand. -
Rob Honeycutt at 07:05 AM on 15 July 2010Part One: How do ice sheets lose ice?
JMurphy... I did catch that at the end. It is just bizarre, though, that the article stands. Goddard is Gilda Radner's Emily Litella in real life! Problem is, most don't remember the "never mind." -
Peter Hogarth at 07:00 AM on 15 July 2010Part One: How do ice sheets lose ice?
Robert Way at 02:54 AM on 15 July, 2010 Sorry to go technical! It isn’t mentioned if Autosub was using a low frequency sub bottom sonar, but my first thought is use one to track any more recent and older sediment layers on a vertical “section” through the sea bed across the ridge and see if the older layers where the ice was “impacting” give us some small clues. The high res bathymetry may also tell us when there have been extended periods of debris dumping on the sea bed at the edge of the glacier, and any newer sediment overlay may again allow us to roughly estimate timing of this. -
muoncounter at 06:56 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
#23: "the case for the conclusion that the Earth ... is warming and that much of this warming is "very likely due to human activities." Bass-ackwards. Suspend your disbelief for a second and actually look at the multiple lines of evidence (extremely well-documented in these pages) that demonstrate that warming is real and ongoing (perhaps even accelerating). Then ask the obvious question: what mechanism makes this happen? -- If you cling to some combination of 'who knows?' and 'natural causes', in which case you find that you have trouble explaining all the observations without invoking something new each time. -- If you accept that human activity is a cause, pieces fall quickly into place. -- If you rule out human activity, what's your explanation? Scientific methods apply here as well. "Just say no" is no more a proof than is "a preponderance of the evidence; but it sure makes more sense when you actually have a preponderance of the evidence. -
JMurphy at 06:53 AM on 15 July 2010Part One: How do ice sheets lose ice?
robhon, if you look towards the end of that article, you will see Goddard's admission that he got it wrong (again). Steven Goddard writes: "Dr. Walt Meier at NSIDC has convinced me this week that their ice extent numbers are solid. So why the large discrepancy between their graphs and the UIUC maps? I went back and compared UIUC maps vs. NASA satellite photos from the same dates last summer. It turns out that the older UIUC maps had underrepresented the amount of low concentration ice in several regions of the Arctic. This summer, their maps do not have that same error. As a result, UIUC maps show a much greater increase in the amount of ice this year than does NSIDC. And thus the explanation of the discrepancy. "it is clear that the NSIDC graph is correct, and that 2008 Arctic ice is barely 10% above last year - just as NSIDC had stated." And I love the declaration at the end of the article itself : The author, Steven Goddard, is not affiliated directly or indirectly with any energy industry, nor does he have any current affiliation with any university. With regard to the latter assertion, I think the following phrase puts it best : 'No sh*t, Sherlock !' -
Alexandre at 06:36 AM on 15 July 2010Part One: How do ice sheets lose ice?
Very informative post. Looking forward to the sequel. -
Rob Honeycutt at 06:21 AM on 15 July 2010Part One: How do ice sheets lose ice?
I found this article titled "Arctic ice refuses to melt as ordered" from The Register written by Goddard in 2008. And now that the ice IS melting as predicted Goddard still refuses to acknowledge that something is going on with climate. This is NOT science! This is NOT skepticism. I know those who don't accept AGW don't like the term denier, but for the life of me I can not think of a term that better describes the activity that Steven Goddard partakes in. -
Alexandre at 06:01 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
Another great text to the "unititiated" level. Very easy to grasp and accurate analogies. -
skywatcher at 05:51 AM on 15 July 2010Part One: How do ice sheets lose ice?
Excellent post. I chanced upon goddard's post on Grace and was horrified by the almost total lack of understanding of basic glaciology. Not that that in itself is a crime, but his subsequent misinforming of those who didn't know better was terrible. What was good though was that I was directed there by a comment on another blog noting that goddard was being taken thorougly to task by someone called Robert, (presumably you, sir!), and kudos to you for braving that pit. Even when he was confronted with the facts, goddard utterly failed to acknowledge his lack of comprehension on how Antarctic glaciers lose mass, or how quickly their flow might accelerate, despite your evidence and patient explanations to the contrary. He was insistent that it would take thousands of years for a glacier to even respond to a change propagating 700km from the coast, based on the utterly bizarre concept that the ice would only respond to the change when it had actually flowed all the way to the coast!! I'm imagining an easing traffic jam - you start to accelerate an awfully long time before you pass the accident, no? Such simple concepts are lost on misinforming D-K's like goddard. The general thing is that it's always necessary to push back against those deliberately misinforming the public - you did a great job in responding directly, and this post continues that excellent work. -
Berényi Péter at 05:32 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
#40 chris at 01:54 AM on 15 July, 2010 Peter has attempted to discount the possibility of reduced thermosteric contribution through deeper ocean heat sequestration by reinventing the laws of physics on thermal expansion of water! It's worth pointing out that he's got that fundamentally wrong. Come on. There was nothing fundamentally wrong with it. Volumetric thermal expansion coefficient of seawater at constant temperature increases with pressure indeed.
At 700 m it is 104×10-6 and it gets 50% more at 3200 m (156×10-6). As a water mass sinks, there is not much adiabatic heating. If it started at 2.72°C at the surface, its temperature would be 3°C at 3200 m.
It is quite possible heat does not actually get to depth this way, but it is not a reinvention of fundamental physics.
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Ned at 05:05 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
No, that's exactly what chris and I are pointing out. A value of +450 GT at the beginning of 2004 just means that there was 450 GT more ice in 2004 than in 2006. In other words, in 2006 Greenland had [X] gigatons of ice. In 2004 it had [X+450], and in 2010 it had [X-800]. We don't actually know exactly what [X] is. Again, the analogy is to temperature anomalies. If a temperature anomaly is calculated with regard to the period of 1971-2000, then temperature anomalies above zero just mean that the temperature is currently higher than it was in 1971-2000, not that it's necessarily rising right now. -
robert way at 04:59 AM on 15 July 2010Part One: How do ice sheets lose ice?
mspelto, I think I have fixed the issue and made my wording more clear. -
actually thoughtful at 04:57 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
So what does figure 2 show? It appears that at the beginning of 2004 the change in Greenland's ice mass was +450 gigatons. At the end of 2004, the change in Greenland's ice mass was +250 gigatons. In 2009 it was -600 and -800, respectively. Shouldn't the anomoly be positive if the ice is growing, and negative if the ice is shrinking?Response: The title for the graph is "Change in Greenland ice mass" but really, what I should've called it was "Greenland ice mass anomaly". I went with the more plain English terminology because anomaly is a technical term. But obviously, there is a reason why scientists use technical terms - they're more precise in meaning and less open to misinterpretation.
Greenland has been losing ice mass every year from 2002 to 2009. So the positive values at the start of the graph don't mean the ice sheet was gaining mass at that point. Those values are just the variation from the average over the whole 2002 to 2009 period. As it's been losing mass over the whole period, that's why the first half of the graph is positive and the second half is negative.
Am strongly considering going back to "Greenland ice mass anomaly". -
JMurphy at 04:44 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
skepticstudent, the argument is not circular at all. Maybe you need to read the whole thing in a more legible form : Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities. (MY EMPHASIS) What, exactly, is circular about that ? You may not agree or believe in the scientific conclusion (just as some can't accept evolution) but that doesn't mean the conclusion is wrong or circular in any way. -
tobyjoyce at 04:40 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
@scepticstudent #23. This topic is about appropriate action to mitigate a risk. A doctor may, for example, suggest a different lifestyle to reduce risk of cancer or heart disease, but your example does not make sense. A doctor who is "absolutely sure" is not an appropriate counter-example to scenarios given above. The IPCC wording regarding APW is "very likely". "Relatively sure" is not a commonly used term for risk, and has no meaning in that respect. The rest of your scenario does not make sense. How suggested mitigations like reducing carbon in the atmosphere (of which the earth has sufficient to maintain life) somehow equates with "remov[ing] your reproductive system piece by piece" over 33 years, completely escapes me. If you are somehow suggesting that ideas for mitigating climate change are "a cure worse than the disease", you are a long way from stating your case, let alone proving it. -
Ned at 04:33 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
skepticstudent, if you construct an imaginary scenario that's not a good analogy for climate change, then of course that scenario might be one where it's appropriate to say the costs of action X vastly outweigh the benefits. So? Picture another doctor, one who says that she's found a small but malignant tumor in your body. Operating soon, before it metastasizes, will be relatively easy and will probably save your life. If you wait too long, the operation would become much more difficult and expensive. If you don't get the operation at all, you'll probably die. Slightly different analogy, opposite conclusion. Neither one really helps us decide what to do about climate change. -
robert way at 04:22 AM on 15 July 2010Part One: How do ice sheets lose ice?
mspelto, You have a point. I think I worded that phrase very cumbersomely, i will try to rectify it. -
mspelto at 04:12 AM on 15 July 2010Part One: How do ice sheets lose ice?
Robert good name change, which makes my comment on annual glacier balance moot. One correction "...an inland shift of the grounding line causes less backpressure through increased calving and basal melting." An inland shift of the grounding line may or may not cause either. If the elevation of the bed is increasing or the glacier fjord is narrowing then this will not occur. It is the thinning and consequent reduction in sidewall and basal friction that drives grounding line retreat, which can make the glacier more susceptible to the same. KR as the glacier goes afloat of course friction is reduced which reduces longitudinal compression and hence tends to increase speed. At the dame time as the glacier goes afloat it loses a principal driving force, gravity, this leads to reduced velocity. And of course it can spread out due to the reduced friction and longitudinal compression. This tends to lead to even more reduction of velocity as thinning and divergence of flow reduce longitudinal extension. -
skepticstudent at 04:04 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
regarded as settled facts. This is the case for the conclusion that the Earth ... is warming and that much of this warming is "very likely due to human activities.” 1. I love the circular logic here, regarded as settled fact, the consensus, the science is settled..... very likely... Picture a Doctor... We are absolutely sure that you have a health issue... We are relatively sure it's your male reproductive system that's causing it so we'll have to remove it. It will take 33 years to remove your reproductive system piece by piece and there's only .06% change in your situation by removing your reproductive organs, but we're very likely sure that is the issue. Who's gonna sign up for that doctor? -
Ned at 03:50 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
Er, one could also read chris's comment making the same point as mine, but 93 minutes earlier.... Sorry for the repetitive redundancy. -
Ned at 03:40 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
Sense Seeker writes: Second, it [Figure 2] seems to show that up to mid 2006, the ice mass was actually growing. That's a common, and understandable, misconception. The zero line in that figure isn't an equilibrium mass balance. It's an "ice sheet mass anomaly" similar to temperature anomalies that are measured with respect to an arbitrary zero point. In other words, the Y axis is (as stated) gigatons, rather than gigatons per year. Any time the line has a negative slope on that graph, it means Greenland is losing mass, regardless of whether the line is currently above or below 0. -
maintain_integrity at 03:18 AM on 15 July 2010Part One: How do ice sheets lose ice?
It seems as if steve goddard and others at WUWT are having a very hard time explaining why a full one-third, or 20 km of the entire loss of 60 km from the Jakobshavn Glacier in Greenland has disappeared from 2001 to 2006. Seems as if the first third, or 20 km., was lost between 1851 to 1913, or 62 years; the second third or 2o km. was lost between 1913 to 2001, or 88 years; and now the last third of the 60 km. loss, was lost between 2001 and 2006, a mere 5 years! Talk about uproar and disingenuous twisting of the facts to prove global warming doesn't exist or that the Arctic has warmed considerably more than the rest of the globe. -
robert way at 02:57 AM on 15 July 2010Part One: How do ice sheets lose ice?
Dennis, I do have to apologize as there was perhaps too much lingo being used here. One of the main ideas of the post is to create a less technical one over the next few weeks so that there can be a post for the general public and one for those really looking to get in depth. I did try to reduce the jargon however and tried to stay away from getting too complicated in my descriptions. I had a friend proofread who identified many things I had to change in order to make it appeal to more of a viewership. Note I also changed the name to Why do ice sheet lose mass because I feel it is more appropriate. Glacier mass loss would require much more in depth of an analysis for proper understanding. -
robert way at 02:54 AM on 15 July 2010Part One: How do ice sheets lose ice?
Hogarth, I have in fact read up on these papers a little and I find them both very interesting. Particularly Jenkins (2010) as the ridge is something that was previously not understood. I wish there was some paleoclimatic way to be able to ascertain an estimate as to how long the ice remained on the ridge as that would potentially tell us when the last significant retreat was. -
AuntSally at 02:52 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
Of course, the other salient point to be made here: Steve Goddard chooses to "publish" his analysis on a blog rather than the the scientific literature. I'd like to challenge him to submit his analysis for legitimate peer review and publication. I'll even help. Journal of Climate, I should think, would be a good place to start ... -
Peter Hogarth at 02:48 AM on 15 July 2010Part One: How do ice sheets lose ice?
Thanks Robert, this is a wonderfully clear and focused article. I've seen first hand some of the charts of high resolution bathymetry from under the Pine Island glacier, which tells a fascinating story. I will ask my colleagues in Norway if any images are available. Very recent publications on this are Jenkins 2010 and Schoof 2010. -
Rob Honeycutt at 02:10 AM on 15 July 2010Part One: How do ice sheets lose ice?
Ned... I suppose Goddard has never seen or heard of a melt water lake. -
KR at 02:09 AM on 15 July 2010Part One: How do ice sheets lose ice?
mspelto - correction taken; I'm still learning some of the basics with regards to glaciers. So a possible reduction of spreading comes from reduced back pressure? That makes sense, but how would it cause reductions in thinning and longitudinal extension? I would think those would increase with lowered friction. -
chris at 02:07 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
Sense Seeker at 22:08 PM on 14 July, 2010 "Second, it seems to show that up to mid 2006, the ice mass was actually growing. It cannot have done that forever, and the quadratic fit looks nice by I do not expect that will hold forever, either. As I see it, this picture could just be a small section in a process of random fluctuation. Any thoughts?" The Y axis is an "anomaly" Sense Seeker, and I don't think the "zero" represents a point where Greenland ice mass in balance between mass increase and loss. So the ice sheet wasn't growing up to 2006 as one might infer from the figure. This is apparent if one looks at longer time period analysis of Greenland mass balance. I can't find a linkable version, but a recent paper by Rignot indicates that the Greenland ice sheet grew overall a little between 1957 and 1977, was pretty much in balance between around ~1977 and 1987, started to lose mass slowly between ~1987 and 1997, and that the mass loss has accelerated since then... Rignot, E et al (2008), Mass balance of the Greenland ice sheet from 1958 to 2007 Geophys. Res. Lett., 35, L20502 link to abstract -
HumanityRules at 01:56 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
17.Ned at 00:28 AM on 15 July, 2010 Good point, nicely made. As you say there are consequences to both 'choices'. People need to take ownership of these consequences. -
chris at 01:54 AM on 15 July 2010Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data
Ken Lambert at 22:52 PM on 14 July, 2010 Not really Ken. There is certainly evidence for an increase in heat content in the deeper oceans as described at great length previously. There's nothing surprising in that; in a world warming under enhanced radiative imbalance, we expect the oceans to absorb heat and some of this will find its way to depths. Peter has attempted to discount the possibility of reduced thermosteric contribution through deeper ocean heat sequestration by reinventing the laws of physics on thermal expansion of water! It's worth pointing out that he's got that fundamentally wrong. Might Peter's "demolition" of von Schuckmann et al. be of a similar nature? The increased rate of Greenland ice melt apparent in Figure 2 above (say comparing 2002-2004 to 2008-2010) amounts to a few tenths of a millimetre of eustatic sea level rise per year. Since sea level measurements are a little noisy, that may simply not be apparent in the data yet, and of course this small rise (around 10% of the absolute yearly sea level rise) may have been countered by a shortfall elsewhere (e.g. mountain glacier contributions); it's pretty difficult to do this "acounting" on very short time periods. And while you're right that "you can't have more ice melt and more steric rise at the same time for a given SLR" (assuming your measurements are sufficiently precise), you can have a little more ice melt contribution with a similar or even enhanced ocean heat content, if some of the latter has found its way to somewhat deeper parts of the ocean. That might have looked a little unlikely 2-4 years ago when SLR seemed to have slowed down somewhat. However that slow down was likely due to a La Nina period and the SLR is pretty much back on its longish term trend. I guess we'll have a better idea as things develop over the next couple of years.... -
tobyjoyce at 01:54 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
HR @3, The situation comes back to the precautionary principle (or the prudence principle); if the prediction is for a global warming of 4C +/- 5C, should we act on the assumption (or hope) that a -1C cooling is what it going to happen in practice? Besides, the irrevocable events are all on the temperature upside. If actions taken prove to be unwarranted by events, they can be undone. Not many people retrospectively complain about the obvious overkill in nuclear defences, missile arsenals and star wars alternatives in the Cold War, though the trillions spent on them would have had better uses. -
angliss at 01:45 AM on 15 July 2010Does partial scientific knowledge mean we shouldn't act?
I've forgotten most of my Philsophy 101 class from college, but one of the things I do remember is that not choosing is itself a choice. There well be many options to choose from, but refraining from choosing any of the options inherently defaults to one of those options (or to another option that should have been included in the options in the first place). In the case of addressing climate disruption, we have two main choices: we either choose act to address climate disruption or we choose to not address climate disruption. Refusing to choose defaults to choosing NOT to address climate disruption. -
mspelto at 01:42 AM on 15 July 2010Part One: How do ice sheets lose ice?
The grounding line is where the glacier goes afloat and it can be a point of weakness but seldom is it a place where tidal or wave action leads to cracking. Typically the grounding line for most substantial ice shelves (Ross Ice Shelf, Amery Ice Shelf) and floating tongues of outlet glaciers is well inland (Petermann Glacier), is quite insulated from waves and the glacier is both thick and strong here. What the grounding line does represent is a location where longitudinal compression is reduced as friction declines, this would cause acceleration, but longitudinal extension due to downslope flow and gradual ice thinning, and even lateral spreading can also be reduced.
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