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Comments 27201 to 27250:
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dvaytw at 00:11 AM on 8 November 2015Hockey stick is broken
This comment will start a bit off-topic and then quickly make its way back, I promise.
As an introduction, I posted a response to Dr. Richard Muller's response to the following question on Quora:
It may interest people to know that Dr. Muller basically rules that forum when it comes to questions about climate change impacts, and IMHO, he's running amok. I don't think it comes from the usual ideological motivators; rather, I think it's the hubris that physicists tend to get that leads them to distrust the work of any scientists other than physicists. That and maybe some misunderstanding with regard to philosophy of science. In any case, here's where I get back on topic.
In my response to Dr. Muller, I quoted Wikipedia to him, pointing out that he'd been wrong in his opinion piece about Dr. Mann's Hockey Stick.
The quote stated that subsequent analyses had refuted McIntyre and McKitrick and upheld Mann's paper; further, that the Hockey Stick has been replicated numerous times using other methods.
It's a bit lengthy, but I'd like to post his last response to this exchange in full, as I found it very interesting and troubling:
First, let me say some words about the IPCC report.
To be considered a scientific conclusion, the rule of thumb amount scientists is that the probability of being wrong should be 5% or less. In particle physics, the standard is even higher, generally a fraction of 1%.
The IPCC defines something as "likely" if the probability of it being wrong is 33%. That is very far from a scientific standard. Sometimes politicians need to make decisions and they base them on less than scientific evidence, but 33% chance of being wrong would never be accepted as a scientific conclusion in any major scientific journal. When scientists say that their result is statistically consistent to 1 standard deviation (that's about the same as "likely") the conclusion in their paper is stated as follows: "No statistically significant effect was seen." I can show you one of my papers in which, for a 2-standard-deviation effect, that is a "2-sigma" effect, with only a 5%b chance of being wrong, I and my coauthors said that the effect was "statistically insignificant." Those are the standards of science.
The IPCC is also very clear that their assessments were never intended to be considered a scientific report.
Your quote about the NAS report, despite the usual reliability of Wikipedia, is mistaken. As I mentioned, I was a named scientific referee on the NAS report, and the report said clearly that there was no evidence that the current temperature is the warmest in 1,000 years.
Don't get me wrong. Global warming is real, about 1.5C over the past 250 years, and it is caused by humans. But the work of Michael Mann on the hockey stick was incorrect, and the errors were correctly pointed out by Macintyre and McKitrick, and the NAS concluded that the evidence could not be used to conclude on a scientific basis that we are now experiencing the highest temperature in the last 1000 years.
I'm curious what y'all's take on this is. It strikes me as, well, quite odd. I feel like, about the question of the use of the IPCC's uncertainty terminology, there's a deep misunderstanding here. Without having read much, I'm quite sure that climate research uses the same Frequentist standards that Dr. Muller is used to and that, if the IPCC is assessing likelihood based on a large number of such pieces of research, all of which purport to be showing statistically significant results, then in fact the IPCC is being even more conservative with its use of such terminology and not less.
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Tom Curtis at 16:50 PM on 7 November 2015The thermometer needle and the damage done
TheHod @1, the current solar insolation averages at 238 W/m^2 globally averaged and allowing for albedo. Assuming the same albedo, that means it was 70% of its current value, or 68 W/m^2 less 4.56 billion years ago. In the middle of the Carboniferious, ie, 0.33 billion years ago it was 97.2% of the current value, or 6.68 W/m^2 less than current values. That is equivalent to 1.8 doublings of CO2, or the equivalent decreasing the 5000-7500 ppm of CO2 (your figures) to 1430 - 2140 ppm.
One billion years from now, the insolation will be 109.6% of current levels, or 22.8 W/m^2 greater than current levels. That is the equivalent of doubling CO2 levels 6.2 times, or increasing CO2 levels to 20,400 ppm. Clearly so large in increase in solar insolation would not be survivable by our civilization assuming currently projectible technologies, so that absent large scale migration to Mars and the Asteroid belt, or actually shifting the orbit of Earth to that of Mars, we will be extinct by then along with all vertebrates on the Earth.
Given, however, that that is 200 times longer than the duration of Genus Homo, 4000 times the duration of the species Homo sapiens, and 83,000 times the duration of agriculture; it is pure fantasy to imagine that anything resembling Homo sapiens or a descendant of our civilization will be present on the Earth at that time. It is a time so distant as to be inconsequential to us, and therefore entirely off topic in relation to the OP.
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scaddenp at 16:30 PM on 7 November 2015The thermometer needle and the damage done
There are several points which might be useful to clarify. Firstly, I am not sure why you think that without mankind, Earth would increase CO2 beyond 500ppm? I mean I do agree, that in some very distant future the sun's increase in output will indeed heat oceans to point where CO2 increases but on say a 100M scale, CO2 content and temperature have trending down. There are long term processes removing CO2.
Second, I am not aware of any serious science predictions that "earth will fry" due to our CO2 emissions. The IPCC AR2 points out that rapid climate change creates many problems and certainly will increase localized disasters of various sorts (including security problems) in many places. I dont think anyone can claim with any certainty that it would "end civilization as we know it", but it would certainly impose a lot strains. Furthermore, best calculations suggest it would be cheaper to mitigate (stop emitting) than adapting (living with consequences).
I am not sure that burning all available fossil fuels will change the time at which the earth will indeed die as the sun gets hotter. For starters, even if we did burn everything and put CO2 up to around 1000ppm, natural processes will reduce CO2 levels again (over 50-100 million years) far faster than the sun is heating.
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longjohn119 at 14:15 PM on 7 November 2015Scientists warned the US president about global warming 50 years ago today
This is a great article to point to the next time some Contrarian Propagandist spouts the Lie that scientists were all predicting cooling in the 70's .....
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TheHod at 11:45 AM on 7 November 2015The thermometer needle and the damage done
Hi guys, wonder if you can help me out or know somebody who can?
When the earth was formed the amount of energy the sun was putting out was x, when we got too the carboniferous era when the coal beds etc were laid down, the suns energy had increased by about 30% to x and the carbon in the atmosphere was between 5000 to 7500 PPM with not even close to runaway and a fiery death for the earth.
Since then the suns energy has increased by another 10 % and we have 400 PPM roughly, since no matter what mankind does the earth sometime in the future will increase the PPM way beyond 400-500 PPM and heat the earth way beyond 2c again which we are now told is the last chance to halt disaster.
So at what PPM will the a earth now fry in the future, because obviously the textbooks say the earth will die in about 4-5 billion years as the sun changes as its energy is used up, so now that figure has to be wrong and has to be changed? -
MA Rodger at 10:42 AM on 7 November 2015Q&A: Is Antarctica gaining or losing ice?
sifeher @17.
There is an error with your use of the Tehachapi Lift Station. The 60MW (0.53TWh pa) is 60MW for each of the 14 pump units (total 835MW apparently) not 60MW for the whole operation. So your numbers need multiplying by 14 (6.45TWh pa). And if the freezy wind is absent in the summer, the pumps will have to be working faster when the freezy wind is blowing. Do not get carried away with the Antarctic cold. It isn't unlimited. Southern sea ice averages some 7,500Gt and you in some manner will be robbing it of 1,000Gt of freeziness to reduce SLR by 300mm per century (if it goes acording to plan).
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scaddenp at 07:30 AM on 7 November 2015Q&A: Is Antarctica gaining or losing ice?
" one of them are substantially off...."
Assumptions or problems with the methodology. But so far not clear. The altimetry method results in issues for the sealevel budget and goes against other studies so I think it will come in for close scrutiny. More science needed.
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Cooper13 at 05:25 AM on 7 November 2015Q&A: Is Antarctica gaining or losing ice?
Tom Curtis @11:
So, if I understand correctly, this new study used the GIA/rebound as a parameter in their altimetry, to 'correct' for that deviation.
But that still doesn't address the question of 'why is the GRACE data showing a significant loss in ice mass' while the altimetry data is showing a gain. If you apply the same GIA assumptions (or, use boundaries of high/low estimates), how would the numbers for past publications using only gravimetric data match up with their equivalent numbers from altimetry?
Using these two different ice-loss estimators (altimetry or gravimetric) cannot show opposite results unless the assumptions being used for one of them are substantially off....
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sifeher at 05:19 AM on 7 November 2015Q&A: Is Antarctica gaining or losing ice?
Jim @9, Michael S. @10 &15, MA Roger @14.
Thanks for the comments. The beauty of these blogs is the exchange of ideas and commenting on them, as you have on my wild IBUC.
I did run some numbers, much more need to be calculated and tested. But let me cite a few figures to support the engineering feasibility of my concept. With 50 years of practical engineering experience, I like to base my calculations on actual engineering practice, rather than theoretical computations. I based the IBUC pumping feasibility on the largest actual water pumping installation I could find, the California Aqueduct, which lifts 3.9 cu.km/yr water over the 1,800 ft high Tehachapi Mountains near Los Angeles. It takes 60 MW to power the 14 huge pumps at the Tehachapi Lift Station. From those figures I extrapolated to the approximately 1,000 cu.km/yr (about 1,000 Gtn/yr) water that would need to be pumped out of the ocean to counter the current 3mm/yr SLR. That is about 250 times what is pumped at Tehachapi. That is a lot of water, about 6 times the volume of water in Lake Tahoe. It would flood the California Central Valley (approx. 100,000 sq. km.) to a depth of 1 m.
By the way, I propose to pump the sea water to the top of the ice sheet along the grounding lines of the WAIS, not to the top of the East Antarctica Ice Sheet. The ice sheet surface elevation along the grounding lines of the WAIS, at the foot of the glaciers, is about 200-300 m above sea level. The best test site would be near the NSF's WISSARD project site on the edge of the WAIS as it meets the Ross Ice Sheet. The WISSARD project has successfully drilled through the 800 m thick ice sheet in this area, opening a 12 in. dia. hole with "hot water drilling" technology. I believe that technology could be scaled up to accommodate much larger diameter pumps and with constant pumping the drill shafts could be kept open year around. Remains to be seen, as a lot of things about this idea need to be tested.
My thinking on meeting the power requirement for hot water drilling and running the pumps year around, is to use large wind generators. The largest wind power turbines currently are about 5 MW capacity used in Denmark. It would take a bunch of those, of course, but there is plenty of wind on Antarctica. To power pumps to lift 1,000 cu.km/yr would require roughly 210 GW power based on the Tehachapi experience. That is a lot of power and thousands of giant wind generators would be needed. But is it technically feasible? I believe it is, if we really have to do it.
The latent heat removal from the "warm" sea water issue, raised by MA Roger @14, I believe that the cold winds swooping down from the heights of Antarctic Ice Sheet would take care of that,. This super cold airflow forms thousends of squar kilometers of sea ice every year around the continent several meters thick. Water spilled on the surface of the ice in Antarctica freezes in seconds during all but the middle of "summer" (so I am told - never been there and it's not on my bucket list). I will be the first to admit, that I don’t have all the answers on this concept. That is why I propose that it should be tested at least on a small scale on an actual test site in Antarctica. So far I haven’t found any takers, but at least I received a reply from the “NSF that it does not fund geoengineering projects”. I will keep trying. I hope we never have to use IBUC, but it would be good to have some solutions to SLR available in case we do need it as a last resort.
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bjchip at 05:10 AM on 7 November 2015There's no tropospheric hot spot
Could use an update with a link to more recent data...
"They also discovered that the results from RSS, NOAA, and the new study all show tropical amplification and are in agreement with the expected amplification from climate models. They state, “There is no significant discrepancy between observations and models for lapse rate change between the surface and the full troposphere.”
http://blog.hotwhopper.com/2015/05/about-that-tropical-hot-spot.html
Moderator Response:[JH] Links activated.
Please take the time to learn how to use the eiditing function to embed a link into text.
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Q&A: Is Antarctica gaining or losing ice?
TonyW - While on the very same subject, and with what appears to be the same authors, the more recent paper has a different abstract and different numbers (2015: 82 Gt/yr mass gain vs. 2012: 49 Gt/y, for example) than the conference paper.
It appears to be significantly updated information.
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michael sweet at 20:43 PM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
MARodger,
You are correct, I should have done the calculations myself. Thank you for posting the numbers.
As you show, it is impossible to pump enough water to the top of the ice sheet. The additional issue of where the energy would go is also impossible to resolve.
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MA Rodger at 19:49 PM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
michael sweet @10.
It would be best to actually demonstrate the calculation rather than leave each visitor to this thread with the task.
Your 5 x 1,000MW power stations would provide some 36TWh per year. To mitigate 1mm SLR requires the removal of 360e12 kg sea water and lifting it 2km requires 20kj/kg or 7.2e18j or 2,000TWh. Note the world(2012) uses 155,000TWh.
Perhaps a bigger problem would be the latent energy this water has to lose to freeze itself - 33,000TWh/mmSLR. (Eternal optimists may dream of this as a source of power for the uphill pumping.) So each kg of pumped water has the capacity of raising the temperature of a kg of ice by 165ºC which means any serious SLR mitigation is going to have an impact on Antarctic climate.
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bozzza at 17:06 PM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
@10, [should I be feeling approximatley apopleptic about now?/]
Si, me gusta etc.........
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TonyW at 15:03 PM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
As bwilson4web indicated, this isn't really a "new" study and I don't know why it keeps being referred to as such. It seems to have been a 2012 conference paper, referenced on NASA's Technical Reports Server and also referenced in this 2012 Nature article. True, it may have received a few edits since 2012 but appears to be essentially the same study, by the same authors. Have I missed something or has almost every report on this missed something?
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Tom Curtis at 10:06 AM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
Cooper13 @8, GRACE measures the mass changes due to the combined effect of Glacial Isostatic Adjustment (plus any other process effecting the altitude of the base rock) plus ice balance. If the baserock of Antartica were sinking, that would confound the results from GRACE. That said, Riva et al (2009) combine GRACE and altimetry data to determine that the GIA adjustment is positive, ie, that the base rock is rising. By their estimate, the effect of the GIA is 100 Gt/year which should be added to the direct GRACE results to get the actual loss in ice mass. That adjustment is uncertain, however. Ivins et al (2013) estimate GIA only contributes 57 Gt/annum to the Antarctic mass gain. Zwally et al list that result (and others) in table 8, having converted it to mm/year uplift. Based on that result and Whithouse et al (2012) who show (according to Zwally et al) 5.4 mm/year uplift, Zwally et al use an estimate of 8 mm/year uplift.
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michael sweet at 08:09 AM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
Sifeher,
Please calculate how much water you could pump up 1,500 meters using all the power produced by five 1000 MW nuclear reactors (cost $50 billion for the plants alone). Disregard friction in the pipes. Estimate the diameter of the pipes needed and how long they would have to be.
I think you will find that the amount of water that you could theoretically pump unto the top of an ice sheet is so small compared to a 1 cm rise in sea level that it would be a waste of time. Many proposals for geoengineering fall over because of the immense size of the ocean and the enormous amount of energy that has to be removed. Proposals to remove CO2 from the air and pump it underground require a business as large as all current companies that remove the carbon from the ground combined.
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Jim Eager at 07:59 AM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
Sifeher, you are aware that the average elevation of the East Antarctic ice cap is 3000 meters, and that most of it lies above 2000 meters, right? Please tell me that you've done the math to calculate the energy requirement to pump a Gt of water that high.
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Cooper13 at 04:52 AM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
I think understand the limitations/concerns with altimetry based datasets that this group used for measurement of ice gains/losses.
Thus, how do these new data coincide with the GRACE datasets, which show significant mass-losses from the Antarctic region?
Is it plausible that we have less-dense snow and ice, which is showing 'more ice' from altimetry, but the gravitational data is still correct in showing actual mass losses from the continent? The gravimetric data have lower spatial resolution than the hi-res altimetry, so it's more challenging to tell where the ice losses/gains are using that method, but if the two methods are showing vastly different directions (GRACE shows losses since 2002), there is clearly an underlying assumption that is incorrect, or an error that is unaccounted for.
From my physics background, the gravimetric data do not 'lie'; if you are detecting lower mass, there simply HAS to be less ice. The altimetry data are inferring mass based on height variations, and perhaps the density variation in the ice is bigger than people have assumed....
Anyone w/ some 'real' glaciology background able to 'weigh in' (pun intended) on this?
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sifeher at 02:58 AM on 6 November 2015Q&A: Is Antarctica gaining or losing ice?
Regarding my idea (Comment 1.) of slowing or stopping SLR by pumping sea water onto the Atarctic ice shield to freez (btw, it would be easier to do it on the WAIS and it may help buttressing glaciers and high speed ice flows), but Jim Eager's comment (3.) is right, a lot could go wrong. That is why I am proposing that we should start testing the IBUC on small scale in connection with the current WISSARD project of NSF along the grounding line of the Ross Ice Shelf. There are a lot of unknowns and risks, but unlimited SLR is a certain global desaster in time. Does anyone believe we will be able to reverse GW by GHG reduction? I don't. I believe we be lucky if we can limit GW to 3 - 4 C by 2100. But even if we could stay below 2 C, Ocean waters will continue to stay warm for centuries, especially if projections of an extra long interglacial period are right. SLR is a problem that needs geoengineering solutions. We have time to develop them, but we better start now. Anyone has a better idea?
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bwilson4web at 18:36 PM on 5 November 2015Q&A: Is Antarctica gaining or losing ice?
This paper is nearly identical to one publish in 2012 that did not receive as much attention. But something else may be going on:
"The paper also pointed out the difficulties in measuring the height of ice in Antarctica, saying that improved tools are needed to better perform the task.
The US space agency is currently developing a new satellite capable of a more accurately measuring long-term changes in ice in Antarctica.
ICESat-2, which will be able to “measure changes in the ice sheet within the thickness of a No. 2 pencil,” is planned for launch in 2018, according to NASA glaciologist Tom Neumann."
Source: https://www.rt.com/usa/320554-antarctica-gaining-ice-nasa/
This paper is seeking support for a follow-up satellite mission, ICESat-2. Whether or not it works, is another question. Just Antarctic accumulation of snow from warmer seas and the higher humidity has long been predicted in the model reports I've read.
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uncletimrob at 18:19 PM on 5 November 2015Q&A: Is Antarctica gaining or losing ice?
This is what I love about science... I observe something and make an hypothesis. Jon observes something different but related - he proposes an alternative hypothesis that is not ncessarily in conflict with me.
Unfortunately the rest of the story is not quite as wholesome:
Mine and Jon's hypotheses are not necessarily mutually exclusive, but someone in an unrelated field eg journalism "detects" a story and posts unscientific crap that mis-represents my and Jon's research to peddle a previously debunked unscientific claim.
Rant over but thank you for a most informative post - I had wondered how the "mismatch" would be resolved.
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bozzza at 16:17 PM on 5 November 2015Antarctica is gaining ice
The wind patterns around Antarctica have been changing over long term observation: the fact that the southern hemisphere is colder than the northern is the start of all methodical theory regarding climate change.
I can't believe Venus ever had water but if it did the science says our oceans will never boil away as there are too many negative feedbacks, the presence of Antarctica obviously being the main one!
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sidd at 08:45 AM on 5 November 2015Q&A: Is Antarctica gaining or losing ice?
What about the sea level budget ? Due to the hard work by Cazenave, Leuilette, Miller and many others the budget was thought to be balanced between steric and mass components, with the latter estimated at 1.5mm/yr. Now, if this paper is to be believed, something other than Antarctica is contributing 0.5 mm/yr to mass component of SLR. This leaves Greenland melt, GIC (other glaciers and ice caps) melt, and land aquifer withdrawal as candidates. I find it quite difficult to believe that any of these was underestimated to such an extent. -
knaugle at 07:17 AM on 5 November 2015Arbitrary focus on hurricane wind speed has birthed a new climate myth
There also seems to be an arbitrary focus on only the Atlantic Basin. Note the "Hurricane" in the title. Yet the relative quiet vis a vis hurricane landfalls in the USA is not necessarily reflective of the Pacific basin nor the Indian Ocean.
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Jim Eager at 06:34 AM on 5 November 2015Q&A: Is Antarctica gaining or losing ice?
Hmmm, pumping Gts of relatvely warm salt water directly up onto the East Antarctic ice sheet. Now what could possibly go wrong with that?
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sifeher at 05:33 AM on 5 November 2015Q&A: Is Antarctica gaining or losing ice?
Correction: In comment 1 - Typo: ...through... should read ...throw...
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sifeher at 03:29 AM on 5 November 2015Q&A: Is Antarctica gaining or losing ice?
This new NASA report just points out that we can't rely on bets and pieces of data on global warming (GW). It is a global phenomenon, as the name implies, thus we need a global indicator to measure it. Global mean sea level rise is the best such indicator. It is clearly rising and maybe accelerating. The only thing can through it off is increased snow (ice) accumulation on Antrctica, which removes sea water from the oceans and deposites it in frozen form on the huge land area of Antrctica. - - This phenomenon could lead to a potential geoengineering solution to reduce SLR by pumping seawater onto the Antarctic ice sheet that would freez and stay there for centuries or milenias (The average surface temperatures over most of Antractica are well below freezing year around and likely to stay there even with much more GW). I call this idea the Ice Build Up Concept (IBUC). It would be costly and challanging, but from an engineering standpoint it is feasible. And if we consider the socio-economic costs of potential multi-meter SLR, what is "costly"? I have proposed it to the NSF, but they are not interested in geoengineering solutions.
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Kevin C at 19:35 PM on 4 November 2015Homogenization of Temperature Data: An Assessment
Yes, I've tried the other worlds with this too. With perfect uncondounded breaks, I recover the 'global' trend in all the worlds except the challenging world 6.
I think there is a subtlety I haven't grasped here. My naive understanding is that with perfect breaks, the fragment method should capture the trend however many breaks there are, until you reach the point where there are not enough runs to bridge all the gaps. More breaks (whether due to confounding or there being more breaks in the data) should add noise to the trend, but that noise should be distributed evenly around the trend.
But that doesn't seem to be the case. It's as if the trends for neighbouring stations with runs bridging breaks come from a different distribution to the station we are trying to recover. If I were determining the breaks empirically I can see why this would be the case, but this is the perfect break case.
I don't know if this 'perfect breaks' problem has any relevance to the real world. But it's certainly important for my understanding of the problem.
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Tom Dayton at 11:53 AM on 4 November 2015Antarctica is gaining ice
If Antarctica really has been gaining mass, we are in deeper doodoo than we knew, because sea level has been rising fast even without any contribution from Antarctica. As the years pass, Antarctica's lowering of sea level (by accumulating water as snow and ice) will decrease until eventually (20 years Zwally estimated) Antarctica will start to contribute to sea level rise. So I very much hope Zwally's new study turns out to be wrong.
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VictorVenema at 09:15 AM on 4 November 2015Homogenization of Temperature Data: An Assessment
Kevin, yes when there are many breaks in a short period in a network, it can be hard to determine which of the stations contains the break. I think that is what you call confounding. Unfortunately, the kind of inhomogeneities that cause network wide biases are often the kind that happen troughout the network during a short period, such as the introduction of Stevenson screen or the introduction of automatic weather stations.
If you have detected all breaks at the right positions, it should be possible to develop a correction method that corrects the large-scale trend error without systematic bias. There would still be a noise error. The decomposition methods (used by the homogenization methods PRODIGE; HOMER, ACMANT) is able to do so and is just a few lines of code as well.
When you work with the validation dataset for homogenization methods of NOAA, it is best not to use only world 1. This dataset has a broad span from too easy to too difficult cases/worlds. If you only test on one, you may easily get the wrong impression about the performance of your method.
You should compare the errors in homogenization (or at least systematic errors such as the undercorrection of trend biases) with the global mean temperature change, not with the local weather noise.
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MA Rodger at 07:31 AM on 4 November 2015Antarctica is gaining ice
The Zwally et al (2015) pdf.
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Antarctica is gaining ice
At this point Zwally et al is quite the outlier, both from GRACE data alone and from the collection of other Antarctic mass balance work.
- Zwally et al might be wrong (or rather, far more wrong than other estimates, outside error bounds), perhaps due to the a snow/ice compaction model that is rather different from what is generally used - a very small error there would throw off their computations.
- Zwally et al might be completely right, indicating that their compaction model is correct and nobody elses is, calling into question all those other works along with GRACE calibrations. I consider this rather unlikely.
- Or Zwally et al might be off-base, but other studies are overestimating mass loss somewhat.
We're going to have to wait and see how the science progresses. At this point, however, most of the evidence indicates some mass loss from the Antarctic continent, Zwally et al is inconsistent with both the GRACE gravity data and estimates of the sea level rise budget, and we need to be careful not to fall prey to 'single-study syndrome'.
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bcglrofindel at 03:12 AM on 4 November 2015Antarctica is gaining ice
From the dictionary for Myth:
1. a person or thing having only an imaginary or unverifiable existence
2. an unfounded or false notion
With this new study and other earlier ones from Nasa, and even the continual record Antarctic sea ice extent lately, Myth isn't the right word for the statement "Antarctica is gaining ice". It's in fact got some fairly substantial factual backing.
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John Hartz at 02:27 AM on 4 November 2015Antarctica is gaining ice
Recommended supplemental reading:
Is Antarctica Gaining or Losing Ice? Hint: Losing., Phil Plait, Bad Astronomy, Slate, Nov 3, 2015
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CBDunkerson at 01:41 AM on 4 November 2015Antarctica is gaining ice
As I understand it, the GRACE results from NASA measure differences in gravitational pull to determine the mass of ice while the Zwally study (also NASA run) measures the height of the ice/snow cover, estimates how much of that height is ice vs snow, and then computes the resulting ice mass.
Is there evidence of significant error/uncertainty in the GRACE data? If not, wouldn't it be inherently more reliable than Zwally's method? Basically, Zwally's study gets to 'net ice gain' by making different assumptions about the amount of snow cover. Assume more snow and we're back to 'net ice loss'. Yet GRACE doesn't have that issue at all... it reacts to gravitational pull. Differences in ice/snow elevation would have a neglible impact on gravitational pull. Only the total mass would matter... so how could it be showing less gravitational pull if there were more mass?
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barry1487 at 22:58 PM on 3 November 2015Antarctica is gaining ice
"Does this make the myth true?"
Myth? It's a new study. It's a good information service that points out uncertainties and alternative opinion. Such opinion may be weighed honestly against other opinion. The results here are a minority view (along with previous Zwally paper). Would it be good to give a robust appraisal of the topic, or reject alternative views if they interfere with the messaging?
Mod reply says SkS is updating old rebuttal posts. I like robust posts that include uncertainties, indicate alternative opinion and sum up honestly. I'm fairly confident that will happen.
(Thanks for the reply, JH)Moderator Response:[JH] You're welcome.
The issue of whether Anatartica is gaining or losing land ice is fairly complex and the all-volunteer author team is busy sorting through all of the recent research on this topic.
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denisaf at 20:07 PM on 3 November 2015The Brave New World of Ecomodernism
Any rational discussion of what will happen in the future nneds to take into account how industrialized civilization actually operates. Technological systems irreversibly use limited natural material resources to provide the goods and services society has become so dependent on. These systems also produce irrevocable wastes, including those that have contributed to irreversible rapid climate disruption and ocean acidification and warming. These technolgical systems age despite the use of natural resources for maintenance. Their operation is an unsustainable process. But most of society will find hard to survive as many of the services, including the contibution to food production and supply of potable water, decline rapidly in the decades ahead.
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andybe at 16:18 PM on 3 November 2015Antarctica is gaining ice
Regarding MA Rodgers' response in 433... "Be mindful that this is not the first time in which Zwally has proclaimed the ERS & ICESat data as showing a net rise in Antarctic ice."
What happened with the previous claim? Was it shown to be in error in the 2013 paper co-authored by Zwally?
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Rob Honeycutt at 06:52 AM on 3 November 2015Satellites show no warming in the troposphere
Roy just posted Nov data for UAH, and it's starting to show a spike.
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scaddenp at 06:00 AM on 3 November 2015Satellites show no warming in the troposphere
I dont think there is criticism of S&C for adjusting satellite data - given changes in satellite, sensors available, orbits etc, there would be problems if they didnt. There is criticism of those who think satellites are better than surface records because they believe they are adjusted less, and also fof S&C because of their stalling in releasing source code and algorithms.
RSS has been under suspicion for some time, and see for example analysis here. It will be interesting to see how the MSU indexes respond to the El Nino since in the past, there has been very strong tropospheric response to ENSO. Radiosondes will provide another measure of that response so we have another way to validate the MSU indexies.
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Infopath at 05:28 AM on 3 November 2015Antarctica is gaining ice
@ 431 & 432 (barry & peter),
Re: phys.org/news/2015-10-mass-gains-antarctic-ice-sheet.html#jCp
I read it a bit differently:
Although the article states:
A new NASA study says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.This should be put into context, as Zwally also says that within a couple of decades (should the current loss rate remain) the losses will catch up to the gainings: "If the losses of the Antarctic Peninsula and parts of West Antarctica continue to increase at the same rate they've been increasing for the last two decades, the losses will catch up with the long-term gain in East Antarctica in 20 or 30 years—I don't think there will be enough snowfall increase to offset these losses."
Am I correct to assume (if this study is correct), that net ice gain would only occur if we reduce the curret rate of ice loss?
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Kevin C at 02:41 AM on 3 November 2015Homogenization of Temperature Data: An Assessment
Thanks Victor. I've been trying to test some of those possibilities for the trend recovery.
I tried homogenizing the 'world 1' data using the known breaks to construct the fragment library, using either the confounded or unconfounded breaks. The confounded breaks lead to underrecovery of the trend.
I then constructed my own source data using the same breaks, so that I could be sure that the breaks were exactly correct. Same problem. So, unless I've made a mistake the issue isn't down to errors in the breaks or missed small breaks.
I hadn't thought about the trend uncertainty, but the weather noise in the station trends is large compared to the errors in the homogenization, so that doesn't look like it. And with my new iterative unconfounding step I do recover the full trend for the benchmark data.
It's a really interesting problem. If it's not a bug there may be some nice science hiding in there.
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VictorVenema at 02:20 AM on 3 November 2015Homogenization of Temperature Data: An Assessment
However the simple homogenization method presented in the report underestimates the impact on global temperatures, both in synthetic benchmark data for which we know the right answer (Figure 2), and in the real world data. Why is this?
One of the ways of understanding this is seeing the computation of the corrections as a regression method. Any error you make, breaks you could not detect because they are too small, spurious breaks you set, errors in the date of the break, will reduce the explained variance of the computed corrections.
There is also a noise errors in the trends you compute, but the explained variance smaller than 100% means that on average you always underestimate the size of the corrections. A colleague of mine has just submitted a proposal to develop a bias correction method and compute the trend uncertainty after this bias correction.
The sea surface temperature is corrected based on measurements and models of the measurement process. There is thus no reason to expect these corrections to be biased. They could still be wrong, naturally, especially because there may have been changes in the monitoring of sea surface temperature that have not been considered, but there is no reason to expect improvement in insight to change this trend in any specific direction.
Combining this, it is more likely than not that we underestimate the magnitude of global warming. This would fit to many other changes in the climate system that go faster than expected (Arctic sea ice, AMOC, snow cover, lake and river temperatures, sea level rise, climate sensitivity from observations compared to other methods, precipitation trends, etc.).
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knaugle at 02:18 AM on 3 November 2015Satellites show no warming in the troposphere
I find it interesting that Dr. Roy Spencer gets a lot of (mostly deserved) criticism here for his interpretation of temperature data, and all the corrections to the UAH temperature data. Yet what really puzzles me is that when I visited Dr. Cowtan's Temperature trends site
http://www.ysbl.york.ac.uk/~cowtan/applets/trend/trend.html
ALL the global, land/ocean, satellite data sets show about +1.4°C ± 0.2°C/decade warming for the past 20 years, EXCEPT for RSS, which is only +0.04°C per decade in that time frame. Similarly, at 30 years, the average warming is about 0.175°C/decade and RSS remains noticably lower than the other sets. So it seems all the agjustments to UAH have brought it more in agreement with the surface data, but it does beg the question what's with RSS?
Moderator Response:[PS] Fixed link
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MA Rodger at 01:35 AM on 3 November 2015Antarctica is gaining ice
barry @431 & peter @432.
Be mindful that this is not the first time in which Zwally has proclaimed the ERS & ICESat data as showing a net rise in Antarctic ice. A workshop paper in 2012 (abstact & video with gap in coverage - here) also resulted in calls here at SkS for revision to this post (along with more forceful demands elsewhere by the likes of the Lord Protector of Wattsupia).
This time round, the journal article is so hot-off-the-press it has yet to appear on-line so it's a little early to be getting all excited. Until the new finding is appraised, best we make do with Hanna et al (2013) which is a paper co-authered by Zwally. It broadly discusses work in-hand plus future developments before concluding:-
"However, it is unlikely that these refinements will change the consensus picture emerging: while Antarctica as a whole is losing mass slowly (assessed to be contributing 0.2 mm yr-1 sea-level equivalent by IMBIE2), Greenland, the Antarctic Peninsula, and parts of West Antarctica are together losing mass at a moderate (~ 1 mm yr -1 sea-level equivalent) rate today (~70% of this mass loss is from Greenland) and rates for each are becoming increasingly negative." (my bold)
Figure 1 from Hanna et al (2013) demonstrates this 'emergence'.
Figure 1 caption. Summary of Antarctic and Greenland mass-rate estimates. In the studies published before 20122 (left) and in 2012 (right) each estimate of a temporally-averaged rate of mass change is represented by a box whose width indicates the time period studied, and whose height indicates the error estimate. Single-epoch (snapshot) estimates of mass balance are represented by vertical error bars when error estimates are available, and are otherwise represented by asterisks. 2012 studies comprise IMBIE combined estimates2 (solid lines), and estimates by Sasgen and others16,20 and King and others11 (dashed lines), Zwally and others19 (dot-dashed lines), Harig and Simons89 and Ewert and others90 (dotted lines).
Note that it is not just a need to reconcile this most recent Zwally paper with the other methods employed to assess East Antarctic ice balance. Both the linked pages @431&432 quote Zwally pointing out that these ERS & ICESat data have to be also reconciled with SLR data.
And my answer to peter's question "Would this Zwally paper make the myth true?" that answer would be - "No". ERS & ICESat data continue to provide some evidential support for the 'Antarctica not losing ice' position which remains strongly a myth when presented as unequivocal fact, and doubly so when the mythical Antarctica ice balance is then presented as some natural global thermometer. Indeed, does it even work as a thermometer for Antarctica?
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Rob Honeycutt at 00:31 AM on 3 November 2015Sea level rise is decelerating
Kerry... You're doing a classic "missing denominator" calculation. You've estimated out that the number of ships displacing sea water is a very large number. That's your numerator. Your denominator is the total tonnage of all the earth's oceans, and that would make the result an extremely small number.
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Tom Curtis at 21:58 PM on 2 November 2015Sea level rise is decelerating
Kerry Randell @42, taking your figures on total tonnage, and assuming the average container loss rate extends back to 1945, and that the average ship tonnage loss is 250 with the average loss also extending back to 1945, that yields a total 31,054,617 tonnes lost as a rough estimate. Given that the density of sea water is 1.025 Tonnes per meter cubed, that leads to an estimated displacement of 30,297,187 m^3 of displacement. Averaged over the ocean surface of 361, 132,000 km^2 of surface area, that leads to an estimated 0.000084 milimeter rise in sea level based on your assumptions, for the entirety of lost shipping in the 20th century.
However, that is likely a significant overestimate. The mass of water displaced only equals the mass of the object if the object is floating. If it sinks, the water displaced equals the volume of the immersed object, which is necessarilly less than the volume of water equal to the tonnage of the immersed object, for if it were not, the object would float rather than sink. Ergo, your initial assumption is completely wrong headed. The mass of water displaced by various vessels sunk at sea is far less than the displacement of the vessels.
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peter12809 at 18:00 PM on 2 November 2015Antarctica is gaining ice
"A new NASA study says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.
The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change’s (IPCC) 2013 report, which says that Antarctica is overall losing land ice."
http://www.nasa.gov/feature/goddard/nasa-study-mass-gains-of-antarctic-ice-sheet-greater-than-losses
Does this make the myth true?
Moderator Response:[JH] Link activated.
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Kerry Randell at 17:26 PM on 2 November 2015Sea level rise is decelerating
The rising Oceans,Global warming or not.
Simple experiment:
Fill a bucket to the top with water, then add a brick.
What happens the water overflows the weight of the lost water equals the weight of the brick, it's called displacement.
Add some thing to a body of water what happens?
Throw a brick in the ocean, no noticeable difference.
But throw billions of tons of bricks in and float thousands of ships and boats of all sizes on then we have Oceans rising,
melting ice:
add a large block of ice in your bucket then fill the bucket to the top, the ice floats above & below the water, as the ice melts will the water overflow? Remembering displacement,
Check out below for some reasons for the rising of the oceans.
Listed below is just a small amount of the reasons.Apparently in WW1 a total of 375 U boats sank 6596 merchant ships, a total of 12,800,000 tons.
The Japanese lost 1,178 Merchant Ships sunk for a tonnage total of 5,053,491 tons. The Naval losses were 214 ships and submarines totaling 577,626 tons. A staggering five million, six hundred thirty one thousand, one hundred seventeen tons,
(5,631,117 tons), 1,392 shipsIt's estimated that 10,000 of these large containers are lost at sea each year, Average tonnage 18 tons
180,000 tons per annumAccording to an annual analysis from insurer Allianz, 94 ships on average(over 100 gross tonnes) each were completely lost in 2013. There are many reasons for a complete loss. “Foundering” (which means sinking or submerging) caused the vast majority of the big losses
Over 30,000 large Ships over 500 tons launched since 1975 not to mention the 100 of thousands sail boats small yatch's ferries etc
Now lets add the land Pushed into the ocean to build Airstrips, Islands & Erosion.
Where doe's the water go, It just disappears, yeah right. “IT RISES”
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NEWTONS LAW:
For every action, there is an equal (in size) and opposite (in direction) reaction
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