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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Recent Comments

Comments 27051 to 27100:

Tom Curtis at 21:03 PM on 8 November 2015

The thermometer needle and the damage done

wili @6, the al jazeera article to which you link indicates that Socrota Island being struck by two cyclones in one season is unprecedented, not that its being struck by a cyclone at all is unprecedented. Indeed, the following map of cyclone tracks shows that while uncommon, cyclones are definitely not unprecedented in the region, with 10 occuring of the Yemeni/Somali coast between 1980 and 2005, and with at least one of those striking Socrota Island and one stricking the Arabian Peninsula almost precisely on the border between Yemen and Oman. Given that single cyclones are unusual, but not unprecedented, nothing significant follows from just one season with two cyclones in the region.

Andy Skuce at 16:52 PM on 8 November 2015

The thermometer needle and the damage done

Well, yes, denisaf and wili, the Burke study only looked at the effect of temperature, not resource depletion, nor extreme weather.

wili at 14:08 PM on 8 November 2015

The thermometer needle and the damage done

Yemen is about to be hit by its second cyclone in a week...after seeing not one cylcone in nearly 100 years.

Do you think maybe, just maybe, something's a bit...out of kilter??

www.aljazeera.com/news/2015/11/rare-cyclone-bears-beleaguered-yemen-megh-socotra-weather-151107221838657.html

earth.nullschool.net/#current/wind/surface/level/orthographic=-309.08,10.96,2584

denisaf at 09:38 AM on 8 November 2015

The thermometer needle and the damage done

This assesment of the relation between climate change and economies can quite easily lead to misjudgment on what will happen in the future because it only deals with some aspects of how civilization operates. The holistic scenario is that society is very dependent on the goods and services provided by a vast, irrevocable aging infrastructure operaated and maintained by using irreplaceable natural resources. Economic growth entails the usage of these natural resources at a high rate without taking into account the divestment of natural material wealth.

A rational consideration of how climate change (and ocean acidification) will affect what happens should take into account what will irrevocably happen to the infrastructure.

scaddenp at 06:32 AM on 8 November 2015

Scientists warned the US president about global warming 50 years ago today

You cannot post images directly, you have to post links to images. See the bottom of the comments policy for tips on how to post images.

PhilippeChantreau at 05:44 AM on 8 November 2015

Hockey stick is broken

I'm surpised he refers to M&M. Perhaps it is a different paper, but the one in which they intended to demonstrate that Mann's statistical methods generated hockey sticks was a fraud. They designed their algorithm to sort curves in such a way that the hockey stick shaped ones would come first, and then they showed only the top sample, which obviously happened to be hockey sticks. I believe there are links in this thread from a couple of years ago.

ingersol at 05:19 AM on 8 November 2015

Scientists warned the US president about global warming 50 years ago today

I have been having fun with overlaying Broecker's grah on the instumental record. I stripped everything but the meteoological record and the combined projection from Broecker. I found a combined instrumental record graph. Calibrated the axes and used Broecker's meteorological record for verticle alignment. I get a different result from Dana's creation with Broecker being closer to the brink than he realized. See what you think.

sifeher at 04:12 AM on 8 November 2015

Q&A: Is Antarctica gaining or losing ice?

Ma Roger @20.

I rechecked my power numbers and found that I did us 60 MW/pump x 14 x 250 (scale factor) to arrive at the 210 GW power requirement estimate. In my proposed concept, it would require 42,000 wind turbines of 5 MW each to power 3,500 pumps of 60 MW (80,000 hp) each. That would be a mega project. But the task of countering SLR is no small deal any way we look at it. Thanks for your interest and attention to details. I would like to continue our chat via email: sifeher@scdinstitute.org

Dcrickett at 02:31 AM on 8 November 2015

Scientists warned the US president about global warming 50 years ago today

I have read many an article on this very subject, and this one is far and away the best. Readable Informative. Complete but not too lengthy. Thanks and congratulations, Mr Nuccitelli!

shastatodd at 02:22 AM on 8 November 2015

The thermometer needle and the damage done

"Furthermore, best calculations suggest it would be cheaper to mitigate (stop emitting) than adapting (living with consequences)."

but stopping emitting, means people would have to radically change their "non-negotiable" lifestyles, and curtail human breeding and we know that isnt going to happen. :(

sifeher at 01:39 AM on 8 November 2015

Q&A: Is Antarctica gaining or losing ice?

MA Roger @20.

Thanks for your comments and corrections. It just makes the challange that much larger, only a question of cost. My whole point in proposing this concept is to suggest a possible solution to SLR in case our grandchildren need it. Something needs to be done because SLR may continue until the next glacesion period which may be many millennia away.

dvaytw at 00:11 AM on 8 November 2015

Hockey 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:

Why do people say "the science is settled" when it comes to climate change? Isn't the point of science that nothing is "settled?"

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.

Tom Curtis at 16:50 PM on 7 November 2015

The 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.

scaddenp at 16:30 PM on 7 November 2015

The 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.

longjohn119 at 14:15 PM on 7 November 2015

Scientists 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 .....

TheHod at 11:45 AM on 7 November 2015

The 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 2015

Q&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).

scaddenp at 07:30 AM on 7 November 2015

Q&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.

Cooper13 at 05:25 AM on 7 November 2015

Q&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....

sifeher at 05:19 AM on 7 November 2015

Q&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.

bjchip at 05:10 AM on 7 November 2015

There's no tropospheric hot spot

Could use an update with a link to more recent data...

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/mar/25/one-satellite-data-set-is-underestimating-global-warming

"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://iopscience.iop.org/article/10.1088/1748-9326/10/5/054007;jsessionid=336015B648DF0E7B22B949A919FAD2E3.ip-10-40-2-81

http://blog.hotwhopper.com/2015/05/about-that-tropical-hot-spot.html

Moderator Response:

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KR at 04:28 AM on 7 November 2015

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.

michael sweet at 20:43 PM on 6 November 2015

Q&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.

MA Rodger at 19:49 PM on 6 November 2015

Q&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.

bozzza at 17:06 PM on 6 November 2015

Q&A: Is Antarctica gaining or losing ice?

@10, [should I be feeling approximatley apopleptic about now?/]

Si, me gusta etc.........

TonyW at 15:03 PM on 6 November 2015

Q&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?

Tom Curtis at 10:06 AM on 6 November 2015

Q&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.

michael sweet at 08:09 AM on 6 November 2015

Q&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.

Jim Eager at 07:59 AM on 6 November 2015

Q&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.

Cooper13 at 04:52 AM on 6 November 2015

Q&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?

sifeher at 02:58 AM on 6 November 2015

Q&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?

bwilson4web at 18:36 PM on 5 November 2015

Q&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.

uncletimrob at 18:19 PM on 5 November 2015

Q&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.

bozzza at 16:17 PM on 5 November 2015

Antarctica 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!

sidd at 08:45 AM on 5 November 2015

Q&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 2015

Arbitrary 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.

Jim Eager at 06:34 AM on 5 November 2015

Q&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?

sifeher at 05:33 AM on 5 November 2015

Q&A: Is Antarctica gaining or losing ice?

Correction: In comment 1 - Typo: ...through... should read ...throw...

sifeher at 03:29 AM on 5 November 2015

Q&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.

Kevin C at 19:35 PM on 4 November 2015

Homogenization 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.

Tom Dayton at 11:53 AM on 4 November 2015

Antarctica 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.

VictorVenema at 09:15 AM on 4 November 2015

Homogenization 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.

MA Rodger at 07:31 AM on 4 November 2015

Antarctica is gaining ice

The Zwally et al (2015) pdf.

KR at 07:04 AM on 4 November 2015

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'.

bcglrofindel at 03:12 AM on 4 November 2015

Antarctica 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.

John Hartz at 02:27 AM on 4 November 2015

Antarctica is gaining ice

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