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Comments 34001 to 34050:

34001. Tom Curtis at 07:21 AM on 27 September 2014
       Your questions on climate sensitivity answered
       

       Russ R @1:

       1) You say "all estimates derived from recent temperature observations, which are consistently lower than those derived from paleo proxy data or computer models" as if it were actually true.  In fact, many estimates based on the instrumental record are as high as or higher than those from the paleo record and computer models.  On average, those from the instrumental record are slightly lower.  Perhaps more germain, the estimates from the instrumental record that you read are biased low due to your sources of information.  But neither of these facts make your assertion true.

       

       2)  You are correct that climate sensitivity is "not a thing" (though neither is g).  Major changes in continental positions, changes in dominant ocean currents, changes in vegetation and rainfall patterns, and changes in GMST will all effect the the value of the climate sensitivity.  Therefore Paleo Climate estimates primarilly provide a sanity range.

       However, you do not think the consequences of that through.

       What it means is that the purportedly low climate sensitivity over the twentieth century is no gauranttee of a continuing low sensitivity into the future.  As global temperatures rise it becomes likely that the low climate sensitivity of recent times (if it is a fact) will revert to the higher non-glacial climate sensitivity from paleodata (ie, regress towards the mean) so that the final impact of anthropogenic forcings will be determined by that higher climate sensitivity than our purported valley.

       You argue against that based on an expected reduction in ice albedo feedback as the planet warms.  That expectation is correct, but there is also an expected increase in the strength of the water vapour feedback as the planet warms due to the Clasius-clapeyron relationship.  The ice albedo feedback is currently near a minimum and is very low compared to that during glacials (for example).  Any major warming, therefore, is likely to result in the increase in strength of the water vapour feedback dominating over the decrease in strength of the ice albedo feedback.

       You also appeal to uncertainty.  In decision making under risk, uncertainty is not your friend.  If your playing Russian Roulette, the game is not made safer if before each go, the gun is loaded with the result of the roll of a six sided die minus 2 cartridges.  On the contrary, the uncertainty makes the game even more foolhardy.  In this case, uncertainty may mean that nailing down the current ECS at a nice midrange 2.5 C does not gauranttee us that it will not have pushed out to 4 C by the end of this century.

       3)  Despite the increase in sea ice in the Antarctic, the decrease in sea ice in the Arctic is larger in magnitude, and the decrease in winter snowfall in the northern hemisphere is larger still.  The net effect is that most models underestimate the ice/snow albedo feedback rather than the reverse.

34002. JoeT at 07:00 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Tom, I was working on my own post and didn't see yours until I submitted it. I'm glad to see we both have the same conclusion.

34003. JoeT at 06:57 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Now that I went over Koonin's references, I think Tom's #8 is appropriate — the one he withdrew -— with bits of #9 thrown in as well. Post #8 is correct because Koonin really is looking at the downward radiation as the greenhouse effect, not the difference between the upward surface radiation and that at the top of the atmosphere. That's the difference between 342 w/m2from IPCC figure 2.11 and (398 - 239) = 159 w/m2. Then from SPM.5 (summary for policymakers) he takes the total anthropogenic forcing since 1750 of 2.29 w/m2. Then he does a net trick — he divides the 2.3 by 503 to get 0.0046, which indeed is less than 0.5% !!! That is he adds the incorrect 342 to the incoming solar radiation of 161 w/m2. Otherwise that number should really be 2.3/159 = 1.5%.

       
       Then he says assume by 2050 CO2 rises to 550 ppm. Then the increase in the forcing is 5.35 ln(550/400) = 1.7 w/m2. Add that to 2.3 and you get 4.0 w/m2 (Koonin says 3.9). Now 4/503 = 0.8%, so to get the 1-2% that he says in the WSJ, he must have taken 4/342 = 1.2%.

       
       Nowhere does he talk about sensitivity however and actual temperature change.

34004. Tom Curtis at 06:46 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       JoeT @28, thankyou for the sleuthing.  Given the footnote it becomes sadly apparent that I was right the first time.  I need to reinstate my comment @8, which discusses this misunderstanding, and withdraw my comment @9 (which while technically accurate, does not discuss Koonin's opinion).

       So specifically:

       1)  Koonin misrepresents the greenhouse effect as simply a function of backradiation.  That interpretation of the greenhouse is false, and has been known to be false for well over three quarters of a century.  In scientific terms, it is like criticizing the planning of the apollo missions because they will not work based on Aristotelian physics.  It is flat earth society material.

       As I said @8, "at base Koonan's claim is based on a simple misunderstanding that shows he completely misunderstands the nature of the greenhouse effect, or that he is completely dishonest, or that he is simply parroting memes provided by others without understanding what the mean and what they are related to. The science really is settled on this one, so there is no fourth option."

       2)  Although Koonin mentions the solar radiation, he appears to be caclulating his percentage from the 390 W/m^2 of thermal radiation (back radiation).  If he wanted to calculate the actual difference in backradiation, however, he ought to include the increase from feedbacks (WV and clouds) as well.  The total effect is an increase of approximately 20 W/m^2 (at equilibrium), or approximately 5% of the total back radiation at the surface.

       3)  Koonin does not even calculate the direct effect of the increase in CO2 accurately.  He appears to add the difference in radiative forcing for the change in CO2 (approx from the current 400 to the future 550 ppmv) to the current total anthropogenic forcing.  By excluding any changes in anthropogenic forcing other than that from CO2 he understates the change in anthropogenic forcing by mid century.  However, he does not state that he is discussing the change in anthropogenic forcing, but in the contribution of CO2 to the greenhouse effect, which makes it peculiar that he should us total anthropogenic up to 2011.  This does not, however, make any difference to his 1-2% value.

       Further, Keenan uses the TOA radiative forcing, not the change in CO2 contribution to the back radiation.  The two are distinct values both because of the higher temperatures and because overlaps with H2O are more significant for back radiation.  Again, this may not make a difference to the 1-2% estimate (due to the overlaps) - but Koonan does not know that.  The values he uses are not relevant to the percentage he estimates (which is  in turn irrelevant to the strength of the greenhouse effect).

34005. Russ R. at 06:21 AM on 27 September 2014
       Your questions on climate sensitivity answered
       

       There are a couple of points I'd make about Lewis & Curry's 1.64 degree C estimate of ECS (and by extension, all estimates derived from recent temperature observations, which are consistently lower than those derived from paleo proxy data or computer models).

       First, and most importantly, climate sensitivity is not really "a thing", in that it's not some fundamental, unchanging constant of the planet (like g= 9.8m/s²). Climate sensitivity is the sum total of a whole array of forcing and feedback mechanisms, which are themselves not constants. So, ECS isn't always going to equal 3.0, or 1.64 or some other fixed value. It can (and very likely will) vary under differing climactic conditions as those underlying forcing and feedback mechanisms vary. Treating ECS like a constant is a useful shorthand for back-of-the-envelope estimates, but it's nowhere close to a law of physics.

       As a simple example, consider Ice Albedo feedback. It only applies at the transition zone of polar ice extent (it has no effect in places that are permanetly frozen nor permanently ice-free), and as that ice extent retreats to higher latitudes with less surface area and insolation, the magnitude of IA feedback weakens, ultimately to zero. So, all else equal, you'd expect net feedback (and ultimately ECS) to be higher at the peak of an ice age vs. during an interglacial period. But all else won't be equal... other feedback mechanisms will each have their own dynamics, the sum total of which is unlikely to remain a constant. As such, different methods of estimation (paleo proxy measures vs current observations) might yield markedly different findings, and both can be entirely correct about the conditions that they measured. So evidence that ECS was 4 degrees Celsius in the distant geological past does not contradict evidence that ECS was 1.6 degrees Celsius in the very recent past. Furthermore, if ECS is not a linear constant, then extrapolations about the future become increasingly uncertain the further out you project.

       Second, models all very sensibly assume ice albedo feedback is positive (i.e. warming causes polar ice to retreat, which causes more sunlight to be absorbed, which causes more warming.) To just about everyone's surprise, for the last couple of decades, the southern hemisphere has experienced the exact oppposite... ice extent has increased in the face of warming, acting as a damper rather than amplifier (i.e. a source of negative feedback rather than positive) which would lower . Nobody can say for certain why this has occurred (there are several good theories), or for how much longer it will continue to happen, but in the long term, the anomaly should reverse and warming should lead to less ice and positive feedback. Looking at the recent temperature record, this anomaly will "contaminate" observations, and likely lead to discrepancies between observation based estimates of ECS and model based estimates. So evidence that ECS was 1.64 degrees C in the recent past does not contradict models that estimate ECS at 3.0 degrees C for the near future.

       Moderator Response:

       [Rob P] - There are no 'recent observations' for ocean heat content back in the 19th century. All these energy budget approaches have to use modelled estimates for that time period. 

        

34006. KR at 03:45 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       JoeT - Thank you, that explains much about Koonin's statements. 

       Koonin expressing anthropogenic forcings as "1 to 2%" of insolation is akin to graphing the 0.9C warming over the last 150-200 years as Kelvin degrees with a baseline of oK - which has been done by denialists multiple times, appallingly enough. See Denial Depot for a rather amusing explanation of how this is done. He might as well have characterized the height difference between basketball player Yao Ming and a lawn gnome using a percentage of the height of the Empire State building. 

       In doing so Koomin is rather deceptively minimizing the extent of the changes, which at this time have increased temperatures to or beyond the peak value at any time in the Holocene, at any time during human civilization (Marcott et al 2013) - with more unrealized warming to come. That's a more realistic scale, one that more clearly describes how these changes will affect us. 

34007. JoeT at 02:27 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Tom Curtis,

       Thanks very much for replying to my question regarding Koonin's statement. I'm still trying to understand it better. I finally came across an article with footnotes in which Koonin explains his reasoning on the CUSP website of which Koonin is the director . Here is the relevant passage:

       [1] AR5 WG1 Figure 2.11 shows the global radiative balance, with the total downward flux on the Earth’s surface estimated as 503 ± 7 W/m2
       (161 W/m2 solar + 342 W/m2 thermal). AR5 Figure SPM.4 shows the total anthropogenic direct perturbation of this balance to be some 2.3 ±
       1 W/ m2, less than 0.5% of the downward flux. If the atmospheric concentration of CO2 were to rise to 550 ppm with all other anthropogenic effects unchanged, this perturbation would rise to be 3.9 W/ m2.

       I'm hoping that you might comment further. Thanks again!

34008. One Planet Only Forever at 01:01 AM on 27 September 2014
       2014 Arctic Sea Ice Extent Prediction
       

       Looks like about 5.2 for the September average. So most predictions were low, and many of them significantly low.

       My oops about this being the 5th lowest. I didn't count the dashed line of 2012 on the NSIDC interactive chart.

       It would appear that predicting annual values needs much more reliable prediction of many difficult to forecast factors. Like many other climate related things, the longer term trend is much easier to predict.

34009. MA Rodger at 19:36 PM on 26 September 2014
       Antarctica is gaining ice
       

       Of course, we all make mistakes. Indeed, I managed to trip over a decimal point myself @289 by converting 1.9cm into 19cm. The trick is to correct mistakes and not compound them.

       jetfuel @291.

       Your explanation for where you obtained your numbers is helpful but it also indicates that you are entirely inattentive to what the numbers you present here actually represent.

       @291 for instance you say that @279 I have "a graph showing only 58 Gt per year loss." This you apparently consider as "only 58 Gt pa" because you are comparing it with the preceeding quoted sentence "According to these studies, the rate of ice mass loss from Antarctica has increased progressively over the past decade and, between 2010 and 2012, fell in the approximate central range 105 to 130 Gt yr−1."

       What you fail to appreciate here is that the graph reproduced @279 is Figure 5 from Willams et al (2014). This source is made palin @279 and you will note that in the quote you present @291, one of "these studies" helpfully listed by the quote is the very same Williams et al (2014). Hey, and guess what? A quick regression of the Williams et al. data for 2010-12 yields 107 Gt/yr. You of course are quoting the average for 2003-12 which will be different if there is an acceleration involved which there obviously is.

       You are also wrong @291 suggesting the 105-130 figure came from this discussion thread. I see no sign of it prior to you introducing it @282.

       And "these studies" do not determine "the snow/ice layer boundary depth" as your comment suggests. "These studies" use GRACE gravity measurements.

       And you may take comfort that such a small proportion of Antarctica is melting away each year but the point is not to preserve Antarctica as a frozen continent. It is to prevent damaging SLR. If Antarctica were to melt to nothing (and the way humanity is acting, that is not so silly on a multi-century time scale) it wound drown 90% of present human endeavour.

       You are probably at liberty to call the NOAA "a bunch of idiots". They likely get called worse fro time to time. But it is you that is wrong in saying the NOAA is "wrong". Their quote of a record breaking August this year is helpfully accompanied by a graph illustrating the record which is thus obviously the record since 1979.

       

       And yes, we are all comforted that Antarctic Sea Ice is not yet showing  the slightest sign of collapse, but that does not make up for melting cryosphere everywhere else in the world. And perhaps, because Antarctic Sea Ice is not part of some grand global equasion, it is also off-topic in this comment thread.

34010. Tom Curtis at 10:37 AM on 26 September 2014
       Antarctica is gaining ice
       

       Sorry, Scaddenp, your mention of "significant" along with KR's discussion of statistical significance seems to have made my mind to skip a few lines and (I suspect) start teaching my grandma to suck eggs.  Just take my comment as a general comment with relevant information and ignore the fact that I addressed it to you.

34011. Tom Curtis at 10:33 AM on 26 September 2014
       Antarctica is gaining ice
       

       Scaddenp @292, Tamino made that claim a couple of years ago, when it was true.  Since then Antarctic sea ice has continued to expand and the expansion is now statistically significant, and was in most of 2013 as well:

       

       Indeed, by pixel count, the Antarctic sea ice extent lies at approx 4 Standard Deviations above the mean for the satellite era.  Of course it is well below that of the pre-satellite era, and approx 10% below that of the 1960s as shown by HadISST (contrary to Jetfuel's claims above).

       Further, although is also a possibility of an error in baselining a transition between two satellite records that has been raised by Eisenmann et al (2014) and discussed by Tamino.  Even if accepted, which the NSIDC does not (I believe), that only accounts for 0.2 million square Km of the record, and the trend is still significant.  It does not place the satellite era record under threat.

34012. Tom Curtis at 10:20 AM on 26 September 2014
       Antarctica is gaining ice
       

       Jetfuel @291, McMillan et al's own finding about the rate of mass loss from 2010-2013 is 159 +/- 48 Gtonnes per year, as detailed in table 1, and also in the sentence immediately following that which you quote, and which reports other results.  That is 65% of the mass loss expected if we assume the 1.9 cm per year is all ice.  Ergo they have included both snow and ice loss in the calculation, and difficulty distinguishing between the two accounts for the increased uncertainty in the mass figure relative to the altitude figure (30% vs 10%).

       In your post @282 you wrote:

       "The paper does state that for the period from 2010 to 2013, the avg ice level is falling at 1.9 cm per year and that there is a 105-130 Gt per yr loss of ice mass. Considering there are 30,000,000 Gt of ice there, and a single 2009 snowfall in East Antarctica deposited 200 Gt of snow, and the report stating that the vast majority of Antarctica is stable, forgive me for thinking that this years 1960'sish sea ice levels down there could have made West Antarctic land ice more stable. How many years of -100 Gt per year until we can round 30 million down to 29.9? 10 centuries by my math."

       And here is the relevant quote from the paper:

       "At the continental scale, the most recent estimates of Antarctic ice sheet mass balance are based solely on satellite gravimetry surveys [Barletta and Bordoni, 2013; Velicogna and Wahr, 2013; Williams et al., 2014]. According to these studies, the rate of ice mass loss from Antarctica has increased progressively over the past decade and, between 2010 and 2012, fell in the approximate central range 105 to 130 Gt yr−1.Our survey puts the contemporary rate of Antarctic ice sheet mass loss at 159 ± 48 Gt yr−1, a value that, although larger, is nevertheless consistent given the spread of the gravimetry-based uncertainties (16 to 80 Gt yr−1). A possible explanation for the discrepancy is the exceptional snowfall event of 2009, which saw an additional ~200 Gt of mass deposited in East Antarctica [Boening et al., 2012; Lenaerts et al., 2013; Shepherd et al., 2012] that, although absent from the CryoSat-2 record, does factor in the gravimetry-based estimates of imbalance. "

       I have italicized your quote @291, from which you also derived the total figures @282.  I have bolded the sentence which reports McMillan et al's own result.  The following sentence contains the only mention of the 200 Gt snowfall in 2009 in the paper, a snowfall you have mentioned several times including @281.  Clearly you have read the paper's report of its own result for it lies immediately between two sentences you have clearly read.  Depite that you chose to report other paper's results rather than those of the paper under discussion, and what is worse, left the impression that you were quoting this paper's results when you did so.  This looks to me like a very open and shut case of deliberate misrepresentation of the paper.  How the moderators choose to view this clear dishonesty, and act on it is up to them.

34013. KR at 09:35 AM on 26 September 2014
       Antarctica is gaining ice
       

       Jetfuel - Yes, there is currently a small (barely statistically significant, IIRC) increase in Antarctic sea ice extent. 

       But this small increase, likely due to increased surface fresh water from land ice melt, increased halocline inhibiting mixing from (relatively) warmer deep water, and wind changes, is but a flyspeck on the wall compared to the observed mid-20th century 25% decline in sea ice extent (de la Mare 1997). 

       You seem to be repeatedly arguing that recent Antarctic sea ice extent is somehow contradictory to observations of a warming globe - and even leaving out the masses of evidence such as thermometers, the Arctic, growth zones, etc, focusing entirely on Antarctic sea ice extent, that's just nonsense. 

34014. scaddenp at 09:23 AM on 26 September 2014
       Antarctica is gaining ice
       

       Jetfuel - and your point is? We know the seaice is a record for recent times - if the conditions that create seaice trend continue, then upward trend will continue. So what? What do you see as the significance of this?

34015. jetfuel at 07:48 AM on 26 September 2014
       Antarctica is gaining ice
       

       I got the 1.9 cm from here in the report linked in michael sweet @273:

       "Results

       The CryoSat-2 observations confirm the continuation of existing signals of elevation change [Pritchard et al., 2009; Shepherd et al., 2002, 2012; Wingham et al., 1998; Zwally et al., 2005], identify regions which have evolved since previous surveys, and allow investigations of new terrain. Between 2010 and 2013, the average elevation of the Antarctic ice sheet fell by 1.9 ± 0.2 cm yr−1. Although most of the observed changes are smaller than expected fluctuations in snowfall (Table 1), those that are not coincide with areas of known dynamical imbalance (basins 13, 18, and 20 to 22) or with episodes of anomalous snow accumulation (basin 6) [Lenaerts et al., 2013]."

       And quoting from the discussion section, I got the 105-130 Gt numbers:

       "At the continental scale, the most recent estimates of Antarctic ice sheet mass balance are based solely on satellite gravimetry surveys [Barletta and Bordoni, 2013; Velicogna and Wahr, 2013; Williams et al., 2014]. According to these studies, the rate of ice mass loss from Antarctica has increased progressively over the past decade and, between 2010 and 2012, fell in the approximate central range 105 to 130 Gt yr−1"

       MA Rodger @279 has a graph showing only 58 Gt per year loss. I am impressed that the snow/ice layer boundary depth can be determined by a satelite, and I am assuming they are ignoring the snow. I had been pondering the 1.9 cm per year ice depth loss as not much at the point where the ice is 13,200 feet thick, but as an avg across the entire continent, is seems like a lot and now i read it is way off base. ratioing the 58 to 2660 Gt calcs above, I convert the 1.9 cm to 4 mm of ice mass loss spread across the entire continent. Of course, 4 mm is an average and the concern is at the places that are falling at 9 m per year.

       I'm sure there are easily a dozen different sources stating that this year is setting records. Me and NBC aren't the only ones getting it wrong. In this case, I'm in with a bunch of other idiots who are getting it wrong. From NOAA in August this year (2014): "This was the largest August Antarctic sea ice extent on record, surpassing the previous record set just last year"

       I compared the Nimbus 1 data from 1964 with this week's extent and there are plenty of areas that have farther reaching sea ice now than then, out off Ross Sea for instance.. Granted, it is a crude comparison, roughly scaling maps from Charctic, and there are areas of greater extent from 1964.

34016. Tom Curtis at 06:39 AM on 26 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       ChrisK @26, I worked out the figures using the total forcings.  To convert to temperature change by 2050, you need to multiply by 0.4-0.55 to convert to the Transient Climate Response.  Hence, 0.4-0.55 C based on the figures I used.  (Those figures were based on eyeballing a graph, and so are not exact.  They are merely close enough for reverse engineering Koonin's claim, I think.)  

       If the change in forcing has time to reach equilbrium, the effect will be closer to 0.75 C, but that ignores the fact that we are not currently at equilibrium, so that there is another approx 0.5 C already in the pipeline.  That then works out as about 3.8% of the current total greenhouse effect in temperature at equilibrium.  As that total greenhouse effect is an equilibrium figure, you should compare equilibrium temperature estimates.

       That figure, is lower than the equivalent figure calculated in terms of forcing because (a) it ignores the Earth System Response which is also incorporated in the total greenhouse effect figure; and (b) as the temperature rises there is a smaller rise in temperature for each W/m^2 additional forcing.  (It is near linear over the range of forcings expected in the near future, but not over the total greenhouse effect.)

34017. ChrisK at 06:19 AM on 26 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Tom Curtis@9: I am still puzzled by the "1 or 2%" in Koonin's editorial.  I have thought that the total greenhouse effect is about 35C and is not that what he means?  (Not that the average reader would know or think that.)  However, if you say it would really be 5 or 10%, 1.75 or 3.5C more by 2050 sounds, too high and he is talking about the change from now until then, as I read it.  0.35 or 0.7C more by 2050 would seem to be more in the ball park.  I am wondering whether these numbers are reasonable.

34018. Tom Curtis at 04:45 AM on 26 September 2014
       It's cooling
       

       Alterna @255:

       1)  The Earth continues to warm as measured by Global Mean Surface Temperature (GMST).  The so called "hiatus" refers to the fact that taken over short time periods, the trend in GMST is not distinguishable from zero.  However, it is also not distinguishable from the IPCC projected rate of warming.  If the former fact means there is no warming, then by parity of reasoning the later fact must mean we are warming at the IPCC predicted rate. That reasoning leads directly to a contradiction.  The correct interpretation is that by our best estimate we are warming at a slightly reduced rate relative to prior periods, but that because of the short term nature of the trend, we are unsure how much the trend has reduced or increased.

       2)  The unstated assumption of the talk about a "hiatus" is that 1998 (the pivotal year for claims of a hiatus) was a year with a normal, or near normal temperature.  If it was not so, determining trends from 1998, or near to but including 1998 is equivalent to a survey claiming the land slopes down as you go inland because most of the land is below the pinacle of a large hill on the coastline.   In fact, 1998 was far above the temperature trend of the time, and from 1998 it is not until 2010 that temperatures fall persistently the 1970-1998 trend, as illustrated below:

       

       Of the years falling below the trend after 1998, all have a low MEI score, indicateing La Nina like (or at best neutral) conditions.  Using the SOI they are even more strongly La Nina like years.  Given this the most natural interpretation is that the ongoing trend since 1970 has continued unabated, and that the "hiatus" is purely an artifact of a transition from a record breaking (or near record breaking, depending on index used) El Nino to a near record breaking (or record breaking, again depending on index) La Nina in 2011/12.  If anything, the surprise is why 2011/12 were so close to the continuation of the trend.

       

       The ENSO explanation of the pause is very simply confirmed by seperately taking the trends of El Nino, Neutral, and La Nina years:

       

       The near exact agreement of the trends show that it is the primary explanation of the phenomenon.

       It is also essentially the same explanation as the idea that the heat has been moved into the ocean (that being the effect of a shift from El Nino to La Nina).

       3)  There is also good, and independent indications of reduced forcings over the later half of the purported "hiatus".  There is no reason why these two explanations should be contradictory.  For all we know, temperature trends may have accelerated without a reduction in forcing, and the ENSO impact.  Taking the two sets of information at face value, it would have.  We therefore need to judge the evidence of the reduced forcings on its merits and not assume that it somehow renders the ENSO explanation invalid.

34019. Tom Curtis at 04:19 AM on 26 September 2014
       Antarctica is gaining ice
       

       Composer 99 @287, the first to papers you link to study late quaternary (ie, 2.6 million years ago to present) fluctuations.  As such they mainly report differences in sea ice extent between glacials and interglacials.  Not having read more than the abstracts, I cannot comment on how accurate they are for distinguishing differences in Holocene sea ice extent.

       Perhaps more usefull are the proxy studies using MSA in ice cores, which show regional variations in Antarctic sea ice extent.  Thus we have Curran et al (2003) showing Antarctic sea ice extent of East Antarctica near Law Dome (80 to 140 degrees Longitude).

34020. Alterna at 03:34 AM on 26 September 2014
       It's cooling
       

       This posts suggests that surface temps are not increasing because the energy is going to another part of earth's energy budget (the ocean). I've also seen the Kaufman, et al. arguments (http://www.pnas.org/content/108/29/11790.full) that the 'pause' in warming is due to less energy entering our system due to a variety of reasons. I'm trying to reconcile the two competing ideas: hidden warming (ocean) versus no actual warming. Can anyone shed light on the current thinking regarding these ideas?

34021. Tom Curtis at 02:48 AM on 26 September 2014
       The 97% v the 3% – just how much global warming are humans causing?
       

       CBDunkerson @108, as a purely technical point, I get uncomfortable calling percentages of agreement below 90% a "consensus".  Calling the level of scientific agreement that AGW is likely very harmfull a "super majority", however, underplays the level of agreement considerably and gives a poorer idea of the level of agreement than calling it a "consensus".

       More importantly, I did not raise a trivial point.  It is important to recognize the difference between rational, and irrational disagreement.  Scientists and economists, for example, can rationally disagree with the proposition that BAU over the coming century will likely result in harmfull global warming.  That is, there can be rational disagreement with AGW as I have defined it.

       I do not think, however, that anybody given current evidence can rationaly disagree with the proposition that BAU over the coming century has a significant risk of resulting in harmful global warming.  Nor indeed, can we rationally disagree with the proposition that BAU over the coming century may not inevitably result in harmful global warming.  From the IPCC assessments, the lower limit of the likely range for ECS combined with the lower limit of the likey range for risk assessments yields a scenario with minimum harm (and just possibly net beneficial) with a roughly 5% probability of occuring.  (With equal probability, of course, we will have a near total disaster.)  I do not consider those like Hansen who are on the upper end of those limits, and should not consider those like Tol (at least Tol a few years ago) on the lower edge.

       In this respect, disagreement about how dangerous global warming will be is quite unlike disagreement about the probability of warming itself with BAU.

       As to "intrinsic" and "closely", while your definition of "intrinsic" is correct, the fact is that judgements of harmfulness and the science of impacts goes well beyond the science of attribution, projections of forcings and determining TCR and ECS.  The judgement of whether or not global warming will be harmful is no more intrinsic to the judgement that it will occur than the judgement that an explosive is harmful is intrinsic to the chemistry of the explosive reaction.

34022. Tom Curtis at 02:25 AM on 26 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Tony W @23, Albert Bartlett's mathematics is correct, but he applies it to the wrong quantities.  At least, he applies it to the wrong quantities for projecting potential future growth, although not for busting some of the absurd things that have been said about sustainability of growth based on fossil fuel use.

       The reason I can say that is that fossil fuel use is not a primary good.  It is not something we do for the pleasure of doing it itself (unless your a Top Gear presenter).  Rather, it is something we do to obtain the means to do something else, ie, to cook food, to be warm in winter and cool in summer, to communicate with the world over the internet etc.  Energy use is itself not a primary good, but it is a at least one step up the chain.

       So, Bartlett's lesson needs to be applied to energy use, and energy consumption if you want to recognize the true limits on growth.

       To start doing, so the total energy production of the human race amounts to the equivalent of 0.028 W/m^2.  That level of energy generation is not considered a problem in terms of global warming.  It follows that if we replaced fossil fuel energy production by some form of nuclear energy production, we could  fully supply the world's current needs, and potentially double it without creating more than local problems with regard to waste heat.  Unlike the case with fossil fuels, that is production which is sustainable in the sense that the fuels can be sustained for thousands of years, or at least they can with breeder cycles.

       That may not be desirable from your point of view.  It is, IMO, far preferable to falling back to human and animal power as the only sustainers of our civilazation for the simple reason that doing so will not sustain our civilization, and will not leave the surpluss of resources that is required for growth of knowledge and the bettering of the human condition.

       More importantly, however, 0.028 W/m^2 is just 0.012% of total solar power incident on the Earth's surface (allowing for no change in albedo).  Taping solar energy allows us to not just replace fossil fuel energy but to meet the energy needs of the probably (not quite) doubling of the human population of the comming century, while lifting global energy use per capita by a factor of 10 to allow the third world to grow economically, and still use only 1% of the global surface for power at 25% efficiency (or 2% at 12.5% efficiency).

       Looking at total available energy resources, therefore, we are not even close to the limits on growth.

       That does not mean solar energy is a formula for unlimited growth.  It is clearly not, and probably allows for continuing growth for another century or two.  In a century or two, of course, it may be possible to sustain further growth by moving factories, and food production of world to make use of more sunlight.  (Simply directing further sunlight at Earth with mirrors creates the same waste heat problem as nuclear.)  At its limit, such a process finishes with the construction of a Dyson swarm (or something further up the technological chain to the limit of a Dyson sphere).   Such a process can expand our civilizations potential energy use (and equivalent food production capacity) by a factor of 100 or more over current solar input to the Earth.  We need not move other suns to the Solar system (as per Bartlett's thoughtless ridicule), but merely use more of the Sun's total energy output - a process with a limit of approximately 2 billion times the Sun's current energy output (or using only 1% for energy 80 billion times our current energy usage.

       I do not know whether or not that will be technically feasible or desirable.  That is a decision for a later generation.  What I do know is that growth need not, and should not stop now, nor until the rest of the world enjoys a reasonable approximation of current typical western standards of living.  And I know that the later is quite possible using solar power.

34023. KR at 00:11 AM on 26 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       TonyW - BC is a significant example in that their introduction of a carbon tax and it's lack of effect on GDP growth indicates that it is indeed possible to grow the economy and address climate change. 

       I agree that it's difficult to extrapolate from a single region to all situations, but I feel that BC's tax demonstrates a very promising strategy. 

       Moreover, there is reason to believe that GDP growth and energy consumption are not inextricably linked - Huang et al 2008, for example, found that there was no relationship for low-income countries, a positive correlation for middle-income countries (growth leading energy use, not the other way around), and actually a negative correlation for high-income countries; GDP growth from conservation and energy efficiency. I wouldn't consider that the last word on the subject, but it's pretty clear that the growth/energy linkage isn't as strong as many right-wing pundits would claim. 

34024. CBDunkerson at 23:53 PM on 25 September 2014
       The 97% v the 3% – just how much global warming are humans causing?
       

       Tom, sure the level of consensus is slightly lower... but still very high and far far from the 'no consensus' view some 'skeptics' push.

       Whether they are "intrinsically" or "closely" connected seems likely to be a largely semantic argument. Indeed, I'd actually describe 'closely connected' as suggesting a stronger link... 'intrinsically' just means that the connection between the two is 'inherent in their nature'. That is, most of the science underlying the two is the same, so anyone familiar with the facts behind one is also familiar with most of the facts behind the other... an intrinsic / natural connection.

34025. Firgoose at 22:09 PM on 25 September 2014
       97 Hours of Consensus reaches millions
       

       @John: Talking of personal, or perhaps it's more personable, I really love the way that a 97's hand shoots up and their face lights up, with the smile turning into a big "Me, me! I know the answer!" grin. :-D

       And the way that the 3%, having nothing to contribute, frown and avert their eyes. Nice touch! ;-)

       You say that "second time around, we'll do things a little differently". Does this mean reusing the same animation or are you planning something different?

       One other small question. Maybe I missed it somewhere but what does "nsh" stand for? Is it supposed to be lowercase? With my eyesight I kept seeing is as the equally mysterious "rish".

       Response:

       [JC] nsh - ninety seven hours

       Like any riddle, obvious in hindsight :-)

34026. MA Rodger at 20:26 PM on 25 September 2014
       Antarctica is gaining ice
       

       I was intrigued by jetfuel's comment @282 concerning McMillan et al (2014):-

       "I did read it, and the bold quote of Tom's from the paper is not visible to me in the report.   ...   The paper does state that for the period from 2010 to 2013, the avg ice level is falling at 1.9 cm per year and that there is a 105-130 Gt per yr loss of ice mass."

       How to make sense of that? The quote is apparently quite promanent within the "report" (as quoted @284) and, with Antarctica being 14 million sq km, an annual 1.9cm fall in ice level would of course result annually in 7mm SLR and 2,660 Gt mass loss. Further the 105-130 Gt figure is not the finding of McMillan et al. and also is not specifically for the period "from 2010 to 2013." This comment from jetfuel is totally nonsensical, something not of this planet.
       And so it proved.
       I tracked down only one potential source and that is where you would expect to find it - the planet Wattsupia. There, back in May, they gathered all the populus at the feet of an idiot called Larry Hamlin who was greatly angered by the reporting provided by The Guardian about McMillan et al. It is Loony Larry who quotes from McMillan et al. in which he doesn't provide sight of the "bold qulte from Tom." However the 105-130 GRACE figures appear, as does the mention of "the exceptional snowfall event of 2009, which saw an additional ~200 Gt of mass deposited in East Antarctica," just as jetfuel has been banging on about down this thread. And while the "falling at 1.9cm per year" is absent, a 0.19mm SLR contribution is mentioned which presents a possible source of a grossly misquoted figure.

       And if anyone is in the slightest bit interested by Loony Larry's thesis, it can be summarised thus:- The Guardian is outrageously alarmist. There is no "doubling" of ice loss and obviously so. Does not McMillan et al. state that it' findings are "consistent" with other studies, so it can't have found a doubling. The Guardian confuse "two distinct issues." The "doubling" is not the rate of ice loss but the SLR contribution which has doubled from 0.19mm pa to 0.45mm pa. Of course Loony Larry says it better than I do. When I summarise his argument, I seem to make him sound like a congenital idiot.

34027. michael sweet at 20:05 PM on 25 September 2014
       Antarctica is gaining ice
       

       Jetfuel,

       It would be nice if we could use the rate of ice loss from three years ago as the rate loss for the future.  Unfortunately, the data MA Rodgers provided at 279 shows a continually increasing loss of ice.  You must include the rate of increase of ice loss.  Then we see that it will not be so long before Miami no longer drains after heavy rains.  Your fact free ramblings are not convincing.

34028. TonyW at 15:18 PM on 25 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       CBDunkerson

       Albert Bartlett's lecture can never go out of date (other than the data used to illustrate points) because it's based on maths and physical realities. Growth destroys the environment, as we've seen, but growth can't continue indefinitely, even if we could figure out how to grow without destroying the environment. The price of solar energy is irrelevant to this, though I doubt the world could convert to solar, due to resource issues and emissions of solar panel production. If it could, the world would have to operate on a much lower EROEI, so growth would end anyway. Kevin Anderson's analysis hasn't been shown to be in error either. By 2020, it will be obvious that either nothing will be done about the problem or that doing something about it unacceptably harms economic growth.

       KR,

       As I understand it British Columbia was already on a downward track with emissions, before introducing that tax, so it's unclear what the impact of the tax has been, or how it has affected emissions in surrounding regions. However, BC is not the world. I'd welcome a revenue neutral carbon tax but it isn't likely, on it's own, to reduce emissions by the 10% per year needed to have half a chance (not 100% chance) of not exceeding the very dangerous level of 2C, though we'd breeze through the dangerous level of 1C.

34029. ubrew12 at 15:03 PM on 25 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Tom Curtis@9:  You said "So, by mid century the direct increase may be only 1 or 2%, but the total increase as a result of that direct increase will be a 5 - 10% increase in the total greenhouse effect... So, Koonan is not incorrect per se, but his claim is framed to cultivate confusion"  And where might we find that confusion first expressed, and most loudly, for the viewing public?  Today on Faux News (2:39 of a 5min video).  

       Gee, that didn't take long...

34030. Composer99 at 12:55 PM on 25 September 2014
       Antarctica is gaining ice
       

       Tom Curtis @285: Deniers making themselves look the fool is well and good, however enough exposure to the same commenter who trots out the same shtick, over and over, eventually just wears out my patience.

       Skeptical Science does a good job of not being overrun with deniers in the comments (as compared to, say, dana1981's blog at The Guardian) but even so I am sure I am safe in assuming there will be no shortage of deniers posting here to maintain a more-or-less constant flow of foolishness (to say nothing of any foolishness posted by yours truly).

       -----

       To keep this comment on topic, I did a Google Scholar search with the terms 'antarctic sea ice history' and found a few papers that might be of interest when it comes to Antarctic sea ice and its extent (especially in light of jetfuel's claims with respect to same):

       - Gersonde and Zielinski 2000 (link), which reconstructs Antarctic sea ice during the late Quarternary 

       - Crosta et al 2004 (link), which does the same in a geographically limited area (the Southern Ocean - Indian Ocean boundary, effectively)

       - Rayner et al 2003, already referred to by Tom Curtis upthread (via Tamino - Tamino's blog post has a link to the paper).

       These papers are unfortunately behind paywalls for me, but as I said they may be of interest when thinking about the current state of Antarctic sea ice, especially any part of the G&Z and Crosta reconstructions occurring in the Holocene.

       My apologies in advance if someone else has already shared one or both papers in a previous comment on this thread. (I have performed a cursory search and believe that not to be the case, though.)

34031. scaddenp at 12:03 PM on 25 September 2014
       Antarctica is gaining ice
       

       Jetfuel has still not actually revealed what point he is trying to make. Obviously the increasing sea ice around Antarctica is significant for him but he has failed to communicate why. The latest seems to be because the trend has continued, somehow a contributing factor (ice sheet melt) must have stopped. This is consistant with other behaviour that places enormous significance on an individual point rather but ignores the trend (eg 2009 ice fall is latest but see also the cherry picking here). Comment 282 would imply he either hasnt looked at or doesnt understand the graphs helpfully posted by MA Rodgers. Unless jetfuel actually articulates his case, I dont think there is much point continuing. We just see repetition and a complete resistance to learning anything.

34032. Tom Curtis at 11:25 AM on 25 September 2014
       Antarctica is gaining ice
       

       Composer 99 @283, I take it then, you do not subscribe to the theory that deniers making themselves look utterly stupid is not a good antidote to the disease in other readers?

34033. Tom Curtis at 11:24 AM on 25 September 2014
       Antarctica is gaining ice
       

       jetfuel @282, googling a sentence is not the same as reading the article.  Nor is failing to read the article is not evidence a sentenc is not in that article.  It is only evidence that your approach is evidence free.  For your benefit, however, here is the sentence with sufficient context to easilly locate it within the article:

       "Introduction

       
       With a capacity to resolve detailed patterns of elevation change at the scale of glacier drainage basins [Shepherd et al., 2002; Davis and Ferguson, 2004; Pritchard et al., 2009; Remy and Parouty, 2009; Shepherd et al., 2004; Wingham et al., 2006; Zwally et al., 2005], repeat satellite altimetry has transformed our ability to study the polar ice sheets. Nevertheless, direct measurements of elevation change have been restricted by the latitudinal limits of satellite altimeter orbits (81.5° and 86.0° for conventional radar and laser systems, respectively), by the reduced performance of conventional radar altimeters over the steep terrain that is typical of ice sheet margins and by the irregular temporal sampling of satellite laser altimeter data due to the episodic nature of ICESat mission campaigns and due to the presence of clouds. These limitations have precluded, for example, comprehensive assessments of Antarctic Peninsula volume change, and altimeter data omission may also explain differences in mass balance estimates for other ice sheet regions [Shepherd et al., 2012]. CryoSat-2 was designed to overcome several of the limiting factors that previous satellite altimeters faced, with an orbital limit extending to 88° and a novel synthetic aperture radar interferometry mode providing measurements of fine spatial resolution in areas of steep terrain [Wingham et al., 2006]. Here we use CryoSat-2 data acquired between November 2010 and September 2013 to produce the first altimeter-derived estimates of volume and mass change for the entire Antarctic ice sheet.

       Data and Methods

       ..."

       (Bolding of section headings in original, bolding of relevant sentence mine.)

       Jetfuel @281, your pet theory.

       That NBC made the same error as you six days after you made it does not prove you derived your theory from them.  Nor does NBC claiming something relating to science to be fact prove it is, given the notoriously poor standard of scientific reporting by MSM.

       Further, trying to score rhetorical points of a point where you have already acknowledged your error (@274) just makes you look silly.  Are you now trying to take that back (with a complete absence of relevant evidence)?  Or are you just trying to sow as much confusion as you can?  Either way you have just ratcheted your credibility another notch lower.

34034. Composer99 at 11:13 AM on 25 September 2014
       Antarctica is gaining ice
       

       I for one would say that jetfuel's 'science by news headline" in #281 and disingenuity in #282 are a sign that jetfuel has worn out his welcome.

34035. jetfuel at 11:01 AM on 25 September 2014
       Antarctica is gaining ice
       

       michaelsweet@280 says:

       "Thank you Tom.

       I note that Tom actually read the cited peer reviewed article. Jetfuel did not read the paper he was criticizing."

       I wasn't criticizing it. I did read it, and the bold quote of Tom's from the paper is not visible to me in the report. When I googled his quote, I got SS as result?

       The paper does state that for the period from 2010 to 2013, the avg ice level is falling at 1.9 cm per year and that there is a 105-130 Gt per yr loss of ice mass. Considering there are 30,000,000 Gt of ice there, and a single 2009 snowfall in East Antarctica deposited 200 Gt of snow, and the report stating that the vast majority of Antarctica is stable, forgive me for thinking that this years 1960'sish sea ice levels down there could have made West Antarctic land ice more stable. How many years of -100 Gt per year until we can round 30 million down to 29.9?  10 centuries by my math.

34036. jetfuel at 10:15 AM on 25 September 2014
       Antarctica is gaining ice
       

       tomcurtis@268 states: "So, Antarctic sea ice extent is in uncharted territory, but only if you are carefull not to look at charts that might bust your pet theory."

       per NBC news: "More sea ice than ever around Antarctica,"

       Whose Pet theory?

        

34037. bill4344 at 09:16 AM on 25 September 2014
       97 Hours of Consensus reaches millions
       

       Yes, this is a really nice piece of work! And the Richard Alley caricature is, indeed, the stand-out. Congratulations and I think you'll find there'll be a lot of people happy to find themselves in this pool of talent in the future (and a tiny handful who won't of course!)

34038. Pat O'Dea at 08:50 AM on 25 September 2014
       97 Hours of Consensus reaches millions
       

       Oscar Wilde once said; "If you tell people the truth they will hate you for it.

       But if you tell it to them with humour they will love you for it."

       Congrats for this marvelous initiative, to all those who worked on it and to all those scientists who participated.

       Keep up the good work.

34039. scaddenp at 05:46 AM on 25 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       As far as I can see Anderson's analysis is based on historical data for economies.  This is not a good guide to what will happen if you try a something completely different (eg a pigovian tax on carbon). As KR points out, you now have data from BC to back that position.

34040. PhilippeChantreau at 02:27 AM on 25 September 2014
       2014 SkS Weekly News Roundup #39A
       

       Worth mentioning inthis thread:

       http://www.lemonde.fr/planete/article/2014/09/24/les-pays-bas-vont-investir-20-milliards-d-euros-pour-lutter-contre-la-montee-des-eaux_4493548_3244.html

       "The Netherlands are going to invest 20 billion Euros to protect against the rise in sea level."

       Excerpt from the article: "About 9 million Dutch people live today in floodable areas of the kingdom, where are also concentrated 70 % of economic activity, sea ports and airports. Chemical plants, natural gas and nuclear installations are present as well and will be the subject of much strengthened protection measures. For public planners, the goal is to avoid a catastrophe that could threaten a potential revenue of about 2 trillion Euros."

       Non official translation by myself.

       It is my conviction that the arguments about how costly addressing the problem now would be have their numbers wrong.

       Moderator Response:

       [PS] Fixed link

34041. KR at 00:10 AM on 25 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       TonyW - British Columbia implemented a revenue-neutral carbon tax in 2008. A 5-year review found that the province had reduced carbon emissions by 17%, with no discernable difference in GDP growth from the rest of Canada. And as a result of the carbon tax they how have the lowest personal income taxes in the country. 

       Every economic change has winners and losers - the Montreal Protocol for CFC's and protecting the ozone layer is a good example. While some established CFC manufacturers lost out, the cost/benefit analyses of that phaseout range from 1:2 to 1:11 depending on assumptions, not even counting the effect of reducing GHGs or a number of economic benefits. This represented a significant boost to the world economy by removing numerous costs to fishing, agriculture, and health. 

       Every economic indication for revenue neutral carbon taxes is positive - and they represent perhaps the most organic and least bureaucratic method of correcting the current lack of accounting for the externalities in fossil fuels. 

34042. Johnb at 22:47 PM on 24 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       I only picked up yesterday from a Crikey column that News International's second largest stockholder is Saudi Prince Al- Waleed Bin Talal Al Saud, the Kingdom's wealthiest Prince. Saudi Arabia's official International position is not unalighned to the current News Corp editorial policy.

34043. Tom Curtis at 22:32 PM on 24 September 2014
       The 97% v the 3% – just how much global warming are humans causing?
       

       CBDunkerson @106, while I agree that they are closely connected, and that in fact BAU will be harmful, possibly catastrophically so, the fact remains that the consensus supporting the later is about 10% less than that supporting the former based on Bray and von Storch's surveys (which are the only ones to test it, SFAIK). "Intrinsically connected" overstates their relationship, IMO, in part because what counts as harmfull is partly subjective, and also because the evidence of future impacts is not so strong as that for current attribution.

34044. CBDunkerson at 21:45 PM on 24 September 2014
       The 97% v the 3% – just how much global warming are humans causing?
       

       The arguments about 'what the scientists in consensus XYZ really agreed to' exemplify a common denier mental block wherein they seem able to believe that each fact exists in isolation of all others.

       That is... they concede that the Cook et al study found a 97% consensus for human greenhouse gas emissions having caused most of the observed global warming... but then argue that there is no consensus that continuing those emissions will be harmful. Which is just plain illogical.

       If we accept that human greenhouse gas emissions have caused most of the observed warming to date then we know that future warming from continuation of the same factors will be harmful. It's like arguing, 'ok yes everyone agrees that smoking caused some people to die prematurely of cancer, but that doesn't mean that anyone agrees more smoking will lead to more cancer in the future'.

       In short, they're treating intrinsically connected things as completely separate. That's a level of crazy even the tobacco apologists never reached.

34045. CBDunkerson at 21:17 PM on 24 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       TonyW, you might want to check your facts before declaring people "delusional".

       http://newclimateeconomy.report/

       Kevin Anderson and Albert Bartlett are out of date. The price of solar energy has been dropping by 50% every few years. When you consider the economic benefits of stopping global warming (and ocean acidification), ending wars over fossil fuels, improving human health by reducing pollution, eliminating the massive global subsidies to the fossil fuel industry, et cetera... solar is already cheaper than any other major power source. Ergo, simply converting to solar will cause economic growth... and that's not even considering the near certainty that the cost of solar will fall by 50% again in the next few years... and another 50% within a few years after that. The costs of wind power and battery storage are also plummeting. It has been obvious to me for a few years now that these changes would inevitably make fossil fuels no longer cost competitive. Most economic analysts have now reached the same conclusions. Only the 'delusional' and mis-informed still argue otherwise... and by 2020 it should be obvious even to them.

34046. TonyW at 16:29 PM on 24 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       "For example, a revenue-neutral carbon tax could create jobs and grow the economy. Two recent studies by the New Climate Economy Project and the International Monetary Fund likewise found that reducing carbon pollution could grow the economy, as summarized by The Guardian."

       That's delusional. Growing the economy and tackling climate change are incompatible, as Kevin Anderson has shown. More broadly, economic growh destroys the environment, as the late Albert Bartlett so expertly pointed out.

34047. michael sweet at 08:54 AM on 24 September 2014
       Antarctica is gaining ice
       

       Thank you Tom.

       I note that Tom actually read the cited peer reviewed article.  Jetfuel did not read the paper he was criticizing.

34048. MA Rodger at 08:30 AM on 24 September 2014
       Antarctica is gaining ice
       

       Regarding recent ice loss data from Antarctica, I was surprised Figure 5 from Williams et al (2014) hasn't made its appearance on this comment thread yet. For the present on-going chatter, it doesn't advance the data beyond that mentioned by jetfuel @270 but it do allow sight of what is the actuality by way of, as jetfuel puts it @274, "Things can change significantly in one year," and perhaps may also stop the trolling on whether years are inclusive or exclusive to some time period.

       

34049. Tom Curtis at 07:35 AM on 24 September 2014
       Antarctica is gaining ice
       

       jetfuel @276, from McMillan et al (2014):

       "Here we use CryoSat-2 data acquired between November 2010 and September 2013 to produce the first altimeter-derived estimates of volume and mass change for the entire Antarctic ice sheet."

       CryoSat 2 was launched in April 2010, and became officially operation in October 2010.  The reason for the "overlap" in 2010 is simply that McMillan et al relied on earlier studies which extended into 2010.  It is not clear, however, that those studies extended their data up to include Nov 2010 in any event, in which case there is no overlap.

34050. scaddenp at 07:34 AM on 24 September 2014
       Antarctica is gaining ice
       

       Jetfuel, you seem to be implying that continuation of a predicted trend is somehow evidence for something new and different in Antarctica. Do you seriously believe that ice loss from the ice sheets has stopped? What is going to be your reaction to the next cryosat result? Do we get a retraction?

       Again, it would help if you would actually state the point you are trying to make here. Why are you so hung up on Antarctica sea ice?

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