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CBDunkerson at 21:07 PM on 11 February 2012Newcomers, Start Here
The fact that people can say false things (e.g. "this is all speculation") doesn't change the reality of well documented scientific research. There have now been numerous scientific studies published, including one just last week... and they all, including the ones done by skeptics, show the same overall results with minor variations... despite using different proxies and methods of analysis. When all available evidence and analysis says one thing and the 'skeptics' are reduced to having nothing but, 'how can we really know anything?', there really isn't any need to respond. Just ask whether it makes more sense to go with the conclusion reached by every single scientific study on the matter or those whose entire position is that they do not (and can not) know anything. Until the false 'skeptics' come up with some alternate theory / data there is nothing there to 'respond' to. -
debunked at 20:22 PM on 11 February 2012Newcomers, Start Here
@CBDunkerson and @Dikran Marsupial: I understand what you guys are saying and accept it as well. It's hard to convince anybody without facts especially those who are more cynical than sceptical. What be the best site or source to read up on the proxy records on temperature data? I remember watching Attenborough interview where he said if fungi didn't exist, the world would collapse. The response someone made to that was 'this is all speculation'. I suspect they could say the say about proxy records. That's the sort of thing I want more clarity on. I mean, how do you respond to that?! -
MangoChutney at 18:57 PM on 11 February 2012Monckton Myth #17: Debate vs. Denniss, Part 2
Anybody know if John Cook is going to challenge Monckton to a written debate? TIA -
dana1981 at 18:06 PM on 11 February 2012The Year After McLean - A Review of 2011 Global Temperatures
Not likely keith :-) It was also clear in July that his prediction was wrong, and yet he stood behind it at that point as well. -
keithpickering at 17:24 PM on 11 February 2012The Year After McLean - A Review of 2011 Global Temperatures
Dana, In fairness, we don't yet know whether McLean is still standing by his prediction or not. He says that his response will surprise us, so perhaps he will surprise us by admitting that he was wrong. -
Tom Curtis at 16:42 PM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
Norman @33, from Siebert et al 2010 (linked by you):"While the rising importance of groundwater withdrawals in global freshwater supply is well established, there is still a large uncertainty on the volumes and spatial distribution of both groundwater recharge and withdrawals. Using a global hydrological model, mean annual direct groundwater recharge was estimated at 12,600 km3 yr−1 which is about one third of the total renewable freshwater resources (Doll, 2009). However, this global estimate explicitly ¨ excludes indirect recharge resulting from runoff events and transmission losses. These indirect recharge processes are dominant in semi-arid and arid countries where interior or coastal alluvial plains receive high volumes of runoff from surrounding mountain fronts (Scanlon et al., 2007). The Tihama and Batinah coastal plains in Yemen and Oman are prime examples. Total groundwater withdrawals are estimated to be in the range 600–1100 km3yr−1or between one fifth and one third of the total global freshwater withdrawals (Doll, 2009; Shah et al., 2007; Zektser and Everett, 2004)."
(Emphasis added) So your own source indicates that discharge of ground water is from half to equal recharge of groundwater. That would indicate that changes in total groundwater inventory globally is either reducing the sea level, or having no effect. Granted that these figures have a "large uncertainty", so it is entirely possible that the net effect is actually to increase Sea Level, but you have not presented relevant evidence to that effect. You have only seemed to do so by presenting half the story. Your comment that "much of this irrigation is in arid regions with slow recharge rates for the aquifers" is irrelevant as we are discussing global, not regional balances. Aquifers can store more water over time, as well as less. Indeed, if recharge exceeds discharge, which on the evidence of your source it probably does, some aquifers must be increasing their storage. -
owl905 at 16:31 PM on 11 February 2012The Year After McLean - A Review of 2011 Global Temperatures
Add a skin to the trophy wall alongside Ricky Lintzen's 2004 NY Times statement that global warming stopped in 1998. For an encore, check Tony T. Watt's claim (somewhere around January 25th, 2011) that with Cycle 25 showing up as a whimper instead of a bang, 2022 would mark "The end of the Modern Warm Period." The tenants of Hothouse Earth are spending too much time distracted with how big the 'future fire' will or won't be. -
NASA Mission Takes Stock of Earth's Melting Land Ice
Norman - You are cherry-picking a single item from the article, and not considering the complete work. The conclusions you then draw from that practice are guaranteed to be incorrect. I strongly suggest that you look at Milly et al 2010 - Table 8.2, where they summarize all the data they present, not just single pieces, and from that conclude a net zero contribution. As well as Table 8.1, where they summarize the external constraints that limit any possible water use contribution to somewhere between 0.0 and 0.3 mm/yr, or a central value <1/20th observed sea level rise. Consider all the data. -
dana1981 at 16:25 PM on 11 February 2012Monckton Myth #17: Debate vs. Denniss, Part 1
Yes, we have seen Monckton's response and are in the process of preparing a response of our own. Keep an eye out for it next week. -
Tom Curtis at 16:24 PM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
Norman @31, yes, but it will add to surface waters at a rate of 5.92 units* per annum, not 6.22. By not quoting the net change you are distorting the picture. How much you may be distorting the picture is shown if we see past your cherry picking of the aquifer with the worst ratio of recharge rates to pump rates from your source. Looking at all Texas aquifers, the 1995 pump rates were 9.16 units per annum, while the recharge rate was 3.92 units per annum, for a net difference of 5.24 units per annum discharged from aquifers to the surface. The relevant ratio is 2.34 to 1, compared to your cherry picked 21 to 1. The point here is not that the Texas total can be scaled to the global figures. It is far too small a sample for that. The point is that unless you provide the figures for both discharge and recharge of aquifers, which you have failed to do, then you cannot determine the net effect on global sea levels. Some of the water will also be retained as increased surface soil moisture, increased moisture content in vegetation and increased humidity in the area of irrigation, but I assume that that is trivial in comparison. But you cannot make the assumption of triviality with regard to recharge rates. Note that I do not know the recharge rates. Globally they may also be trivial. But you need to either cite them to establish that, or to cite a peer reviewed source to that effect. Finally, a cherry pick which shifts the determined ration by almost an order of magnitude (8.9:1) is particularly egregious, and demands some explanation and, IMO, apology. It may be OK to knowingly publish misleading information at WUWT, but it is not acceptable here. * units not given in source. -
dana1981 at 16:23 PM on 11 February 2012The Year After McLean - A Review of 2011 Global Temperatures
Yes, making a testable prediction is laudable. However, continuing to stand behind that prediction when it is clearly wrong, not so much. -
Pierre-Normand at 16:13 PM on 11 February 2012The Year After McLean - A Review of 2011 Global Temperatures
McLean's methodology would satisfy Popper's criterion not just if he can derive testable predictions from it but also if he shows some proclivity, after some prediction was falsified, to discard the theory that his methodology rested upon. (One big weakness of Popper's framework, though, is that it's often unclear in particular cases if it might not be reasonable to cling to a theory that has yielded false predictions and rather revise some auxiliary hypothesis. This is a common occurrence in the history of science. But in the present case, it isn't obvious what mere auxiliary hypothesis could have thrown McLean off. It would be interesting to hear his explanation.) -
Norman at 16:02 PM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
KR @25 From the article you linked to. "Gornitz (2001) compiled estimates of mining rates for specific countries from various sources; those explicitly reported rates totaled about 61 km3/year (or 0.17 mm/year sea-level rise) both for recent years and for the last half-century. Gornitz extrapolated that value by assuming that the ratio of mining to total groundwater withdrawal was similar globally to what it was in the studied regions. Depending on the details of the extrapolation, this approach led to a wide range of estimates of 0.17–0.77 mm/year for the gross effect of groundwater mining on sea-level rise." The problem is the report I linked to (which does not seem to work now) states the deep ground water use for irrigation is 545 cubic kilometers of water a year (and rising) Try it here again. Groundwater use in irrigation -a global inventory. In your link it states that 61 km^3 is equivalent to a 0.17 mm/year sea rise. If the more correct figure for the acutal global amount of deep water being used for irrigation is 545 km^3 (and much of this irrigation is in arid regions with slow recharge rates for the aquifiers which is described in the link), that comes out to 8.93 times more than 61. If 61 is responsible for a 0.17 mm sea level rise per year, 8.93 times this amount would be equal to a sea level rise of 1.52 mm/year. Multiply this by 7,for the GRACE study years that gave melting ice as responsible for 12 mm rise in sea level and the deep water withdrawal (with very slow recharge rates), and you have an equivalent of 10.63 mm of total sea level rise from pulling water from aquifiers. -
NASA Mission Takes Stock of Earth's Melting Land Ice
muoncounter - The chapter from Milly et al 2010 notes that "water content of the global atmosphere (≈25 mm water equivalent) is tightly constrained thermodynamically", and therefore they consider the remaining water to either be on/in the land surfaces or in the ocean. Norman - My initial comment on this thread was in response to your mistaken statement that "...the water added to the system via irrigation is fairly close to the amount of water added by melting ice. Meaning the sea water will continue to rise regardless if the ice melting stops and the problems of the future will still remain." I believe I have referenced sufficient data to indicate that is incorrect - that our water usage (despite climate effects on local water availability) is not having any significant effect on SLR, that you are only looking at one side of the equation. Unless you have relevant comments and references indicating that Milly, Chao, and others, and their data, are somehow wrong, unless you can demonstrate that we have increased net flow to the oceans and hence affected SLR, I fail to see the point of chasing that particular red herring. And that includes external constraints on our net water flow - the contributions from thermal, haline, and ice melt to SLR severely limit the range of any additional anthro contribution. I believe the remainder of the discussion on aquifers versus physical impoundment versus redistribution of terrestrial water supplies is off topic in this thread. Perhaps you can take this to one of the discussions on climate change related droughts? -
PrezMulkeyUnity at 15:54 PM on 11 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
I have been directly involved in the hockey stick war. I have been been an active research ecologist for over 20 years, and during the last 10 years I have focused on climate change and its effects on living systems. During part of my recent career, I was employed as science advisor to the Century Commission for a Sustainable Florida, a legislatively mandated commission. In March of 2007, while giving an invited report on climate change to a select committee of the Florida legislature, a conservative legislator rose from his seat and declared me to be a liar and demanded that I be dismissed. Indeed, I was asked to step from the podium. Only one newspaper in the state carried the story, and my employers did not so much as apologize for my treatment. Democracy in action, right? My sin? I had shown the hockey stick. When I approached the legislator who had objected, I discovered that he did not know that the National Academy and reviewed Michael Mann's work and found it to be fundamentally sound. Indeed, it was not apparent that he even knew of the existence of the US National Academy. After the climate gate emails were released, the prestigious journal Nature referred to the push back from the oil soaked Irrational Right as a "street fight." I could not agree more. I have carefully read and evaluated Mann's work and I find it to be of the highest standards of scientific integrity. He has been vindicated by numerous reviews. Despite continued harassment, he continues to find time to do excellent research. I have the greatest respect for him as a colleague and role model. To date 32 national academies have endorsed the fundamental reality of human caused climate change. Numerous professional organizations have also made clear statements to support the mainstream science. 97% of all climate scientists agree. NSF, NASA, NOAA, USDA, the NPS, and the CDC have active research programs predicated on the reality of human-caused climate change. The clarity of the climate change threat could not be greater. It is most sobering to realize that our present emissions trajectory will result in a global average warming of over 5 degrees C by 2100. Such a planet will not sustain civilization in any recognizable form. The excess CO2 that is pumped into the air today will affect our planet for thousands of years into the future. I am not an alarmist, but I am alarmed. You should be too. I urge everyone to read Mann's book. It is well written and compelling. Any publishing scientist who reads it will likely be chilled to the bone. I have contributed to the climate scientist legal defense fund, and urge all of you to do the same. http://climatesciencedefensefund.org/ Stephen Mulkey, PhD President, Unity College Unity, ME 04988 -
Monckton Myth #17: Debate vs. Denniss, Part 1
And to continue that quote: "In sum, a strategy must recognise what is possible. In climate research and modelling, we should recognise that we are dealing with a coupled non-linear chaotic system, and therefore that the long-term prediction of future climate states is not possible. The most we can expect to achieve is the prediction of the probability distribution of the systems future possible states by the generation of ensembles of model solutions. This reduces climate change to the discernment of significant differences in the statistics of such ensembles." (emphasis added) And hence the use of model ensembles, each running a non-linear coupled system with slightly different initial conditions and modeling - marking out the probability distribution that we can expect from the climate. We can (in climate) make probabilistic predictions that it might (in average) be rainier or dryer in a particular region. But we'll never be able to predict exactly what the weather on a particular Tuesday a decade from now will be... Monckton's out of context quote is deceptive. And he's an experienced enough writer and speaker to understand that. -
Norman at 15:42 PM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
Tom Curtis @26 The rate of replacement of underground water storage depends upon location. In wet areas the groundwater removed it easily replaced. In dry areas this is not the case and the drier areas are the ones pumping up most of the the deep ground water (that is not being replaced). In wet areas irrigation is not a highly needed activity. Here is a short article that describes the situation. In Texas a chart in this document Ogallala Aquifier. it shows the rate of pumping out of the large aquifier is 6.22, while the recharge rate is 0.3. The rate of pumping water out of the Ogallala is 21 times greater than the recharge rate. This means that the water pumped out of this aquifier will indeed add to the surface water amount. Yes it will add to the surface storage, the atmosphere and yes the ocean as well. -
Jim Eager at 15:20 PM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
Bob, I didn't say anything at all about irrigation or sea level, I just pointed out that the nice neat divisions are not so nice and neat, as you just did as well. -
jmsully at 15:15 PM on 11 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Owl905, you forgot the Chinese sailing over the ice free north pole and discovering America (albeit a couple hundred years after the Vikings). -
IanC at 15:14 PM on 11 February 2012Monckton Myth #17: Debate vs. Denniss, Part 1
What also needs to be emphasized is that the quote regarding predictability is that the phrase is quoted out of context by Monckton from the IPCC TAR. The section this quote appears in section 14.2.2.2 Balancing the need for finer scales and the need for ensemblesIn sum, a strategy must recognise what is possible. In climate research and modelling, we should recognise that we are dealing with a coupled non-linear chaotic system, and therefore that the long-term prediction of future climate states is not possible. The most we can expect to achieve is the prediction of the probability distribution of the system's future possible states by the generation of ensembles of model solutions.
If the sentence after the quoted text is included, it completely changes the meaning of the text quoted by Monckton. Ever since Lorenz discovered chaos, it is recognized that we can't forecast climate the way we approach weather forecasting, and what we are after is the probability distribution of global surface temperature in Jun 2100, not the precise temperature. -
Jose_X at 14:19 PM on 11 February 2012Monckton Myth #17: Debate vs. Denniss, Part 1
Fitz1309, the original context should have been preserved but wasn't. For example, the first reply is Monckton literally pointing out how the IPCC says that (long-term) prediction is impossible. He is correct. The IPCC also says that while we cannot know with 100% certainty, we can manage how much confidence we have with various predictions. So Monckton pointed out an obvious point implied already in current climate papers and the majority of scientific work (managing levels of confidence and error). Monckton's failure was in suggesting that this lack of 100% certainty means we have almost no clue. Now, Monckton never said the we have no clue, but his speech was such to possibly create the impression in the minds of many. Unless you want to get into a silly war of semantics, it's best simply to ask Monckton to clarify his position. Does he believe, as his speech sounded to "me", that the IPCC does not make a projection/prediction of x or y with fairly high certainty. Getting angry doesn't help. The goal is for people to understand. If they feel they misunderstood Monckton, some will over time simply learn not to trust Monckton without first getting clarification and may get used to waiting for the summary version by others who do chase down the details. They may even start seeing Monckton as a clever speaker whose words suggest one thing different than what he will put on paper with his signature. -
Steve L at 13:14 PM on 11 February 2012Still Going Down the Up Escalator
DM @ 132 -- Thanks. It's all about finding the time. Probably I spend too much time reading and commenting to do much learning of how to actually do (& therefore better understand) stuff. I'll endeavor to re-prioritize; I suspect there are many of us who would benefit from this effort. Thanks again for your good example. -
Bob Loblaw at 12:33 PM on 11 February 2012Still Going Down the Up Escalator
RobertS @ :for some unobservable, unverifiable parameter like "slope" under the assumption that your straight line model is correct (and several other similar comments) You keep putting terms like "slope", "average", etc. in scare quotes, as if they have no meaning. You seem unwilling to agree that such an entity can be a property of the underlying process itself, rather than the analysis of the data. Let's look at calculus. Let's take the function Y=x^2. Not linear. Yet calculus says that we can calculate the slope at any value of X by taking the derivative of Y with respect to X. Numerical methods also tell us that we can get a pretty close approximation to that slope by taking pairs of (X,Y) values close to that point and calculating the slope of the linear segment between the points. Is that slope a property of the function Y=X^2, or a property of the analysis? Can the results of the analysis tell us anything about the function? Can you give a straight answer without resorting to an argument that tries to pretend that words don't mean anything? -
Eric (skeptic) at 12:30 PM on 11 February 2012Still Going Down the Up Escalator
EliRabett, Thanks for the example. Are observations are uniformly spaced? I assume that daily or seasonal cycles are already averaged out in some way? I don't think those are difficult problems but the methods can sometimes be controversial. Once the cycles are removed is there any other role for spectral analysis? Are there any a priori statistical tests for the residuals or trends in the residuals? By what method are nonlinear trends in the residuals measured? How do we know that we have sufficient data for that method? -
Bob Loblaw at 12:17 PM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
and, Jim, some won't. Some will fall on land. And some of that will run off into streams and eventually reach the sea, and some will soak into the soil, and some will eventually make back into deep aquifers... ...so you can't look at this by pretending that one small portion of the water cycle is everything. Taking the number that represents the removal for irrigation and expecting that it all ends up raising sea level is wrong. -
Jim Eager at 12:03 PM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
But muoncounter, what goes up by evaporation comes down as precipitation, and depending on the location, some of that will end up in the ocean. -
muoncounter at 11:55 AM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
Norman#24: "water is being added to the surface system. Some will be impounded, some will end in the sea." And some will end in the atmosphere. Per the USGS, ... of the water used for irrigation, only about one-half is reusable. The rest is lost by evaporation into the air, evapotranspiration from plants, or is lost in transit, by a leaking pipe, for example. Sounds like there is a high level of uncertainty in the fraction of groundwater that reaches the ocean. You neglect, as well, the fact that groundwater depletion is a major factor in land subsidence, exacerbating coastal sea level rise. This is an argument so thin as to be transparent. -
scaddenp at 11:48 AM on 11 February 2012Newcomers, Start Here
"only have data running back to a 100 years" This is highly inaccurate. We only have instrumental data going back a little over 100 years but we have data in various forms covering millions of years. This also seeks to avoid the issue that climate theory is based on physics and validated daily in countless data sets. Do we not send a rocket to Mars because we only have data on gravity going back 200 years? -
Tom Curtis at 11:48 AM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
Norman @21, you make the assumption that extracted groundwater is not being replaced. That is not correct. Although groundwater is not being replaced at the rate at which it is being extracted in many aquifers, surface water is still making its way underground. Therefore simply taking the figure of the consumptive use of ground water as being the net addition to surface waters is inaccurate. -
Bruce at 11:36 AM on 11 February 2012Major Study of Ocean Acidification Helps Scientists Evaluate Effects of Atmospheric Carbon Dioxide on Marine Life
With available instrumentation both pCO2 and pH can be measured with enough accuracy to determine aragonite saturation . We know that here along the Calif. coast we seasonally flirt with undersaturated water . Putting long term biological data sets together with carbonate chemistry requires bringing pH sensors to existing biological sites. Getting funding to maintain weekly or biweekly larval settlement studies has always been very difficult . Industry has funded a 20 year by weekly study on sea urchin recruitment in calif. and the oyster industry maintains a along term dataset for oyster recruitment in washington . Other than those two baselines we don't have have much to go on. At some point the public will demand real world evidence and maintaining a long term record will be more convincing than lab studies. Bruce -
EliRabett at 10:56 AM on 11 February 2012Still Going Down the Up Escalator
It might become even a teensy bit clearer if one considers a series of measurements of something unknown made in a black box with only a digital readout on the cover. Eric doesn’t know what the instrument is. Eric doesn’t know how accurate or precise the instrument is. Eric doesn’t know what the instrument is measuring. Eric doesn’t know if what the instrument is measuring is changing in time. All Eric knows is the numerical (digital) representation of what he reads on the indicator. Eric diligently records the numbers and then arranges them in a table as a function of time. We know that Eric never gives up so he gives us a long series or maybe not. Eric can now use statistical analysis to estimate the probability of there being a trend or not and to estimate the trend and the uncertainty in the trend. The residuals and trends in the residuals can be used to estimate the probability of the trend being linear or higher order (since everything reduces to a power series we don’t have to directly deal with anything but polynomials. From that point of view accepting or rejecting the hypothesis that the behavior of whatever is being measured is unchanging is simply checking if the zeroth order term in the series is the only significant one). From this POV, the residuals tell us of the summed variability of the what is being measured and the measurement device. We would, of course, have to break into the box and calibrate the instrument against a well characterized source to separate accuracy and precision. -
NASA Mission Takes Stock of Earth's Melting Land Ice
Norman - It does matter in terms of sea level rise (SLR). Groundwater depletion is a serious ecological issue, reducing the carrying capacity of many regions. But the total amount of water making it's way to the oceans is what matters in terms of SLR. You have to add up all the sources and sinks of terrestrial water to see what's going on. A more recent (and complete than Chao) reference is Milly et al 2010 - Terrestrial Water-Storage Contributions to Sea-Level Rise and Variability. Considering groundwater depletion, irrigation, impoundment, etc., they state: "When we consider only those processes ... in which we place medium to high confidence, we obtain a zero net trend in sea level. This is consistent with the most likely range of ≈0 to 0.3 mm/year deduced [from external constraints] ... for the past two decades ..." (emphasis added) -
Norman at 09:01 AM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
KR @23 I think we are not on the same page. Water impoundment is not the same concept as adding water to the surface water system from groundwater sources. The number you give is for the total amount of water that has been impounded by mankind to date. The number I gave is a yearly extraction of groundwater sources and a lot of that is depleting the ground water supply at a much faster rate than entering it. This means the water is being added to the surface system. Some will be impounded, some will end in the sea. The impounded water is a static amount that will change only if new lakes are made. The irrigation is a every increasing amount. Also irrigation rates are going up so more water is being extracted. Groundwater use for irrigation - a global inventory. -
NASA Mission Takes Stock of Earth's Melting Land Ice
Norman - Looking at the amount of water used is not very informative without also looking at the amount of water retained, the input to irrigation. From Chao et al 2008 - "By reconstructing the history of water impoundment in the world's artificial reservoirs, we show that a total of ∼10,800 cubic kilometers of water has been impounded on land to date, reducing the magnitude of global sea level (GSL) rise by –30.0 millimeters, at an average rate of –0.55 millimeters per year during the past half century." (emphasis added) Your assertion that there is significant sea level rise from irrigation is, in fact, incorrect. -
Tristan at 08:19 AM on 11 February 2012Hockey stick is broken
KR and DB You guys are champs. Thanks a lot. -
DMCarey at 07:56 AM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
@michael sweet, I may be mistaken, but I believe Camburn was, in this case, referring solely to people living on Greenland. Those occupying coastal areas over the rest of the world are a different, and altogether more serious, concern. Absolutely incredible, and terrifying, the sheer scale of the ice loss per year -
Norman at 07:42 AM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
From the article "The total global ice mass lost from Greenland, Antarctica and Earth's glaciers and ice caps during the study period was about 4.3 trillion tons (1,000 cubic miles), adding about 0.5 inches (12 millimeters) to global sea level. That's enough ice to cover the United States 1.5 feet (0.5 meters) deep." One problem is that even if the ice melting halted the oceans would continue to rise at about the same rate. The result of irrigation pulling water from aquifiers that had the water locked away and now going into the surface water balance. "Of the total irrigated area worldwide 38% is equipped for irrigation with groundwater, especially in India (39 million ha), China (19 million ha) and the United States of America (17 million ha).[9] Total consumptive groundwater use for irrigation is estimated as 545 km3/year. Groundwater use in irrigation leads in places to exploitation of groundwater at rates above groundwater recharge and depletion of groundwater reservoirs." source of quote. 545 km3/year equals 5.35 x 10^11 tons of water a year. cubic kilometers to tons conversion calculator. In the 7 year period of the Grace study you would have extracted 3.745 trillion tons of water from groundwater sources that are not being recharged by surface water so this basically will add this much water to the surface (at least for many years). So the water added to the system via irrigation is fairly close to the amount of water added by melting ice. Meaning the sea water will continue to rise regardless if the ice melting stops and the problems of the future will still remain. -
Dikran Marsupial at 07:13 AM on 11 February 2012Has Global Warming Stopped?
Eric (skeptic) "Why would linear models be exempt from that?" They are not really, if they are intended to be a model of the data generating process. However they can also be used as a method of estimating the local gradient of the data generating process, in which case they need only be locally congruent. The choice of model depends on the nature and purpose of the analysis. For the graph in 63, I would say it is not a reasonable model for "recovery from the LIA" as GMST is already higher than the temperatures prior to the LIA. See also my comments in post 64. However please do not discuss the LIA any further on this thread as it is clearly off-topic. -
Eric (skeptic) at 06:58 AM on 11 February 2012Has Global Warming Stopped?
Dikran, I didn't see this thread with comments when I posted on the staircase thread, only the print version. One of my questions is answered in the comments, that complex models should be congruent with some underlying physics. Why would linear models be exempt from that? Second, there is a linear trend shown in post 63 that is labeled "recovery from the LIA", which appears to be an estimate of an average natural warming trend. Is that a valid model of the "recovery" or is it invalid? (IMO, not really valid). There are a variety of arguments about the LIA and recovery from http://climate.envsci.rutgers.edu/pdf/FreeRobock1999JD900233.pdf (a heavier emphasis on volcanic activity and other natural factors) to http://www.arp.harvard.edu/sci/climate/journalclub/Ruddiman2003.pdf (natural factors are mostly cooling and warming including post-LIA is anthropogenic). I don't believe the science is settled on that topic. -
Mammal_E at 06:54 AM on 11 February 2012The Year After McLean - A Review of 2011 Global Temperatures
Under "Short-Term Natural Temperature Influences", "aggression" should be replaced by "regression".Moderator Response: [DB] fixed, thanks! -
Still Going Down the Up Escalator
Addendum to previous post - The model used also depends on whether that model makes physical sense. One of the primary arguments against 'step' models, even though they can fit the data with considerable statistical significance, is that physically they just don't make sense in terms of thermal inertia and the mechanics of heat transport. -
Still Going Down the Up Escalator
Eric (skeptic) - The use of a linear model in the figure you reference is entirely appropriate for the question asked, which is in determining that recent warming does not fit a linear trend to the last 150 years of data. Without the linear fit in that figure, you wouldn't be able to evaluate the question. Linear fits are a minimal model, perhaps the easiest to evaluate based upon limited data - and almost always an excellent first pass. Fitting a 2nd or higher order polynomial requires fitting additional parameters, meaning more information is required to fit such a model with statistic significance. As Dikran has pointed out in several conversations, the model used when looking at any data set is dependent on the question asked, and whether the data statistically supports such a model over alternatives. -
jimspy at 06:16 AM on 11 February 2012Volcanoes emit more CO2 than humans
The link to "Morner 2002" is broken. Can I get a good one? Sadly, I need it. -
Dikran Marsupial at 06:13 AM on 11 February 2012Still Going Down the Up Escalator
Eric (skeptic) models can describe, explain or predict; how well they perfoem any of these tasks depends on the appropriateness of the model. If you are not sure what a model represents, why not ask on the appropriate thread (I? -
Eric (skeptic) at 06:06 AM on 11 February 2012Still Going Down the Up Escalator
I am sorry about the LIA digression, I was obviously not clear on what I meant by bringing it up in this thread. For an example, see Figure 4 here The linear trend shown there encompasses some natural warming and cooling transitioning to manmade warming with natural variations. IMO, it is not a suitable use for a linear model. According to Dikran above a model describes and explains. The use in that link explicitly predicts but is not explicit about what it is predicting (natural?, anthro plus natural? anthro exceeding natural?) -
Hockey stick is broken
DB - Thanks for the links. Tristan - From that discussion: "It appears [Jolliffe] now discredits decentering, and he's entitled to his opinion. But the hockey stick remains when using centered PCA, and when using no PCA at all. The claim that it's nothing but "utterly bogus artifacts" is what's really bogus." - Tamino For those who are interested in the subject, Tamino has a fairly extensive discussion of Principal Component Analysis (PCA) which is still on the intertubes here: Part 1 and Part 2Response:[DB] Tamino also deals with the PCA/non-PCA kerfluffle in this post at RealClimate:
http://www.realclimate.org/index.php/archives/2010/07/the-montford-delusion/
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Dikran Marsupial at 05:29 AM on 11 February 2012The Year After McLean - A Review of 2011 Global Temperatures
McLean should be praised for having made a testable prediction, that at least is good science (Popper would have approved) even if the basis for the prediction wasn't. -
Jim Eager at 05:16 AM on 11 February 2012NASA Mission Takes Stock of Earth's Melting Land Ice
Thanks, Yvan. I agree, if that is a real measure of aquifer drawdown then it is very worrying indeed. -
Tristan at 04:56 AM on 11 February 2012Hockey stick is broken
Sorry JH Principal Component Analysis. -
Tristan at 04:54 AM on 11 February 2012Hockey stick is broken
KR I completely agree with your comment. That said, I'm still interested in the whole MM03 vs MBH debacle. I can't find the original reference, I think it may be one of Tamino's vaporised posts, but here's the context from everyone's favourite website.Response:[DB] Links to the once-lost Tamino/Open Mind posts can be found in this post here:
http://www.skepticalscience.com/Open_Mind_Archive_Index.html
The post you seek is located here:
http://web.archive.org/web/20080911215131/http://tamino.wordpress.com/2008/08/10/open-thread-5-2/
The specific portion of the thread in question begins here:
http://web.archive.org/web/20080911215131/http://tamino.wordpress.com/2008/08/10/open-thread-5-2/#comment-21873
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