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Tom Curtis at 19:22 PM on 28 May 2011Can we trust climate models?
trunkmonkey @42, based on calculations by Schmidt et al 2010, removing all of the Earth's atmosphere's CO2 would reduce radiative forcing by 31 Watts/m^2, globally averaged. That represents a loss of energy of the order of 5*10^23 Joules per annum ignoring feedbacks. For comparison, according to the NODC the top 700 meters of the worlds oceans have gained around 15*10^22 Joules over the last 55 years, or less than a third of that which would be lost in a year with the complete removal of CO2. At that rate it would take just 12 years to lower a volume of water equal to the top 300 meters of the oceans surface from 14 degrees to 0 degrees. Of course, with feedbacks, the heat would escape at a faster rate initially, but then at a reducing rate while the planet cools. Perhaps you are being confused because you are not taking into account the logarithmic decline of forcing with increasing CO2 concentration. To obtain a reversed forcing of similar magnitude by increasing CO2 concentrations, we would need to instantly increase CO2 levels to around 90 thousand ppm. I assure you that if you modelled that scenario, temperature increases would be suitably rapid to satisfy you. Alternatively, if you merely halved the CO2 content instantly, cooling would closely match the rates of warming obtained for doubling CO2 levels. -
okatiniko at 18:30 PM on 28 May 2011The Critical Decade - Part 1: The Science
sorry a sentence is incomplete : wouldn't be desirable to quantify the confidence level at which we can exclude that the current warming rate (approx 0.5 °C in 30 years) has occured in the past ? -
okatiniko at 18:10 PM on 28 May 2011The Critical Decade - Part 1: The Science
the statement "Neither multi-decadal or century-scale patterns of natural variability, such as the Medieval Warm Period, nor shorter term patterns of variability, such as ENSO (El Niño-Southern Oscillation) or the North Atlantic Oscillation, can explain the globally coherent warming trend observed since the middle of the 20th century." seems to be rather firmly established. However the content of the report doesn't really confirm this strength. The only detailed argument presented in the report is "The Medieval Climate Anomaly (MCA), a somewhat warmer period from about 1000 to about 1250 or 1300 AD, has sometimes been invoked to infer that the contemporary warming is nothing unusual in the Holocene and that it is thus likely due to natural variability. However, the bulk of evidence for the MCA comes from the northern hemisphere, which makes it difficult to determine whether the MCA was truly global in scale. Furthermore, a spatially explicit synthesis of all available temperature reconstructions around the globe suggests that the MCA was highly heterogeneous, even in the northern hemisphere, with globally averaged warming much below that observed over the last century (Mann et al. 2009; Figure 9). Thus, the MCA is different in magnitude and extent from contemporary warming (Figure 10)." I don't really see how strong this argument is. IPCC has defined a scale of "likelihood" with confidence intervals : wouldn't be desirable to quantify the confidence level at which we can exclude that the current warming rate (approx 0.5 °C in 30 years) ? is it at 90 % ? at 99 % ? what is the accuracy of globally averaged warming 1000 years ago ? -
Paul D at 17:36 PM on 28 May 2011The Stockholm Memorandum
Impressive that Murray Gell-Mann was a participant. -
trunkmonkey at 16:30 PM on 28 May 2011Can we trust climate models?
I'm still stuck on the Hansen 2010 thing about pulling all the CO2 out of the GISS and having GMAT drop 6 degrees C in ONE YEAR, and dropping to snowball earth level in a decade. I suspect we all agree that the glaciers to support this could not possibly form this fast. And the thermal inertia of the Oceans? If CO2 is only in the models as radiative forcing, how is it that it's removal (unforcing?)is 7 times more powerful than it's forcing? -
alan_marshall at 15:59 PM on 28 May 2011The Critical Decade - Part 1: The Science
"There is a very large body of internally consistent observations, experiments, analyses, and physical theory". Indeed, and it is just this internal consistency that is lacking from the sceptic's arguments! -
Eric (skeptic) at 14:42 PM on 28 May 2011Monthly Climate Summary: April 2011
I will look forward to reading that. Crook is interesting, he analyzes and simulates two cases: 1) "This convergence line developed as a cold air surge, forced by previous convection over the Rocky Mountains, propagated eastward, and encountered the low-level southeasterlies over the Plains." 2) Around 1550 LT, several convective storms developed as a low level wind surge moved up from the south and strengthened the convergence line." But then he had difficulty initiating convection in his simulations. He blames measurement and initial conditions to deflect the blame from where it properly lies, the fidelity, scale and even chaotic physics of his model. He seems quite willing to downplay the horizontal forcing that he acknowledged and focus only on vertical forcing perhaps triggered with a few well placed horizontal temperature anomalies. His simulation results are not very convincing. -
Tom Curtis at 14:14 PM on 28 May 2011Can we trust climate models?
Albatross @40, I assumed that it is a compounding 10%, not a fixed value. On that basis, 1.1^7.28 =~= 2, so the climate sensitivity he uses is 7.28*0.3 =~= 2.2 degrees C per doubling, which is quite close to the 2.4 figure he discusses in the last complete paragraph of the first column on page 461. -
Albatross at 13:41 PM on 28 May 2011Can we trust climate models?
Tom @38, I may be reading/interpreting this incorrectly, but the footnote to Broecker's Table 1 says: "Assumes a 0.3 C global temperature increase for each 10% rise in the atmospheric CO2 content". Wow, scientists ahead of their time. -
scaddenp at 13:04 PM on 28 May 2011Can we trust climate models?
The Manabe and Wetherald paper is here -
Albatross at 13:01 PM on 28 May 2011Monthly Climate Summary: April 2011
Eric @30, Sorry, while I agree with some of what you are saying. A careful review of the papers I provided at 27 and 29 and the literature on severe storms (something that I happen to be very familiar with) is not consistent with what you are saying in your post. I am busy now, but will post on this as soon as possible. -
Eric (skeptic) at 12:12 PM on 28 May 2011Monthly Climate Summary: April 2011
My citeseer link above seems to be incomplete (uses cookies maybe?) Try this instead http://acmg.seas.harvard.edu/publications/leibensperger2008.pdf (see fig 4 and note that the surface cyclones are quite often reflected from the upper lows and should have similar trends. -
GFW at 11:56 AM on 28 May 2011Even Princeton Makes Mistakes
I got my PhD from Princeton ... and in fact it was while I was there that Happer returned from Washington. (Aside: Lucky for the younger prof also in atomic spin-polarized physics, he'd pressed for early tenure review and got it shortly before Happer's return - but that's not part of this story.) Anyway, back then I didn't know much about climate or AGW (I was naturally focused on my area of research). But I distinctly recall Happer grousing about his dismissal, and I asked him what the issue had been. He didn't say anything about climate or AGW, and instead implied it was a disagreement over whether high voltage power lines cause illnesses. In retrospect, that's fascinating, because if the true issue was AGW, then this dissembling was because speaking to another physicist (even if only a grad student) he felt safer using another controversy where the "alarmist" viewpoint probably was alarmist so he could sound reasonable and principled. -
Eric (skeptic) at 11:47 AM on 28 May 2011Monthly Climate Summary: April 2011
Albatross, those models for the end of this century (lots of unknowns) are mildly interesting but even their elevated CAPE don't hold a candle to the dynamics in the weather models of today. For example, here's the discussion before the Oklahoma outbreak this past Monday http://www.wxforum.net/index.php?topic=11669.0 The dynamic factors they talk about have nothing whatsoever to do with "a 1 g/kg in low-level atmospheric moisture has significant implication for thunderstorms", but in this case the opposite: "unlike the last 2 days when limited areal coverage precluded more than a slight risk...we may have the opposite problem today with storms becoming too numerous and updraft competition limiting the chances of any one storm to maintain dominance" The primary dynamic factor in this particular discussion was the "very potent negative-tilt upper trough" There are a number of interesting and somewhat conflicting trends in that type of activity. This paper http://stratus.ssec.wisc.edu/papers/key-chan_cyclones_grl1999.pdf shows an increase in upper low frequency in spring in midlatitudes worldwide, but it varies by location as shown here http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.143.290&rep=rep1&type=pdf with a small downward trend in surface cyclone frequency over the N central and NE US from 1980 to 2006 An trend resulting from the increase in low level moisture that you mentioned is most likely to show up as an increase in rainfall intensity : http://journals.ametsoc.org/doi/abs/10.1175/2010JHM1229.1 rather than violent weather which has other more important factors behind it. -
Tom Curtis at 11:06 AM on 28 May 2011Can we trust climate models?
Albatross @36, I'm either looking at the wrong article or I simply cannot find that table. Broecker's Climactic Change: Are we on the brink of pronounced global warming?" (1975) discusses work by Wanabe and Wetherald, and by Rasool and Scneider, and concludes that climate sensitivity for doubling CO2 lies between 2 and 4 degrees, but he employs a value of just under 2.4 degrees per doubling (0.32 per 10%, compared to the 0.3 per 10% he used). Using this value, and making no allowance for aerosols or (so far as I can see) thermal inertia he calculates a temperature increase relative to approximately 1850 of 1.1 degrees C. HadCRUT3v gives a 0.9, which very close considering the limitations of his methods. As the prediction was made while global temperatures where falling, it puts the lie to one of Happer's claims, but that is the subject of another thread. -
scaddenp at 10:22 AM on 28 May 2011Can we trust climate models?
Manabe's model is a marvel of what could be done at the time but the man it was primitive. Its worth thinking back to what else was going on at time. First ice core was bring drilled. d18 thermometry on benthic forams was really setting Milankovich in concrete. Four years later I would be doing my first finite element modelling on rock deformation - card stack at 2am in morning on a Burroughs main frame. The substantial lesson I think though is that the basics of climate arent that complicated. It puts a lie to the idea that climate modelling is somehow curve fitting. -
Albatross at 09:37 AM on 28 May 2011Can we trust climate models?
Scaddenp @35, I just had a quick read of Broecker's 1975 paper. Absolutely incredible how well his projections are working out, not only for CO2 but the global SAT as well. But I should not be surprised, as you say, pure physics, and that solid foundation has been understood for a very long time. I'd like to see a comparison between Broecker, Hansen and Lindzen. Broecker's seminal work really does need highlighting more. And look at the 3 C warming for doubling CO2 that is shown in one of Broecker's Tables.....amazing. Did Manabe's model runs from 1991/1992 produce an estimate of global SAT? I can't recall seeing that in the paper, but I have not looked at it in a while. -
scaddenp at 07:32 AM on 28 May 2011Can we trust climate models?
Aerosol distribution may also have been factor in SH. Model design is primarily about accurately representing physics but this is a complex task. That the models work for paleoclimate validation is at least a sign that they are not radically wrong. So indeed the future would tell - but how much future prediction do you think it needs? The incredibly primitive model that was the basis of Wally Broecker's 1975 prediction still allowed him to predict 2010 temperature pretty well. Okay, CO2 isnt has high as he thought it would be and Manabe's model had sensitivity too low, but note that this prediction was made before GISS existed, before any millennial paleoclimate temperature record was around. In short, pure physics. In 10 years time, after another solar cycle to test the Argo temperatures will people still be saying that models are unproven and lets see if they can predict the future? -
Kevin C at 07:31 AM on 28 May 2011Can we trust climate models?
Sigh. I got the most important equation wrong. It should of course read: T(t) = Sum_s ( F(t-s) R(s) ) + c -
Kevin C at 07:25 AM on 28 May 2011Can we trust climate models?
#29 Thanks for the description Charlie. I've actually just coded it up in python, 'cos that's what I know. Here's what I get using a two-box model with unmodified forcings. I optimise 5 parameters: the equilibrium temperature, the scales and the periods of the two exponentials.
That looks pretty much identical to Hansen's "Green's function" version in his figure 8b - the difference being that his response function is determined from running a step function in ModelE, and mine is from fitting the 20th century climate with a 2-box model.
The formula of the response function is as follows:
R(t) = 0.0434*exp(-t/1.493) + 0.0215*exp(-t/24.8)
(where t is in years).
The temperature as a function of year is then given by the equation:
T(t) = Sum_s ( F(t-s) R(t) ) + c
where F(t) is the forcing and c is -0.0764641223, which is a constant which fits the equilibrium temperature.
The next step is to see if there is enough data to do a realistic cross-validation, and if so to play with different parameterisations of the response function. I'm not sure whether to include an ENSO term like Arthur did (which gives a much better fit at the cost of adding another parameter - that's bad given that overfitting is a concern), or work with an ENSO-removed temperature series.
What was the point of all this? It demonstrates my point1 in #1 that if you just want global temperatures, you don't need a complex climate model. You just need the forcings. 20th century climate provides enough of a constraint on the system behaviour that you can then predict then next few decades with a single equation.
So, one answer to the question in the title of this article, "Can we trust climate models?" is "It doesn't matter". We can deduce what will happen to global temperatures over the next few decades for any given set of forcings empirically by looking at the 20th century.
Of course if you want to go beyond a few decades, or if you want to know about anything other than temperature, or if you want to know what will happen at a regional or smaller scale, or if the behaviour of the system changes drastically, then you need a climate model.
1 Well, not really my point. Hansen and Held and Tamino and Arthur and Lucia and probably others did it before me.
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David Horton at 06:59 AM on 28 May 2011Even Princeton Makes Mistakes
Eric the Red "I seriously doubt anyone would believe that Greenland was "green" during the Viking colonization". I think you will find that is exactly what they do believe - Greenland was called Greenland because it was green I think is the phrase. That is they literally believe that three was no ice cap and all the ice has "reformed" during the last 500 years or so. And when they say "England was exporting wine from grapes" (can't find the quote) they literally believe that England had turned into a sort of northern Italy perhaps, where vineyards blossomed on every hill and happy peasants in light summer clothing, brows sweaty, toiled to get the grapes in and begin stamping on them in vats. Because most of the contributors to SkS are rational human beings we tend to underestimate the extent to which Happer and his friend (among a number of others here and elsewhere) are not. They do hold ideas which bear no relation to reality and base their response to global warming on them. -
arch stanton at 06:59 AM on 28 May 2011It's cosmic rays
Philippe - I was hoping you would notice this since we had this discussion on another thread a few weeks ago. You were right. ;-) -
sustainable07 at 06:54 AM on 28 May 2011Skeptical Science Educates My Students
pirate @ 60 Do you understand the qualifications of the National Research Council and that their members are selected the leaders of the American Academies of Sciences? Do you really want to equate their findings and recommendations to any blog, no matter how careful and science-based? Do you understand the peer-review process and how it develops and shapes science, using the scientific method? The peer-reviewed literature is cited extensively in the following report, linked by Prof. Mandia: Advancing the Science of Climate Change (2010) "As discussed in the following chapters, scientific evidence that the Earth is warming is now overwhelming. There is also a multitude of evidence that this warming results primarily from human activities, especially burning fossil fuels and other activities that release heat-trapping greenhouse gases (GHGs) into the atmosphere. Projections of future climate change indicate that Earth will continue to warm unless significant and sustained actions are taken to limit emissions of GHGs. Increasing temperatures and GHG concentrations are driving a multitude of related and interacting changes in the Earth system, including decreases in the amounts of ice stored in mountain glaciers and polar regions, increases in sea level, changes in ocean chemistry, and changes in the frequency and intensity of heat waves, precipitation events, and droughts. These changes in turn pose significant risks to both human and ecological systems." (p. 19) http://books.nap.edu/openbook.php?record_id=12782&page=19 "…In practical terms, however, scientific uncertainties are not all the same. Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities." (p. 21-22) On its website, the National Academies describe the origins of the NRC as follows: "In 1916 the Academy established the National Research Council at the request of President Wilson to recruit specialists from the larger scientific and technological communities to participate in that work. Recognizing the value of scientific advice to the nation in times of peace as well as war, Wilson issued an executive order at the close of World War I asking the Academy of perpetuate the National Research Council. Subsequent executive orders, by President Eisenhower in 1956 and President Bush in 1993, have affirmed the importance of the National Research Council and further broadened its charter." http://www.nationalacademies.org/about/history.html -
dana1981 at 06:30 AM on 28 May 2011The Critical Decade - Part 1: The Science
MattJ - again, that's a direct quote from the report (all bullets are taken straight from the report). I suppose you're right that some people have doubts, but not informed, rational people. The report likely refers to no doubt amongst the climate science community. -
MattJ at 06:21 AM on 28 May 2011The Critical Decade - Part 1: The Science
The article says, "There is no doubt about this statement." Actually, there is a lot of doubt about it, as you can see by looking at today's Huffington Post (and many other similar source). Now to be sure, all that doubt is irrational, even highly irrational. But it still dominates public perception, so it is even more irrational to deny its very existence. So I suggest the author amend to article to read, "There is no rational doubt about this statement". For that is clearly true. -
Stephen Baines at 05:48 AM on 28 May 2011The Critical Decade - Part 1: The Science
Based on their wording, my guess is that they are trying to avoid the whole "it can't be acidification of the ocean's pH is >7" nonesense. "Less alkaline" gets around that, but they said "less alkalinity" instead by mistake. The proper opposite to acidity is basicity, which almost noone uses. -
bbickmore at 05:21 AM on 28 May 2011Roy Spencer’s Latest Silver Bullet
Arkadiusz @43, I'm not going to go hunting down papers that some random poster references inadequately. (Titles? Journal names? Volume and page numbers?) The oldest trick in the book is for some ignoramus to say, "What about these 50 papers?" as if that constituted an argument. No, you need to explain what you think is so compelling about each of those papers and give full references. Maybe I would feel motivated to go look them up, then. In any case, I still don't understand the rest of your argument. I think maybe we're hitting a language barrier here. -
ubrew12 at 05:11 AM on 28 May 2011Even Princeton Makes Mistakes
Happer's speciality is spin-polarized physics. From his Princeton website: "In most of our work we use circularly polarized laser photons to pump angular momentum into electron spins, and we use hyperfine interactions to transfer angular momentum from the polarized electrons to the nuclei." In reading this article, and the comments, I had a feeling this was the same person I'd run across before (i.e. that guy also worked in spin-polarized physics). I think my earlier comment to a skeptic who quoted Happer was: 'you're the sort of person who would hire a plumber to fix his car.' Happer has every right to publish his opinion on this important topic. And we have every right to treat his opinion as uninformed as might be expected of a spin-polarization physicist. A lot of these guys work 80 hr work-weeks trying to be the best in their field. That, sadly, makes them LESS informed than the general public about topics of a more general nature, that don't intersect with their speciality. Many of the comments here express amazement that a Princeton professor could hold such easily refuted falsehoods about AGW. I'm not amazed at all. Subatomic physicists are held in a little too much acclaim by the general public. These are not supermen and most of them know their limits. -
boba10960 at 04:42 AM on 28 May 2011The Critical Decade - Part 1: The Science
Yes, I just checked the original document and the error is repeated on pages 6, 8 and 27. Alkalinity is a difficult concept to master quantitatively, so it is not surprising that the authors of the report would have trouble with it. -
Albatross at 04:31 AM on 28 May 2011Temp record is unreliable
BP @203, Try reading the thread every now and then. It was KR quoting Braganza et al 2004, who said "observed diurnal temperature range (DTR) changes are actually much larger than predicted by models". It's a pity it was fabricated." Actually BP, you need to read very carefully what you wrote @191. I know what Braganza found, and KR's reading of the paper @186 is correct. Braganza (2004): "Observed DTR over land shows a large negative trend of 0.4C over the last 50 years that is very unlikely to have occurred due to internal variability. This trend is due to larger increases in minimum temperatures (0.9C) than maximum temperatures (0.6C) over the same period." Inconvenient for you and Watts is that Fall et al's work brings the models into closer agreement with the observations. Watts loses again. Also, the models did not predict a statistically significant decline over much of the contiguous USA between 1950 and 1999, consistent with the findings of Fall et al. (see Fig. 3 in Zhou et al. 2010). Watts loses again. What was fabricated? By whom? The only things that was possibly fabricated was the following claim made by you @191 when you said: "Or, alternately, you can insist the temperature record is reliable, but the fast increasing DTR is inconsistent with model predictions." Do you see that word "increasing" that you typed? Perhaps you meant to say was something like "the rate of decrease in observed DTR is greater than that predicted by the models over the USA". Do you not read what you type before disparaging others? Again, if anything, Fall et al's work actually brings the models into closer agreement with the observations over the USA, and one of the paper's authors Dr. John Nielsen-Gammon agrees with that. Another "skeptic" bubble burst.... KR, @186 "The issues with day/night temperature range are quite different - you might profitably look at Braganza et al 2004, who note that observed diurnal temperature range (DTR) changes are actually much larger than predicted by models, most likely because of insufficient accounting for temperature driven cloud increases in those models." -
dana1981 at 04:30 AM on 28 May 2011The Critical Decade - Part 1: The Science
The alkilinity statement is taken directly out of the report, so you'll have to take it up with the authors! -
Stephen Baines at 03:49 AM on 28 May 2011The Critical Decade - Part 1: The Science
boba's right. Alkalinity has a very specific definition in chemical oceanography. The ocean is getting less alkaline, in that pH is declining, but alkalinity is not decreasing. Very confusing, I know. Wikipedia is actually pretty good on this point. -
David Lewis at 03:47 AM on 28 May 2011Climate Change Denial book now available!
I see GE is making big news proclaiming how cheap solar power will be within a few years. Bloomberg (http://www.bloomberg.com/news/2011-05-26/solar-may-be-cheaper-than-fossil-power-in-five-years-ge-says.html) has a story quoting GE's global research director, Mark Little: "If we can get solar at 15 cents a kilowatt-hour or lower, which I’m hopeful that we will do, you’re going to have a lot of people that are going to want to have solar at home,” Contrast that "coming real soon now" of 15 cents kWhr with your statement in "Climate Change Denial" that nuclear, at the price MIT said it could be produced for now, i.e. 6.7 cents kWhr, is "not cheap" and therefore we should not be putting any money into nuclear. You make statements about solar in your book that carefully avoid putting the cost into an understandable form, i.e. cost per kWhr now or at some date, you claim the problems with solar "have been largely solved", and you lump nuclear advocates with climate deniers together as opponents of solar who don't know what they are talking about, i.e. "this is contrary to the views expressed by nuclear and denial advocates". James Hansen is a nuclear advocate who happens not to be a climate science denier, or a solar opponent. -
boba10960 at 02:46 AM on 28 May 2011The Critical Decade - Part 1: The Science
Excellent summary of information that is valuable to have at ready access! However there is an error in the statement: "The alkalinity of the ocean is decreasing steadily as a result of acidification by anthropogenic CO2 emissions." Rising atmospheric CO2 does not change the alkalinity of seawater. Rather, rising CO2 lowers the concentration ratio of carbonate ions to bicarbonate ions, while maintaining a constant alkalinity. It is the concentration of carbonate ion that is thought to most affect calcification by organisms. -
Philippe Chantreau at 02:38 AM on 28 May 2011Temp record is unreliable
If BP is refering to Anthony Watts' miserable operation, I stand by my statement. There is data analysis to substantiate. -
Philippe Chantreau at 02:31 AM on 28 May 2011It's cosmic rays
THanks for that link Arch. The real problems with the GCR hypothesis are unresolved. The effect is weak at best, whatever particles are created are too small, and no possibility for a particle growth process has been put forth yet. -
Rob Honeycutt at 02:09 AM on 28 May 2011Even Princeton Makes Mistakes
Mike @ 100... "Really, you might as well give up on this, unless you like banging your head against a wall." I believe the point to an article like this from Chris Colose and anyone else who publishes a response to Happer's article (or posts comments like these to articles) is to not give up. I would never assume that anything we say here, Chris says, or even the other faculty at Princeton say will have any impact whatsoever on Happer's choices. As I stated before, this is ideological for him... he doesn't care what we think about the science. But I will continue to bang my head against these kinds of walls. I encourage people like Chris to continue to do so as well. And hopefully others will also continue to point out when people like Happer attempt to confuse the public. To say nothing is to be complicit with Happer's statements. -
John Russell at 01:46 AM on 28 May 2011Has Global Warming Stopped?
Thanks, Doug. For the record, you'll find the response where I used the info in the thread here. -
Bern at 00:35 AM on 28 May 2011The Climate Show Episode 13: James Hansen and The Critical Decade
Holy guacamole, John - it takes you an hour and a quarter to get to UQ??? I guess you're on the other side of the city centre then... or are you talking peak hour? That might only be 5 k's through Toowong & St Lucia, in that case! Gotta love Brisbane traffic, especially on Fridays. :-P (for those who aren't familiar with the traffic in Brisbane, I frequently average less than 30km/h on my trip to work along a 100km/h-zoned freeway, although my record is three and a half hours for the 17km trip home) A good show, in any event. I quite enjoyed the Hansen interview, although I'm going to have to listen to it again, got kinda distracted by upset offspring.Response: I was factoring in peak hour - turns out I didn't quite get to the end of the show on the drive home. -
arch stanton at 00:32 AM on 28 May 2011It's cosmic rays
JoeRG and anyone reading this discussion might be interested in the new topic posted at RC -
John Russell at 00:08 AM on 28 May 2011Has Global Warming Stopped?
I'd be very grateful if someone could provide an update on this topic (to answer someone elsewhere). Would data gathered in the last year alter the statement that "...there has (only just) been no statistically significant warming since 1995... etc."?Response:[DB] Tamino examined this issue back in January here.
Based on his analysis, the warming since 2000 is statistically significant (the error bars do not include zero):
Considering the Aughts (the decade 2001-2010) were the warmest in the instrumental record, with 2010 being tied for the warmest year on record, you can safely say that global warming is still happening today.
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DSL at 23:41 PM on 27 May 2011If It's Not Sex, Drugs, and Rock 'n Roll, what is it? Creativity maybe?
There's plenty of optimism out there. * There's the widespread tendency to believe that everything's going to be ok because technology will save us. * There's the widespread tendency to believe that everything's going to be ok because the free market will save us. * There's the widespread tendency to believe that everything's going to be ok because god(s) will save us. * There's the widespread tendency to believe everything's going to be ok because, hey, "it's ok here, and I'm middle class, educated, and insured, so I'll survive" and since the middle class controls cultural production, the overwhelming message in cultural production is "we'll be ok." * There's the widespread tendency to believe that things are going to be ok because everyone knows that people who prophecy doom are extremists, one and all nutjobs--whether scientists or not. * There's the widespread tendency to believe that things are going to be ok because "we've been through tough times before." * There's the widespread tendency to believe that things are going to be ok because all we really need to do to solve something is talk about it . . . and keep talking about . . . and keep talking . . . [no doubt true, but action at some point . . .] All of this optimism is the momentum of BAU. If you want to use "culture" to change culture, don't directly address the issue. Write a bunch of scripts for stage and screen that have as a central crisis people not heeding the obvious and then having to pay the price (include the elements of technological failure, market failure, and religious failure -- good grief, just turn the last hundred years of actual human history into a TV show). Get that "meme" (a word that means "idea" but doesn't sound as dangerous) out there, let it sink in, and then deliver a strong comprehensive dose of evidence. -
skywatcher at 23:24 PM on 27 May 2011Even Princeton Makes Mistakes
Apologies for being a little O/T but some context for Happer's Greenland misinformation: It's an egregiously false statement of Happer's to suggest Greenland in the Holocene has been anything other than a mostly ice-covered continent with small zones of climatically marginal, but viable, land mostly in two regions of the southwest. We know from isotope data that Norse Greenlanders' diet evolved from mostly terrestrial to mostly marine over the lifetime of the settlement (e.g. Arneborg et al. 1999, Radiocarbon), indicating a move from a pastoral terrestrial farming lifestyle, like Iceland or Norway, to one dominated (up to 80%) by a marine diet. But we also know they survived the transition, and were not reliant on outside aid for their basic subsistence. Trade, e.g. export of walrus ivory, and a large reason for the colony, is another matter. A leading modern hypothesis for the demise of the colony is that the walrus ivory trade to Europe dried up, because of African ivory and/or political change in Scandinavia. There are other hypotheses (e.g. Inuit encroachment from the north), but the hypotheses are not often dominated by the coincident climatic deterioration (e.g. a couple of accessible refs: Dugmore et al 2008; Ogilvie et al 2009). The climatic deterioration reduced but didn't eliminate the growing season (and they adapted anyway), and the glaciers advanced a small distance (~1-2km), certainly not down into the area of settlements. Popular perceptions of glaciers bulldozing the settlements, or the Norse dying of cold just don't hold up to scrutiny of the evidence. And as ever, local temperature changes in Greenland (or English wines, see Tom's post #101) on the order of 1-2C don't disprove anything in regard to global climate sensitivity except that they do support higher climate sensitivity values, and say nothing in regard to modern global temperature forcing drivers. Coincidentally, Greenland's modern temperature is pretty close to that during the MWP, so areas of green that you see in summer Google Earth or Modis imagery are comparable to those present 1000 years ago. But don't be fooled into thinking that the green areas all turned white in the LIA - they turned just a little less green! -
Tom Curtis at 23:11 PM on 27 May 2011Even Princeton Makes Mistakes
Dikran Marsupial @106, your point about natural variability is well illustrated by one particular model run (shown in lime green). Measured temperatures have, it turns out, been tracking it quite closely except for 2005 (which was above it). After 2010 the lime green model shows another decline in temperature, and continues to lie below the 17 model mean until around 2035, but by 2100 it lies well above the mean. Clearly very short periods are not sufficient to validate long term trends. Given that, and given that the measured values lie within the confidence intervals, and given that the measured trend is very close to the predicted trend, I think that Happer's claim that "...since the predicted warming has failed to be nearly as large as computer models forecast..." is simply false. They are very nearly as large as predicted by any reasonable measure. I suspect that is too subtle a point for Dr Cadbury to admit error on, however (if any point is not too subtle for that). -
Tom Curtis at 23:00 PM on 27 May 2011Temp record is unreliable
Berényi Péter @209, the accompanying "zonal mean" graph is exactly that, an accompanying graph. It is not published by GISS apart from the relevant map which is hte primary data; and nor was it published apart from it here. As such people seeing it are unlikely to be confused into thinking the zonal mean from 60 to 80 degrees south represents anything but the obvious measured anomaly rather that the equally obvious grey unmeasured areas. Further, the important thing is the 0.05 global mean anomaly between the respective periods. If you think noticing a large number of temperature measurements where you claim there was only one, and noticing that no claim was made of measurements in unmeasured areas contrary to your claim is without substance, then no wonder you are a denier. However, seeing you object to that map, consider the following which, as it compares 1940-1960 to 1970-1990 is more relevant to your claim of no warming between 1950 and 1980. Notice that the anomaly is 0.08 degrees C. Or perhaps you would prefer a simple comparison of 1950 with 1980 which has a 0.29 degree c anomaly. Clearly you claim is false. As this post shows that, you will no doubt consider it also without substance.
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Dikran Marsupial at 22:49 PM on 27 May 2011Even Princeton Makes Mistakes
Tom Curtis@105 It is worth pointing out that the model projections estimate only the forced component of any trend (i.e. the trend due to changes in forcings), whereas the trend we actually observe is composed of both the forced component and the unforced component (i.e. "natural variability"). As a result, we shouldn't expect the model trends to be a precise match for the observed trend. The spread of individual model runs gives an indication of the plausible magnitude of the unforced component, so if the observations lie within the spread of the model runs, then the models are as accurate as they claim to be. Very clearly from the diagram, they are. The claim that "since the predicted warming has failed to be nearly as large as computer models forecast" is indicative of a rather poor understanding of climate physics, how climate models work and how they are used. The claim clearly is not factually correct as the model forecast says that trends that are smaller than the observed trends are plausible, but trends a little larger are more probable. -
Tom Curtis at 22:35 PM on 27 May 2011Even Princeton Makes Mistakes
Apologies to Dr Cadbury and all. I made a significant error in my graphic manipulations which I have now corrected below:
In light of this I have to amend my claims as follows:
a) The measured trend is slightly less than the trend of the 17 model mean;
b) Just three of eleven measured values lie on the 17 year mean with the rest lying below it;
c) Two measured values (2000 and 2008) lie below the lowest prediction by any model for that year; and
d) No measured value lies on or above the highest predicted value for any year.
Clearly I jumped the gun (and should probably have known better. The Earth is in fact warming slower than model projections. It is just marginally slower, slow enough that I needed to lay the full 35 year trend of measured valued along the mean to ascertain the trend was slower. Consequently I still consider Happer's claim unwarrented. But having gone in so hard rhetorically on a mistake, I hardly expect to convince anyone of that. Oh well ...
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lord_sidcup at 22:29 PM on 27 May 2011Even Princeton Makes Mistakes
Happer is the first I have come across to claim wine was exported from England in the Medieval period. Is there really going to be any reliable documentary evidence of English wine exports 1000 years ago? Smacks of exaggeration and hyperbole to me. -
Eric the Red at 21:54 PM on 27 May 2011Can we trust climate models?
Scaddenp, I agree that the climate responds to the forcings of the time. The LIA in the SH was probably mitigated by the vast stretch of ocean. Going forward, the climate will also respond to the strongest forcings. If that becomes CO2, then I would expect to see substantial warming. If we observe a strong solar minimum, then I would expect that to dominate. The fact that the models reflect the past has little to do with the accuracy of the models, but is a reflection of past temperature inputs into the models. Afterall, who would design a model which did not accurately reflect the past. The true test of the models will come in future temperature projections and observations. Unfortunately, this may take several years (decades). I also agree that temperatures are not accelerating. However, I would add that recently temperatures are neither increasing nor decreasing; 2010 being sandwich between a cold (relative) 2009 and start of 2011. Is this the start of a long-term decrease as GC maintains, or simply a blip in a long-term increase? Stay tuned, and watch nature, not tv. -
Berényi Péter at 21:52 PM on 27 May 2011Temp record is unreliable
#208 Tom Curtis at 14:01 PM on 27 May, 2011 With the exception of water near the West Antarctic Peninsular, and hence Orcadas Base, the anomaly south of about 60 degrees is not shown in the anomaly map you are objecting to. But it is shown in the accompanying "zonal mean" graph (with no error bars whatsoever).
Your remark, therefore, is without substance.
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