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JMurphy at 08:04 AM on 25 March 2010The 5 characteristics of scientific denialism
RSVP, Climate Science involves a lot more science than the use of models. There is lots of 'hard' science going into substantiating the present situation and the projected situations coming from models. But don't despair : there are lots of people out there improving the models all the time and I doubt if they would agree that they are ignoring or unable to consider all significant factors. What factors do you think they are missing or not working on, or do you think they should just give up because it's too difficult ? -
gallopingcamel at 08:00 AM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
KR (#46), My reasons for wanting to reduce CO2 emissions have nothing to do with the CO2 concentration in the atmosphere. That is the IPCC's motivation, please don't try to associate me with their Alarmist science. With regard to the Loehle paper, this is another example of the inability of statisticians to reach agreement. When you are talking about small changes, statisticians will tell you whatever you want to hear. Does a few hundred ppm of CO2 matter? In my opinion the answer is "NO" if you think in the larger context of geological time. Loehle may be "low balling" the CO2 trend while the IPCC is more inclined to exaggerate. Who is right? Your guess is as good as mine. -
A peer-reviewed response to McLean's El Nino paper
A quick note about my last comment - I'm commenting on the abstract, content, and conclusions of Mclean's (submitted, rejected) reply, not the original paper. -
A peer-reviewed response to McLean's El Nino paper
Looking at the Mclean reply HumanityRules pointed out, they spend a lot of time defending their derivative operator, and argue the coherence of their results with the known temperature variations. Great - I have some arguments with what their bandpass filtering method actually shows, and the Foster paper (submitted) has a strong argument that this bandpass fits arbitrary data equally well, but those are all parts of reasonable scientific discussions. In the paper McLean et al in fact say; "Fea10 state that the method of derivatives that we employed would minimize long-term trends. We completely agree..." However, in their abstract and conclusions they then state something else: "We explain that there are natural mechanisms that might account for the strong coherence of Southern Oscillation Index and mean global temperature. Our research did not set out to analyse trends in mean global temperature, but, should any such trend exist, it follows from our analysis that in most part it could be a response to the natural climate mechanisms that underlie the Southern Oscillation." (Italics added for emphasis) This statement about long term temperature trends is, by their own admission, unsupported. There is NOTHING about long term trends discussed. It has no place in either an abstract or conclusion for this paper. -
Jesús Rosino at 07:51 AM on 25 March 2010Humans are too insignificant to affect global climate
Damn it, I have ruined the cartoon by giving the clue just in the following line! :P -
Jesús Rosino at 07:48 AM on 25 March 2010Humans are too insignificant to affect global climate
When facing this argument I always like to bring this cartoon. (Clue: cyanobacterias) -
Adam C at 07:15 AM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
Missing from this discussion (I believe) is a mention of why there exists a tipping point beyond which collapse of the Greenland ice sheet becomes inevitable. The key to the continued existence of the ice sheet is altitude - the ice is over 2500 m thick in places, including the southern extent which lies below the Arctic Circle. For every hundred metres lost to melting, the temperature of the surface ice will rise by (roughly) another Celsius degree simply from the effects of lower altitude. Once the height of the ice sheet decreases below the current equilibrium line, Greenland will continue to completely melt even if temperatures go back down. -
What CO2 level would cause the Greenland ice sheet to collapse?
Camel, in 31 I would have to say that you're throwing up a strawman argument. I don't believe anyone expects that controlling carbon emissions would drastically (if at all) drop the 380ppm current CO2 levels, throwing us into massive glaciation. That would require halving CO2 levels AND a solar minimum! It would be nice, however, if we could moderate the current climate changes to minimize disruptions to sea levels, drinking water supplies, weather patterns, etc. Posing a complete and well-nigh impossible reversal of a centuries long trend is really just a distraction... Second topic: Reading the article you point to in 33, the Loehle paper fits various curves (including a 'Saturated' one?) to 51 years of data, arguing that the recent Hofmann fitting the IPCC models to it (exponential growth) is inaccurate. I haven't downloaded the original Hofmann paper ($$$), but even in the abstract they state: "Here we show that the anthropogenic component (atmospheric value reduced by the pre-industrial value of 280 ppm) of atmospheric carbon dioxide has been increasing exponentially with a doubling time of about 30 years since the beginning of the industrial revolution (~1800)." That's x4 as much data than Loehle uses; why didn't Loehle use all the data? And if Hofmann doesn't use all the data, why didn't Loehle pointedly note that!? I also observed that Loehle states his alternate curves "...capture current trends in both the first and second derivative without any assumption of mechanisms." I do a _lot_ of curve fitting; over-fitting a short curve segment with an arbitrary equation is almost unavoidable. You need to restrict the potential curves to those based on the best understanding of the mechanisms involved, or you will be thrown off by data noise. The IPCC curves he's comparing to are based on carbon emission estimates - Loehles' alternate (and short) curve fits are not based on _any_ physical process described in his paper. The only time you should try arbitrary fits is if you have no idea as to the underlying mechanism, and there as to get clues as to what that mechanism is. You certainly can't assert predictive power beyond WAG's from arbitrary fits, nor invalidate a mechanism without a compelling alternative. I have to say I'm not impressed by any scientific insights from the various Loehle papers... -
thatnumber5 at 06:33 AM on 25 March 2010CO2 was higher in the past
More a question than a comment. What is the science behind the statement "solar output was about 4% less than current levels"? Is the sun's output increasing over time? -
Berényi Péter at 06:28 AM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing
McConnell et al.
Science 7 September 2007: 1381-1384
DOI: 10.1126/science.1144856
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John Russell at 05:21 AM on 25 March 2010Is the science settled?
The sceptics now tend to say, "the science isn't settled", because for a long time politicians and others have been saying, "the science IS settled". And from their standpoint those politicians are right. I would suggest that from any practical, meaningful point of view anyone but a scientist would be very sensible to believe that at 95% probability, to all intents and purposes, the science IS settled. At those odds, to stake one's children's future on that 5% doubt is sheer irresponsibility. Of course, that's not to say scientists should not constantly test and retest the theories while ever any doubt remains; until a time arrives when to continue questioning whether the world is really flat puts the remaining sceptics firmly in the lunatic fringe. Though, of course, there's still a very faint chance they could be right... -
CoalGeologist at 05:21 AM on 25 March 2010Is the science settled?
Like so many other skeptical “cocktails”, this one is 2 parts straw man, 1 part red herring, with a dash of plausibility, shaken, not stirred. The "straw man" misrepresents the degree to which scientists both recognize and acknowledge that there are still legitimate areas of uncertainty and imprecision in our understanding. In this regard, the IPCC and the climate community have been very frank, in general. For example, see: NASA: Global Climate Change Uncertainties One almost never hears actual climate scientists saying, "The science is settled" (or if they do say something like that, it's usually misunderstood), whereas one hears this frequently from skeptics. I'm particularly bothered when skeptics precede their complaint that ‘the science isn't settled’ with the disingenuous lead-in, "I'm tired of hearing... (that the science is settled)" If they are so tired of hearing this, why do they keep saying it? The "red herring" aspect of the argument represents an apparent effort to shift the dialog away from the actual scientific evidence toward a contrived argument over whether the scientific "gestapo" is trying to stifle dissent and suppress alternative views. There is, unfortunately, a tiny dash of plausibility to this, although there’s no indication that it has posed a serious problem in the peer-reviewed literature. Focusing on an imagined conspiracy to suppress debate is a distraction from consideration of the real evidence. One recurrent straw man entails confounding of two distinct conclusions reached by the IPCC: 1) "Warming of the climate system is unequivocal..." and 2) "Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations." Here's how one AGW skeptic combined these two statements in a recent Op/Ed piece in the Wall Street Journal (21 Feb 2010): "'Unequivocal." That's quite a claim in this skeptical era, so it's been enlightening to watch the unraveling of the absolute certainty of global warming caused by man." Tragically, what is unraveling in this “skeptical era” is honest debate. -
nerndt at 05:18 AM on 25 March 2010Is the science settled?
I found this a very well written article addressing the most fundamental concern I have always had for AGW - CO2. Correlation or causation. Do any models and charts show the margins of error of the instruments used to gather the data and then compare it to the CO2 correlations? Can the effects of water vapor be removed from the studies to better isolate the effects of CO2? It all seems to easily be explained as results that are well within the noise characteristics of the studies! Having close friends who design space stations where deciding whether to paint portions white or black because they caused drastic effects on the thermal expansion of the material and the localized heat effects constantly points me back to the issue that black soot resting on the ground from coal power plants probably cause more radiative energy collection than an entire atmosphere of increased CO2 levels produced by man (by probably orders of magnitudes). Our knowledge of clouds and how they function in regards to reflecting or absorbing the suns energy is still a complete mystery(being the largest contributor by 20x more than any other to atmospheric warming effects). I feel the information showing we have increased the levels of C02 in the atmosphere are clear. The effects are extremely unclear (isolation of only gas effects in parts per million in effecting thermal radiation have never been shown). We need to step back, try to isolate as many components as possible so we can scientifically determine what we actually know and what we do not know. Trial and error. True isolated research studies of CO2 gas fluctuations in parts per million in atmospheric conditions, removing effects of containers, liguids, and solids which may bias the results tremendously. By taking a complex system, isolating the components and understanding their effects, then putting them together piece by piece into a system we can begin to understand the truth. I have not seen anything close to this approach yet in looking for the scientific evidence to support AGW. Just correlation papers without proving causation. Can anyone help steer me to meaningful scientific information? -
SLRTX at 04:58 AM on 25 March 2010Is the science settled?
Marcel (#27) - Well said. As for the on-going policy discussions on this thread, keep in mind: 1. Climate science and policy are 2 different things. The consensus is that the science of AGW/ACC is real. Policy consensus is highly debatable. 2. The timing of the effects of climate change are still unclear. We see changes now. We can predict other changes, given different rates of rising global temperatures. But there will be effects. Some too rapid for societies or ecosystems to adjust. Food riots? That's nothing compared to water riots. Overall though, there is growing concern that even if we halt all CO2 output, and other forcing effects of humans immediately, we may not be able to stop these effects. We just don't know where that tipping point is with a high degree of certainty. (That's where we continue to learn more about the positive/negative forcings on our climate.) Have we passed the tipping point? Are we near it? Is it far enough in the future that we can stem the tide of negative effects with proposed policy changes? That's the uncertain part of climate change. But the science proving our contribution to AGW/ACC to the point of consensus is solid and sound. -
tobyjoyce at 04:55 AM on 25 March 2010Is the science settled?
oracle2world: "How about the default assumption is that the result is uncertain?" Well, when I drive to work tomorrow, there is a low probability that I will be involved in a car smash, the outcome is undertain so it is ok not to wear my seat belt? I will be dropping my daughter at school - should I tell her not to bother with her seat belt because the chance of a car smash is "uncertain"? The possible negative consequences would be so catastrophic that I fully intend to wear my seatbelt, even with the low expectation of a smash, and make sure my daughter has "belted up". Suppose out best theory says that the global surface temperature will change by between -1C and +4C between now and 2100. Should we bet the farm on the -1C being more correct than the +4C, given that a rise over +1.5C would be catastrophic for large regions of planet earth? There is a very important Prudential Principle that says we act in good time to take preventive action as efficiently as possible. -
ProfMandia at 04:45 AM on 25 March 2010Is the science settled?
BTW, the Trenberth paper is available here: http://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/EnergyDiagnostics09final2.pdf A great paper for the science provided but it is also a great paper because it clearly shows how scientists think, i.e. they are not looking for reasons to support AGW, they are just looking for answers and using data get those questions answered. -
tobyjoyce at 04:43 AM on 25 March 2010Is the science settled?
Dear Oracle2world (#9) I did not follow the OJ case closely, but it is only a metaphor. Don't get hung up on it. Simpson's success in avoiding a guilty verdict at his first trial came from an $1million+ defence team who knew how to exploit human doubts and human empathy. My point is that opponents of AGW are similarly engaging with human emotions. Knowing the case is scientifically unanswerable, they are using similar fallacious arguments as were used in the OJ case. It is a case that tells us something about how we form a judgement from evidence, and how we so often can get it wrong. -
muoncounter at 04:30 AM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
At 31, gallopingcamel offers this: "With regard to meltwater pulses, Disney did a good job on a collapsing ice dam in "Ice Age"." Hardly. For example, the draining of glacial Lake Agassiz 8500 years ago showed up in the sedimentary record in the Rhine River delta. Although this is a newspaper article, it cites a recently published study by Dutch geologists, quoting: "They determined that the collapse of a glacial wall near present-day Hudson Strait in northern Canada triggered a two-stage draining of the lake that sent global sea levels soaring by about three metres — “double the size of previous estimates,”" Quoting further, "“The (Agassiz) event is often seen as an analogue for possible future freshening of the North Atlantic,” they state, “and serves as a test case for assessing the sensitivity of ocean circulation to freshwater perturbations in climate models.”" And then there's the little problem of drought: Warming air stimulates evaporation from not just the oceans, but from soil as well. From Early warning signs of Global Warming: Droughts and Fires": "The environmental and ecological consequences of the summer 1999 drought in the eastern United States provide examples of situations that may become more frequent as climate changes. Without freshwater to rinse out rivers and streams, salt water encroached further up rivers in many areas of the mid-Atlantic coast (USGS, 1999)." That saltwater kills crops and contaminates fresh water supplies in the lower reaches of the river basins. It's a double whammy: "Decreased freshwater runoff also led to increased salinity and low oxygen conditions in Chesapeake Bay, causing fish kills and other ecological changes. As future sea level rise shifts the saltwater-freshwater boundary farther inland, droughts will exacerbate the geographic extent and impacts of saltwater encroachment into coastal aquifers." And then there's fire: by way of anecdotal evidence, in the US over the past few years, it seems as if each summer's national news is full of more widespread and more intense wildfires. Increasing fire frequency is confirmed by this botantical study. In 41, Mr. Camel posits: "it all depends on whose ox is being gored"? Let's see: floods, drought, fire... drought is often associated with famine and no doubt insects and shallow water critters will figure this out first, giving us locusts and frogs. How many more plagues do you want? -
Marcel Bökstedt at 04:22 AM on 25 March 2010Is the science settled?
There is another strong reason for considering the general picture of AGW as settled. The reason is that there is no alternativ theory that explains the climate record we have. With a "theory" I mean a model with an underpinning in theoretical science (physics), which does give precise verifiable predictions. Such a theory is vulnerable in many ways - a climate theory can be falsified by inconvenient data from this century, by various historical data going back millions of years, by attacks on its theoretical foundations etc. The more possibilities to falsify it, the better for the theory: If the attacks don't kill it, they strengthens it. AGW has survived a strong onslaught for a long time. There is no alternative climate theory which has an even faintly resembling status. There are some thoughts which have ended up as "skeptical arguments" on this site, but nothing coherent, nothing that has a strong theorertical backing and gives predictions (or post-dictions) for a large number of measurable quantities. The fact that there are so many "skeptical arguments" shows that AGW is a strong theory - it can be attacked in many ways. Don't misunderstand me. Actually I see a lot of weak spots and unclear areas in the AGW theory. But it is an honest, falsifiable theory. And no one has been able to come up with a competing explanation with an even faintly resembling status. I'm sure there will be modifications of the climate models, as we come to understand the climate better. But I don't see even the beginning of a "paradigm shift" away from AGW. There is no new paradigm in sight to build that shift around. -
Philippe Chantreau at 04:20 AM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
Right gallopingcamel. So we are left with the choice of managing a risk at the 1 to 200 years horizon or at the 20000 years horizon. Tough one. And indeed this blog is not into solutions. It is into addressing widespread nonsense like "it's cooling", "it's the sun", "it's cosmic rays", "Jupiter is warming" and numerous others. That is plenty of work already. Since you are in favor of soon, drastic emission reductions, nothing prevents you from starting a blog on solutions. I will certainly be a reader. -
Phila at 03:51 AM on 25 March 2010Is the science settled?
Oracle2world, First, nuclear power is not a "solution" to AGW. It's one element of a response, the value and feasibility and timing of which depends on a number of variables, including logistical and financial and legislative issues. It would need to be accompanied by other measures that, I suspect, you'd be likely to oppose. Second, a number of "treehuggers" -- a term that seems to me to violate this site's commenting guidelines, BTW -- are indeed "hopping all over nuclear," precisely because they think it's necessary to reduce CO2 emissions. This reappraisal of nuclear power has actually been going on for years, so I'm a bit surprised you don't know about it. Here's a story from 2006.Berényi Péter at 03:39 AM on 25 March 2010Is the science settled?
You may notice Danish elctricity comes at a price.Ned at 03:35 AM on 25 March 2010Is the science settled?
However, if the negative feedbacks are not understood, then absolutely no conclusion about future temperatures can be made. None. Nada. I don't think that's a productive method for dealing with uncertainty. It's much more useful to try to characterize the uncertainty and use that to guide decisionmaking. If you're building a school in California, you don't know when and where and how large the next earthquake will be. Do you (a) ignore earthquakes, since they can't be accurately predicted; or (b) use models to estimate the risk, then build in an extra safety margin to account for the uncertainty?Tony Noerpel at 03:10 AM on 25 March 2010Is the science settled?
Hello Oracle2world The CO2 explanation is rather easy to understand and explains the Earth climate extremely well during the entire Phanerozoic including the hothouse Eocene and also the snowball Earth events during the Proterozoic. It also does a remarkable job of explaining the climate on Venus. The natural variablity you refer to isn't a scientific argument. It does not explain anything, does not pretict anything and cannot be falsified or proven. All one can say is that the Earth can freeze over solid or become an insufferable hothouse rather arbitrarily and any observed change inbetween would be within the natural variability of the Earth climate. Fifty years from now the Earth will have a climate somewhere between a snowball and a hot house. You think? I guess why you are confused is that there are lots of other stuff which affects the climate besides atmospheric CO2 and taking everything into account gets pretty complicated. But the CO2 bit is pretty easy. Also, we are going to run out of fossil fuels. We are just not sure when and the sooner we prepare for that, the cheaper the cost to the economy. It has never been demonstrated that ignoring the AGW problem is less costly than addressing the problem. Denier arguments concerning the economy are pretty weak compared to AGW theory. Heck, replacing the Appalachian water shed lost to mountain top removal is probably enough to break the economy all by itself even if we didn't burn the stuff. I don't understand why it isn't economic suicide not to address AGW. Deniers have never explained that. best regards Tonyoracle2world at 02:56 AM on 25 March 2010Is the science settled?
Dear Ned: "... Since most of the uncertainty involves negative feedbacks, the default assumption should be that warming will in fact occur." How about the default assumption is that the result is uncertain? I don't believe anyone disputes the earth has warmed out of a glaciation 8,000 years ago in our CURRENT ice age (yes we are still in an ice age), and warmed out of a little ice age. The question is whether mankind has a discernable effect on climate. Now you can get a true conclusion from false premises, and every single AGW argument could be false but still correctly conclude mankind is bad bad bad. (Even a blind squirrel stumbles across an acorn from time to time.) However, if the negative feedbacks are not understood, then absolutely no conclusion about future temperatures can be made. None. Nada. Additional cloud cover could easily swamp any contribution of CO2. Within the uncertainty that is as valid a guess as any other. Not well understood means just that, no one knows. Basing conclusions on "I don't know" is just another WAG, that climate enthusiasts have no shortage of.SLRTX at 02:40 AM on 25 March 2010Is the science settled?
Nothing is absolute certainty. If we expected to understand everything in life to an absolute certainty, society wouldn't function. We ride in a car, knowing there's a chance we'll end up in an accident. We fly in a plane, knowing there's a chance we'll end up in crash. But, we still drive. And we still fly. Why? We, and those around us have reached a consensus that, for all practical purposes, it's safe to drive, and it's safe to fly. The so-called "skeptics" imply that climate science has only worked the issue of climate change from one angle. If that were true, then these "skeptics" are claiming the science doesn't work from a position of skepticism. That's not how this works. Scientists are skeptical, and they check the other side of the argument to cross-check their results. If they miss something, someone else will be sure to call them on it later. They work to answer the question, "can something else explain the results that have been seen?" Is climate change caused by "natural variation?" To some degree (excuse the pun) there are natural forces at work. But under cross-checking, these forces cannot account for the changes we're seeing today. Natural forces cannot account for current changes. Now what about past variation, or current, short-term fluctuations? These have been explained. There are viable, credible explanations for natural causes for these variations. But the current changes cannot be explained, using the same causes for past changes. So yes, there have been changes in the past - all caused by natural forcings. And there are short-term fluctuations - el nino, shifts in the jet stream, etc. But overall, there has been a rise in global temps that cannot be explained by natural forces. There has been NO credible reason for this other than humans causing it. Is this known to an absolute certainty? No. But next time you drive or fly, ask yourself, "How can I be certain I won't die in a fiery crash?" Then decide if you should continue driving or flying, or just get out and walk. After all, science gave you that car and plane. It took a "settled science" to create that. In closing, to anyone who continues to repeat the chants about "there is no consensus", "it's all natural variation", and "it's happened before", I'm skeptical of your claims. Prove your case in a positive manner, instead of throwing up negative arguments, like "what about this", or "what about that". Ok, what about YOUR claims? Where's the proof? I am skeptical of your claims.Ned at 02:34 AM on 25 March 2010Is the science settled?
oracle2world, you have the application of Occam's Razor backwards here. Since most of the uncertainty involves negative feedbacks, the default assumption should be that warming will in fact occur. We can say with a high degree of confidence that we are increasing the concentrations of CO2, CH4, N2O, halocarbons, etc. in the atmosphere. We also have a high degree of confidence that all of the above act as greenhouse gases, reducing the outgoing flux of longwave radiation. We have a high degree of confidence that a reduction in outgoing LWR will warm the planet until outgoing LWR comes back into balance. Finally, we have a high degree of confidence that on a planet with oceans, this warming will then be amplified by a well understood water vapor feedback. There are less well understood positive and negative feedbacks. You can argue that one or another of these is overestimated or underestimated. But the simplest and most coherent position is that the world is going to warm because of the stuff listed above. If you want to make the case that it's not going to warm, your argument becomes more complicated and uncertain, because you have to either explain away the basic physics or get into the ugly details of biogeochemical feedbacks.JMurphy at 02:26 AM on 25 March 2010Is the science settled?
Oh, and ProfMandia has just reminded me of another so-called 'skeptic' fallacy, recently re-posted : tackling AGW will 'trash the world's economy'. Usually followed-up by : 'The poor (who I am very concerned about indeed) will be the ones most affected. Is that what you want : cos that's what you'll get.'oracle2world at 02:23 AM on 25 March 2010Is the science settled?
#8 That paper was very interesting. Appears to be peer-reviewed to boot. Focuses on general circulation models, uncertainty, and "parameters" which I keep reading about. When something isn't understood, a parameter is used, that of course supports the conclusion desired.JMurphy at 02:22 AM on 25 March 2010Is the science settled?
So-called 'skeptics' also like to use the 'argument' : 'See, the science isn't settled, despite what you and your scientists say !' When asked to point out who actually says that, the response is usually along the lines of 'Fat Al Gore said it, to boost his fortune'. Or something like that. When asked to actually prove it, all I have ever seen is a report about Al Gore giving evidence before some US Committee, where the reporter writes that that is what Al Gore has stated. Nothing definite or proven, but more than adequate for denial purposes.ProfMandia at 02:17 AM on 25 March 2010Is the science settled?
oracle2world states that addressing AGW will trash the world's economy. Hardly. Not addressing AGW will CERTAINLY trash the world's economy. Please see: The Copenhagen That Matters by Thomas L. Friedman in the NY Times. An excerpt: Although it still generates the majority of its electricity from coal, since 1990, Denmark has reduced its greenhouse gas emissions by 14 percent. Over the same time frame, Danish energy consumption has stayed constant and Denmark’s gross domestic product has grown by more than 40 percent. Denmark is the most energy efficient country in the E.U.; due to carbon pricing, through energy taxes, carbon taxes, the ‘cap and trade’ system, strict building codes and energy labeling programs. Renewable resources currently supply almost 30 percent of Denmark’s electricity. Wind power is the largest source of renewable electricity, followed by biomass. … Today, Copenhagen puts only 3 percent of its waste into landfills and incinerates 39 percent to generate electricity for thousands of households. Cap and trade has also worked in the US with regard to sulfur dioxide (SO2) emissions. SO2 emissions lead to acid rain and during the 1980s, acid rain was devastating lakes and forests in the east. In 1988, Congress passed a cap and trade scheme to reduce these emissions by 50%. By 2004, regulated polluters reduced their emissions by 40% more than required! The Dept. of Energy estimates that the cost to limit emissions ended up being a mere 0.6 percent of the polluters operating expenses. When CFCs were to be regulated/banned, there were similar claims of economic hardship. Like the other claims, these have not panned out. I also point you to: How to Talk to a Conservative about Climate Change which addresses costly consequences to a "do-nothing" approach to AGW.Berényi Péter at 02:16 AM on 25 March 2010Is the science settled?
You have left out black carbon (soot), which is a very effective agent in melting snow, even in the absence of any warming. Of course, it can increase temperatures as well by decreasing surface albedo in snowy regions, hence increasing ASR (Absorbed Shortwave Radiation). Early 20th century warming of the North Atlantic region is due to this soot effect. Even now soot from American industry and wildfires is deposited on Greenland snow en masse. It is also the kind of pollution that can easily be mitigated, with immediate local benefits.
On the other hand, regarding CO2 you have only demonstrated two points beyond any reasonable doubt.
- Atmospheric carbon dioxide level is increasing
- CO2 does absorb (and emit) IR radiation at certain wavelengths
Ian Forrester at 01:54 AM on 25 March 2010Visual depictions of Sea Level Rise
New Moore Island is now No More Island. Disputed Bay of Bengal island 'vanishes' say scientistsoracle2world at 01:52 AM on 25 March 2010Is the science settled?
Dear #9 ... and what about the Duke rape case? The prosecutor indeed covered up information that exonerated the defendents. Academics signed a letter piling on without a second thought. And for what? The academics had nothing riding on the outcome of the case. The prosecutor had won his election, he could have released the evidence, ended the case, and moved on. The OJ case was circumstantial, which is ALWAYS a difficult case to try. The cop committed perjury on the witness stand. The glove doesn't fit, and DNA tests in other jurisdictions have been falsified. The standard was reasonable doubt. Monday morning quarterbacks thought the standard had been reached, the jury didn't. That is our system of justice. Even if the simpliest explanation is that OJ was the doer. To push your rope analogy, imagine a rope with a lot of fuzz, like yarn. It looks thick, but the fuzz makes it difficult to determine how strong it is. It could be a piece of yarn, or a piece of steel wire inside. AGW assumes inside the fuzz is something, others say no one knows, not enough to trash the world's economy.chris at 01:33 AM on 25 March 2010A peer-reviewed response to McLean's El Nino paper
re HR 18:11; 24 March, 2010 Interesting. That clarifies why the editor(s) chose not to publish the McL et al response to Foster et al's comment. McL simply didn't address the points raised by Foster et al. In fact the McL response reinforces the fallacies of their original paper that Foster et al highlight, since they admit that the large apparent contributions of ENSO to variance in the temperature records (72% of variance in MSU atmospheric temperature; 68% of variance in RATPAC radisonde atmospheric temperature), doesn't actually apply to these variances at all, but to the smoothed and derivatized data.... ...which is obvious and exactly the point that Foster et al made, and having admitted that, there isn't really anyrhing left of substance to their paper that differs from previous analyses. ...and of course, McL et al didn't address Foster et al's critique of the non-sequiter of McL et al that "mean global tropospheric temperature has for the last 50 years fallen and risen in close accord with the SOI of 5–7 months earlier shows the potential of natural forcing mechanisms to account for most of the temperature variation." [Note that McL et al reintroduce a similar but rather more blatant non-sequiter in the abstract of their blog response, and that in itself should render their response unpublishable, at least in that form.] There isn't really the "right of reply" that McL consider they were denied in their blog pamphlet you linked to. Editors would certainly be expected to invite a rsponse to a comment on their paper. But this response should conform to basic scientific standards, the foremost in these circumstances being that it should address the points in the comment. McL et al. didn't do that, but chose to restate the erroneous points in their paper, assert their correctness and to bluster instead. All this doesn't matter from a scientific point of view. We're pretty much back where we always knew we were, various bits of people's time having been wasted. I suspect McL et al consider they've done a pretty good job altogether....tobyjoyce at 01:27 AM on 25 March 2010Is the science settled?
Your characterisation of science puts me in mind of a recent book on the OJ Simpson trial by Vincent Buglosi, who prosecuted Charles Manson in the 1960s. OJ Simpson, almost everyone now agrees, was guilty of murdering his ex-wife and her lover. There was blood evidence, he fled when the cops tried to arrest him, he had a history of violence etc. Yet his defence team persuaded the jury of three simple propositions: - There was a chain of evidence which had to be strong at every link. - Any broken link destroys the chain, and therefore the whole case ("If the gloves don't fit, you must acquit"). - The chain was tainted by an irredeemably racist cop, and you could never be sure that the cop had not "fitted up" all the other evidence. This is similar to the case against AGW - ALL the evidence must be beyond doubt, a single contrary piece of evidence "falsifies" the AGW case, "corrupt" scientists cannot be trusted ("Climategate"). Bugliosi counters with another metaphor - the evidence is not a chain but a rope of many fibres. Some fibres may be weak, and even fail. But overall, it the combined strength of the fibres that make the case. One "falsification" does not destroy a case or a science - usually that fibre can be repaired. A jury may discount a single piece of contrary evidence if the remainder of the evidence is sufficiently strong (in their estimation). The can still make a decision "beyond reasonable doubt". Bugliosi's view is close to the science philosopher's view of science - only when evidence against a theory begins to accumulate (several fibres start to break) will scientists contemplate a new or alternative theory. These are what Thomas Kuhn called "paradigm shifts". Climate science has a pretty strong bundle of fibres comprising the evidence, which you set out here. The AGW paradigm is paramount in climate science, but of course is never 100% beyond doubt.gallopingcamel at 01:27 AM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
David Horton (#37), It seems that I am irritating you and that is not my intention. In an effort to set up a more cordial exchange of views, my favorite adjective for greenies is "well-intentioned". Furthermore I support the idea of reducing CO2 emissions drastically and soon. However, this blog is not into "solutions" as yet. My points thus far have been that the MVP affected the Greenland ice sheet and to suggest that expanding glaciers have mostly negative consequences from a human perspective. I have tried to cite sources such as Wikipedia that you will not dismiss without reading. I don't understand your sarcastic tone while mentioning the efforts by monks to exorcise advancing Swiss glaciers. It is well documented and in at least one case it seemed to work. As John Cook mentions (#36) this is an amusing anecdote. When (not if) the Laurentide glacier re-establishes itself all the way to New York City it won't be amusing any more. I guess it all depends whose ox is being gored.Arkadiusz Semczyszak at 01:26 AM on 25 March 2010Is the science settled?
Percentage uncertainty is still too large in relation to the proposed costs (Stern Report). For example, CO2 from the soil (one of the main arguments of skeptics) has the same isotope ratio. The process of decomposition in the soil can not be examined from a satellite. CDIAC soil respiration determined on the basis of a properly working (Interannual variability in global soil Respiration, 1980-94.) Covering Although 14 years of research, but ... "Soil respiration in terrestrial ecosystems worldwide is estimated to be 50-75 Pg C/year (Raich and Schlesinger 1992 ). The carbon cycle in soil has attracted much attention because it accounts for the second largest flux from terrestrial ecosystems, behind gross primary production (100-120 Pg C/year). In comparison, fossil fuel emissions contribute over 5 Pg C/year. [...]"(Duke University - http://www.biology.duke.edu/bio265/ajm21/intro.html). @ jsam "Very cogent and well written." In a well-known magazine "Skeptic" containing treated acute assessment (review) in numerous publications throughout the skeptical science (not just the climate) is the article: http://www.skeptic.com/the_magazine/featured_articles/v14n01_climate_of_belief.html Let me quote just one sentence: "It turns out that uncertainties in the energetic responses of Earth climate systems are more than 10 times larger than the entire energetic effect of increased CO2." Very cogent and well written.?ProfMandia at 01:26 AM on 25 March 2010Is the science settled?
Ken, Here is what Bony et al. (2006) founbd when reviewing the literature: Water Vapor (1.80 ± 0.18 W/m2/K) Lapse Rate (-0.84 ± 0.26 W/m2/K) Clouds (0.69 ± 0.38 W/m2/K) Surface Albedo (0.26 ± 0.08 W/m2/K) Knutti and Hegerl (2008) and IPCC (2007) conclude that various observations show a climate sensitivity value of about 3oC, with a likely range of about 2 – 4.5oC and that 2C seems pretty well constrained if you throw out Lindzen's work. I will download that Trenberth paper now. Bony, et al. (2006). How well do we understand and evaluate climate change feedback processes? Journal of Climate, 19, 3445 - 3482. Knutti, R. & Hegerl, G. (2008). The equilibrium sensitivity of the earth's temperature to radiation changes. Nature Geoscience, (1), 735 - 743.jimvj at 01:24 AM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
John: In #34 you responded: "The more serious impact from disappearing glaciers is the eventual loss of a source of seasonal drinking water for hundreds of millions of people." That point needs to be fleshed out. If AGW reduces the annual snowfall in the glacier regions long term, then not only will the glaciers disappear, but the available water will also decrease. If not, then without glaciers all that snowfall will melt in the spring/summer, potentially causing flooding. To counteract this more dams would have to built. The glaciers act as dams that smooth out the effects of seasonal temperature variations.Berényi Péter at 01:16 AM on 25 March 2010Visual depictions of Sea Level Rise
Sea level rise relative to what? Consider the following imege pair:
The first one is Figure 3 from the post above while the second one is something completely different. Still, the overall pattern is rather similar. How can that be?
Well, Geoid Height (undulation) is a tricky concept. GPS satellites provide heights above a reference ellipsoid, usually GRS 80. This ellipsoid is supposed to be a fair overall representation of the shape of Earth in a sense that it would be the closest (least squares) approximation of the actual gravitational equipotential surface defined by average sea level over all the oceans.
In reality, this ellipsoid is defined by a standard adopted by the XVII General Assembly of the International Union of Geodesy and Geophysics in 1980.
As such, it is a "frozen" approximation. Neither its accuracy is better than that of pre 1980 measurements nor does it follow changes in the shape of Earth.
One would think there must be a secular change in the parameters of the best fit reference ellipsoid, glacial rebound alone should produce such an effect. Mantle material deep down is moving poleward, with time making Earth a bit more spherelike. Using a fixed reference surface like GRS80 this effect is ignored.
Anyway, we are not interested in sea level change relative to an arbitrary reference surface, but to some equipotential surface instead. On such a surface there are neither ups nor downs, everything is on the same level relative to everything else. If sea level rises relative to it, it should get to a level of higher gravitational potential, i.e. it goes up. As the gravitational acceleration is fairly constant, this potential difference can be measured in milimeters as well.
How do we define such a surface? In principle it is simple. It is enough to determine vertical direction above each point on Earth by local gravimetry. The equipotential surface is the one having a normal vector with the same direction as the local vertical at each point.
In practice small pathes of an equipotential surface can be constructed this way (useful for e.g. mining operations), but due to undersampling and error accumulation, over longer ranges this method is useless.
The problem is that inhomogenities in Earth density have a direct effect on local "vertical" direction, so the real equipotential surface is rather crinkly. As we move up (and get farther from local inhomogenities) the surface tends to get smoothed out. Satellite orbits are only sensitive to low spatial frequency changes in the verical. So. If we fancy the equipotential surface as a sum of spherical harmionic functions, lower order harmonics can be estimated from satellite orbits, higher (more crinkled) ones can not.
The result is a surface which is close enough to the actual equipotential surface, althogh its individual normal vectors can differ considerably from the local vertical direction. The shape of the surface having a nominal zero potential, that is the same as average sea level at a particular time (as far as it can be determined) is called the geoid.
For practical purposes this shape is not defined by spherical harmonic coefficients, but by geoid heights (also called undulations) relative to the reference ellipsoid. The second map above depicts this representation.
Undulations have a fairly large (almost 200 meter) range, many thousand times larger than supposed changes in sea level. They are known with a rather low accuracy as well (estimated errors are sevaral meters).
There is no legitimate reason to be a correlation between undulations and local sea level trends. If we do observe one (as we do indeed), it can only be due to a poor job done by Ssalto/Duacs products
in separating true sea level trends from other factors.
See also Determination of Global Sea Level Rise and its Change with Time by Martin Ekman
oracle2world at 01:16 AM on 25 March 2010Is the science settled?
Well, great article. Finally says aerosols have a lot of uncertainty. And science is never settled. So why don't we just completely discard the "settled" nonsense. However ... "To argue that the 5% that is poorly understood disproves the 95% that is well understood betrays an incorrect understanding of the nature of science." sort of ignores the 5% might be really really important. Doesn't disprove any of the other 95%. This is so common in science there is even a saying, that goes something like "Another Beautiful Theory Slain By An Ugly Fact". People have languished in prison for heinous crimes, convicted by evidence beyond a reasonable doubt, and later exonerated by DNA testing. Maybe 1% of the evidence changed the conclusion. If aerosols are poorly understood, and not modeled by the computer models ... none of this counts for much. The AGW theory of course is that small increases in a rare gas in the atmosphere has far ranging effects. Nothing unusual about a theory where a small amount of something effects big changes (aka catalysts). By the same token, aerosols have an enormous effect - and I don't think that is really under dispute. Volcanic eruptions, SO2 pollution, etc. So if a part of the theory is poorly understood, and not modeled, that can completely change the conclusions ... there is a problem. What they call a Big One. An automobile can have 99.9% of its parts working, proven, "settled", understood, and if a wheel falls off - we still consider it a failure. And let me explain what science is. The "best" theory is considered to be the least long-winded explanation for a dataset. Occam's Razor. We use the model that the earth goes around the sun, not because of any inherent "truth", but because it simplifies the mathematics enormously. The dataset, what dots of light move across the sky when, doesn't change regardless if you use the "universe revolves around the earth' model. The dataset of interest in climate change is temperature. CO2 emissions and increases caused by mankind, while interesting, are not exactly what concerns people per se. So, in line with Occam's Razor, what choices of the least long-winded explanation can be used for avg global temps over time? a. a convoluted theory with CO2 as key variable, that gets more and more convoluted all the time b. temps are within normal variance If b. above, then none of the whining about species disappearing, sea levels rising, etc., etc. matter either. Just one more challenge for life to adapt to, which it has for billions of years. So for anyone using the word "science" ... ask them about Occam's Razor, and if they appear puzzled, figure they are not a scientist. Sort of the "litmus test". Anyone here know what litmus paper is?chparadise at 01:14 AM on 25 March 2010Is the science settled?
I also like Nature's editorial take on this very topic about a month ago now. They mentioned that there's four areas where the science isn't really settled, and they're by and large dealing with predicted effects of climate change. But, to use the term "the science isn't settled" ends up playing into skeptics hands, when in fact we're using the term in a different manner.Ken Lambert at 01:13 AM on 25 March 2010Is the science settled?
What you have left out of your discussion John is the effect of net response of the climate system. Dr Trenberth in his AUG09 paper "An Imperative for Climete Change Planning: tracking Earth's global energy" attributes in Fig 4. responses due to Radiative feedback of -2.8W/sq.m and water vapour and ice albedo feedbacks of +2.1W/sq.m giving a net response of -0.7 W/sq.m. This must be added to the net purported anthropogenic radiative forcings of 1.6 W/sq.m which reduces the total net imbalance to +0.9 W/sq.m. There is no direct measurement of these amounts in an atmosphere with an incoming net heat flux of roughly 240W/sq.m. There is also a wide range of uncertainty about the effect of doubling of CO2 to 560ppmv. Increasing surface and tropospheric temperature will raise outgoing longwave radiation (OLR)and some suggest a rise as low as 0.5 degK and others 2-6 degK for this doubling. Such a wide range is an indication that for practical climate change prediction - the claimed well known AG forcings are not much good for such purpose when large unknowns are added and subtracted.ProfMandia at 00:54 AM on 25 March 2010Is the science settled?
This settles it! :) Just kidding. The Scientific Consensus is my attempt to show why we have enough confidence to take action now. I recently posted on Bart Verheggen's blog the following: I agree that waiting another 30 years will give us more validation but that is comparable to telling a person who we think may have cancer to wait 30 years to see if it kills him. If we are right about AGW, we do not have the luxury of waiting. I wish it were otherwise.Svatli at 00:53 AM on 25 March 2010Is the science settled?
From an article in The Economist:In any complex scientific picture of the world there will be gaps, misperceptions and mistakes. Whether your impression is dominated by the whole or the holes will depend on your attitude to the project at hand. You might say that some see a jigsaw where others see a house of cards. Jigsaw types have in mind an overall picture and are open to bits being taken out, moved around or abandoned should they not fit. Those who see houses of cards think that if any piece is removed, the whole lot falls down. When it comes to climate, academic scientists are jigsaw types, dissenters from their view house-of-cards-ists.
http://www.economist.com/displayStory.cfm?story_id=15719298jsam at 00:21 AM on 25 March 2010Is the science settled?
Very cogent and well written.mspelto at 23:44 PM on 24 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
One point that is not being accurately made in this post is the cause of GIS outlet glacier acceleration "How does it happen? The Greenland and West Antarctic ice sheets sit on bedrock that is underwater. As the oceans warm, they melt the ice sheets from below - this causes the ice sheets to slide faster into the ocean (van den Broeke et al 2009). This is what is being observed now by satellites". --this is not wrong but not correct either. The warm water can only melt the bottom of floating sections of ice tongues. These are very limited in Greenland. The key to acceleration of marine terminating outlet glaciers is to reduce ice thickness at the glacier front. Thinning causes the glacier to be more buoyant, even becoming afloat at the calving front, and is responsive to tidal changes. The reduced friction due to greater buoyancy allows for an increase in velocity. This is akin to letting off the emergency brake a bit. The reduced resistive force at the calving front is then propagated up glacier via longitudinal extension in what R. Thomas calls a backforce reduction (Thomas, 2003 and 2004). The acceleration observed is not primarily due to meltwater acceleration or melting of the floating ice tongue bottoms. These processes maybe happening in some places. It is thinning of the ice tongues that by whatever process that leads to the acceleration. It can be surface melting, it can be basal melting. http://www.realclimate.org/index.php/archives/2008/04/moulins-calving-fronts-and-greenland-outlet-glacier-acceleration/Response: Thanks for clarifying my over-simplified explanation.RSVP at 21:49 PM on 24 March 2010The 5 characteristics of scientific denialism
"JMurphy How is it a 'soft science' ? " Physics is physics. Climate science is "based" on physics (and other hard sciences), and there is nothing within climate science that can be inconsistent with these fundamentals. In order to structure a hard physical model with precision, you need to isolate all significant factors. Global climate is simply too complex to lend itself to this level of determinism. And there is nothing wrong with this fact except for the confusion created by those that cant understand this difference.
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