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John Cross at 22:01 PM on 25 March 2010A brief history of our iPhone app
Just saw this post - what exactly do you mean by saying that being called John Cross has been bugging you for ages ;-) Best, JohnResponse: Where have you been?! -
Berényi Péter at 21:33 PM on 25 March 2010Visual depictions of Sea Level Rise
#78 Peter Hogarth at 08:55 AM on 25 March, 2010 "Do you really think the positioning guys have got it so wrong?" Yes, I do. It happens all the time when trying to detect a tiny little signal submerged in a sea of noise. In this respect it is the same story as all the other empirical proofs of AGW except CO2 trends for the last fifty years. Poor S/N ratio, urgent drive to see something, sophisticated filtering strategies, mirage. The image is linked to Interactive Geoid Computation page, you can verify this claim by clicking on it. It is created by James R. Clynch, a geodesy professor, retired now, while working for the Naval Postgraduate School. It is part of the OC 2902 Web Based Course Reference Material. The Monty Python thing is something completely different. -
We're heading into an ice age
Thanks for the thoughtful responses. I hope you are right about an ice age being so slow. But it is probably the only factor that would justify an increase in CO2 at this time. My background is that I am a retired science librarian with an earned PhD. That should qualify me to do compreshesive searches of the current literature and to understand what I find. I do question those who want to divide comment into either "warmer" or "denier." And I do want us to consider many other questions other than "Is it getting warmer?" I think it is getting warmer. I wonder if that is good or bad. And I am not convinced that it is bad. -
thefrogstar at 18:12 PM on 25 March 2010Skeptical Science housekeeping: Contradictions, URLs and getting hacked
Dohhhh... "Thank you", not "Tank You". -
thefrogstar at 18:11 PM on 25 March 2010Skeptical Science housekeeping: Contradictions, URLs and getting hacked
Tank you, HumanityRules. Post #14 refers to "they" 9 times out of the 11 'arguments/counter-arguments', but I don't consider myself to be one of "they", or making the same arguments. I have my own questions, and this site is the best one (yet) that I have found where they might be answered. -
HumanityRules at 17:03 PM on 25 March 2010Is the science settled?
54.Philippe Chantreau at 16:18 PM on 25 March, 2010 "the fact is that energy conservation is almost totally absent from the mentalities here" Here's a graph showing USA car fuel consumption. The modern world is a more efficient place in terms of energy use than previous generations. It's just we are luck to get to use much more of it, it's what makes our lives seem so pleasant.
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Marcus at 16:50 PM on 25 March 2010Is the science settled?
Well Oracle, when fresh water supplies dry up due to loss of glaciers in some parts of the world, & due to reduced rainfall in others, then a lot of people are going to regret their love of the warmer weather. Crops in warmer conditions also reach senescence earlier-meaning reduced biomass prior to harvesting (i.e. *less food*). So we'll have a combination of reduced rainfall & increased aging of crop plants in the various bread-baskets of the world-how do you think thats going to impact our quality of life? Meanwhile, some of the best means of reducing CO2 emissions also carry a number of related benefits-like the cost savings from weather proofing homes & businesses, reduced air pollution from the burning of coal & petrol, reduced stress from unnecessary time spent in traffic jams & the extension of the life of our many NON-RENEWABLE resources. Perhaps that is how the scientists need to sell it, because right now its only the "we'll be rooned" mantra of the Fossil Fuel industry that is getting through! -
HumanityRules at 16:49 PM on 25 March 2010Is the science settled?
(**John comment 50 doesn't seem to be displayed**) 51.scaddenp at 15:15 PM on 25 March, 2010 As we all know Pielke isn't a climate scientist. You reject every last word of it? It seems any paper that questions the concensus is rubbish. Is this how we come to a concensus? Even if the data they generate is flawed. And lets face it no data in climate science seems perfect. You still have to deal with the limitations of the empirical data they highlight. I think Trenberth's paper highlighted the poor data quality in the mid-upper troposphere as well. If it is the case that this region is key to water vapour feedback then it's not good enough to not know. -
Philippe Chantreau at 16:18 PM on 25 March 2010Is the science settled?
HR says "What stopped natural runaway warming in the past?" I believe that we briefly looked at this before from a purely mathematical point of view. If a feedback effect is less in magnitude than the change that triggered it initially, there can be no runaway. As to the discussion on energy prices in the US, the fact is that energy conservation is almost totally absent from the mentalities here, from the end consumer to industries. Waste is pervasive. Energy prices could go significantly higher without too much pain provided the appropriate conservation measures are implemented. -
James Wight at 16:02 PM on 25 March 2010Is the science settled?
Good post, John - was this the one that was intended to be no. 100? In one sense I agree with the skeptics that the science isn't "settled"; but to the extent that I do agree, it has more to do with the nature of science than the nature of AGW. Science doesn't "prove" things, it draws tentative conclusions from the available body of evidence, and continually revises its conclusions as new evidence comes in. Also, I can't remember ever hearing a scientist say that "the science is settled", so the whole argument seems like a straw person to me. Incidentally, should this post be listed as a response on the arguments page?Response: No, this wasn't the planned #100, that one is yet to come (see if you can pick it :-)
Nowadays when I add a new skeptic argument, I post it first as a blog post. Then I give it a day or two for the comments to nitpick all the typos which is a helpful form of proofreading/peer-review. Sometimes I find people misunderstand a point I was trying to make so I clarify the wording. Then once the dust has settled, I add it as a skeptic argument on the arguments page.
Long story short, I've now added the 102nd skeptic argument "The science isn't settled". Not quite happy with "The skeptic argument" excerpt. I like to quote a really short, succinct explanation of the skeptic argument but haven't been able to find any skeptic article that really nailed it in a single paragraph. Sing out if you find a good example. -
BlankCanvas at 15:22 PM on 25 March 2010Is the science settled?
Great read. Every time I read the posts and comments I always have numerous questions, and come to the conclusion it is mind boggling complex. For instance John, your answer in 43, is there any way of knowing that global temperatures have risen or gone down in a smaller time span during geological time periods, say 200 years? Then what bothers me is: How much percentage of the total warming is due to humans? Isn't it the fact that climate goes in and out of equilibrium swinging from cold to warm and vice versa? Are we in a natural warming trend with AGW on top? If this is the case how much CO2 needs to be absorbed for instance by oceans, in other words how high would sea levels rise to get back to stability in climate? But then again CO2 seems not to be the only culprit.Response: The natural temperature trend if humans weren't around would've been one of slight cooling (Meehl 2004). The following figure shows model results of how climate should've behaved with no man-made forcings:
Figure 1: Climate model results from natural forcings compared to observations (black line). The red line is the average of the four-member ensemble. The pink shading is the model range. The blue line is the ensemble mean and the light blue shading is the ensemble range (Meehl 2004).
CO2 is not the only culprit - there are many forcings that drive climate. But CO2 is the dominant forcing and of more concern, is the fastest rising forcing. -
scaddenp at 15:15 PM on 25 March 2010Is the science settled?
re: Paltridge et al. A little misleading. Now show me some reproduction of the effect without using mixed sensors. Even Peikle rejects the paper. It cant be hard to find more detailed comment on this paper (and I dont mean breathless stuff off CA). -
scaddenp at 15:09 PM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
I see that the "they are throwing data bit" has been answered for you before but you obviously havent accepted. Tamino correctly answers the charge that there was no fraud - the data is not "selected" to show warming. Reduced glaciation MIGHT be a benefit - but only if it happens slowly. Do you seriously believe that 10mm/year would be a good thing? How many refugees from salt-poisoned deltas is your country going to take? -
gallopingcamel at 14:29 PM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
KR (#50), Peace! You are right, it makes absolutely no sense to exclude a large proportion of the data from the statistical analysis. On another thread I was asking how one could justify discarding 80% of the surface weather stations (the station drop off problem). Most of the folks on this blog thought that was fine because Tamino (a statistician) assured them the answer was not affected. Picking up on your mystic connection, William Blake (1757 - 1827) already imagined that a truly wise individual could do a great deal with very little information, maybe as little as one weather station or one grain of sand: "To see a world in a grain of sand and a heaven in a wildflower, hold infinity in the palm of your hand and eternity in an hour." Until we get much smarter we are going to need all the data we can lay our hands on and a bunch of statisticians to sort it out for us. scaddenp (#49), statisticians as you insist can be very useful. Just be careful not to trust them if what they are telling you defies reality or common sense. My point about the CO2 concentration was that we are living in a low CO2 era. In the past there have been periods with >4,000 ppm concentrations. In this context a few hundred ppm is just "noise". Getting back to the context of this thread, suggesting that the melting of the Greenland or polar ice caps is a "catastrophe" is Alarmist nonsense. The negatives of reduced glaciation are more than offset by the benefits. -
Marcus at 13:59 PM on 25 March 2010Is the science settled?
Humanity Rules, given the cost of fossil fuels these days, I'd argue that our continued reliance on them will have a far, *far* greater chance of stunting the economies of developing countries than a shift to a low carbon economy. The US DoE is already trialling a number of Biomass Power plants which make use of waste methane to efficiently generate both electricity & heat-all whilst removing a potent greenhouse gas from the atmosphere. Also, as the source of fuel is local-& cheap-it will allow for more rapid economic development. No doubt the fossil fuel industry will do its level best to kill projects like this-as it hurts their bottom line. Thats the real choice we face here HR: allowing our planet to keep warming vs hurting the profits of the fossil fuel industry. Guess which option I'll pick? -
HumanityRules at 13:24 PM on 25 March 2010Is the science settled?
"What's the uncertainty?" I don't know but..... This analysis which takes the data through to 2007 (beyond trenberth). It shows a mixed picture of water vapour trends in the troposhere. It also suggests that present models have got things wrong. It also says "Put the other way around, increases in total column water vapor in response to global warming do not necessarily indicate positive water vapor feedback, since very small decreases of water vapor in the mid-to-upper troposphere can negate the effect of large increases in the boundary layer." Trends in middle- and upper-level tropospheric humidity from NCEP reanalysis data. Garth Paltridge & Albert Arking & Michael Pook Theor Appl Climatol (2009) 98:351–359 So a "Straight dependence on temperature" seems a little to simplistic. -
Bern at 12:47 PM on 25 March 2010Is the science settled?
#35 Berényi Péter: Yes, Denmark's electricity prices are about triple those in the USA. But Denmark also uses about half the electricity per capita as the USA does. Slightly less than half the total energy usage per capita, in fact (including all sources of energy). So the *real* cost of electricity in Denmark is only about 1.5 times what it is in the USA. Enforcing energy-efficiency standards could easily reduce consumption in the USA by 20-30% over the next few decades. In nearly all cases, the net cost would be zero or negative (i.e. people would save money) in the long term, even just based on current cost (ignoring any future increases in the cost of oil, coal, or any form of carbon tax). Why is that not worth doing? Personal anecdote: I recently bought a diesel-powered car. I now spend about $25 per week on fuel, where I used to spend $45 (diesel & petrol are about the same price per litre here at the moment). Going for a more fuel-efficient vehicle saves me $1000 a year on fuel costs, and it didn't cost any more than an equivalent petrol vehicle. What's not to like? (I'm unsure of how well the new car would go on 100% biodiesel, but that's a possibility, too). -
Is the science settled?
HumanityRules, as to the Loehle link in #41 you posted; I find his various curves oddly chosen, lacking (as he states) any kind of descriptive model, and selected to fit 1/4 of the data in the paper he's arguing about. I've discussed that in a few posts here, which I'll link to rather than boring people again... I can over-fit a near infinite number of curves to data given choices as to the number of free parameters and error levels. That has no consequence to the consensus view unless (a) the consensus view fits the data poorly, (b) the alternative view fits better, (c) this points towards a different model, and (d) this alternative model allows predictions, testing, and confirmation. Loehles curves only satisfy (b) for a subset of the data. -
scaddenp at 12:12 PM on 25 March 2010Is the science settled?
'Moralising about grandchildren is pointless - I see your future warming and raise you stunted economic growth in the developing world." I see one as more deadly than the other and I am unconvinced about the "stunted economic growth" bit in developing world. They can use renewables too. At least they are no WORSE off if their fossil fuel use is capped and developed world reduces. This is still frankly dodging the risk analysis. You want to trust an unknown and probably non-existent model rather than a known and working one on grounds that have no basis in science. daisym: There is at least a reasonable convergence between model estimates of sensitivity and empirical estimates. These alluded to uncertainties have been greatly reduced between TAR and AR4. -
daisym at 11:41 AM on 25 March 2010Is the science settled?
From what I've read, CO2 by itself, can raise atmospheric temps by maybe 2oC, and the global climate models have to assume that cloud effects must provide positive reinforcement for CO2 to raise temps further. It also is my understanding that scientists are divided on whether clouds provide positive or negative reinforcement, and by how much. Is it not the case that until cloud effects are better understood, the case for AGW will remain truly unsettled?Response: "Is it not the case that until cloud effects are better understood, the case for AGW will remain truly unsettled?"
Arguably the key question surrounding global warming is climate sensitivity. I didn't touch on it in this post as I'm planning to devote a post on this subject shortly. We've established empirically that more CO2 is trapping more heat which raises temperatures. The big question is whether feedbacks amplify or reduce this warming. When you add up water vapor, clouds, ice sheet albedo, etc, is the net feedback positive or negative? And how big is it?
We can sidestep the issue of all the various individual feedbacks and jump straight to the question of net feedback by looking at empirical data - how has climate responded to forcings in the past? A multitude of studies, looking at different periods, using different metrics, all tend to cluster around a single answer - the climate sensitivity for doubled CO2 is 3°C.
This gives us the final overall answer to how climate will respond to rising CO2. The net feedback is positive and the climate is fairly highly sensitive to changes in energy balance. So while we have a lower understanding of the individual feedback components, multiple lines of empirical observations give us a higher understanding of the net feedback response. -
HumanityRules at 11:40 AM on 25 March 2010Is the science settled?
"Straight dependence on temperature." What stopped natural runaway warming in the past? Negative feedbacks? Moralising about grandchildren is pointless - I see your future warming and raise you stunted economic growth in the developing world.Response: "What stopped natural runaway warming in the past? Negative feedbacks?"
This is a very interesting question - I've been reading about this in Hansen's Storms of my Grandhildren. There are a number of factors. One is that the sun's output was lower back in the days when CO2 was much higher (in fact, it is BECAUSE the sun's output was lower that CO2 was higher but that's a discussion for another time).
Another factor is that warming in the past was over geological time periods, thousands or millions of years, so over these periods, negative feedbacks have stopped natural runaway warming. This is because negative feedbacks also act over thousands or millions of years - continental weathering removes CO2 from the atmosphere, terrestrial sinks absorb CO2, etc.
The difference between then and now is that current warming is happening so fast that these long-term negative feedbacks don't have time to make a significant impact in slowing down the warming. I find this a particularly fascinating (albeit disturbing) subject and would like to take some time to track down Hansen's references and write a post about it. Now, to find some time... -
scaddenp at 11:18 AM on 25 March 2010Is the science settled?
"what's the certainity about water vapour? What's the uncertainty? Straight dependence on temperature. Can you point me to the controversy? As to others, the uncertainties are bounded. To cause a rise in temperature you have to a trend in the others. At the moment we have a model for climate which does an excellent job of accounting for past and present climate at many different levels. This does not discount the possibility of some unknown which will give rise to an even better model - but that's not the way to bet. Got grandchildren you want to stake on the possibility of some future better model giving us less rapid warming? Me, I am too risk-averse. The prediction is at least good enough for killing all subsidies on fossil fuel and investment in sustainable energy instead. -
PaulK at 11:11 AM on 25 March 2010Understanding Trenberth's travesty
Zinfan94, You wrote: "Why is it that the skeptics claim both low ice sheet melts and level OHC. These two extremes taken together contradict observed SLR, and contradict GRACE data." Further to my post above, you really should read Cazenave et al 2008, which is the consensus science view on reconciliation of TG data, altimetry, ocean mass balance (including GRACE data) and ARGO data. It calculates steric sea level rise (thermal plus salinity) from 2003 to 2008 from Altimetry minus mass balance (two different ways) as 0.31mm/year, and independently calculates the value by thermal expansion from ARGO data as 0.37mm/year. This uses 0-900m ARGO data. It concludes:- QUOTE The steric sea level estimated from the difference between altimetric (total) sea level and ocean mass displays increase over 2003–2006 and decrease since 2006. On average over the 5 year period (2003–2008), the steric contribution has been small (on the order of 0.3+/−0.15 mm/yr), confirming recent Argo results (this study and Willis et al., 2008).ENDQUOTE You will note that there is no room in this analysis for any additional deep OHC, quite the contrary. Either Schuckmann or Cazenave has some further explaining to do in order to reconcile these two papers. -
HumanityRules at 10:58 AM on 25 March 2010Is the science settled?
loehle link http://www.ncasi.org/publications/Detail.aspx?id=3282 -
HumanityRules at 10:56 AM on 25 March 2010Is the science settled?
I take your point on the evolutionary development of science. I also think that most, if not all, of paragraphs 2 and 3 are non-contraversial for alarmists and nearly all deniers. You skipped an important and contraversial point with regard to CO2 radiative forcing. The energy trapped by CO2, as shown by figure 1, is insufficient to cause the catastrophic effects imagined by the IPCC. It requires help from water vapour, whats the certainty around that? Because this seems more contraversial than CO2 itself. Again most thinking skeptics seem to accept CO2 as a mild GHG. About the last paragraph. It seems that many of the possible 'natural' variations in the system a poorly understood and this lack of knowledge seems to strengthen the case for CO2. Convince me that the certainty we have about CO2 isn't in some part derived from the uncertainty we have about other parts of the sytem such as clouds, aerosols, the bioshpere etc. Something missing from this article is future projections. Take this work from Loehle which suggests many possible snenarios for future CO2 levels, many of which fall below the IPCC lower limit. I wonder about the speculative nature of this process. You seem to have highlighted some of the less contraversial aspects of climate science. -
jamesqf at 10:37 AM on 25 March 2010Was Greenland really green in the past?
Seems like you all are missing a very important point about Greenland, which you can discover for yourself by visiting any site (like Google Maps) that has satellite pictures taken in the summer. Greenland IS green around the edges (and probably always was), and those edges are all that you're going to see from a Viking longship, or from a settlement on the shore. Around the southern part (where the Viking colonies were) the icecap is many miles inland. (Nor would the Vikings have been unfamiliar with the idea of inland glaciers, or thought them remarkable, as both Norway and Iceland have plenty of them.) There are a lot of theories as to why the Greenland settlements failed. "Climate change" is only one, and in my (non-professional) opinion, at best at minor contributing factor. More likely is that the colonies were just too small to be self-sustaining, so that when regular European trade stopped, they dwindled and failed. More information on past & present Greenland can be found here: http://www.greenland-guide.gl/ -
nealjking at 10:14 AM on 25 March 2010Is the science settled?
nernt, #28: Isolating the effects of the different greenhouse gases can be done using models, but is not trivial, because they do not just add up linearly: The effect of water vapor and CO2 is not the same as the sum of the effects of each alone: It just doesn't work that way. Unfortunately, the atmospheric physics involved in understanding how the models work is not too simple either. You could look at Pierrehumbert's book, if you're up for the math. A historically oriented approach is Weart's "The discovery of global warming", at the AIP website: http://www.aip.org/history/climate/summary.htm The scientific support is not based only on correlations, as if people had seen a trend and then tried to explain it. The PREDICTION of global warming was made over 100 years ago, and argued for several decades. The correlation comes as a CONFIRMATION of an expected result: That's very different from a "post hoc, ergo propter hoc" ("after this, therefore because of this") approach. It's more like "I was looking for this, and here it is!" -
jondoig at 10:10 AM on 25 March 2010CO2 lags temperature
Modelling of past deglaciation by Ganopolski & Roche (2009), summarised in this PIK media release, found both the delayed Arctic warming and the rapid onset of Antarctic warming (i.e. leading CO2 rise) was mainly due to melting northern ice sheets cooling the oceans and disrupting ocean circulation: "During the terminations of the glacial cycles due to orbital forcing, the vast ice sheets covering Northern America and Eurasia melted rapidly causing a large fresh water flux into the oceans sufficient to disrupt the Atlantic meridional overturning circulation (AMOC) over many thousand years. The disruption of AMOC, in turn, dramatically reduced the oceanic heat transport from the Southern to the Northern Atlantic and led to a delay in the Northern Hemisphere warming and, at the same time, a more abrupt and strong warming in the Southern Hemisphere. The latter is the primary mechanism explaining Antarctic temperature lead over CO2." -
Marcel Bökstedt at 10:01 AM on 25 March 2010Is the science settled?
kdkd> I am not an expert on this stuff, I'm trying to learn, but I think that the numbers quoted by Ken Lambert are not directly relevant to the question. In the paper, Trenberth tries to figure out how heat moves around different parts of the Earth. The "imbalance" is heat that has not been accounted for. However, the global warming does show up in the balance as the "radiative feedback" of -2.8 W/sq.m, which is supposed to correspond to the observed increase in temperature of 0.75 degrees C. According to Trenberths paper, the imbalance was very small 40 years ago, but has now grown substantially. It seems that we don't know exactly where it goes. That we don't know what happens to it makes Trenberth sad (cf the purloined letter), but he assumes that besides warming the surface of the planet, it goes into warming the ocean, making clouds and such. Clever guys, please correct me if I have misunderstood. -
Marcus at 09:40 AM on 25 March 2010Is the science settled?
Berenyi, by world standards the United States pays an unusually low price for electricity. Here in Australia the average price of electricity is around AU$0.25/kw-h, yet we get very little of our electricity from renewable sources-so there seems little correlation between electricity type & electricity costs (a fact further emphasized by a look at the domestic energy price list provided by Turboblocke). Also, whilst the cost of renewable energy technologies has actually fallen over the last 20 years (& is predicted to continue-due to improvements in materials costs & storage technologies) the price of electricity from coal & nuclear have risen, & are predicted to rise further as the fuels become more scarce & as the price of oil & diesel continue to increase. Might I also remind you that the price of coal-fired electricity in the late 1800's & early 1900's was around US$3.00/kw-h (in today's terms), but this didn't stop the development of an electricity grid! -
Marcus at 09:33 AM on 25 March 2010Is the science settled?
So apparently 95% certainty isn't high enough to take "expensive" actions to curtail CO2 emissions. If a doctor told you he was 95% sure that the black mark on the X-Ray was a malignant tumor-a tumor which will kill you without expensive & debilitating chemotherapy-would you say "oh well, I'd rather just take my chances"? Unlikely. The whole cost thing is a total straw man anyway. Most of the best methods for GHG mitigation also come with numerous side-benefits. For example using car-pooling or public transport to commute to work every day, instead of driving yourself, will reduce transport-related CO2 emissions, but they'll also reduce your commuting costs, reduce on long-term vehicle maintenance costs, reduce commuting-based stress (& hence lift worker productivity) & reduce levels of harmful emissions such as benzene (a carcinogen) & particulate emissions (a cause of lung disease & asthma). Of course there's the added benefit that it will make oil last longer too. By the sound of it, the only *cost* will be borne by the oil industry, who will see reduced profits due to less petrol being sold. So that leaves me of the view that most contrarians are simply acting to protect the financial interests of the fossil fuel industry! -
Berényi Péter at 09:22 AM on 25 March 2010Is the science settled?
#32 Turboblocke at 08:26 AM on 25 March, 2010 "it's not so outrageously expensive as the Wiki article claims" On current rate 0.2671 € cents is 35.59 US cents. It is not much cheaper than the 42.89 US cents found in the wiki article. Remember, US price is 9.28 US cents/kWh. Also, only about 20% of Danish electricity is generated by (extremely expensive) wind turbines. The rest is produced by nuclear plants and/or imported from Sweden and Norway. -
David Horton at 09:13 AM on 25 March 2010Is the science settled?
John you might want to look at the "95% probability" business, which, as on this thread, gets misinterpreted wildly. The kind of probability being referred to in science is to do with an individual experiment. You do an experiment, you get a set of results, you do statistical calculations to work out what is the probability (based on number of samples, number of results in a certain direction) that the result could be due to chance. This isn't the case, in any meaningful sense, with global warming. There is no "experiment", there are multiple observations of an astonishing range of different kinds. Some of these observations do lend themselves to statistical analysis - for example storm frequency, numbers of record high temperatures, Arctic ice extent, comparison between temperatures in different decades. Others do not - for example species movements, glacier retreat, droughts, ocean acidification, breeding and flowering seasons. But the point is that ALL of these observations, statistically based or not, head in the same direction. So the question really becomes - what is the probability that all of these observations would trend in the same direction? You can't, as far as I know, calculate a formal statistical probability on this, it would be meaningless. But even taking the ones where you can work out individual probabilities, what are the chances that you would get 95% here, 90% there, on a series of individual observations, where these observations all rely on a well known physical property of greenhouse gases? And then add the non-statistical trends. The "chances" of this set of observations all being due to chance must be trillions to one, not 20 to 1. -
kdkd at 09:05 AM on 25 March 2010Is the science settled?
Ken Lambert's argument in #4 has been irritating me for quite a while (on a separate forum). My understand of the physics is not good enough to understand the energy balance equations fully enough, but there are three problems I see with it. 1. He assumes that co2 sensitivity is at the lower range predicted. As far as I can see the minimum co2 sensitivity should be about 1.6ºC - the observed data does not support lower figures. 2. that the negative feedback effects are at the upper range of the confidence interval and the positive feedback effects and co2 responses are at the lower end of their confidence intervals - i.e. he is assuming non random distribution of the parameter estimates, which is a big nono without evidence to back it up. 3. There's a bit of wishful thinking - I think he's making the assumption that co2 sensitivity figures apply only to the first doubling in co2 levels - so to take his conservative estimate that if co2 doubles on pre-industrial levels by 2050 then we get 1.6ºC warming, but then a further doubling by say 2100 will not cause the same warming. This seems to me theoretically suspect. So can anyone help me understand the problems with Ken's argument better, or have I already hit the nail on the head? -
What CO2 level would cause the Greenland ice sheet to collapse?
My apologies, Camel - I mixed CO2 predictions with temperature, I suspect due to reading too many climate papers at once. Slapping head now... must get more caffeine! The IPCC models fit the total data for CO2 quite well, and previous predictions from those models were quite accurate. Loehle can't argue that arbitrary curves (from a recent subset of the data) invalidate the IPCC model unless he can argue that the IPCC model doesn't fit (it does) and supplies a possible alternative model with superior data fit and prediction accuracy for consideration (he doesn't). I believe he's just over-fitting a short segment of the data to argue that the IPCC model lacks predictive power, and he hasn't made that point at all convincingly. The existence of alternative theories, such as this interesting one on space/time and metaphysics have no impact on the consensus - unless there's actual evidence for them. Some 'guesses' are indeed better than others. -
Peter Hogarth at 08:55 AM on 25 March 2010Visual depictions of Sea Level Rise
Peter Hogarth at 19:58 PM on 22 March, 2010 Where does your second image come from? it seems to link to Monty Python?! I disagree that the overall pattern is "rather similar", apart from the land/sea boundaries. I see as many differences as similarities. I disagree that the Ssalto/NOAA/NASA/ESA/CSIRO etc data products are wrong, and I think you are again confusing reference frames, but this is forgivable. Do you really think the positioning guys have got it so wrong? -
What CO2 level would cause the Greenland ice sheet to collapse?
Gallopingcamel (#48), the IPCC estimates range up and down quite a bit, based on different model inputs for our CO2 activity - previous predictions from these models (even the worst case) all appear to underestimate the current temperature. Loehle posits a couple of curve fits, with no discussion of how they were selected, and states that he has "no assumption of mechanisms". His curve fits are lower than the IPCC's model, which has previously been shown to underestimate the temperature trend. That would hint to me that his curves (not models!) are unlikely to be accurate representations of the underlying physics. Add that to his previous papers, and I might suspect an agenda shaping his interpretations, rather than data-driven modeling. Now, I could fit a near infinite number of curves to the data, depending on how many degrees of freedom and fit error estimates I wanted to apply. Some would be higher when extrapolated out, some would be lower. The IPCC curves fit the data within known noise limits, with high confidence - I can't tout my assorted fits as an argument against the IPCC model unless I have a compelling alternative model, one with (a) descriptive power (fits past data), (b) predictive power (makes testable assertions about the future), and (c) some support in physics. Loehle also doesn't use anywhere near as much data as Hofmann; I consider that a critical failing in any argument for data fitting. 210 years versus 51? Dropping 75% of the data makes for a poor argument, which I think you have argued in the past. I have ongoing issues with trash on my lawn - random garbage. I could look at known behavior of my neighbors (beat up trash cans), wind (gusty), and model my neighbors trash blowing onto my yard. Or, I could posit invisible gnomes with personal grudges who bring in trash at night from miles away, placing them in cryptic patterns with mystic importance. That might be a better fit to the trash pattern. Which guess is right? Well, I suspect the one based on observed physical interactions would be more likely... Loehle's curves are (IMO, mind you) the equivalent of the gnomes. No basis in a model of the world, not driven by any p<95 issues with the curve fitting; they seem driven more by a wish for a different conclusion than scientific criticism. -
Turboblocke at 08:26 AM on 25 March 2010Is the science settled?
Re # 21 Danish energy comes at a price... from the EU official source here: http://www.energy.eu/#domestic it's not so outrageously expensive as the Wiki article clims. -
scaddenp at 08:14 AM on 25 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
"Do a few 100 ppm of CO2 matter?" Well without our GHG we would be a frozen ball. Does that matter to you? Are you seriously positing that our GHG in the atmosphere arent giving us a warmer planet? In context of geological time, humans dont matter but they do to me. As to your contempt for statistics,- well they are abused in political dialogue but they are essential tool for science. What science operates without statistics? The problem is that statistics need to be wielded by the competent. -
Marcel Bökstedt at 08:10 AM on 25 March 2010CO2 was higher in the past
thatnumber5> Yes, the radiation from the sun is increasing. But as Ned says, it increases very slowly. I don't have a good reference for this right now, but try this wiki article on the faint young sun paradox. The general idea is that astronomers think that they have good models for the evolution of stars like the sun, so in particular, they can compute solar output from the age of the sun. -
unreal2r at 08:06 AM on 25 March 2010Is the science settled?
The "it will cost too much" or "it will wreck the economy" arguments are among the most misdirected. In relative terms, fixing the levees around New Orleans would have been much more economical than repairing the damage - without accounting for the human consequences. If you apply Occam retrospectively it becomes pretty apparent that, on the off chance the still "unsettled" science has some probabilistic merit, it will be far less costly to act now than wait until every property within surge distance of an ocean or tidal estuary is rendered valueless. -
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?
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