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Dan Olner at 17:42 PM on 4 August 2010Confidence in climate forecasts
Apologies for being critical, but I think this was a little over-simplistic. The most effective 'skeptic' meme about climate modelling is the 'too complex' argument. If someone asks "how come you can predict climate in 100 years but not weather in three weeks?", how will you answer? Saying you're building the equivalent of model steam trains is not going to help with that. There's an intuitive answer: climate is more like the seasons than like weather. One is caused by the angle of the Earth to the sun, the other by heat trapped by carbon, but it's the same principle: the system has a boundary condition, given by an external forcing. Temperatures can go up in winter and down in summer: that won't alter the seasons. Related, what role do feedbacks have? Lovelock's Daisyworld is a nice little model example. An albedo negative feedback there can keep the system's temperature within bounds - but external forcing, boundary conditions, win out in the end in that particular toy model. How much is that like our world? In what ways is it not? On that last question, I'd love to know what others think. One might argue: a negative feedback can only delay the effect of an external forcing. As in Daisyworld, where temperatures are regulated temporarily, but eventually snap back to where they would have been without the feedback control. Alternatively, albedo effects *do* actually change the energy throughput of the system, so feedbacks are not just internal effects, moving energy around within given boundary conditions. Related to that, how much can CO2 be considered a boundary condition in the same way seasonal forcing can? Have I got that all wrong? To sum up, I think we really need simple, intuitive ways to get at the core of what models can and can't do, not to mention what different kinds of model are good for. (Daisyworld = to get across a point about what systems *can* do to regulate themselves, which is why the wikipedia critique of 'lack of realism' doesn't count. Realism wasn't the model's aim.) -
Doug Bostrom at 16:51 PM on 4 August 2010Grappling With Change: London and the River Thames
GC inspired me to go hunting for some numbers on adaptation costs. The short answer is "It's going to be a lot but we don't have much of a clue exactly how much." Chapter 2 of this book provides the most recent completely comprehensive approach to summarizing "we don't know." "We don't know" is not information useful for formulating plans. This really is a heck of a mess. -
ubrew12 at 16:04 PM on 4 August 2010Confidence in climate forecasts
For 20 years I've been a spacecraft thermal engineer. I maintain thermal models of satellites so that I can predict their temperature over their 15 year lifespan. This increases due to degradation of materials. Earth is a satellite, so the broad concepts required for predicting its temperature over time are trivial to me, to the point of boring (it helps I was once a PhD candidate in Atmospheric Science, but left to become what I am). I would like to say its been amusing to watch the general public wise up to the reality that physics is actually codified in computers to model physical behaviors like those of satellites, but I also have children. And it is definitely not amusing considering what such general ignorance coupled with arrogance has condemned them to. -
Doug Bostrom at 16:00 PM on 4 August 2010Confidence in climate forecasts
That #3 sounds rather desperate. -
Doug Bostrom at 15:52 PM on 4 August 2010Grappling With Change: London and the River Thames
Oops, pardon me, I exaggerated. Only about half the Dutch will need to be relocated, a mere 8,000,000 or so, they can be packed into the rest of the country. Nothing to worry about, leaving aside the possible bankruptcy problem.
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Doug Bostrom at 15:34 PM on 4 August 2010Grappling With Change: London and the River Thames
GC I was thinking of the Florida Keys residents as opposed to the Dutch. Speaking of the Dutch, I wonder what sort of pumps will be necessary to move the entire Rhine river up and into the ocean? Also, where do they apply for passports once all the money spent trying to save the country has been squandered on building a national snorkel and no more credit is extended? "Hi, we are the bankrupt Dutch, please take us in, all 16,500,000 of us! We can do your laundry!" Maybe it would be better to spend all the money on something else and minimize the hassles. Some people are gonna be -really- mad when they crack their history books and see we knew the fundamentals of this scenario in 1980 and essentially were bamboozled into creating the final, largest fossil fuel subsidy of all, rearranging vast swathes of human culture in the interest of shareholder value. "But we were not quite sure!" will sound very lame. -
thingadonta at 15:30 PM on 4 August 2010Confidence in climate forecasts
"there is no doubt on the basic story that the earth's average temperature is going to rise 2 to 3 degrees over the next 50 to 100 years." This isn't what the IPCC says. There is, according to the IPCC, roughly a <=10% doubt. So according to you, the IPCC 'doesn't undertand how the science works, or is being deliberately misleading'. To say there is "no doubt" shows you don't understand the science. -
John Brookes at 15:27 PM on 4 August 2010Grappling With Change: London and the River Thames
Perth Western Australia is also sinking, due to our reliance on the Gnangara mound aquifer for our water supply. -
gallopingcamel at 15:16 PM on 4 August 2010Grappling With Change: London and the River Thames
doug_bostrom, The Dutch approach does indeed seem "quite implausible" but they are strongly determined to continue living where they do, regardless of rising sea levels. In my view, such adaptation is admirable but at some point it will be necessary to move to higher ground, whether one lives in Galveston, New Orleans, London, the Florida keys, Holland or Bangladesh. There is archaeological evidence of human habitation where the Black Sea is today leading some to speculate that this may be related to the story of Noah in the Bible and the Koran. -
thingadonta at 15:04 PM on 4 August 2010Why I care about climate change
You don't need a religious foundation to motivate one to pursue social values. But what strikes a scientist like me, is that if one can't perceive the natural underpinnings of a faith/religion like Christianity, it's no wonder one can't tell the natural underpinnings in something like climate change. I like, Doug Bostrom above, go as far as the Cosmological Constant, but believe religion is entirely a social construction, which has evolved in the human condition, and which has both positives and negatives. I recommend the book by Daniel Dennet "Breaking the Spell, Relgion as a Natural Phenomenon", in which he examines religion's natural, rather, than supernatural underpinnings, and humankind's evolved predisposition to certain kinds of religious faith in general. -
huntjanin at 14:52 PM on 4 August 2010Confidence in climate forecasts
This may not be the right place to post this, but let me mention that three sections of my book-in-progress on sea level rise are now available in clean drafts. These are: (1) the Preface, which describes the IPCC; (2) the Introduction, which offers a beginner's primer on global warming; and (3) Chapter l, which explains why rising sea levels are important to us. Should you wish to read any or all of these, and to give me your most critical comments on what you read, please contact me off-line at huntjanin@aol.com. -
Doug Bostrom at 14:35 PM on 4 August 2010Grappling With Change: London and the River Thames
I've a feeling London flood management plans are not done, if this brand new information is any indication. -
Doug Bostrom at 14:30 PM on 4 August 2010The Past and Future of the Greenland Ice Sheet
Just in: This morning I interviewed James White, the director of the Institute of Arctic and Alpine Research here in Boulder, for KGNU radio’s “How on Earth” science show. White is a paleoclimatologist — he studies ancient climates to understand better how Earth’s climate system works. He has just journeyed back from the Greenland ice sheet, where he has been part of an international science team working on the North Greenland Eemian Ice Drilling project, or NEEM... In White’s view, it’s already too late to turn back the clock on climate change to save low-lying coastal cities like Miami. The ice cores that he and his colleagues drill from Greenland and Antarctica tell us that the last time greenhouse gas concentrations in the atmosphere were as high as they are today, the world was even warmer than it is now, Greenland was largely deglaciated, and sea level was 10 to 15 feet higher. Oops, we broke the planet. What did our parents say? "It's all a lot of fun until somebody gets their eye put out?" Full story w/link to interview audio: Message from the Eemian. -
Doug Bostrom at 13:47 PM on 4 August 2010Grappling With Change: London and the River Thames
GC, it's pretty much an open-and-shut case that geology, geographical problems and general environmental conditions particularly of the outer Florida Keys make the Dutch approach quite implausible. Take a look at maps and you'll see what I mean. I'm not saying that adaptation is not possible anywhere, mind you, just that some places can and should be written off forthwith; we can put certain locations on the very top of the "dump" list and should not bother further with them. The Florida Keys seem to be on the wrong end of that list. Encouraging residents into imagining their younger children will be enjoying their middle years where Ma and Pa lived would be something less than right. It's an old problem, really. There are places on the mainland here in the U.S. that have become increasingly indefensible due to coastal erosion yet the Fed responds to local boosters by assisting with insurance on parcels regularly inundated by storm surges. Cnute, but minus the humility, heh! -
Daniel Bailey at 13:45 PM on 4 August 2010Confidence in climate forecasts
Perhaps most importantly for the purposes of this post: if the physics of the models were wrong, the computer you're reading this on and the Internet over which the data is transmitted wouldn't exist. And that would be a tragedy. :) Thanks, Kevin! The Yooper -
apeescape at 13:40 PM on 4 August 2010Has Global Warming Stopped?
oops, that should read "Of course the R^2 is going to be higher as you increase the degree." -
apeescape at 13:39 PM on 4 August 2010Has Global Warming Stopped?
fydijkstra, I calculated the power for your 1st graph (Cohen's f^2 as effect size), and I got 0.400 for the linear fit, and 0.389 for the 4th order poly fit. Aside from power though, poly regressions are just Taylor expansions about the data. Of course the R^2 is going to be lower as you increase the degree. You can use poly fits if you think there is a physical mechanism that shows a curvilinear relationship, you can go ahead and use it (and any other transformation). But because you're using it for such a short series (with decently noisy data), the poly fit gets great fits for the short term fluctuations instead of the trend. The poly fit that you have here is more reminiscent of the 1998 burst, instead of the trend. As a simple sensitivity analysis, you can change the value of 1998, and see the change in R^2 for the linear fits and the poly fits. I would bet the latter will be affected more strongly. -
Has Global Warming Stopped?
ABG - you made an excellent post here. Over-fitting the data is entirely too easy, and will usually give you bad results. You can always penalize fits of unknown data heavily by their polynomial order, increasing the penalty according to data variance, in order to avoid overfitting. But if you have any information on the underlying physical processes, use the simplest fit that goes through the center of variance. Otherwise (as you clearly show with your last figure) you're overfitting into la-la land. -
Temp record is unreliable
BP - an excellent and very interesting posting you present here. Kurtosis of the GHCN data set may be due to any number of things - I would put "weather" at the top of those. I'm not terribly surprised to see the temp kurtosis varying considerably over time, albeit with a rather constrained distribution (your figure 7); simple changes in year-to-year variability (tight means and lacks thereof) might account for that. If it were driven by station number reduction I would expect to see a trend in it, which I don't from your graphs. As to the temperature shift - that appears independent of kurtosis in your figure 7. Your standard deviation graph is much smaller than the rest - only 1967 to present. I would love to see it over the entire course of the data. As it is I would hesitate to draw any interpretations from it. The skewness, on the other hand, is extremely interesting. Smaller station counts should increase the variability of skewness - I'm not seeing that in the post-1993 data, but we may not have enough data yet. An upwards trend, a shift towards positive skewness, on the other hand, indicates more high temperature events than cold temperature events, which is exactly what I would expect (Figure 2) from an increasing temperature trend, matching the temperature anomalies. The skewness seems to me to be more related to warming trends than station bias, considering other analyses of station dropout which apparently bias temperature estimates slightly lower, not higher. The station dropout would therefore operate counter to the trend you see in skewness - it has to be stronger than the station dropout. Again, thanks for the analysis, BP. I do believe it supports the increasing temperature trends (which you might not like) - but a heck of a lot of work. -
kdkd at 13:19 PM on 4 August 2010Temp record is unreliable
BP #96 You can save a lot of bother first by computing the same set of statistics on the other temperature records, and seeing if the summary distribution statistics that you're observing are different for each dataset. In fact this would improve the rigour of your analysis because you could then demonstrate that you're not jumping in with the preconceived notion that the temperature record is dud. Your use of words like "its gets worse" also detracts from the quality of your reporting. "Another interesting feature of this data" is a perfectly good phrase that helps to de-emphasise your preconceived notion of what's happening with the dataset. Also, are you correcting for the different sample size at each point in time with your measurement. If you haven't this casts strong doubt on the validity of your analysis to date. -
Stu at 13:10 PM on 4 August 2010Why I care about climate change
ChrisG @ 74 Oh, no matter, but I would take a different outlook at John's response at #22. Time and space don't require matter to exist, but matter does require time and space. I kind of got what John was saying @22, but I think you're both right to some extent. Time and space don't require matter to exist, since both of those things exist in a perfect vacuum. But then so does a teeming broth of virtual particles doing something or other with zero-point energy (I've read all about this but it's conceptually so wierd I don't understand it). Do these virtual particles count as matter? Anyway, what John said in its entirety was "As is my understanding, there is no time before the big bang and no space outside the universe - time and space require matter to exist" and the premise is correct in my book, even if the conclusion may not be. I am also a Christian, and this is why I understand God to be eternal and unchanging. He is not part of the universe, and hence is unbound by time, which is a property of the universe. But yes, sadly, some of my motivation for coming here is that there is always someone wrong on the internet. I would prefer us not to feck up the planet any more too. -
Alden Griffith at 13:09 PM on 4 August 2010Has Global Warming Stopped?
Sorry, I'm at a conference right now so I haven't been able to reply as much as I would like. fydijkstra, Simply comparing R2 values between models with different numbers of parameters doesn’t tell you much. Fitting a higher order polynomial always increases your R2 value, which does not mean that the model is correct. To demonstrate, let’s try to decide which is the correct model below:
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Waste heat vs greenhouse warming
Some more explanation about black-body and real-life object emissivity and absorptivity, greenhouse effect, etc.: Every material has an absorption spectra. The emission spectra is identical in distribution (peaks, valleys, etc.), but the emission spectra is scaled by the temperature of the material. This scaling is proportional to the 4th power of the temperature. A "black-body", a theoretic 100% emissive material, has well defined spectral curves at different temperatures. Actual materials have spectra that will always be <= the black body energy at any wavelength. "Gray-body" materials (liquid water is a good example) come close to black-body spectra, while others like C02 have spiky spectra (always less than the black-body spectra for equivalent temperatures). When a material is in radiative equilibrium (assuming no other inputs), it's at a temperature where the emission spectra is scaled identically by temperature to the absorption spectra, and hence the same amount of radiative energy is emitted as is received - no energy changes, no temperature changes. Materials with low absorptivity at thermal wavelengths (like N2, O2, as they are too small and have no dipole moments) are essentially transparent (gasses/liquids) or reflective (solids) to IR - they do not heat or cool well through thermal radiation. A silver plate, for example, won't heat up in daylight very well - low absorptivity in that spectra. CO2, CH4, and H20, on the other hand, readily absorb at IR wavelengths. When they radiate (at a rate dependent on their temperature) they do so in an incoherent, isotropic fashion - random photons in random (spherically distributed) directions. In the greenhouse effect, an atmosphere with GHG's present will have surface IR absorbed by the GHG's, heating them. The GHG's will radiate spherically, which means half the emissivity spectra goes back to the surface. From outside the atmosphere, half the photons at the emitted wavelengths don't come out of the atmosphere. This changes the emissivity spectra of the planet, giving a smaller integrated spectra (and energy) emitted at any particular temperature. If the emissivity spectra is changed (absorption remaining the same, as daylight is 99% not absorbed by GHG's), energy emission changes as well, and there is an energy imbalance. Energy will accumulate or disperse, temperatures will change, until the atmosphere radiates the same integrated energy as it receives. -
Bern at 12:43 PM on 4 August 2010Grappling With Change: London and the River Thames
That was an absolutely fascinating read, thanks, Doug. I hope to see more articles appearing on here about the solutions to the problems brought by climate change. -
Manwichstick at 11:35 AM on 4 August 2010Why I care about climate change
Why I care about climate change... I am in the physics education business, and I really don't like the honourable hardwork that my colleagues do be belittled, undermined, and tainted by others. -
gallopingcamel at 11:17 AM on 4 August 2010Grappling With Change: London and the River Thames
michael sweet (#12), In 1981 I was living in Schiedam (the gin capital of the world) on reclaimed land and had a chance to watch the Dutch in action. They were dredging channels for ocean going vessels and then the dredgers dumped the solids into places where large pumps were set up to transfer the materials inside the dikes. Where I was living was 7 meters below mean sea level and much of the exposed soil was still too salty for most kinds of vegetation. I sometimes wonder what that area looks like 30 years later. This Dutch approach should be much easier to apply in the Florida keys. -
Berényi Péter at 11:17 AM on 4 August 2010Why I care about climate change
#61 RSVP at 02:14 AM on 4 August, 2010 under Soviet domination, countries in Eastern Europe relied more on public transportaion and used horses for farming in great numbers before the fall of the Berlin Wall. They didnt realize that they were ahead of the times with their "backward" psuedo-ecological farming methods. Unfortunately this comment is flawed in multiple ways. I have first hand experience of those times and I can tell you that system was in no way ahead of the times. Or if it was, that is, if there is still anyone out there working on a return, you may have very bad times in store indeed. On the other hand, your idea of "backward" psuedo-ecological farming methods of communist countries has no relation to reality whatsoever. At least in Hungary it was pretty cutting edge with machines, chemicals, advanced research, high yields and untold damage to the environment. The horses were actually slaughtered en masse after the 1956 revolution to prevent reprivatization of small farms once and for all. And instead of advanced public transportation one had this:
(Yes, girls as well)
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Berényi Péter at 10:43 AM on 4 August 2010Temp record is unreliable
#93 KR at 12:48 PM on 2 August, 2010 it's pretty obvious that you are searching for problems with the temperature records. However, in your search for problems of any kind, you are really ignoring the full data, the statistics Yes, it is obvious, the more so because I've told you. And it's also pretty important to get acquainted with individual cases, otherwise you don't even know what to look for. BTW, you are perfectly right in stating the full dataset has to be taken into account and that's what I am trying to do. It just can't be done in a single step, not even Rome was built in a single day. Even so, I am happy to announce there is something I can already show you, related to the structure of the entire GHCN. I have downloaded v2.mean, and wherever there were multiple records for a year/month pair at a site identified by a 11 digit number in v2.temperature.inv, I took their average. Then I have computed monthly average temperatures for each site and got temperature anomalies relative to these values. A 5 year running average of these anomalies for all the sites in GHCN at any given time looks familiar:
More than 0.8°C increase is seen in four decades. However, standard deviation is huge, it varies between 1.6°C and 1.9°C. That is, the trend is all but lost in noise, which fact is seldom mentioned.
But it gets worse. Skewness of temperature anomaly distribution can also be computed.
It is really surprising. I put the two measure into the same figure, because the similarity in trends is striking.
Skewness is the lack of symmetry in distribution. In GHCN it has changed from strong negative to strong positive in four decades.
In the the sixties temperature anomaly distribution used to have a long low temperature tail, while currently it is vanishing and changing into a long high temperature tail.
Temperature anomaly and skewness does not always go together. The transient warming between 1934-39 did just the opposite.
Now, changes in skewness of temperature anomaly distribution are either real or not.
In the first case it begs for an explanation. As the warming in the thirties was certainly not caused by CO2, it can even turn out to be a unique fingerprint of this trace gas.
However, it can also be a station selection bias and that's what I'd bet on.
Kurtosis of GHCN temperature anomaly distribution is also interesting. If this distribution would be normal, kurtosis would be zero. But it is not, and changing wildly.
The last thing I'd like to show you for today is a temperature-kurtosis phase graph. After 1993 it turned into an entirely new direction and walked out to uncharted territory.
It's happened just after the dramatic decrease of GHCN station number. Obviously there was a selection procedure involved in determining which stations should be dropped and it's unlikely it was a random one.
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HumanityRules at 10:24 AM on 4 August 2010Why I care about climate change
61.RSVP at 02:14 AM on 4 August, 2010 "Commenting... under Soviet domination, countries in Eastern Europe relied more on public transportaion and used horses for farming in great numbers before the fall of the Berlin Wall. They didnt realize that they were ahead of the times with their "backward" psuedo-ecological farming methods. The same may apply still in parts of India, etc., but things are changing fast, unfortunately... or??" I'm shocked, all I can think is you don't really take responsibility for your own ideas. You need to snap out of your fantasy of pastoral idylls and embrace the reality of the sitations you describe. Over the years I've seen some junk written in the name of environmentalism, this is up near the top. I'm trying to recall an article I read in The Ecologist magazine that celebrated 'communities' living off rubbish dumps in Brazil, blind to the degraded lives these people were living. Your comment falls into this category. -
HumanityRules at 10:13 AM on 4 August 2010Why I care about climate change
50.adelady at 20:36 PM on 3 August, 2010 These societies are resourse poor, it seems strange that you imagine that power generation can stand outside that general truth. It's the problem of thinking small or thinking local, you ignore the bigger picture. What's driving society today is not what happened in the 19th century but the needs of the market now and the specifics of international relations today. Climate science politics/policy is just another tool to resolve those issues, look how in Copenhagen it was used to fight a proxy war between the BRIC nations and the industrialized West. I see climate politics moving in a similar way to the Israel/Palastine or the N.Ireland peace processes. These processes are/were not really about changing anything but about redefining what is acceptable behaviour. Outcomes don't really matter, and are in fact problematic, the most important aspect is to continue to talk, talk, talk. It's on this basis that climate change politics has been embraced by some politicians and the media not for any scientific reasons. The odd thing is that it appears on the surface that environmantalism and the response to AGW are both radical positions but they fit much better into deeply conservative ideas that view humans as a problem that needs controlling rather than agents for change. With those ideas driving the process there is no real hope for any of us to expect greater control over our lives. -
Doug Bostrom at 09:56 AM on 4 August 2010Why I care about climate change
John refers to his faith in explaining his motivation to perform an act of charity manifesting itself in a purely secular fashion and he's to be excoriated for that? I don't believe there's a higher power other than the cosmological constant or something to that effect but I -think- I can see from where John's motivation derives, it's not that complicated. His instinct is toward giving for the betterment of others, this inclination is strengthened by the -good- examples to be taken from scripture. Such an impulse should not be so threatening as to unleash a stream of venomous generalizations having nothing to do with what goes on between John's ears. There's a calibration problem here. Get a grip. -
Doug Bostrom at 09:39 AM on 4 August 2010Grappling With Change: London and the River Thames
Now here's a pretty rigorous writeup on Florida, w/sea level increases derived strictly from 2007 IPCC estimates: Climate Change in Coastal Areas in Florida: Sea Level Rise Estimation and Economic Analysis to Year 2080 ( from the Center for Economic Forecasting and Analysis at FSU, pdf). Same deal as London, basically. Big money swamped in greater or lesser quantities depending on whether people pay attention and try to manage the situation. -
Rob Painting at 08:59 AM on 4 August 2010Grappling With Change: London and the River Thames
Michael Sweet @12 "Your thousand cuts sounds reasonable to me. How many will it take to wake people up?" Two thousand. -
kdkd at 08:57 AM on 4 August 2010Has Global Warming Stopped?
fydijkstra By the way, I did this multiple regression preocedure myself soe time ago, and while in before the mid-20th century solar effects were much larger than the co2 effects, after the mid 20th century, the effect was reversed. ENSO really didn't contribute much to the regression once the effect of solar and CO2 were accounted for. This is strong evidence that your "we can just show it obeys a mathematical function, and ignore causality" is incorrect. -
Icarus at 08:57 AM on 4 August 2010Grappling With Change: London and the River Thames
Fascinating article, and not too long in my opinion. Inevitably when you're reading something like this, thoughts and questions arise, and in a short article they can't all be addressed, so you're left wanting more. This was very good. -
Doug Bostrom at 08:23 AM on 4 August 2010Grappling With Change: London and the River Thames
Michael here's a reasonably informative document from the Nature Conservancy: Initial Estimates of the Ecological and Economic Consequences of Sea Level Rise on the Florida Keys through the Year 2100 Of course some folks have problems with NGO reports but the Nature Conservancy document includes many physical facts suggesting blithe talk of "adaptation" excludes the Florida Keys, meaning they're not "viable." It's a whole other interesting topic that the Nature Conservancy should be producing detailed economic impact materials leaving silence from other quarters. I did a google search on "tampa sea level planning" and found this: Sea Level Rise in the Tampa Bay Region -
DarkSkywise at 08:15 AM on 4 August 2010Why I care about climate change
John C may not be here because someone's wrong on the Internet, but I definitely am. :D I don't have kids. I'm not a Christian. (If anything, I would be a Jedi.) I just really really really abhor deliberate misinformation and the way teh interwebs is being used for speading it. Fortunately, John gave me my own little corner @ SkS to do something about it. (Click any Dutch flag on SkS, and you'll find werecow & me there. Hey, maybe we could do a Who's Who page one day, so you can meet all the people working on SkS whose stuff you'll never read because, well, you can't?) ;) Yes, someone's wrong on the internet, but thanks to John, someone's less wrong today too. Excelsior! (Or was that too Stan Lee-ish?) :D -
kdkd at 08:13 AM on 4 August 2010Has Global Warming Stopped?
fydijkstra #43 It would be overfitting if I used a 15-grade polynomial to describe the trend of 15 data points, but that is not what I did. With a 15-grade polynomial we could even fit the effects of El Niño and the eruption of a volcano. With a 4-grade polynomial these incidents remain part of the noise. If your polynomial fit were a valid model, you'd have to show it was reproducible over different time periods, and different starting dates, using different (independent) data sets. A plausible mechanism as to why your polynomial fit would be better than alternatives would also be good. However, in terms of dealing with the noise, what is far far better, rather than a straight polynomial regression, is to use multiple linear regression to filter out the "noise" components of the temperature increase, leaving the co2 increase by itself, as this helps provide a causal mechanism as explained by Adam C in #48 -
michael sweet at 08:01 AM on 4 August 2010Grappling With Change: London and the River Thames
Doug, Thanks for the reply. I live in Tampa, Flrida (my house = 20 meters). I saw a newspaper article two years ago where people who live in the Florida Keys (elevation about 1-2 meters) were discussing how to cope with 18 inches (the minimum IPCC estimate) and saying it was too much. I have seen little else in the newspaper. Most of Florida south of my house is near sea level. If they start requiring major projects to be able to withstand sea level rise it will be very difficult to plan for. Maybe I will write the planning department for Tampa and see what they say. Your thousand cuts sounds reasonable to me. How many will it take to wake people up? -
Doug Bostrom at 07:55 AM on 4 August 20101934 - hottest year on record
Broadlands: It would be absurd to think that some sort of conspiracy has taken place but some plausible explanation should be available for this consistent trend. I'll be you're right. Why not just ask?: "Questions? For all climate questions, please contact the National Climatic Data Center's Climate Services and Monitoring Division: Climate Services and Monitoring Division NOAA/National Climatic Data center 151 Patton Avenue Asheville, NC 28801-5001 fax: +1-828-271-4876 phone: +1-828-271-4800 email: ncdc.info@noaa.gov To request climate data, please E-mail:ncdc.orders@noaa.gov " -
chris at 07:52 AM on 4 August 2010Plant stomata show higher and more variable CO2 levels
David, I'd say the science is pretty straightforward, especially with respect to Geocarb and AIRS: Geocarb: Geobarb has essentially nothing to say about absolute atmospheric [CO2] levels during the ice age cycles represented in deep Antarctic cores. Here’s what Berner says about his Geocarb model with respect to absolute values of his modelled [CO2], and the temporal resolution [***]:” Results are expressed as RCO2 which is defined as the ratio of mass of CO2 in the atmosphere at time t divided by the mass at present, and the results are compared to a standard run, where best estimates of the various input parameters are used. To convert RCO2 to CO2 concentration, because of appreciable errors inherent in this kind of modeling, a rough value of 300 ppm can be used to represent “the present.””
And:”It should be emphasized that GEOCARB modeling has only a long time resolution. Data are input into the model at 10 my intervals with linear interpolation between. In the case of rock abundance data, averages for up to 30 my time slices are sometimes used. Thus, shorter term phenomena occurring over a few million years or less are generally missed in this type of modeling.”
Clearly the model (which is constructed to assess weathering-dependent carbon cycling during the Phanerozoic) doesn’t attempt to determine precise [CO2] levels (”because of appreciable errors inherent in this kind of modeling, a rough value of 300 ppm can be used to represent “the present.”). And since it has 10 million year resolution with linear interpolation (up to 1 mya resolution in the Geocarbsulf version I linked to above), it can’t really say very much about the [CO2] levels during the ice age cycles. That’s pretty clear isn’t it David? We should take account of what the inventor of the model says about his model! AIRS and graces: You point out that daily AIRS retrievals can show lower mid-tropospheric [CO2] at the poles than at mid-latitudes. In monthly averages the differences are smaller (and it depends on the month of course, sometimes the polar regions have higher [CO2] than mid-latitudes). So why not take your point to its logical conclusion? Averaged yearly the differences are small (a few ppm). Since, in assessing fossil leaf stomata, or ice cores, the data is at least yearly averaged, we really should consider yearly-averaged AIRS data in assessing any difference between globally averaged and polar [CO2], yes? In which case your argument based on daily or monthly AIRS retrievals has little merit. stomata: Yes, there are apparent differences in some of the stomatal [CO2] reconstructions compared to the [CO2] measured in Antarctic cores. We all agree that [CO2] in ice cores are temporally averaged. For the high resolution Law Dome core, some stomatal data are in broad agreement with the ice core data, and some differ. In all cases the stomatal scientists highlight rather large uncertainties in their data. At some point the stomatal scientists will no doubt come to some consensus about the best methods for addressing the fossil stomatal data. Otherwise, one needs to be very careful not to over-interpret stomatal data. They have very large associated uncertainties (this is obvious from inspection of the training sets used to generate calibration curves). Since there is no absolute relationship between [CO2] and stomatal indices, the data can only be used for species that still exist today (in order to calibrate the particular analysis), and one has to make the assumption that the physiological response to varying [CO2] is the same 100’s of 1000’s to millions of years ago, as now. Fossil plant stomatal analysis is a nice method for estimating low resolution [CO2] levels and changes in the deep past. But there isn't really a basis for discounting ice core data in favour of stomatal data. Apart from anything else it’s difficult to imagine a process that would give rise to a depth-independent 20% reduction in [CO2] levels that is exactly constant between numerous different high resolution and low resolution cores through 1000’s of metres of ice. [***] R. A. Berner and Z. Kothavala (2001) Geocarb III: A Revised Model of Atmospheric CO2 over Phanerozoic Time American Journal of Science 301, February 182-204. -
Adam C at 07:46 AM on 4 August 2010Has Global Warming Stopped?
#43 fydijkstra: Actually, a linear model is appropriate. The combination of the logarithmic relationship of forcing to concentration with the exponential increase in concentration over time should be expected to create a roughly linear relationship between forcing and time. If you're unsatisfied with the fit, filtering out some of the noise makes more sense (given the underlying physical theories) than simply increasing the polynomial power. Correlation, as we are constantly reminded, does not prove causation. -
Broadlands at 07:45 AM on 4 August 20101934 - hottest year on record
JMurphy and Doug... OK. Here are some numbers. The first column shows weighted monthly temperatures for the 48 contiguous states (no Hawaii or Puerto Rico) derived from the original 1921 US Weather Bureau monthly reports... the Tables in the Condensed Climatological Summary. Example: http://docs.lib.noaa.gov/rescue/mwr/049/mwr-049-12-0684.pdf The average temperature (°F) for each state is given in these official reports. Only the contiguous 48 are used. The second column gives the temperatures from the NCDC-NOAA 1895-2009 US database where, presumably, the same historical information is given for each state, each month. The third column is the amount that the NCDC has lowered each temperature. JAN 36.0 33.8 2.2 FEB 38.5 35.9 2.6 MAR 49.5 47.5 2.0 APR 53.7 52.2 1.5 MAY 61.9 60.5 1.4 JUN 72.1 70.8 1.3 JUL 76.1 75.3 0.8 AUG 73.0 71.6 1.4 SEP 69.0 67.7 1.3 OCT 56.4 54.9 1.5 NOV 44.7 42.9 1.8 DEC 36.7 34.5 2.2 YEAR 55.6 53.9 1.6 Note that the annual average for 1921 has been lowered by 1.6°F. This lowering has the net effect of removing the year 1921 from its position as the warmest year on record in the US... as the Weather Bureau observed in several annual reports I cited earlier. The same pattern of lowering can be found in other years. I've checked 1934, 1938, 1940. All of the original Weather Bureau temperatures have been systematically changed and all have been lowered. The winter months have been lowered more the summer months...every time. It would be absurd to think that some sort of conspiracy has taken place but some plausible explanation should be available for this consistent trend. -
Doug Bostrom at 07:45 AM on 4 August 2010Has Global Warming Stopped?
Regarding Al's pointer to The Register (At it again, El Reg? Steven Goddard jilted 'em but they're discouraged...) there's a much fuller treatment here though the full text still seems locked away: Signs of reversal of Arctic cooling in some areas -
Peter Hogarth at 07:39 AM on 4 August 2010Plant stomata show higher and more variable CO2 levels
David Middleton at 07:00 AM on 1 August, 2010 “AIRS shows higher mid and low latitude CO2 levels than ice cores show for Antarctica” Slightly: Check out these recent visualizations of global CO2 measurements, but look at the Arctic values. You then state: “That the ice cores are not resolving decadal and century scale CO2 variations very well and that CO2 levels recorded in Antarctic ice cores should yield lower values than just about any other method used to estimate past global CO2 levels” I disagree. The following data from six different cores post dates that used in Van Hoof somewhat.
(Source NOAA Paleo Ice core data).
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Waste heat vs greenhouse warming
RSVP: Emissivity equals absorptivity for an object in thermal equilibrium. Please read that link - nothing is a perfect black-body (although the ocean is close), emission curves may be smooth (gray-body) or spiky (GHG's, many minerals), but all scale like a theoretic black-body with temperature. If we didn't have any greenhouse gasses in the atmosphere, the Earth would be 33C colder, as the Earth radiated directly to space through the IR transparent atmosphere. The atmosphere would also be colder, as it would only be heated by conduction/convection, no IR. GHG's only warm things up by absorbing IR leaving the planet, sending half the thermal energy they have back at the Earth (radiating energy in an isotropic spherical distribution), instead of letting it go out to space, thereby reducing the total emissivity (emission spectrum) of the Earth. And more GHG's mean more warming. Period, end of story. No cooling, unless you count the stratosphere cooling because all the heat is being kept close to the surface of the earth. You have failed to do the most elementary reading on greenhouse gasses or emissivity, thrown around red herrings such as the 'double-slit experiment', made incorrect claims about energy cancellation in microwaves, ignored the measured energy flows of the Earth/atmosphere system to argue for convection, and not understood thermal diffusion in a gas. If you are not just trying to crank people up, you are certainly failing to understand the information we have pointed you towards. I think this will be my last post on this topic. -
Al2807 at 07:05 AM on 4 August 2010Has Global Warming Stopped?
I found this article http://www.theregister.co.uk/2010/08/02/arctic_treering_cooling_research/ I'm sure there's more than the article says, since it appears to give the impression of an study to back up the idea that climate change is only due to solar activity. But I'm not a subscriber of the magazine that contains the full paper. http://instaar.colorado.edu/aaar/browse_abstracts/abstract.php?id=2668 Can anyone with access have a read and comment about the paper itself?. -
Chris G at 06:52 AM on 4 August 2010Why I care about climate change
John @63, Coincidentally, there is a psychological term for refusing to accept unpleasant information. It is classified as a defense mechanism and is called denial. RSVP @69 and DCWarrior @64, Another avenue to consider is that it isn't necessarily the scientists telling rich people they have to give up their treasures. I suspect that is at least in part a ploy by the very rich, (I read somewhere that the fossil fuels industry controls around 20% of the world's wealth.), to convince other people to pursue a strategy that contributes to the wealth of the very wealthy for as long as possible. A fair number of the studies that report that doing something to reduce carbon emissions will wreck the economy have been funded by those making a great deal of money from the sale and use of fossil fuels. ("If you do what they tell you, you'll have to give up your toys! They are evil and wrong!") Be skeptical, be very skeptical, but consider both sides when you are asking why is this person telling you what they are telling you. Also, rich is relative. If you are sitting on an air-conditioned building while reading this, you are richer than 75% of the world's population. -
macwithoutfries at 06:39 AM on 4 August 2010Has Global Warming Stopped?
The other thing that I was expecting would have been that 15 years is the WRONG INTERVAL - the correct interval is at least 22 years (or multiples of 22 years) and I believe you will see far more significance if you do the analysis like that !!! -
Phil at 06:38 AM on 4 August 2010Why I care about climate change
Albatross @76 Yes, it has occurred to me since my last post that since EWM only measures the difference between winter and summer mortality, then a low EWM is not necessarily a good thing, since it would rise with a very low summer mortality! Clearly the EWM for 1999-2000 was due to excess alcohol consumption over the millenium celebrations :-)
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