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How climate skeptics mislead

Posted on 13 June 2010 by John Cook

In science, the only thing better than measurements made in the real world are multiple sets of measurements – all pointing to the same answer. That’s what we find with climate change. The case for human caused global warming is based on many independent lines of evidence. Our understanding of climate comes from considering all this evidence. In contrast, global warming skepticism focuses on narrow pieces of the puzzle while neglecting the full picture.

What is the full picture? Humans are emitting around 30 billion tonnes of carbon dioxide into the air every year. This is leaving a distinct human fingerprint:

Signs of warming are found all over the globe (here are just a few):

On the question of human caused global warming, there’s not just a consensus of scientists – there’s a consensus of evidence. In the face of an overwhelming body of evidence, the most common approach of climate skepticism is to focus on narrow pieces of data while neglecting the full picture.

Let's look at an example. One popular skeptic argument has been to cast doubt on the surface temperature record. Skeptics claim thermometers are unreliable because surroundings can influence the reading. They reinforce this by showing photo after photo of weather stations positioned near warming influences like air conditioners, barbeques and carparks. The Skeptics Handbook goes so far as to say "the main 'cause' of global warming is air conditioners".

This myopic approach fails to recognise that air conditioners aren't melting the ice sheets. Carparks aren't causing the sea levels to rise and glaciers to retreat. The thousands of biological changes being observed all over the world aren't happening because someone placed a weather station near an air conditioner. When you step back and survey the full array of evidence, you see inescapable evidence of warming happening throughout our planet.

Our understanding of climate doesn't come from a single line of evidence. We use multiple sets of measurements, using independent methods, to further our understanding. Satellites find similar temperature trends to thermometer measurements. This is despite the fact that no carpark or barbeque has ever been found in space. Prominent skeptic Roy Spencer (head of the team that collects the satellite data) concluded about the HadCRUT surface record:

“Frankly our data set agrees with his, so unless we are all making the same mistake we’re not likely to find out anything new from the data anyway"

Our climate is changing and we are a major cause through our emissions of greenhouse gases. Considering all the facts about climate change is essential for us to understand the world around us, and to make informed decisions about the future.

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Comments 51 to 100 out of 229:

  1. Berenyi Peter is clearly providing a lovely example of the skeptic tactics as seen in John Cook's opening post. One would think that was his purpose! Here it is. We have multiple direct temperature measures showing warming (surface temperatures, satellite measures, ocean temperatures etc). Additionally we have all sorts of natural changes (glaciers, sea ice, flowering dates etc etc) which are most likely driven by higher temperatures [it would be remarkable if the changes all occurred without higher temperatures]. Yet Berenyi is asking us to believe the work of one person which, if correct, invalidates merely one of our multiple direct temperature records. If that one measure has errors, what causes the measured warming in all the other records Berenyi? And why does the natural world act like it's warming, at the magnitudes we are observing? Add to that the fact that Spencer has a history of bias, and has not submitted this work to any form of review, and it seems plain where the mistakes most likely lie. Not with the multiple independent lines of evidence, but with the one study claiming to show that one of the lines of evidence has a problem. Especially when many published works have shown the UHI effect to have a minimal impact on global (or US or whatever) temperatures - e.g. here, linking to Menne et al 2010. And Berenyi you don't answer the fundamental questions that frankly invalidate your arguments before it gets started - that by ProfMandia (BTW I really like your site PM) on independent evidence, or Marcus @44 - that population hasn't exactly increased in the Arctic, even by a small amount! And you don't explain the graph you posted, nor is it explained in your links, therefore we can hardly trust it.
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  2. #50 muoncounter at 23:51 PM on 13 June, 2010 Temperature records for most US states are searchable with a snazzy map-based interface here; many are continuous back to 1895 How comes your several-states curves don't even resemble to GISS temperature history for entire US? Please, explain.
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  3. #51 skywatcher at 23:57 PM on 13 June, 2010 If that one measure has errors, what causes the measured warming in all the other records Berenyi? Good question. However, it is for another thread, not this one. Apparently other datasets have their own problems, unrelated to this issue except strong incentive to make data consistent with one another by whatever means available. Spencer has a history of bias, and has not submitted this work to any form of review, and it seems plain where the mistakes most likely lie Looks like another attempt on argumentum ad hominem. If it seems indeed plain where the mistakes most likely lie, would you be so kind as to make them explicit for the rest of us instead of wasting our time? population hasn't exactly increased in the Arctic, even by a small amount! Absolute increase may be small, but logarithm of local density of population & structures around the few stations still used by GHCN almost certainly has increased a lot. It would be nice to get actual data on that. Check for example Canadian Settlement of Eureka on Ellesmere Island Nunavut. "Building continues in Eureka with the latest structure - an operation centre, completed in 2005"
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  4. There's an interesting lecture by Thomas Karl for those who are interested in urban heat effect. Do watch the lecture video, it contains plenty of interesting things. Links are here with an overview.
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  5. Berényi Péter, you used data already corrected for UHI, even if you do not like their method. You applied the correction to the global average, i.e. to all the stations as opposed to the stations affected, and did not use any gridding. Note that even Spencer didn't go (yet) that far as providing numbers for the global impact. If you don't like "AGW alarmists" methods, you may want to try Zeke's posts at The Blackboard, you'll learn how to do it properly from a "semi-skeptic" source.
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  6. In post #16, thingadonta said, I'll give some concrete examples, off the top of my head. There is no evidence that volcanism was stronger in the Cretaceous and that is why the c02 levels were higher and T was warmer. It is a superficial consensus focred to fit into the 'model'. Possibilities ignored include continental configuration and changes to ocean currents. This is darned near smoking-gun proof that thingadonta simply doesn't know what he/she is talking about. It is clear that thingadonta doesn't understand the basics of the carbon cycle. Long-term CO2 levels are not driven simply by volcanic activity. They are also driven by *rock weathering*. Rock weathering is the process by which exposed rock material (primarily silicate) reacts with CO2 in the atmosphere, with the ultimate result that the carbon ends up sequestered as calcium carbonates in ocean sediments. Volcanic activity driven by tectonic activity can re-liberate that carbon into the atmosphere. The amount of CO2 put into the atmosphere by volcanoes depends not only on the absolute amount of volcanic activity, but on the locations of the volcanoes (relative to the big carbonate sediment deposits). If ocean-sediments particularly rich in carbonates are being subducted under a continent, the volcanoes there will generate lots of CO2; otherwise, they will generate less. During times of tectonic uplift (i.e. formation of mountain ranges), silicate weathering rates increase (due the the greater amount of silicate rock material exposed to the atmosphere), and more CO2 is removed from the atmosphere. So even in the case where you don't have a heck of a lot of volcanic activity, CO2 levels can still rise over the long term if there aren't a lot of big mountain ranges building up and exposing rock material that can weather and remove CO2 from the atmosphere. If you have volcanoes being fed by carbonate-rich rock being subducted, and you don't have a lot of new silicate rock being exposed by the atmosphere by uplift, you can still (over the long term) get high CO2 atmospheric levels without an "unusual" amount of volcanic activity. The reason that current CO2 levels are now much lower than they were during the Creteceous is that about 50-55 million years ago, the Indian subcontinent began to collide with the Eurasian tectonic plate. This began the formation of the Himalayan mountain range. As the Indian subcontinent continued to smash into Asia, the Himalayas continued to build up, exposing lots of rock to atmospheric weathering. This weathering began removing CO2 from the atmosphere, ultimately bringing down the CO2 concentration to recent levels. So long-term CO2 levels don't depend simply on volcanoes; they also depend on rock weathering rates which in turn depend on tectonic-plate-driven mountain-building activity. The current (long-term) historically-low atmospheric CO2 levels can be credited to the Himalayan mountains, which have exposed tremendous amounts of rock material that has been weathering and removing CO2 from the atmosphere. This is not controversial, "cutting-edge" science; this is Earth-science 101 material, the same sort of stuff that would be taught in an introductory class at a community college. And this is just the sort of basic stuff that "skeptics" should make an attempt to learn before they start putting their two-cents' worth in discussions about global-warming. The fact that thingadonta thinks that paleoclimatologists don't understand why CO2 levels where higher during the Cretaceous betrays his/her ignorance of the subject. thingadonta's statements about ocean acidification betray further ignorance. He/she seems to be completely unaware of the impacts of CO2 concentration *rates of change* (vs. absolute CO2 levels) with respect to carbonate buffering. Very rapid rises in CO2 levels (what we are seeing today) can "outrun" the ocean-buffering capacity, resulting in much greater pH changes than slower increases of CO2 levels (of the same magnitude). It's not just absolute CO2 level that we are concerned about; it's the *rate of change* that is also a big issue. thingadonta also seems to be completely unaware of the Paleocene Eocene Thermal Maximum event and its implications, but that will have to wait for another post.
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  7. Apparently other datasets have their own problems, unrelated to this issue except strong incentive to make data consistent with one another by whatever means available. Conspiracy theories lack scientific credibility. Seriously guys, arguing with someone who has their mind made up is pointless. The urban heat effect is a red herring, drawing you in to the tangled mess where you can't see the forest for the trees.
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  8. @ Beranyi Peter. We already have pointed out the obvious errors-the fact that these records have already been corrected for urban heat island effect, yet he sees fit to correct them A SECOND TIME; the fact that his claims about UHI bias don't gel with the fact that satellite & ground-based records are almost identical for the last 30-year period; the fact that it fails to explain the warming trend over the oceans & in extremely isolated & unpopulated regions of the world; the fact that neither you nor Spencer has given a very good rationale for the "corrections" you apply. Neither you nor Spencer supply any *evidence* that population density has the effect on UHI that you both claim-& your claims run entirely counter to the most recent complaints about UHI by other so-called Skeptics-namely that there are too many Urban Weather Stations. Also, if you seriously expect us to entertain the notion that a relatively recent increase in population (not population *density*) of just a handful of people in the Arctic is sufficient to give lie to over 50 years of temperature records in that region, then we're going to need a little more proof than just your say-so! Also, for the record Beranyi, it is not ad Hominem to pull a scientist up for their past errors. His bias in terms of the satellite data he worked on (even if it wasn't deliberate) is a matter of public record-as is his refusal to correct his data after the error was pointed out to him. Yet you choose to believe this *single* person-over the scores of scientists who've been working on this data for decades-simply because he's saying what you want to hear. That's not *science*-that's more akin to Religion or Ideology!
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  9. "'Global warming' refers to the global-average temperature increase that has been observed over the last one hundred years or more." -- Roy Spencer Even Spencer agrees that global warming is real.
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  10. On February 25, 2009, a Princeton physicist named William Happer testified in the Senate. I first read his testimony on the Virginia Mining Association. It said on page 3 at the bottom that the footnotes were "added" by the SPPI. It's not clear to the reader if these are Dr. Happer's footnotes that have been added or if the SPPI made them up later for the paper. Most of the footnotes took the reader to articles by Lord Monckton, who mischaracterizes the research of the scientists he "cites, " so I figured the SPPI must have done this because Happer is a scientist and would not base his testimony on what a non-scientist says. I later found Dr. Happer's testimony on the official Senate site. He didn't have any footnotes after his testimony to document his views. If I were testifying in the Senate, I would include footnotes. I thought Dr. Happer would be mad that someone added footnotes to his official testimony, but on his own site Dr. Happer directs the reader to the SPPI version of his testimony with the added footnotes and to a blog Marc Morano did for Senator Inhofe. I think this is very misleading "scientific" testimony and wrote about it. http://legendofpineridge.blogspot.com/2010/06/why-did-drhapper-let-science-and-public.html
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  11. MattJ #1 There seems to be confusion about the collection of surface temperatures. Scientists don't do it: Phil Jones like Santa Clause travelling all around the world every day to read thermometers. No: temperatures are the providence of meteorologists. Watts proves that metiorologists aren't scientists every day.Temperature sets are collected, collated and stored by national meteorologic services. Scientits access this information at the end of the process. In the 60's, the local bank manager in the small ontario village where I lived collected data for Ottawa. Here in Nova Scotia the nearest station is at a Natural Resources office. The nearest station on Environment Canada's website is at a NS Agricultural research station. The thousands of people installing, maintaining and reading these stations aren't scientists. It makes one wonder how they became part of the criminal scientist's conspiancy.
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  12. #53 BP - for another thread? Look at the first sentence of John Cook's OP. The issue of multiple, corroborating lines of evidence is at the core of this thread and is one of the core issues you and Spencer refuse to deal with. "strong incentive to make data consistent"... black helicopters, anyone? As Marcus has described, quite how you expect the temperatures over the whole Arctic to be ascribed to the addition of a small number of people is remarkable, and distinctly unscientific. By your logic, if someone builds a few houses on the far side of Eureka from the weather station, it's readings might jump up by 0.3C or something!! Which is equally a trivial point as the high Arctic has experienced warming many times that magnitude...
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  13. #55 Riccardo at 01:10 AM on 14 June, 2010 you used data already corrected for UHI, even if you do not like their method Of course I don't like it. It has the opposite effect. Instead of removing bias due to increasing population density it amplifies the spurious signal. Do you want me to repeat the analysis with raw data? BTW, you could do that exercise yourself and let us know the result. http://data.giss.nasa.gov/gistemp/sources/gistemp.html ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/v2/ Note that even Spencer didn't go (yet) that far as providing numbers for the global impact. Yet. But what I did follows from his study in a straightforward manner. To really debunk this, you should show
    1. either average doubling time of local population density around GHCN stations flagged rural being extremely large (> 250 years) during the past century
    2. or UHI is negligible (< 0.027 K) for population density doubling
    I don't see how either one is tenable. But I have no doubt you can show us.
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  14. BP @53, No Skywatcher is right about Spencer's bias. As someone noted at Deltoid, here are the titles from his two most recent blog posts: ""Warming in Last 50 Years Predicted by Natural Climate Cycles" Well, he only looks at N. Hemisphere temperatures for starters...... Updated: Low Climate Sensitivity Estimated from the 11-Year Cycle in Total Solar Irradiance It seems that he is making the mistake of comparing transient climate sensitivity (TCR) with equilibrium climate sensitivity (ECS). Regardless, even his value of TCR is in fact at the low end of the range of ECS reported in the IPCC. If one calc. the ECS using his value for the TCR one gets a number (+2.55 K) close to the +3K reported by the IPCC. I could be wrong about my interpretation of his analysis identifying the TCR, but the title remains misleading. Funny enough, not any of his supporters are commenting on that thread."" So Spencer's estimate of TCR is actually not low, and he is not comparing apples with apples when he compares his value of TCR with the range for ECS reported by the IPCC. That, IMO, is misleading. BP, also, Spencer and Watts have not published their work on the US surface temperatures. Moreover, the UAH data are fraught with problems, and are not the high-quality data you seem willing to believe at face value-- read their "README" file, and is the outlier when compared to long term trends in RSS, RATPAC and various global SAT records, with perhaps the exception with HadCRUT. Here is a graph comparing the RATPAC data with the SAT data: Notice in the above figure how the warming trend in the global radiosonde data (mid-tropospheric temperatures) is greater than that in the global SAT data. As others have pointed out, you (BP) are neglecting that multiple, independent lines of evidence corroborate the warming in the global SAT records, and the reasons (both natural and anthro) for that warming have been established and discussed. Re Spencer's project. Menne et al. have published papers on the US SAT record, and Hansen et al. have something ready for submission which addresses many of the tired old red herrings which you are floating here. I also agree with Skywatcher that what you are doing here perfectly describes the tactics often used by contrarians. You accuse others of failing to see the big picture BP, but I fear that by nitpicking and confirmation bias may in fact be preventing you form seeing the big picture as shown by John Cook and others.
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  15. Berényi Péter, waiting for the time and the will to do the job by myself I do not pretend to disprove something with naive calculations done by hand. Honestly, I think it's safer to trust the results replicated by many others. As for the upside down UHI effect, the first thing to do is to compare rural vs urban stations to see if it's true that rural stations has warmed more than urban stations as you claim:
    Apparently not. So at the very least the sign of the correction everyone make is correct. P.S. Please note that I intentionally showed a graph from a "non-alarmist", "non scientifically corrupted" source.
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  16. #64 Albatross at 02:56 AM on 14 June, 2010 You accuse others of failing to see the big picture I have done nothing like that, you may re-check. In fact quite the opposite. I said the big picture is not a scientific notion and only has some heuristic value, if any. Individual issues has to be scrutinized one by one in depth. This is why I refuse to engage in an unbounded discussion about diverse lines of evidence right now and try to focus on a single theme. Not much success so far. BTW, the only thing I rely on from Dr. Spencer's analysis is the approximately logarithmic dependence of UHI on local population density. Otherwise the magnitude of the effect can be estimated from multiple independent sources. It is not complicated stuff, really easy to understand. I am a bit surprised you guys seem to abhor even the slightest effort.
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  17. @29 Marcus- Thank you for taking the time to refute those arguments. I don't actually think they are the best the skeptics have to offer, but they do follow the "skeptic" pattern of focusing on some tiny detail, and blowing it all out of proportion. I don't always have the knowledge to refute them (sometimes I do, but I forget!).
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  18. #65 Riccardo at 03:29 AM on 14 June, 2010 at the very least the sign of the correction everyone make is correct Riccardo, you can do better than that. See IPCC TAR WG1 2.2.2.1 Land-surface air temperature. "The last paper also separates rural temperature stations in the Global Historical Climatology Network (GHCN) (Peterson and Vose, 1997) from the full set of stations which, in common with the other three analyses, have been screened for urbanisation effects. While there is little difference in the long-term (1880 to 1998) rural (0.70°C/century) and full set of station temperature trends (actually less at 0.65°C/century), more recent data (1951 to 1989), as cited in Peterson et al. (1999), do suggest a slight divergence in the rural (0.80°C/century) and full set of station trends (0.92°C/century). However, neither pair of differences is statistically significant." Therefore the sign is indeterminate at best. However, as I've already tried to explain, this is irrelevant, since no huge differences are expected in temporal history of local logarithmic population density between densely and sparsely populated areas. What really counts is the population history of any single site along the time axis. There is no way to correct for this effect by looking at simultaneous data on nearby locations. Still, that's what people do. As world population has quadrupled in 109 years between 1900 and 2008 you should compare present day locations not too far away from each other with a fourfold local population density difference. We do know that surface temperature difference due to UHI between city centers and the surrounding countryside can be as large as several °C. On the other hand population density in cities can't possibly be a millionfold higher. As 1,000,000 ~ 220, if UHI effect is proportional to logarithmic population density indeed, one twentieth of the temperature difference above is a lower bound of UHI for population density doubling. Therefore the figure I have used (0.16°C for doubling) is reasonable.
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  19. #67 actually thoughtfull at 04:08 AM on 14 June, 2010 they do follow the "skeptic" pattern of focusing on some tiny detail, and blowing it all out of proportion I have bad news for you. That's what scientists do all the time. It's their daily job to focus on tiny details, blowing it all out of proportion if you will. There is no other way. If you are looking for nice holistic visions, find a politician or someone involved in Bach flower remedies.
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  20. Apparently other datasets have their own problems, unrelated to this issue except strong incentive to make data consistent with one another by whatever means available.
    When the facts aren't on one's side, one can always fall back to the good 'ole conspiracy theory... It's especially ironic since his hero Spencer's UAH satellite product shows warming that is entirely inconsistent with Spencer's claims that it's all due to UHI screwing up the surface station record. BTW Spencer's partner on the UAH satellite analysis effort, John Christy, is on record, as part of an NRC review panel, as saying the the surface station temperature record is as accurate as the satellite record.
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  21. BP, re missing the big picture. Perhaps I am mis-interpreting what you were trying to say in your post at #3. Anyhow, let us not get sidelined by semantics. Spencer should publish his work if he thinks it has merit, until then it remains some intriguing blog science. Really busy today, but hope to join the discussion tomorrow some time.
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  22. {snip}
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    Moderator Response: Geo Guy, please read Links before posting these well-debunked myths.
  23. #70 dhogaza at 05:53 AM on 14 June, 2010 When the facts aren't on one's side, one can always fall back to the good 'ole conspiracy theory... No need for conspiracy theories, plain conformism is enough. BTW, what particular facts are you talking about? Elaborate, please. "the surface station temperature record is as accurate as the satellite record" No doubt about that.
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  24. Naomi Oreskes and Erik M. Conway wrote a great article recently in Yale Environment 360 titled "Global Warming Deniers and Their Proven Strategy of Doubt" The upshot of the article is this: For years, free-market fundamentalists opposed to government regulation have sought to create doubt in the public's mind about the dangers of smoking, acid rain, and ozone depletion. Now they have turned those same tactics on the issue of global warming and on climate scientists, with significant success. I admit I'm a liberal, and prefer 'managed capitalism' to free-market capitalism (so you are forewarned in what follows.) By way of street cred, I was in a PhD program in mesoscale meteorology 25 yrs ago, when global warming first became a 'no-brainer' among the Atmospheric Science community, but left and went back to Engineering cuz the math in ATM was just... wow... Anyway, here goes: I don't believe the fight against the deniers will be won by scientific arguments on Global Warming. Instead, it will be won by arguments on free-market unmanaged capitalism. In essence, you don't win a war by fighting it defensively, on your turf. You win it by fighting it offensively, on their turf, for their castle. Once the 'castle' of the free-market unmanaged capitalism ideology has been burnt to the ground, denial activities will dry up. Never before has there been so much ammunition with which to conduct this battle: it is practically washing up on America's Gulf shore in the form of tar balls. Sadly, I think the progressive community splits itself in this fight, with the 'hard-core' progressives suggesting that ALL capitalism is bad, even managed capitalism. With half its forces out trying to siege the wrong castle, progressives fail in taking down the castle that really matters. Hence, while the IPCC continues to pile up evidence, it may not matter as greatly as we think because the deniers have us on our turf rather than theirs. The general public doesn't know better, but they assume 'where there is smoke, there is fire', and therefore assume that global warming is controversial, because they are attacking our castle. Hence, the fight against Climate Change cannot succeed until they are attacked on their turf, rather than ours. There is abundant evidence, now, that 'free market' unregulated capitalism is disastrous for any society that adopts it. Its just a question of whether the disaster can be externalized (to Iraq or the oceans) or not. Although the first rule of any crusader is to learn to lie, especially to themselves, the anti-global-warming crusaders who fein indifference to attacks on free-market ideology are nevertheless vulnerable. That is because the same technique they are using against Climate Change also works against them: 'where there is smoke, there is fire'. If enough people put up enough of a stink about the very real shortcomings of free-market unmanaged capitalism, the anti-Global Warming group will eventually be forced to acknowledge their underpinings. Or, at the very least, channel precious resources away from their denial activities to 'defend the castle' of free-market capitalism. Sorry if I offended anyone on this blog: I know scientists are legendary 'do-it-yourself'ers, and therefore suspicious of 'common action'. But, the attack on Global Warming has nothing to do with science, and everything to do with the idea of 'common action'. Sometimes, as now, we all have a vested interest in the commons. And that is like a Dentists Drill to those who have swallowed the Ayn Rand mythology. Powerful vested industries (i.e. oil and coal) are only too happy to feed their paranoia
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  25. ubrew12: I tried something like this on a blog post called: How to Talk to a Conservative about Climate Change
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  26. #52 Berenyi Peter, Actually, the GISS graph looks exactly like a large area average ought to, with smaller +/- extremes than locally derived averages. Click image for full scale. Click for full scale. I like the 15 year trailing average on the large area indices, as it gives a look at the underlying long period signal. For example, in the 11 states and GISS graph, GISS has 2 distinctly linear segments with nearly the same slopes: 1920-1946 and 1978-2009. That seems to rule out at least three skeptical suggestions: a). Air conditioning causes spurious temperature readings -- there were very few AC units in use during the Depression. b). Random temporal events such as volcanic eruptions -- how do random events produce the same slope at two different times? c). Its the sun -- those are neither sunspot nor TSI variation periods. Rather, one has to ask: is there another mechanism for increasing temperatures that can produce such a systematic effect? If so, what other measurable effects go with that mechanism?
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  27. BP and Spencer ascribe physical meaning to a simple regression coefficient, from the regression of one-year average difference in temperature between station pairs (ambitiously labeled "Station warm bias") on their difference in population. Interpreting a simple regression coefficient in this manner assumes that in every relevant way except population, the station pairs are identical. I doubt many journal reviewers would buy that; the word "spurious" would probably come up. They would also not be impressed by the application of a cross-sectional coefficient from this analysis as if it characterized change over time. But without that leap from correlation to process, the analysis could claim no relevance to trends that in reality are derived from anomalies, not absolute temperatures. More than a century of data is available for hundreds if not thousands of stations where we can also roughly enumerate local population. There are quite direct ways to test the hypothesis that stations with higher growth rates have steeper temperature-anomaly trends, but this isn't a serious attempt to do so. One interesting feature of many century-long records, not just station measurements but other temperature-related indicators, is that they resemble not just the global upward trend, but its specific 20th-century pattern of early rise, mid-century leveling or decline, then steep rise again after 1970 or 80. I see that not always but quite often, including places far from the population centers.
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  28. John Cook:"On the question of human caused global warming, there’s not just a consensus of scientists – there’s a consensus of evidence. In the face of an overwhelming body of evidence, the most common approach of climate skepticism is to focus on narrow pieces of data while neglecting the full picture." Rather than get into a specific issue here, I will simply point out that this is a perfectly respectable scientific approach. Check out how Einstein's general relativity supplanted Newton's gravitation. IIRC, Einstein's GR even predicted consequences that were apparently false. Potentially all it takes to *completely* overturn a theory is a very small amount of evidence. For the record, I don't think the evidence is overwhelming except on the things that are generally agreed upon. There is little disagreement that CO2 will , on its own, cause warming or that the last 100 years or so has seen a significant warming trend. There is a lot of disagreement, however, on what the sensitivity of the climate to CO2 increases is high. Cheers, :)
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  29. Oops, my typing got away form me above - this sentence -"IRC, Einstein's GR even predicted consequences that were apparently false." should read "... predicted consequences that appeared to be false when it was originally proposed. On closer analysis, it was, of course, seen to be accurate.
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  30. 34 David Horton There has been a short period of global warming which explains the whole list the cause maybe wholly CO2, partially CO2, barely CO2 or not CO2. I find the two extreme positions (wholly and not) difficult to accept in a chaotic, naturally variable system that is poorly observed and understood. Secondly when it comes to the potential impacts of global warming I worry the science is full of tunnel vision, it is almost funny the way climate change is invoked to explain almost all changes in the natural world. Extinct is a natural process, 99.9999% of all extinctions happened before hominids appeared on the earth. I accept we can cause extinctions but it's still the case that it's human expansion and change in land use that have the greatest impact. On changes in seasons and phenological changes it seems that species have always had to adapt to climate induced ecological change. I think it's uncontroversial to say the temp record of the 20th century is a combination of a natural cycle with a warming trend imposed upon it? I was trying to find the amplitude of that natural cycle. It looks to be ~0.3-0.5oC over 15years. So species are always having to adapt to change, in fact Darwin called it Adaption. My interest isn't really in seeing the theory collapse it's in trying to confront the implications of the politics of climate change, in terms of the science this is more associated with the conclusions drawn from the data rather than the data itself. Take one of John's bullet points "Species are becoming extinct" surely at best that should be local population extinctions based on data presented in the associated paper. Already we conveniently drop an important distinction to emphasis the danger.
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  31. HR - so what natural cycle other than ENSO is impacting the global temperature record and what is your evidence for it? If you have no external forcing, then all you have is heat redistribution and that doesnt explain the energy imbalance. As to extinctions - the problem that causes extinction is rates of change that are too fast for adaptation. Now humanity is certainly bringing in the too-rapid change with habitat destruction and change, but a climate that warms too fast is an additional and global cause. Compare warming rates now with the rates of change during the ice age cycle. I worry about media and greens getting tunnel vision but I dont think you can project it onto science.
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  32. #80 "it is almost funny the way climate change is invoked to explain almost all changes in the natural world." That's a bit of an exaggeration, surely. But given that most scientists do believe that global warming will have a broad range of global effects, why would this surprise you? Honestly, don't you think it'd be much, MUCH stranger if AGW were real, but its effects were strictly limited in time and space, thanks to some physical process of which no one has any inkling? For me, the oddest thing about many "skeptical" arguments is the simultaneous claim that climate is too complicated to predict, and too limited in influence to affect virtually every aspect of life on earth. Granted, certain predictions may be wrong, but that argument cuts both ways: they may be too optimistic, rather than too bleak. Whatever uncertainty exists doesn't necessarily work in our favor. Right?
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  33. HR, you claim that because most extinctions in Earth's history are natural, that we should simply ignore those extinctions caused by human actions. By that logic, because most forest fires are natural, do you agree that we should simply ignore those which are caused by arson? Even if said arson leads to the destruction of your home & all your possessions? This merely highlights how ludicrous such an argument is-yet still it gets bandied about by those supporting the interests of the Fossil Fuel Industry & other highly destructive corporate entities.
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  34. Berényi Péter, if our best estimate of the difference in the trend between rural and urban stations is 0.05 °C/century (which is determined with an error, not indeterminate) there's no much room for a big UHI effect however calculated. This is what those data tell.
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  35. J. Scott Armstrong (Ph.D., MIT, 1968), a Professor at the Wharton School of Management, University of Pennsylvania, is the author of Long-range Forecasting, the creator of forecastingprinciples.com, and editor of Principles of Forecasting (Kluwer 2001), an evidence-based summary of knowledge on forecasting methods. He is a founder of the Journal of Forecasting, the International Journal of Forecasting, and the International Symposium on Forecasting, and he has spent 50 years doing research and consulting on forecasting. (Armstrong@wharton.upenn.edu) Kesten C. Green of the International Graduate School of Business at the University of South Australia is a Director of the International Institute of Forecasters and is co-director with Scott Armstrong of the Forecasting Principles public service Internet site (ForPrin.com). He has been responsible for the development of two forecasting methods that provide forecasts that are substantially more accurate than commonly used methods. (Kesten.Green@unisa.edu.au; and Willie Soon ...: "Our research findings challenge the basic assumptions of the State Department’s Fifth U.S. Climate Action Report (CAR 2010). The alarming forecasts of dangerous manmade global warming are not the product of proper scientific evidence-based forecasting methods. Furthermore, there have been no validation studies to support a belief that the forecasting procedures used were nevertheless appropriate for the situation. As a consequence, alarming forecasts of global warming are merely the opinions of some scientists and, for a situation as complicated and poorly understood as global climate, such opinions are unlikely to be as accurate as forecasts that global temperatures will remain much the same as they have been over recent years. Using proper forecasting procedures we predict that the global warming alarm will prove false and that government actions in response to the alarm will be shown to have been harmful. [... !!!]"
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  36. I have a problem with some of the points at the beginning of this post: The first one: Ice sheets are melting In the link we are presented with graphs that show that both polar ice sheets are melting. They cover the period 2002-2009. This is a little confusing to me: I thought discussions about long term climate change ought to be based on considerably longer observation periods than 7 years. What am I missing here?
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  37. About the second point (signs of warming): Sea levels are rising Figure 3 in the post: Visual depictions of Sea Level Rise shows that, while the sea level is mostly rising, in large parts of the Pacific it is actually falling. A lake can have a higher level in the end where water runs in, and a lower level where it runs out, but how can an ocean over 15 years show rising levels in one part, and at the same time falling levels in another part? Can we trust such results? Other than for short time variations (due to atmospheric pressure) the ocean level should be one and the same, I think. Water flows until differences are evened out.
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    Response: Ocean level isn't completely homogenous - thermal expansion means cooler areas of the ocean are lower and warmer areas are warmer. What we have with global sea levels are two independent measurements - tidal gauges and satellites - giving consistent results.
  38. <<"Marcus at 15:45 PM on 14 June, 2010 HR, you claim that because most extinctions in Earth's history are natural, that we should simply ignore those extinctions caused by human actions.<< On the other hand, acting to conserve nature is about as unnatural as you can get. When you observe animals in nature, they are directed soley by instinct, not their rationale; and yet conservationists appeal to Man's particular faculty to reason in order to work in harmony with nature. The most natural thing would be to let this situation just "takes it course" come hell or high water. (i.e., hell in the form of global warming. High water, rising sea levels). Lurking behind AGW is this idea of a time bomb that will catch us off guard sometime in the future, and moreover, that the last thing to trust in in Nature and God's Providence.
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  39. #84 Riccardo at 15:52 PM on 14 June, 2010 if our best estimate of the difference in the trend between rural and urban stations is 0.05 °C/century [...] there's no much room for a big UHI effect however calculated. This is what those data tell. That's not true. Those data only tell us effect of growing population density on surface temperature is similar at sites classified either "rural" or "urban" by GHCN. It tells nothing about the absolute magnitude of the effect. Population density distribution tends to be self-similar (fractal) over scales spanning several orders of magnitude. As population density increases, this structure is expected to be approximately preserved. That is, while population increases much faster in densely populated ("urban") areas than in sparsely populated ("rural") ones, the ratio of population density between different regions only changes slowly. Should UHI effect be a quasi-linear function of local population density, your claim ("there's no much room for a big UHI effect") would certainly be justified. But it is not the case. UHI turns out to be a surprisingly linear function of logarithmic population density, therefore temperature difference between two spots would not change due to UHI as long as the ratio of local population density is constant between them. The ratio of two functions being constant does not impose a restriction whatsoever on the rate of change of the functions themselves. The only question remaining is the magnitude of the UHI effect expressed as temperature change for a doubling of local population density. If your number (0.05°C/cy) for UHI trend is adopted, it implies a local UHI effect magnitude of 0.027°C/doubling on average, because global population density has doubled almost twice during the past century (quadrupled in 109 years). With such a low UHI constant the Urban Heat Island Effect would be unobservable, even with sensitive instruments. It would simply get lost in weather noise. Your figure means if population density in city center is a thousand times more (and that's stretching the limits) than in the surrounding countryside, temperature difference between the two places (the UHI effect) would be around 0.27°C. In fact one neither have to be a scientist to detect UHI, nor instruments are needed. It can be felt. By anyone traveling from countryside to city or back. And that means the effect is huge, at some places it can be as large as 3-4°C for population density differences considerably less than a thousandfold. Therefore my estimate of 0.16°C/doubling is a conservative one. World population has doubled about 1.83 times during 20th century. Those people had to settle somewhere. But it was never their priority to avoid GHCN stations at all cost. Therefore population density around some GHCN stations doubled less than 1.83 times, and more around others. On average population density has increased as the global rate even if a GHCN station happened to be nearby. With an UHI constant of 0.16°C/doubling average warming due to UHI effect in GHCN was 1.83×0.16°C ~ 0.29°C, meaning 45% of 20th century warming as measured by the Global Historical Climatology Network is due to Urban Heat Island Effect and has no climatological significance whatsoever. This line of reasoning is so simple, obvious and self-explanatory, that claims about UHI not having any significant influence on historical surface temperature reconstructions should be considered extraordinary. And as we all know the weight of evidence for an extraordinary claim must be proportioned to its strangeness.
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  40. Comment to sign number three: Seasons are shifting Whereas I am sure there lies an enormous effort behind compiling the report quoted (for first flowering index), I think that as support for climate warming this is third rate science. A big issue is made out of the claim that spring comes some 3 days earlier now than 250 years ago, without noticing that, within this long time period, flowering varies between day 120 and day 170! Looking at 25 year averages, there are maxima and minima that differ more than ten days from each other, but the only thing the graph is used for, is comparing the first and the last 25 year average. What I find more interesting is that the first 90 years show a trend upwards (later spring) by almost 10 days, then there is a solid trend downwards for the following 70 years (down 10 days), which is then followed by a marked trend upwards for 50 years. In the last decades the average moves down again. All this really tells me, is that the first flowering index goes up and down, as centuries pass!
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  41. Berényi Péter, we are going to be circular. Indeed you're maintaining the point you made before which, in my opinion, is untenable for the reasons said before that it's not worth repeating. Given that you talked about extrordinary evidence, you should admit that the extraordinary conclusion is a logarithmic dependence of UHI effect on population starting already at very low values. Data show otherwise, even when they are categorized according to population density as in the graph I showed before (didn't you notice?). It's pretty hard to explain how is it possible to have a diverging effects on going to lower population densities and indeed Spencer didn't even try in the blog post and you didn't question but blindly accepted it. We all are still waiting for the extraordinary evidence.
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  42. BP #89 BP I found a reference some time ago (since lost) with an estimate of waste heat from industrial and domestic processes released into the atmosphere across the continental USA. From memory the number was between 0.3 and 0.5W/sq.m. (I could be wrong here) Since waste heat is a component (probably a large one) of the UHI, do you have any information on an estimate of this number? Since we are talking 0.9W/sq.m for Dr Trenberth's TOA imbalance driver of AGW, a 0.3 - 0.5 W/sq.m figure would be a significant component. Also note that I think that a large chunk (60%) of Willis' heat equivalent of 0.1W/sq.m OHC increase in the deep oceans below 700m has been found by your geothermal reference. See Post #77 here: http://www.skepticalscience.com/news.php?p=2&t=77&&n=202
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  43. Berényi Péter writes: This line of reasoning is so simple, obvious and self-explanatory, that claims about UHI not having any significant influence on historical surface temperature reconstructions should be considered extraordinary. BP, with all due respect, I have repeatedly pointed out your tendency to un-skeptically latch on to poorly tested ideas and hastily conclude that they falsify large swathes of the scientific consensus. This latest comment of yours is a case in point. It just seems so confused that one hardly knows where to begin. BP writes: UHI turns out to be a surprisingly linear function of logarithmic population density, therefore temperature difference between two spots would not change due to UHI as long as the ratio of local population density is constant between them. First, unless I'm missing something, this "turns out to be" is based heavily on one blog post by Roy Spencer. And the rest of that sentence makes no sense! Perhaps you meant to write "as the ratio of log population density is constant..."? Then there's this: With an UHI constant of 0.16°C/doubling average warming due to UHI effect in GHCN was 1.83×0.16°C ~ 0.29°C, meaning 45% of 20th century warming as measured by the Global Historical Climatology Network is due to Urban Heat Island Effect and has no climatological significance whatsoever. Where does that 45% come from? It appears to me that you're comparing your estimate of an "average" UHI effect to the 20th century global temperature trend. But 70% of the world is ocean! So even your excessively high estimate of UHI would actually account for only about 13% of 20th century warming.
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  44. Ken Lambert at 23:22 PM on 14 June, 2010 "Since we are talking 0.9W/sq.m for Dr Trenberth's TOA imbalance driver of AGW, a 0.3 - 0.5 W/sq.m figure would be a significant component." It would be if it were a significant number. In fact it isn't. It's around 0.028W.m^2 globally averaged. Flanner, M. G. (2009), Integrating anthropogenic heat flux with global climate models Geophys. Res. Lett., 36, L02801 The notion that geothermal heat flux has made a significant contribution to the recent increases in deep ocean heat content [*] isn't supportable without evidence that the geothermal heat flux has coincidentally increased enormously during the same period. Remember that the dissipation of heat from the earth interior to the surface is expected to occur at a rather constant rate given by the constant (in the 10^4-10^6 year timescale) generation of heat by radioactive decay and the temperature gradient to the surface. Globally averaged this amounts to around 0.1 W.m^2. There's no evidence that this has increased dramatically (i.e. doubled!) during the last few decades. ----------------------------------------- [*] the work of Greg Johnson and his collaborators is a good starting point; e.g.: Johnson GC et al. (2006) Recent western South Atlantic bottom water warming Geophys. Res. Lett. 33, L14614 Johnson GC et al. (2007) Recent bottom water warming in the Pacific Ocean J. Climate 20, 5365-5375. Johnson GC (2008) Warming and Freshening in the Abyssal Southeastern Indian Ocean J. Climate 21, 5351-5363. Ozaki H et al. (2009) Long-term bottom water warming in the north Ross Sea J. Oceanograph. 65, 235-244. Johnson GC et al. (2009) Deep Caribbean Sea warming Deep Sea Research. 1 –Oceanograph. Res. 56, 827-834. Johnson GC (2008) Reduced Antarctic meridional overturning circulation reaches the North Atlantic Ocean Geophys. Res. Lett. 35, L22601
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  45. Global land+ocean temperature trends since 1979 are +1.6C/century for RSS, GISS, HADCRUT, and NCDC (or +1.3C/century for UAH). I don't see any way that the satellite records could be influenced by the UHI effect. But in any case, even a rather inflated estimate of +0.29C/century UHI effect on land would be +0.08C/century globally (land is 29% of the world). So BP's estimate of the UHI effect would be 5% of the current global temperature trend (for RSS, GISS, etc.) or 6% (for UAH). Note that that "29% land" figure includes vast expanses of completely uninhabited areas in Antarctica, Greenland, the Sahara, etc. I'm not sure how much effect UHI has there, but that's all included in this 5% (or 6%) figure.
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  46. HumanityRules at 14:25 PM on 14 June, 2010 "On changes in seasons and phenological changes it seems that species have always had to adapt to climate induced ecological change. I think it's uncontroversial to say the temp record of the 20th century is a combination of a natural cycle with a warming trend imposed upon it? I was trying to find the amplitude of that natural cycle. It looks to be ~0.3-0.5oC over 15years. So species are always having to adapt to change, in fact Darwin called it Adaption" That's incorrect on several levels: The globally averaged amplitude of natural cycles (or quasiperiodic variations in surface temperature arising from oscillations in the climate system) is likely in the region of 0.1-0.2 oC (see e.g. [*] and [**]). A recent analysis of the contributions of these natural oscillations concludes that they have made near zero contribution to the warming since the start of the 20th century [**]. Your final point confuses (i) the component of species "fitness" that encompasses somatic or phenotypic compatibility with the range of (climate) variability within their ecosystem (one could call this "adaptedness"), and (ii) "adaptation" in the Darwinian sense, which involves the (genetic) acquisition of phenotypic traits that increase the fitness of a species with respect to a particular ecosystem. There is no question that "fit" species are (by definition) compatible with the range of meteorological diversity within the particular climate regime they inhabit. The point at issue is the ability of species to adapt to changing environmental conditions as climate regimes shift rapidly under the influence of global warming. Species that are adapted to a particular climate regime with its inherent variability, are likely to be poorly adapted to a considerably different climate regime. They're unlikely to be able to acquire the adaptations by which they might retain fitness, since Darwinian adaptation is a slow process. Therefore under rapidly changing climate conditions species migrate (as is being observed in the real world) or if this is not possible, they may likely become extinct. [*] Zhang, R., T. L. Delworth, and I. M. Held (2007), Can the Atlantic Ocean drive the observed multidecadal variability in Northern Hemisphere mean temperature? Geophys. Res. Lett., 34, L02709 [**] K. L. Swanson et al. (2009) Long-term natural variability and 20th century climate change. Proc. Natl. Acad. Sci. 106, 16120-16123.
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  47. #91 Riccardo at 22:30 PM on 14 June, 2010 you should admit that the extraordinary conclusion is a logarithmic dependence of UHI effect on population starting already at very low values Well, you have not mentioned so far you think the logarithmic dependence breaks down for low population density values. If this is what you claim, you should also supply an alternative hypothesis about the approximate form of the function in this range. However, before you venture to do that, you may prefer to have a look at this article: INTERNATIONAL JOURNAL OF CLIMATOLOGY Int. J. Climatol. 23: 1889–1905 (2003) Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/joc.971 THE URBAN HEAT ISLAND IN WINTER AT BARROW, ALASKA Hinkel at al. Barrow, Alaska is a fairly northern (71°17′44″N) village, with 4581 inhabitants in 2008. As the GHCN criterion for a township being flagged "rural" is to have less than 10,000 inhabitants, it is classified rural indeed (WMO No. 70026). In spite of this Hinkel at al. 2003 have found an average winter (December-March) UHI of 2.2°C there (relative to the surrounding countryside). Therefore we may safely conclude there exists at least one rural GHCN site where UHI is not negligible at all. Data show otherwise, even when they are categorized according to population density as in the graph I showed before (didn't you notice?) You mean this figure, I suppose. I don't see how is it related to the (non)logarithmic dependence of UHI. It has two categories, less than 2/km2 and more than 500/km2, but nothing about how the distribution of stations in each category has changed over time. Without this information nothing can be calculated, therefore based solely on this graph the logarithmic hypothesis can neither be confirmed nor refuted. You may also study this one. Atmospheric Environment Volume 7, Issue 8, August 1973, Pages 769-779 doi:10.1016/0004-6981(73)90140-6 City size and the urban heat island T.R. Oke Unfortunately I have no access to it right now, but he studies settlements ranging from ten thousand to two million inhabitants and has found logarithmic dependence of UHI in this range with ΔTUHI = log10(pop) where pop is population of the city. It is equivalent to an UHIE of 0.22°C/doubling (of city population). As area also increases with increasing population, the rate of increase in population density is lower. Therefore if Oke's formula is accepted, about 70% of 20th century warming is accounted for by UHI. Of course he has not studied settlements below 10,000, but his formula still gives a 2.92°C UHI for the lower end. I guess his values are a bit high, but as the Barrow, Alaska case shows, not an order of magnitude higher than reality. A UHI of 0.16°C/doubling (of population density) still looks like a safe bet.
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  48. #93 Ned at 23:58 PM on 14 June, 2010 Perhaps you meant to write "as the ratio of log population density is constant..."? For God's sake, NO! Do I have to explain logarithms? (logarithm of quotient is the difference of logarithms, at least last time I've checked it was that way)
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  49. #94 chris at 00:06 AM on 15 June, 2010 The notion that geothermal heat flux has made a significant contribution to the recent increases in deep ocean heat content [*] isn't supportable without evidence that the geothermal heat flux has coincidentally increased enormously during the same period Yes. But geothermal heat flux is still an important driver of OHC, if not on short timescales like this. The oceans have to get rid of that heat somehow, otherwise it would warm them up at a 0.0002°C/year rate. If all the sea ice would have gone (as it was during Eocene times), surface waters got warm even in arctic seas, downwelling of water close to ice edge would stop (due to lack of ice edge), in just a hundred thousand years (which is nothing on geological timescale) even abyssal waters would warm up to 20°C. In half a million years the entire ocean would be boiling. Actually it would not. Circulation would resume long before that, at a higher than present day temperature.
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  50. BP, my apologies, I read that sentence ("therefore temperature difference between two spots ...")carelessly and leapt to an incorrect conclusion about what you were doing. Fortunately that was irrelevant to the rest of my point, however, and I stand by the comment that your proposed UHI effect (0.29C/century over land) works out to approximately 5 or 6 percent of the current global trend, whether measured using satellites or surface observations.
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