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Comments 110901 to 110950:

  1. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Tobyjoyce, I haven't heard that statement before :-) I browsed around a bit and it appears that the Dutch have been making polders from marshes and lakes for over a 1000 years already (but possibly even 2000 years) where the first polders used gravity to drain the area into (tidal) rivers when their water levels were sufficiently low enough. It was only after 1400 that the first windmills arrived. The windmills were eventually needed because of the compaction of the peat soils (possibly some 2 meters!) due to water drainage and higher boezem water levels due to ever more polders draining their excess water into those canals. Among other things, the need for new polders was created by a fast growing population which needed fuel (from peat in those days) which eventually, due to several factors, resulted in the accidental creation of new lakes and reduced dry land area via erosion of the soft lake banks. This was one of man's earlier environmental 'disasters'. By pumping the lakes dry further erosion was prevented and created new fertile land as a bonus. Early geoengineering to counter environmental challenges at work and the Dutch master it! ;-) Creating and maintaining a sizeable polder is, ofcourse, not a task for a single person, so all who had a stake in the polder would usually cooperate (this period might be the source of your quote!). But not everyone is able to do so ofcourse, hence unions were established. Everyone with a stake was forced to pay to the union, an ancestor to the modern municipality, which in turn would ensure good maintenance. The unions would slowly start to merge into ever bigger unions called 'waterschap' covering multiple municipalities, creating a separate specialist government layer rather unique in the world. The first waterschap was created in 1255. Developing new polders became a profitable speculative business due to high land prices in the years 1550-1650 and more audacious new plans attracted ever more speculators. Eventually this bubble blew like many other bubbles to come when land prices dropped during the construction of polders causing often massive loss of private capital. It looks like the story of the Dutch polders holds some valuable lessons to the current generations which seem largely to have learnt nothing from history. I'm sorry about the length of this post, it got a bit out of hand. :-)
  2. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Heh. I wasn't referring to you, or to anyone else in particular. I was just using that as an example of the kind of remark that tends to hinder rather than promote useful discussions.
  3. Urban Heat Islands: serious problem or holiday destination for skeptics?
    Thanks for the link, Michael. I agree that it's important to know how significant BP's regression model is. However, it's also very important to know how representative BP's set of stations is. As I noted above, his stations show a much larger warming than other people's reconstructions using station data over the same decade. That bias seems like an indication that his stations aren't necessarily representative of the actual land surface record. That wouldn't be as big a concern if he were using gridding, kriging, or some other method to compensate for the irregular distribution of stations. As we recently saw in another case, the "cooling" he reported after just averaging a bunch of met stations in Canada turned out to actually be "warming faster than the world as a whole" once the spatial autocorrelation in his data was taken into account. If the F-statistic indicates very low significance for his model, then it's probably not worth bothering about anything further. (And in fact, my purely uninformed guess is the model is not at all significant.) But if the model seems prima facie strong, I'd like to see a map of the stations used, or a table of their coordinates, or something like that.
  4. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    #29 Ned I wasn't getting riled up, I was just rolling my eyes a bit, and hoping I was being Poed. }|
  5. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    This is a good topic for discussion, by the way, if sensible people can avoid getting riled up over silly remarks like "just another attempt to scare up more support for the warmista agenda!" It's an area where the science is genuinely still being worked out, and where there really is more fertile ground for genuine skepticism.
  6. Urban Heat Islands: serious problem or holiday destination for skeptics?
    BP: Since Dr. Hanson has shown here that the warming trend in the rural stations and at very dark stations is the same as at stations that have large urban developments, how can you claim that you have something worthwhile? You have cited a blog post on WUWT as your primary source. You claim your correlation is "not very strong" without saying what the correlation is. You have not said anything that Dr. Hanson has not already shown in a peer reviewed study is wrong. "I think" is no better than "I doubt it" if you have no supporting data. Your claim that one person moving into a 10 km2 area would raise temperatures significantly is completely unbelievable without solid data. Extraordinary claims require extraordinary proof. You have "not very strong" so far. That doesn't make the grade.
  7. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Since I tend to be harshly critical of many of BP's do-it-yourself analyses, let me say that I think his graph is pretty robust this time. It doesn't matter whether you use a 25-year smoothing, 10-year smoothing, or no smoothing. It also doesn't matter whether you just count the number of hurricanes, add up their category #s, or only look at major storms. There isn't really any long-term trend in hurricanes making landfall on the US. Now, maybe "hurricanes making landfall on the US" is not a good proxy for global tropical cyclone numbers, I don't know. But this isn't an issue of smoothing or of how you count the storms.
  8. New presentation debunking Monckton's critique of IPCC predictions
    factfinder... Can you direct us to where the greenhouse effect was disproved in 1909?
  9. Berényi Péter at 05:13 AM on 4 September 2010
    Hurricanes And Climate Change: Boy Is This Science Not Settled!
    #24 Turboblocke at 03:38 AM on 4 September, 2010 what does that do to the trend, as it dilutes the recent rise? Ten year running average looks like this: There is a recent rise indeed, but it's a far cry from being unprecedented. More like a recovery, even if it is a bit fainter than the scary surge around 1880. See The Deadliest, Costliest, and Most Intense United States Tropical Cyclones From 1851 to 2006 from NOAA National Hurricane Center. BTW, there are only three category 5 hurricanes on record that made landfall in the US. 1935 "Labor Day" 1969 Camille 1992 Andrew Years with category 4 storms: 1856, 1886, 1893, 1898, 1900, 1915(2), 1919, 1926, 1928, 1932, 1947, 1954, 1957, 1960, 1961, 1989 and 2004. Again, no increasing frequency is seen.
  10. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Dammit, I must not have been fully awake when I read that graph. Though in fairness, I wasn't the one making the comparison. Anyway,in that case, BP's findings directly contradict what I've heard in talks on this issue and read in sources like the 2008 CCSP report, at least on Atlantic hurricanes (although I'll admit that my investigation into this issue has been somewhat limited). I'd still like to see what it looks like with a lower amount of smoothing, though. As for your statement about the "last couple of years", this is too vague to tell me anything useful. If you're talking about ten years, then maybe it's relevant. If you're talking about two, then it's meaningless in this context. And I'd want to know your source for those claims. Also, I don't know if you were being facetious about "warmist agendas", but I'll just hope you were.
  11. citizenschallenge at 04:24 AM on 4 September 2010
    New presentation debunking Monckton's critique of IPCC predictions
    Ditto to that. Great educational video. Keep them coming! Since we are on the topic of Monckton I'd like to mention my layperson's critique of SPPI and their braintrust Chris Monckton. I'm reviewing aspects of Monckton's message that are beneath the dignity of serious scientists to pursue. Claims and issues that are nonetheless relevant to the struggle against the "AGW is a Hoax" industry. If you curious please visit: http://citizenschallenge.blogspot.com Peter M.
  12. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Werecow We're talking apples and oranges here one is about frequency the other about intensity. Over the past couple years the worlds total cyclonic energy has dropped to at or near all time recorded lows.This is just another attempt to scare up more support for the warmista agenda!
  13. New presentation debunking Monckton's critique of IPCC predictions
    Alden is putting together some really great presentations here. I hope he keeps more of these coming.
  14. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    BP: it's all very well taking a 25 year average and justifying it by saying we're talking about climate not weather... but what does that do to the trend, as it dilutes the recent rise? What's the trend just using basic yearly data?
  15. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Cynicus, I concede your superior knowledge of the Netherlands. Diamond uses polders as a metaphor for the nations of the world as a whole. He quotes a Netherlands acquaintance: "You have to be nice to your enemies because he may be the one operating the neighbouring pump in your polder". I am sure polders could not have been maintained without co-operation within and between the people who live in them. If one fails, they all fail.
  16. Climate change: Water vapor makes for a wet argument
    CBDunkerson@ 35, Thanx for replying.....I understand now the mechanism of how greenhouse gasses work. I guess my question now is why CO2 trumps water vapor as the prime greenhouse gas even though there is so much more water vapor in the atmosphere relative to CO2 and other greenhouse gases.
  17. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    This is very confusing, indeed. The data (NOAA) analyzed below seems to suggest that in the NA the frequency is increasing. Not only is it increasing, but follows the temp variations pretty close. The analysis also tries to take in to account the reporting problem and appears to be pretty thorough. http://residualanalysis.blogspot.com/2010/04/intensity-or-frequency.html
  18. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    #16: "There is no increase in severity whatsoever, a slight decrease, if anything. " I still maintain, as I did the last time this came up, that this isn't a valid measure. Ask anyone who lives on the Gulf Coast: a season with 3 cat 2 storms is NOT more severe than a single cat 5. And tropical storms, which are missing from your severity index are counted in number making landfall -- as they should be. The supposition that older storms are uncounted is just that -- supposition.
  19. Quantifying the human contribution to global warming
    Lots of comments to respond to overnight. RSVP - I'm not sure why you think the CO2 radiative forcing is dependent upon the atmospheric temperature or solar irradiance. The solar forcing is a different calculation entirely. The CO2 forcing should just depend on the increase in atmospheric CO2 concentration, as the formula shows. HumanityRules - yes, the warming from a doubling of CO2 alone should be about 1.2°C. However, climate sensitivity takes into account all variables which change in response to increasing CO2, not just water vapor. I'll be working on a rebuttal on "climate sensitivity is weak" this weekend which will discuss this to some degree, but estimates of the value are based on empirical observations, among other things. It's not just the water vapor feedback which determines the sensitivity value. As for the Arctic study you reference, unfortunately I don't have access to the full paper. However, they suggest that when the Arctic warms, the Antarctic should cool. Currently both are warming, which would seem to throw a wrench in the spokes of this natural warming theory. TOP - as Ned shows, CO2 is not saturated. Additionally, if you check the formulas in this post again, you'll see that it's not a linear relationship between the radiative forcing and CO2 concentration, but a logarithmic one.
  20. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Ah, yeah, sorry, I Guess I missed the part about assigning it to the middle year. You compiled these data yourself? Could you post the ten year running mean for comparison purposes?
  21. Urban Heat Islands: serious problem or holiday destination for skeptics?
    Berényi Péter, there are a number of lines of reasoning that suggest that the eventual "downstream" impact of UHI on global temperature trends is pretty small. Given that, it's hardly surprising that most scientists who hold that view haven't focused on trying to quantify this effect better. There are plenty of problems worthy of investigation in science. What seems interesting and important to you won't necessarily seem equally interesting and important to others. But that doesn't address KDKD's question! Given that you have done a regression analysis that seemed convincing enough to be worth writing about here, what was the statistical significance of the model? You did the regression; I assume you must have the numbers for F-test, 95% CIs, things like that. Is your model relating population density and warming trend significant? You say the correlation between the two is "not very strong" ... can you be a little more informative than that?
  22. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Thanks for the reference to the Power Dissipation Index, which would seem to be a fairly critical piece of science. I would suggest that an article be written about the history of increasingly powerful storms, their impact, and projections. The insurance companies have already incorporated this into their operating models, as evidenced by the difficulty in getting homeowners insurance for coastal residences.
  23. Berényi Péter at 01:22 AM on 4 September 2010
    Hurricanes And Climate Change: Boy Is This Science Not Settled!
    #17 werecow at 01:18 AM on 4 September, 2010 No, it runs up to 2009. The 25 year running average makes it look shorter. But anything less than three decades is just weather, not climate, is it?
  24. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    #16 Your graph runs up to 1995. Pretty much all of the increase over normal values seen in the Pew Center graph comes after that year.
  25. Berényi Péter at 01:11 AM on 4 September 2010
    Hurricanes And Climate Change: Boy Is This Science Not Settled!
    "this graph, also from the Pew Centre, shows a 40% increase in North Atlantic tropical storms over the historic maximum of the mid-1950" "North Atlantic tropical storm" is a very bad concept if it comes to history. Before the satellite era many such storms must have gone unnoticed. Hurricanes making landfall in the US on the other hand are pretty well documented, if not for any other reason, because of insurance issues. There is no increase in severity whatsoever, a slight decrease, if anything. You can check it here.
  26. Berényi Péter at 00:44 AM on 4 September 2010
    Urban Heat Islands: serious problem or holiday destination for skeptics?
    #34 kdkd at 00:20 AM on 4 September, 2010 Yes, pretty good job description. It's just not my job. In fact I am surprised it is not done already, because it is the only reasonable way to quantify temporal UHI effect on surface temperatures. Comparing trends for "urban" and "rural" sites is worthless.
  27. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    I would suggest that the scale for the y-axis for the storm frequency plot seems like it was chosen to deliver a certain impression. How about a 0 to 16 scale to improve the appearance of objectivity? However in any case, this is a great summary. Some clearly unsettled science makes for a different tone to the discussion, which I enjoy.
  28. Quantifying the human contribution to global warming
    TOP writes: CO2 is about saturated so adding more has little effect compared to other GHG which are not saturated. Sorry, nope. This is a common misconception, however. See Is the CO2 effect saturated? on this site, or (for more detail) A saturated gassy argument (by Spencer Weart) ... or see the really excellent explanation of this issue over at Science of Doom: CO2 – An Insignificant Trace Gas? – Part Eight – Saturation
  29. Urban Heat Islands: serious problem or holiday destination for skeptics?
    BP #34 Actually your analysis is worthless until you report the statistical significance of your regression model. What's the value of its F statistic (does it predict better than change)? What's the value and statistical significance of the correlation coefficient (i.e. is the slope significantly different from zero)? Until you report these key parameters, it's not actually possible to determine whether your model is any use at all.
  30. Berényi Péter at 00:17 AM on 4 September 2010
    Climate change: Water vapor makes for a wet argument
    "when something else causes a temperature increase (such as extra CO2 from fossil fuels), more water evaporates. Then, since water vapor is a greenhouse gas, this additional water vapor causes the temperature to go up even further—a positive feedback" Not so fast. Water vapor distribution in the atmosphere is always uneven (it is not a so called well mixed gas). GHG effect also depends on its distribution (which is pretty fractal-like), not only on its quantity. If upon heating this distribution does not simply scale up, but gets a bit more uneven, WV "feedback" can easily get neutral or even negative. Any empirical data on higher moments of atmospheric humidity distribution? One thing is sure. The more uneven water vapor distribution gets, the higher the radiative entropy production of the Earth system becomes. In an open thermodynamic system with many degrees of freedom the maximum entropy production principle tends to hold. It is like self organized criticality (e.g. in sandpile dynamics). In even more simple terms as soon as some radiative flux gets "trapped" by GHSs, it punches a hole in the water vapor canopy where the excess radiation can freely escape to space. The exact mechanism by which it happens is not important, it should happen somehow due to pretty basic principles. Anyway, hot and humid air usually ascends, expands, cools down adiabatically, water condenses, latent heat released, precipitation falls down to surface, relatively hot dry air is released at cloud top, moves sideways, cools down radiatively to space, descends. It is a hole like the one I've mentioned above.
  31. Urban Heat Islands: serious problem or holiday destination for skeptics?
    Nice, BP. Of course, I have a lot of reservations and concerns about your analysis, starting with the question of how representative the data are. You've narrowed the GHCN list down to a fraction of the list, and the time period to a single decade. That's going to make your analysis quite noisy, I would expect. And in fact, the mean trend you find (3.2C/century) before you apply your population correction is quite a bit warmer than most of the land-only reconstructions for that same decade (1990-2000). The seven I looked at averaged 2.25C/century for the same period. So there are two possibilities -- either your station sample is unrepresentative, or your process does not provide a good estimate of the final impact of UHI on the gridded (or otherwise spatially weighted) land temperature reconstructions that other people are doing. If we assume that your subset of stations is representative, and the actual 1990-2000 land trend (after correction for UHI) really is 1.5C/century as you report, this would reduce the global (land/ocean) trend over the same period by about 12% ... from 1.87C/century to 1.65C/century. Given the various weaknesses in your analysis, I think this 12% is probably an overestimate for the effect of UHI on the global trend. I don't know whether it's as low as the 3% calculated above, but I would be very surprised if it's as high as 10%. Oh, yes ... I probably agree with BP's comment here: Perhaps satellite shots of night light distribution is a better proxy for UHI than population density trends averaged over administrative districts.
  32. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Maybe an analogy to this might be a person found guilty of murder, sentanced to death, killed by the state only later to be found innocent. You're going to struggle to convinced everbody this is an example of justice working.
  33. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    There is another possible spin to this rather than this is the scientific method at work. It strikes me the real contention around this subject is the heat generated on the subject around 2005/2006. Maybe much less should have been made around the short number of years of rise, whether the data was flawed or not isn't really the issue. You also neglect to show that the past few years have been fairly ordinary storm seasons which I guess also makes it difficult to keep on screaming about the subject in the same way. It's really not good enough to say things are OK because we now have balance, the question should be what was the driving force of the frenzy in the first place.
  34. Quantifying the human contribution to global warming
    Looks nice until you put it in context including H2O.

    CO2 closes off the right hand side of the H2O absorption band and CH4 contributes to the left hand side. One thing that is clear from this graph is that climate sensitivity changes with absolute temperature.
    The total spectrum of all atmospheric gases is given in the bottom plot. This shows a "window" between 0.3 and 0.8 microns (the visible window), which allows solar radiation (without the lethal UV component) to reach the earth's surface. "Earth radiation", the upwelling infrared radiation emitted by the earth's surface, has a maximum near 10 microns. The total atmosphere plot shows that a narrow window (except for an oxygen spike) exists in the range of wavelengths near 10 microns.Iowa State
    The effect of CO2 on absorption of IR and re-radiation is not linear as the equations above suggest. Once a certain level is reached adding another molecule has much less effect. Think of window shades. Once they are shut, closing them more has little or no effect. Nor does a decrease in CO2 below 280ppm cause a negative forcing which the equation for dF suggests. The absorption bands (wavelength regions) for carbon dioxide are nearly saturated, but those for other gases are not, so one additional molecule makes a larger impact.
    Iowa State

    CO2 is about saturated so adding more has little effect compared to other GHG which are not saturated.

    Iowa State
  35. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Thanks Graham "two recent peer-reviewed studies completely contradict each other" Is this Landsea and Holland? If not any chance of the references?
  36. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Cynicus (no. 10). Good post. I'm going to use Rotterdam as one of my "poster children of sea level rise." You seem to know a lot about the Netherlands: I'm guessing that you are Dutch. In any case, if you do know a lot about Rotterdam and sea level rise, I'd like to hear from you off-list. Email me, if you want, at huntjanin@aol.com
  37. How we know an ice age isn't just around the corner
    You know, I don't think there's enough information in the graph above. Here's an improved version, with some additional content -- I've added in total solar irradiance (TSI). Clearly, over the last 30 years, CO2 and temperature keep rising (green and red or dark-red lines), while PDO (blue) is fluctuating and solar irradiance (yellow) is stable or declining. It should be noted that this kind of visual correlation is not actually how scientists attribute climate change. This graph doesn't prove that CO2 causes the observed warming. But the graph is certainly consistent with the claim that CO2 causes the observed warming, and that solar and PDO are not the cause. So ... anything else we should add into this figure? There's still a little white space left in there.... :-) Apologies for straying off-topic. -------------- More fine print: See above for sources of PDO, temperature, and CO2 data. Solar irradiance data from University of Colorado, shown annually and with a 22-year LOESS smoothing function.
  38. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    tobyjoyce, a bit offtopic, but your polder-to-polder pumping strategy you described is not correct. Polders are usually surrounded by two ring levees with a canal in between the levees which is called the 'boezem'. Excess water from the polder is pumped into the boezem canal. The boezem canals are interconnected by even more canals, eventually leading to the sea or the IJsselmeer lake where the surplus water is pumped (or under free-fall via a 'spui' which is a type of sluice that can provide an open passage) into the Northsea. The water level in the boezems is approximately equal to the old lands and thus higher then levels in the polders (which used to be lakes), up to several meters. In times of drought or stale-water conditions in the polder fresh water can also be let in from the boezem into the polder, effectively reversing the flow of water. On the subject of AGW and sea level rise: Pumping is a lot more costly (in terms of construction, maintenance and energy use) then free-fall dumping of excess water into the sea. So as sea levels rise and the lands in the western Netherlands are slowly sinking due to isostatic rebound from the last ice age as well as compaction of peat soils due to deep level water extraction, the time excess water can be cheaply dumped in free-fall during low tides will shorten. Unfortunately rainfall is also expected to intensify, causing greater peak demands for water removal. These factors combined will require more pumping installations and more energy usage for keeping the lands (and polders) dry. Which, ofcourse, will cost society some serious money.
  39. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Huntjanin @ 6 - indeed, storm surges have been the principal cause of salt intrusion into soils of the Pacific Islands for some years now. 2005 was a particularly bad year for powerful cyclones in the region. The Cook Islands were hammered by 5 cyclones in just over a month!. Check out some of the photographs here: Five Weeks of Fury I don't know if you're familiar with Niue, but my wife and I holidayed there back in the late 1990's. It's basically a giant rock thrust up out of the ocean. The Niue Hotel, where we stayed sits atop a cliff face perhaps 30 meters high. I fished off it a few times, it's quite a drop, the few fish I did catch fell back into the ocean. Anyway, cyclone Heta hit the island in 2004 & the accompanying storm surge completely obliterated the hotel room we stayed in. I couldn't believe it when I first saw the press coverage, 40 + meter waves!. If you have a look at these photos here, near the bottom of the page you can see the hotel manager standing outside, and the sea in the background gives some idea of how high above sea level it actually is. In fact most of the dwellings pictured are well above sea level - along the same cliff face. Must have very frightening when the highest point on the island is only about 60 meters above sea level.
  40. How we know an ice age isn't just around the corner
    Not trying to pile on here, but here's a helpful comparison for GallopingCamel: Note that the blue line (Pacific Decadal Oscillation, or PDO) doesn't match the red and orange lines (temperatures, from surface [GISS] and satellite [RSS]) very well ... especially during the last three decades. In contrast, the green lines (log of CO2, from ice core [Law Dome] and direct measurement [Mauna Loa]) match the temperature record more closely. Adding in the effects of other greenhouse gases, and subtracting the effects of volcanic and anthropogenic aerosols, would make this match even closer. Bottom line, ocean oscillations can't explain the observed temperature trend. Greenhouse gases can. -------------- The fine print: PDO data from University of Washington. Surface temperatures from GISS land+ocean. Satellite temperatures from RSS. Law Dome CO2 from NOAA NCDC. Mauna Loa CO2 from NOAA ESRL. PDO and temperature data shown in monthly and 120-month LOESS smoothed versions. Law Dome CO2 dating based on "air age" with 20-year smoothing. Mauna Loa CO2 (monthly) are seasonally adjusted. Both CO2 data sets were log-transformed (base 2). Data sets with differing units (PDO, temperature, log[CO2]) have been scaled to fit on the same graph.
  41. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Daved, The paper can be viewed here. Their models do not consider CO2 but instead consider SSTs and atmospheric and ocean circulation patterns. Those models do a good job of representing modern TC actvitity so there is reasonable confidence in their Pliocence "forecast".
  42. Berényi Péter at 22:31 PM on 3 September 2010
    Urban Heat Islands: serious problem or holiday destination for skeptics?
    I have selected 270 GHCN stations worldwide with a reasonably uniform distribution over land in such a way, that all of them had almost complete coverage of the years between 1990 and 2000. Then I have computed base 2 log population density difference of that decade for each station along with temperature trend at that location. The stations are divided into three classes according to population density around them in 1990: dense: more than 15/km2 medium: between 0.8/km2 and 15/km2 sparse: below 0.8/km2 (but at least 0.01/km2) As you can see the scatter plot is not very different for these categories. Therefore, if there is a dependence of UHI on local population density, it extends well below 1/km2 indeed with no breakdown of the relation in sight. But the most important finding is that there is a (not very strong) correlation between these two parameters, so a regression line can be computed. Average temperature trend for these stations was about 0.32°C/decade between 1990 and 2000. But part of this increase is due to the 0.2 increase in base 2 logarithmic population density during this timespan, so we have to consider the regression line at zero. It is about 0.15°C/decade there. So more than 50% of the trend is due to increase in local population density around GHCN stations (most of the rest is probably NH soot pollution over snow and ice). This effect is also known as UHI (Urban Heat Island), although as we have seen it has not much to do with urbanization as such, it's just the local effect of increasing population density, even in very sparsely populated areas. I think this is the proper way to look for an UHI effect in land surface temperature records. That is, one should analyze the connection between changes in local population density around measurement points and surface temperature trend at the same location. I am afraid it is not done (yet) by those, who are responsible for maintaining these datasets, although by now many thousand billion dollar political and business decisions are dependent on their correctness (or its lack thereof). Also, I can see the problems with the GPWv3 dataset. Perhaps satellite shots of night light distribution is a better proxy for UHI than population density trends averaged over administrative districts.
  43. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Miekol, #2, More like "more than 500 years" for dyke building in Holland, rather than 100. Jared Diamond has a good section on Holland in his book Collapse, which I am re-reading. The dykes go hand-in-hand with a co-operative ethic. Each "polder" (dyked area) pumps water into the neighbouring polder until it reaches the sea. Each polder depends on the one nearer the sea. Ironically, the Dutch had the world's first capitalist economy and stock-exchange. Also, the world's first speculative bubble (in tulip bulbs). We may have a lot to learn from the Sutch experience!
  44. Climate change: Water vapor makes for a wet argument
    davidwwalters, no CO2 doesn't 'hold onto' heat energy at all. Think of each CO2 molecule as a tiny spinning mirror which is transparent to visible light, but reflective to infrared. A photon of sunlight hits the CO2 molecule and goes right through... down to the surface where it heats up a rock or something. The rock then emits a photon of infrared radiation upwards towards space. With no greenhouse gases in the atmosphere that heat would just go up and escape. WITH CO2 and other GHGs it goes up, hits a CO2 molecule, and bounces off in a random direction. Maybe it continues going upwards (to escape or bounce off another GHG molecule) or maybe it goes back down and 're-heats' the surface. The greenhouse effect does not work by 'trapping heat' within molecules of greenhouse gases. It works by slowing down the rate at which heat escapes the atmosphere into space. That heat winds up in molecules of other gases, liquids, and solids rather than just traveling up and out to space.
  45. The surprising result when you compare bad weather stations to good stations
    @Dappledwater: just replace "blood pressure" with "EKG". Definitely, if the cardiac graphs recorded by people of dubious competence were very similar to the ones recorded by the experts, it would be a surprising result that would suggest further investigation is needed before declaring the patient as "healthy" or "sick". For EKGs we do have guidelines, it's not too difficult to record them incorrectly if you don't know what you're doing, equipment may be out of date, it gets replaced, etc etc. Just like with USHCN stations. This should help understand the relevance of the analogy. @michael sweet: for the n-th time, we are not talking about "warming trends" in general. We are talking about the warming trends that appear for both well-sited and poorly-sited USHCN stations. This is the topic of the blog but for some reason people keep trying to talk about something else (in your case, the content of the AR4 SPM of all things). Please try to stay on-topic.
  46. Climate change: Water vapor makes for a wet argument
    -I'm no scientist, but I want one who is to explain how the phase change of water affects water vapor's role as a green house gas relative to CO2. My understanding is that when water vapor condenses as water droplets in clouds, it releases its latent heat energy at that point. So, water constantly is gaining and loosing heat energy, and CO2 just holds on to the heat energy?
  47. How we know an ice age isn't just around the corner
    GC #27, using the UAH temperature data we can calculate five year average global anomalies; 1990-1994: -0.04 1995-1999: 0.14 2000-2004: 0.18 2005-2009: 0.23 All other data sets show GREATER warming. So no, this is not a matter of 'which data you look at'. ALL data sets show warming and your claim of cooling the past ten years (the hottest decade on record in all data sets) is simply false. The years 2007-9 were relatively cool... but then 2010 thus far is at +0.55 C anomaly in the UAH data... which is higher than the 0.52 C record they have for 1998.
  48. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    Would someone like to write Basic post on storm surges? I think they are likely to cause a good deal of damage to lowlying places in the years ahead.
  49. Sea level rise: the broader picture
    HumanityRules at 14:18 PM on 3 September, 2010 If ENSO is affecting MSL variations about the longer term trend then we need records longer than a couple of maximum ENSO "cycles" to begin to be able to determine any underlying acceleration trend that is not biased by this variability (to do with Nyquist criterion, sample rate theory, - hope this makes sense). Looking over the longer term, I was trying to create a chart showing annual trend of 17 year gradients throughout the tidal/altimeter record, which I hoped would answer (or allow more informed discussion on!) your point as well as the valid ones Ken made earlier on the 1930s/1940s rise rate. However I realized Church 2008 has already done something similar with 20 year trends: Whether we tack on the 3.3mm 17 year altimeter trend to this or not, we see that there is an accelerating trend throughout the overall record, relatively high acceleration in the early 20th century, and more recent acceleration in the late 20th century. These trends and possible causal factors are discussed in more detail in Woodworth 2009.
  50. How we know an ice age isn't just around the corner
    GC @ 29 - as Phil Scadden has pointed out, the PDO 30 yr cycle thing seems to be based on imagination, not the data:

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