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Tom Curtis at 00:15 AM on 16 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK, I checked your site and the source of your data, which is not an official source. To compare the data with official sources, I checked the Australian Bureau of Meteorology (BoM) statistics for Brisbane Airport. The clear conclusion is that your analysis of Brisbane temperatures is wrong. To what extent this is due to dodgy data, and to what extent due to statistical errors as identified by Dikran Marsupial I cannot say. The first thing I noticed is that the station identification numbers do not match. Nor is the station identification number used by your source used by BoM for any station. Further, there are slight differences in the specified location as to longitude and latitude. Checking nearby stations, I determined that your site was closer to Brisbane Airport than to other nearby BoM sites (Cape Moreton, Brisbane City, Archerfield and Amberly). So if the numbers you have come from an official BoM site, they do come from Brisbane Aerport. I then proceeded to check the daily values for May, 2011. I noticed that your figures differ from the BoM figures with regard to Minimum Temperature and Relative Humidity for May 1st; on Relative Humidity for May 2nd; Minimum Temperature and Relative Humidity on May 3rd; and on Minimum Temperature for May 4th. I did not bother checking any further. For just 12 values, your sight differed from BoM figures for 6 of those values. It is a reasonable presumption, therefore, that your analysis is based on faulty data and cannot be assumed to accurately reflect reality. For the record, BoM calculates trends and means for Brisbane Airport. For the period 1910 to 2010, the the mean temperature shows a positive trend of 0.04 degrees C per decade; the Minimum Temperature shows a trend of 0.11 degrees C per decade, and the Maximum temperature shows a trend of - 0.02 degrees C per decade. Almost all of the cooling in the Maximum trend was between 1910 and 1960, with the trend in the last half few decades of the twentieth century being positive. The greatest trend in the mean temperatures has also been in that period, but the greatest trend in minimum temperatures was in the period 1960 to 1990. Obviously the diurnal temperature range has narrowed over the preceding century (-0.13 C per decade) although recently it has widened noticeably. -
Bob Lacatena at 00:12 AM on 16 June 2011Forecast: Permanently Hotter Summers in 20-60 years
37, Eric the Red, My goodness, did you even read the link you sent? It completely destroys your position. Apparently I have to be more specific with you. Please provide an exact quote, by Dr. Latif, which supports your claims about his position on the matter. If you can't, just drop it. It's OT. Actually, even if you can, just drop it, it's OT. And this isn't the place to discuss the fact that solar activity as long since been eliminated as a factor in recent warming, or the silly and unscientific approach of clinging to magical decadal oscillations as some sort of reason to ignore CO2 levels. As Albatross said, time to get back on topic. If you want to keep posting about Latif, you can do so here, but don't expect me to join you. Your position is absurd to the nth degree and rebutting such complete nonsense holds no interest to me. -
Chris G at 00:04 AM on 16 June 2011The greenhouse effect is real: here's why
Scaddenp, I noted that as well, but decided I'd let Arkadiusz find truly relevant articles since I did not find a quick counter in Google scholar. But also, I still did not get it right at #25. If the source of the extra C in the past was methane from permafrost or clathrate, then the 13C / 12C ratio would be the same as fossil fuels. So, even if you showed that the increases that occurred in pre-history had the same isotope signature of the fossil fuel release currently, I'd think that would only be an indication of an organic source of the carbon instead of something like a flood basalt. In any event, I think Sphaerica has it. Everything is tied together and it would be difficult to ferret out the signature of the initial trigger. It might be safer to stick with a simpler narrative that we know we are releasing carbon with X isotopic ratio, and the ratio in the atmosphere (and ocean) has shifted to look more like X than it did. We know that CO2 inhibits the outbound flow of LW energy, and that there is no "saturation" level. Then add in that we have already seen all the indications of a warming world. -
Eric the Red at 00:02 AM on 16 June 2011Forecast: Permanently Hotter Summers in 20-60 years
Sphaerica, I have not been able to link to the audio directly, but you can access both the powerpoint presentation and accompanying audio here: http://deepclimate.org/2009/10/02/key-excerpts-from-mojib-latifs-wcc-presentation/ Do you really believe that temps will rise in a true solar minimum? IF that is the case, then we can once and for all eliminate solar activity from the climate forcings. The same can be said for decadal oscillations. -
MoreCarbonOK at 00:01 AM on 16 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Henry@Bern I am sure my results are repeatable, but it is a lot of work. Don't think you can do it in 5 minutes. Forget about confidence intervals, you re. to it means you have not understood my method. You have to get access to the original reported data and plot the average reported monthly values against time. You can do that in Excel, which affords you to quickly get the trendlines. As an example, here is one of the first stations that I evaluated. It is an island that lies south of South Africa. this is how you must do it. http://www.letterdash.com/HenryP/marion-island-assessment-of-climate-change-in-the-southern-indian-ocean-due-to-the-increase-in-greenhouse-gases -
MoreCarbonOK at 23:38 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
@Eric The link reports that the file is damaged. I should report that it has not happened often on my pool table that minima were rising higher except for in the case of Honululu, which, as I said before, could be due to volcanic action. The minima in the arctic (Norway) was also slightly higher but only just. All in all, the maxima rose a lot faster than minima. And that means the warming is natural. @Dikran Dikran says: I have a long list of peer-reviewed journal articles on statistical methodology, and so I find your hubris rather amusing (-Inflammatory and ideology snipped-).Moderator Response: (DB) Please take care to formulate your comments to better comply with this site's comment policy. -
Albatross at 23:38 PM on 15 June 2011Forecast: Permanently Hotter Summers in 20-60 years
Eric @34, As I demonstrated @30, you misrepresented his talk at WCC3. Anyways, can we please (pretty please) get back on topic. -
Bob Lacatena at 23:24 PM on 15 June 2011Forecast: Permanently Hotter Summers in 20-60 years
34, Eric the Red,Prof. Latif stands by his statements and predictions, and that we should not open the champaign until...
Citation, please. Evidence. I have seen nothing except frustration from Dr. Latif at how deniers misrepresent his statements and work, so you have to come through on supporting this, or else this is a particularly egregious and unforgivable inaccuracy on your part....the potential for unpredictable external influences and the recent press release concerning the potential for a another solar minimum.
Citations please. Evidence. And I don't care about press releases, I care about scientific studies. A vague insinuation based on an anonymous press release is meaningless (and desperate). [And what do you think happens if we do have a solar minimum, temps rise but not as much, so we foolishly burn even more CO2 because people like you think everything looks just wonderful... and then the solar minimum ends? And when we finally cut back, the negative aerosol feedback ends? What exactly are you arguing for? Hesitate and be fooled into allowing an ultimate 6˚C temperature rise?] -
Eric (skeptic) at 23:08 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK, I can't find Easterling's 2005 paper online. Here's a paper that references that paper and uses some of that data (showing minimum temperatures rising faster than maximums): http://ams.confex.com/ams/pdfpapers/100659.pdf -
Eric the Red at 23:07 PM on 15 June 2011Forecast: Permanently Hotter Summers in 20-60 years
Sphaerica, Prof. Latif stands by his statements and predictions, and that we should not open the champaign until we see whose projections better match the climate observations. I will not admit a mistake, as I have not misrepresented his predictions. However, I will move on. Interesting is the timing of this discussion about Latif's work concerning the potential for unpredictable external influences and the recent press release concerning the potential for a another solar minimum. -
Dikran Marsupial at 22:59 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Bern, that answer is better than most, but again what happens if the interviewer thinks it is too indirect and presses for a definitive answer. Then you end up having to say "no it is not significant", but you have made it look as if you had made a concession and had been evasive. Note it is also pretty much what Jones actually said, other than having started by giving a direct answer. Nothing Jones actually said implies that it hadn't warmed since 1995, but the Daily Mail reported it that way anyhow. Note Jones actually said a bit later in the interview "I'm 100% confident that the climate has warmed", so the quote is there. N.B. If he said specifically that it had warmed since 1995 he would again be accused of scientific malpractice as you are not supposed to claim that something exists based on a failed test of statistical significance. It is the fault of hypothesis testing, which is rather broken in the way it is applied in science. -
Bern at 22:52 PM on 15 June 2011Speaking science to climate policy
What's the residence time of aerosols compared with that of the other GHGs? If they're not too dissimilar, then it'll even out even if we cut emissions of aerosols. Assuming, of course, that human emissions are the only source of the other GHGs, which seems perhaps incorrect given the permafrost melt going on. Either way, just considering the CO2 forcing (and the fast feedbacks) would give a lower bound for the committed warming, right? -
Bern at 22:46 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Dikran: perhaps a better answer would be along the lines of, "Over that interval, the warming trend is only 93% significant, which doesn't meet our usual standard of 95% significance." Correct, answering the question (if slightly indirectly), and with a much better chance of letting the audience know it's only *just* failing the significance test, but the trend is definitely still upwards. Of course, you'd say that would be reported as "[it] doesn't meet our... standard", and you'd probably be right, too. But it'd be a lot harder to spin it into "Phil Jones says it hasn't warmed since 1995", given that there's a clear statement that it *is* warming. Pointing back to the original quote would highlight the amount of word-twisting that had to go on to get the desired headline. -
Dikran Marsupial at 22:44 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK ROTFLMAO, as it happens my field of research is a branch of statistics, and I have a long list of peer-reviewed journal articles on statistical methodology, and so I find your hubris rather amusing! Do note however that I have pointed out two specific flaws in your analysis, and for all of your bluster, you haven't even attempted to address either of them. That speaks volumes for the strength of your analysis. -
Bern at 22:40 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Ok, my stats is rustier than the Titanic, but I downloaded the data for Amberley, Australia, from the BoM. I used Amberley (35km west of Brisbane) as the BoM page was telling me the Brisbane airport station only opened in 1992 (the old one closed in 2001), whereas Amberley is continuous back to 1941. Ran some analysis in LibreOffice, and the 37-year least-squares linear trends are very similar to what MoreCarbonOK lists for Brisbane. Except... the standard errors ranged from 29% to 312% of the trend magnitude. For the one month that got a negative trend (December), the trend was -0.011 +/- 0.045 (95% conf interval). That's one hell of an error bar, and a good reason why real climate analysis looks at more than one site. Interestingly, the trends were highest in the cooler months, and lowest in the warmer months. More-or-less what you'd expect from greenhouse warming... :-) -
Dikran Marsupial at 22:38 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
John Russell I can be convinced, all it would take is for someone to make a suggestion of an answer that I can't pick significantholes in. I am pretty sure that no such examples can be found, but it would only take one example to prove me wrong. If I can find a way of misinterpreting the answer, you can be sure the Daily Mail can! Media training is vital for any scientist that need to have contact with the press, but nothing can provide a 100% bulletproof defense. -
John Russell at 22:33 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Dikran -- OK, I guess I'm not going to convince you that there is a better way to give the same honest answer as Jones did, but in a way that is less likely to play into the hands of those wishing to deny. I wish we could go back in time and I could give him a bit of training. The answer would still be up to him, of course, but perhaps he would see there would be better ways of expressing it so as not to give the Daily Mail their headline on a plate. -
MoreCarbonOK at 22:28 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
@Dikran says: "Of course none of that changes the fact that your analysis is statistically nonsense and that you refuse to address statistical criticism of it". My method of statistics is sound as it is the way it should be done. If you want to evaluate ground stations you have to determine the exact slopes from the trendlines that will tell you the temp. increase noted over time. You want to tell me that that is ridiculous? I put it to you that either you do not want to hear the truth or you are just plain ignorant. You can either can stay in your ignorance (and that of the IPCC) or you can learn something from me: http://www.letterdash.com/HenryP/more-carbon-dioxide-is-ok-ok It is your choice. -
bartverheggen at 22:24 PM on 15 June 2011Speaking science to climate policy
The numbers and reasoning is taken from Ramanathan and Feng (2009). Total greenhouse forcing is 3 W/m2, which exists approx half of CO2 and half of the other GHG's. With a sensitivity of 3 deg per doubling (or 0.8 deg per W/m2) this comes to 2.4 deg. -
Dikran Marsupial at 22:18 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
John Russell That is pretty much my point, we can all make suggestions, but they will end up not being any better than Jones' from the point of view of how they will be misrepresented by the media. Remember the skeptic media has access to scintists who can advise them of how they can spin whatever is said. For the first possible answer, that would come accross as extemely condescending (even if true) and evasive, and again you would end up with the skeptic media saying that this was the killer question that Jones wouldn't answer. In the second case, the interpretation is incorrect (as I pointed out earlier in the thread) and you will end up with the skeptic media saying that Jones did not understand statistical hypothesis testing. We are on the same side, I'm just pointing out that it (this particular question) is a no-win situation, mostly because statistical hypothesis testing (as is commonly performed in science) is deeply counter-intuitive. -
MoreCarbonOK at 22:16 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Skywatcher says: "I assume you're cherrypicking stations that appear not to show a trend?" I only started in the SH because I live in the SH. I found no warming in the SH. No cherry picking. Everything was random. Why don't you check it out yourself? I must warn you: It is a lot of work. Gathering the data from the station and putting it in Excel. But perhaps you can get some students to help you? I only later picked up on a trend of no warming in the SH and more warming in the NH. You tell me why. Anyone? I am just as puzzled about that. It means that I now have to balance my pool table. Equal no. of SH and NH. It is just like playing pool again!!! http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming -
John Russell at 22:09 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Dikran -- hey man, I'm not a scientist so I can only make suggestions. OK, here's another way to answer. The interviewer asks; "Do you agree that from 1995 to the present there has been no statistically-significant global warming?" Possible answer: "Does the audience understand the scientific meaning of 'statistically-significant'? Because without understanding that phrase my answer is likely to confuse." Interviewer says (though I think it's unlikely): "It means that there's a probability of 95%." Scientist response: "Precisely" (or whatever needs to be said to establish that statistically significant means a 95% probability). "In fact the statistics give us 92.8%, which I'm sure we'd all agree is a pretty high level of probability -- though perhaps not quite the level that scientists would call the 'statistically significant' level of 95%. So, does that meet the Dikran test? -
Dikran Marsupial at 22:05 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK wrote: "I was only interested to find out if anyone here has any idea as to why there seems to have been no actual warming in the southern hemisphere whereas the warming in the northern hemisphere is clearly more pronounced." which is, shall we say, rather inconsistent with your earlier statement: ". I said that it does not make any difference whether or not there was any significant warming if it can be proved (as I have done) that the warming is natural and not man-made." It isn't even true that there has been no SH warming, as has been pointd out to you already. If you really want to know the answer to that question, then why not read the chapter on regional climate change in the IPCC WG1 scientific basis report? I suspect the difference in land cover is a large part of it. The southern oceans have a massive thermal inertia, which will be buffering the SH from AGW more than the NH, which has less ocean. Of course none of that changes the fact that your analysis is statistically nonsense and that you refuse to address statistical criticism of it. -
MoreCarbonOK at 21:55 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
@Eric From opening the link that you gave, I cannot see the (original) data & info only an abstract. -
MoreCarbonOK at 21:50 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
@Dikran See 74 again I was only interested to find out if anyone here has any idea as to why there seems to have been no actual warming in the southern hemisphere whereas the warming in the northern hemisphere is clearly more pronounced. Anyone? -
Eric (skeptic) at 21:39 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK, what do you think of this study http://www.agu.org/pubs/crossref/2005.../2005GL024379.shtml -
Dikran Marsupial at 21:37 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
John Russell Had Jones answered that way, he would be subject to the criticism that a lower standard of statistical evidence was required for evidence infavour of AGW than was required of evidence against the mainstream position. The Daily mail would be reporting "Double Standard by IPCC Scientists Exposed". Jones had not performed a U turn, but that didn't stop the press reporting it that way. -
Dikran Marsupial at 21:33 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK From your comment here: "Every month of the year at a weather station treated as a new test." From your the link you provided to your website: "The first result clearly shows that there has been no significant warming in Brisbane during the past 35 years." In both cases, emphasis mine. So, you still have not addressed the point that data for individual station data cannot be used for reliable estimation of secular trends, you have not addressed the point that looking at a multitude of trends in the way that you do is a recipe for cherry-picking (c.f. multiple hypothesis testing problem), and all you want to do is try and evade the point about your incorrect usage of statistical terms. The inability to address (never mind accept) criticism is what makes someone a denier rather than a skeptic. It is your choice. -
skywatcher at 21:33 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
#82, you're falling into the massive trap of cherry-picking your data. One could ask why you picked your selected 'random' sites from around the world, but you fail because you don't aggregate sites together to remove the variability of weather, as Dikran has stated several times. From Braganza et al, 2004: "Observed DTR [Diurnal Temperature Range] over land shows a large negative trend of ~0.4C over the last 50 years that is very unlikely to have occurred due to internal variability. This trend is due to larger increases in minimum temperatures (~0.9C) than maximum temperatures (~0.6C) over the same period." And a quote from Alexander et al, 2006: "When averaged over the globe, almost all of the temperature indices show significant changes over the 1951–2003 period. Trends in temperature indices, as detailed below, reflect an increase in both maximum and minimum temperature. There is also generally a much larger percentage of land area showing significant change in minimum temperature extremes than maximum temperature extremes. The magnitude of the trends is also generally greater for minimum temperature related extremes. This finding is in agreement with previous studies using monthly global data, e.g., Jones et al. [1999] and regional studies using daily data, e.g., Yan et al. [2002]." Funny you suggest that the southern hemisphere is not warming either, in HADCRUT3 it shows a steady and significant warming trend, check woodfortrees for the data. The aggregated signal for Southern Hemisphere stations is clear warming. I assume you're cherrypicking stations that appear not to show a trend? -
Eric (skeptic) at 21:32 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
I assume the null hypothesis of Jones is that GAT is not changing? That appears easy to disprove using each monthly GAT change as an independent test. But each monthly change is not an independent test because there is lots of autocorrelation (here is a made-up example: http://www.duke.edu/~rnau/411trend.htm) IOW, GAT might increasing "since 1995" because it shows 16 year increases (and decreases) over the entire record (~120 years of monthly GAT) so the current rise is not unusual. My question is, if some statistical test can determine the significance of the "since 1995" rise in the context of the whole record, doesn't that become a test for natural variability? -
John Russell at 21:30 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Dikran writes: "What if the interviewer presses for a direct answer "so the increase in temperature is not statistically significant then?"." Easy. If pressed by the question you suggest, you respond, "Yes, it is, 1995-2009 is statistically significant at a 92.8% confidence level." You can be pretty sure that any reporter will have to accept that, as they don't know anything about significance levels. Whether the bloggers afterwards try to make something of it is irrelevant; at least the Daily Mail doesn't print that you've done a 'U' turn. -
Eric the Red at 21:29 PM on 15 June 2011Speaking science to climate policy
Bart, how did you arrived at a current "committed" value of 2.4C? It appears that you are attributing higher warmer to the gases other than CO2. Is this correct? -
MoreCarbonOK at 21:21 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
@Dikra But I did say that not. Just go back to 74. I said that it does not make any difference whether or not there was any significant warming if it can be proved (as I have done) that the warming is natural and not man-made. So the whole argument about the confidence interval is a non-issue. You think that it not on tpoic? I say that the actual global warming can be easily assessed and is in the region of ca. 0.02 degrees C annum since 1974. It is accompanied by a reduction in humidity of ca. 0.02% per annum since 1974. But it not the minimum temps that have pushed up the global temp. It was the maxima. So the global warming is natural. It as easy a pie. Check it out yourself. http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming -
Dikran Marsupial at 21:02 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK O.K., so if you are not doing formal hypothesis test, you should not use the words "test" and "significance" with relation to a trend as that is what those words imply. You should know that from stats 104. You will also note that the topic of this article is statistical significance. Secondly, even if you are not performing formal hypothesis tests, the multiple test issue still applies to informal test. If you test enough you will always be able to find the result you want. That doesn't mean that the argument is correct. It is a recipe for cherry picking (whether inadvertant or deliberate). You still have not addressed the point that you can't use station data to detect the secular variation known as climate. Calculating trends separately for each month only makes that problem worse. Read the articles by Glen Tamblyn that I pointed out to you, and if you think your method is better, then lets discuss it on that thread. -
MoreCarbonOK at 20:40 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK@dikran You do not get it yet. There is no hypothesis testing going on here. All the slopes (inclines or declines) measured are for real and they show real history. Mostly taken from 1974. I don't trust the data from long before that. Perhaps start here: http://www.letterdash.com/HenryP/more-carbon-dioxide-is-ok-ok until you get to the point where you see why and how we started my pool table on global warming. -
Dikran Marsupial at 20:22 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK wrote "Every month of the year at a weather station treated as a new test". So how do you deal with multiple hypothesis testing issues? BTW, you do also know that the weather noise at individual stations is very large compared with the expected trend (so for station data you would not expect to see a statistically significant trend at station level). Spatial averaging averages out the weather noise and leaves you with whatever secular variation is in the data (i.e. what we call climate rather than weather). That is why climatologists look at long term regional or supra-regional trends, not trends at individual stations. See Glenn Tamblyn's excellent series of articles starting with this one for more information. -
MoreCarbonOK at 20:18 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK@macoles I know my stats and I know my method is right. Just average monthly temps as recorded / versus time. Every month of the year at a weather station treated as a new test. Example: look at the results from Brisbane: http://www.letterdash.com/HenryP/no-global-warming-in-brisbane-australia Just doing the linear regression in EXCEL it calculates the trendlines automatically....(In the old days we had to sit with a calculator!!) the slope you get (temp versus time) is the average increase noted over time. there are no errors. This is it. It is as easy as pie. If you don't understand it how I got those results you must study Stats 104. I see you also don't know why the southern hemisphere shows no warming. Quite a difference (see 2nd table from my pool table, mean average temp.) No global warming as a result of an increase in green house gases, in any case. http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming -
macoles at 19:17 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK @74, edit to my post @76 (otherwise your yearly trend error range is +/- twice maximum monthly variation divided by 35 years) should be: (otherwise your yearly trend error range is +/- twice maximum monthly variation irrespective of the 35 years of data) -
macoles at 19:10 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK @74 Perhaps average each data set's year to year difference for each month over the 35 years. That way any single unusual year gets averaged out. Unfortunately its 35 times the work you've already done, but that's the treatment the data needs to reduce your errors by a factor of 35. As to the wisdom of only using a tiny sample of available stations, well I hope they are at least well spaced for latitude. I'm sure you'll appreciate that the amount of greenhouse warming depends on the latitude and is strongest at the poles. -
Dikran Marsupial at 18:56 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
John Russell O.K., so you don't start by agreeing. What happens if the interviewer presses for a direct answer "so the increase in temperature is not statistically significant then?". Not giving a direct answer in such situations means you end up making a fool of yourself, c.f. e.g. Paxman versus Howard. As I said, not giving a direct answer to the question would end up with the hostile media presenting it as "the question Phil Jones wouldn't answer". The last thing we want is for scientists to act like politicians (or at least to sound like them)! Tom Curtis Had Jones said "That is more because of the short interval being considered than the size of the increase." it would not have been an accurate/honest statement. The lack of statistical significance is due to the size of the increase, it is too small given the noise level and the size of the window. "Of course, whether the rise meets a statistical test makes no difference to it impact on melting ice sheets, and increased range of tropical diseases." would also attract criticism by those who would attribute ice melt to natural ocean cycles etc. That is probably a bogus explanation of course, but they would point out that you were basis a causal link between global warming and ice melting where the global warming was not statistically significant and hence you should not claim it exists (following normal scientific practice). Basically if it is O.K. for you to ingnore the result of tests of statistical significance, why isn't it O.K. for them? -
macoles at 18:48 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
MoreCarbonOK @74 Visited your site and eyeballed the data table. How are you calculating the C/yr each month for the various sites over the 35 years? I see a lot of your sites have wildly swinging average rates between the months! Over 35 years this would be completely implausible. You need to make sure that you are properly fitting linear trends to each data set, and not simply calculating using only the first and last values of the set (otherwise your yearly trend error range is +/- twice maximum monthly variation divided by 35 years). I haven't done statistical trend fitting myself, but I'm sure there is some good advice on the internet somewhere. Hopefully someone here can offer a suggestion for you. -
adelady at 18:07 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
Global warming doesn't 'happen' at the local level. Global warming affects the whole of the global atmosphere and ocean systems. And because of that general, global, warming we observe and measure different events at different, specific, localities. Therefore we see more or less warming/ drying/ flooding/ snowing/ melting in different places and seasons. The planet's climate is not uniform in the first place. So there's no reason to expect that effects of a general change will be uniform in any particular, specified localities. -
bartverheggen at 17:35 PM on 15 June 2011The Planetary Greenhouse Engine Revisited
I had left a link to your 'Princeton' article on Jeff Id's blog, where he lauded Happer's WUWT article. That precipitated his interest in your post. -
bartverheggen at 17:33 PM on 15 June 2011Speaking science to climate policy
If you separate out the (long lived) greenhouse forcing and the (short lived) aerosol forcing, the 2 degree target suddenly looks a lot closer. The total radiative forcing by greenhouse gases (CO2, CH4, CFC's, N2O, O3) is around 3 W/m2, with which we have ‘committed’ the planet to warm up by 2.4 °C (1.6-3.6 °C), according to a climate sensitivity of 3 °C (2-4.5 °C) for a doubling of CO2. The observed amount of warming thus far has been less than this, because part of the excess energy is stored in the oceans (amounting to ~0.5 °C), and the remainder (~1.3 °C) has been masked by the cooling effect of anthropogenic aerosols (Ramanathan and Feng, 2009). This simple analysis shows that the ‘2 degree target’ of maximum acceptable warming is looming on the horizon, as the climate equilibrates and aerosol pollution is cleaned up. -
Bern at 17:06 PM on 15 June 2011Climate change is real: an open letter from the scientific community
David Horton: yes, it's the "You don't agree with me, ergo you are evil incarnate" school of thought. The way I look at it is to consider population demographics. For instance, I work in a company staffed almost exclusively by university graduates with at least bachelor-level degrees. I gave a recent presentation on global warming science (which was well received), and was somewhat surprised at the level of maths comprehension - it was quite a bit lower than I had assumed. Yet these people are amongst the brightest 15-20% of the population (or at least their schooling results indicated that). Many of the commenters that we see cropping up are likely in the lower 50% of the demographic pile. That's not to say they disagree because they're stupid - it's to say that climate science isn't an easy thing to understand, and unless it's explained carefully, in the right way, people will misunderstand it, even some very intelligent ones. Combine that with some media & bloggers that either don't understand or deliberately misrepresent climate science, and voila! You've got a large pool of people who not only don't understand climate science, but are actively being told that those 'evil scientists' are somehow part of a giant conspiracy to fool us all. I've heard a number of climate myths repeated here at work, and many people are surprised when they hear what the science actually says. Then, finally, remember that the squeaky wheel gets the grease - i.e. you only pay attention to the ones that shout loudest (or post comments on blogs & articles). The vast majority don't pop up on the radar. -
MoreCarbonOK at 16:51 PM on 15 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
I wonder. I think it does not matter whether the increase in temps. is statistical significant or not. What is important though is whether the warming is man-made or natural. My conclusion is that it was natural warming. Namely, there is no proof of any heat entrapment caused by an increase in GHG’s. Except on Honolulu, maybe, but that result there seems a bit suspicious to me. In hindsight, I forgot that we have volcanic activity there. So I should not have visited that station. http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming So you can all stand on your heads now and scream at the nations to stop using fossil fuels but even if you were able to stop that now, or reverse it, it would not change the results. Now I will admit that some type of systematic error may be incorperated in my results but essentially we are still comparing apples with apples, assuming the equipment used all over the world to measure temps. is more or less the same. What is interesting to note in my results is that there has been no global warming on the SH (the first 5 stations in the tables). It all happens in the NH. Any ideas as to why that is? Anyone? -
jonicol at 15:53 PM on 15 June 2011Examining Dr. John Christy's Global Warming Skepticism
Thanks for the helpful comments Albatross. Being new to blog discussion and I viewed a discussion on Christy's climate science as being exchanges on scientific issues. I now realise that the heading of the post indicates the topic for discussion - in this case the errors made by Christy, Spencer and Lindzen. -
scaddenp at 15:09 PM on 15 June 2011The greenhouse effect is real: here's why
"Former natural warming have the same "isotopic signature" as the present " I dont see how that can be concluded from the paper. This is part of investigation into carbon cycling with glacial cycle but it looked at 14C/12C ratios. 14C is handy for determining age of carbon. However, 14C ratios in modern atmosphere tell you nothing much except that we exploded nuclear devices in the atmosphere ruining any useful science. Instead, carbon cycle has to be investigated by 13C/12C ratios. Because fossil carbon is heavily depleted 13C, it shows excess CO2 in atmosphere is from fossil fuel not from ocean. -
Albatross at 15:03 PM on 15 June 2011Examining Dr. John Christy's Global Warming Skepticism
Jonicol, say hi to Tom Harris (the head of your sister astro turf "skeptic"/disinformation group in Canada (ICSC)) from us. How about "Friends" of Science, any connection between ACSC and them? The ICSC links to your group, FoS, and ClimateDepot, and NewZealand CSC, ICECAP and SPPI-- quite the social network dedicated to misinforming. But I digress. This thread is about Christy's crocks. You claiming/asserting above that @52 that <"I could find none which goes deeply enough into the science to show "WHY" they are wrong. " is a rather odd strawman argument to make. First, you could start by actually reading the main post and following the links therein. If that does not suffice, then you can use the search function here at SkS to find articles dedicated to refuting Christy (and Lindzen and Spencer). Third, there is plenty of science and information, both here and in the scientific literature refuting Christy (and Lindzen and Spencer). Finally, while your post @52 is lengthy on pontification and rhetoric, but very short on substance and on science. -
Chris G at 14:45 PM on 15 June 2011The greenhouse effect is real: here's why
Regarding my post @14, I mangled something in memory. I was thinking of radioactive decay, which would equalize the 14C in both fossil fuels and other sequestered carbon, but 13C is stable, and so would not be affected by long sequestration. However, apparently plants prefer 12C; so, that preference is what makes the difference between carbon bearing rocks and fossil fuels. So, it would indeed be surprising if the isotopic composition of the carbon in atmosphere were the same as today. However, I haven't see that yet.
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