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pielkesr at 13:15 PM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
dana1981 - Regarding "However, as Santer et al. (2011) showed, "Because of the pronounced effect of interannual noise on decadal trends, a multi-model ensemble of anthropogenically-forced simulations displays many 10-year periods with little warming." In short, you're asking the wrong question. The long-term trend is often masked by short-term noise over periods on the order of a decade." I assume you are convinced the linear trend will then pick up soon. I am not as convinced as you are as I have less confidence in the models. However, time will tell which of us is correct. I agree; its time to move on. -
skywatcher at 13:14 PM on 13 October 2011Understanding climate denial
Bibliovermis, quite correct. Jonathon, if three scientists say the Earth is warming at 0.1, 0.2 and 0.3C per decade, +/-0.05C, is there a consensus that the Earth is warming? Note I did not ask if there is a consensus on how much, or if the warming rates are harmful in any way. That is a different, diversionary question. In real climate science, there is not agreement on every detail, such as the exact values of climate sensitivity, but there is agreement that the climate is sensitive to forcing, and that the forcing is mostly our fault. -
pielkesr at 13:12 PM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
muoncounter - The linear regression is certainly correct. However, it appears a two-piece linear regression split about 2002 fits the data better. Also, why have you not extended to to September 2011? -
Bibliovermis at 13:09 PM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
WoodForTrees: RSS MSU TLT plotted with 17 year mean The 17 year timespan determined by Santer, et al. is not flat. Based on this dataset, my expectation of the 17 year mean is 0.32 for 2016 and 0.42 for 2021. The raw temperature anomaly has wide divergence from that mean, so I am not going to hazard a guess. -
dana1981 at 13:03 PM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Dr. Pielke, you suggest TLT is not evolving the way models predict, and ask"what is your expectation of the RSS MSU LT temperature anomalies over the next 5 and next 10 years?"
However, as Santer et al. (2011) showed,"Because of the pronounced effect of interannual noise on decadal trends, a multi-model ensemble of anthropogenically-forced simulations displays many 10-year periods with little warming."
In short, you're asking the wrong question. The long-term trend is often masked by short-term noise over periods on the order of a decade. However, we're going to explore this issue in greater depth in an upcoming blog post, so unless you have anything more to add to this particular discussion, we should move on to point #3. -
muoncounter at 12:50 PM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
pielkesr#76: "What is the purpose in disagreeing with a plot of the data?" So if we do not disagree with a plot such as this:
we must conclude there a number of short periods with 'little if any warming.' If these short flat spots are real and if they can be taken as signals of 'natural variation,' why would that matter over the long term? The long term warming trend swamps these supposed natural variations.
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Bibliovermis at 12:22 PM on 13 October 2011Understanding climate denial
If the question is "Is the value greater than zero?", then yes - they are in consensus. -
Jonathon at 12:13 PM on 13 October 2011Understanding climate denial
Let me get this straight skywatcher. You feel that if one person believes that the climate sensitivity is one, and another believes that it is five, then they are both part of a consensus that believes that the range is between the two values? I think that constitutes disagreement. That is where we differ. I believe you are the one being debunked here. For the record, death would be a catastrophic event (on a personal level) as oppose to a minor injury. It was very relevant to the example, and not a diversion as you claim. It is awfully arrogant to claim that someone who disagrees with you is in error, especially since you have failed to show how I am wrong. -
Bibliovermis at 12:13 PM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
It is not a disagreement with the data. It is a disagreement with the usage of the data. You agree that the timespan is too small to smooth out natural variability. Why push an irrelevant point then? It would not be valid to say that there was rapid warming in 2009 and 2010. -
pielkesr at 12:08 PM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Albatross - Linear trends are used in Christy et al since that is what everyone is using and we were examining the data using that widely applied (but inadequate) metric. If you look at the RSS MSU data, the data tells us that there has been little if any warming in the lower troposphere since ~2002. There is no other way to spin the data. You can make the claim that this is due to natural variability and I agree with that. However, it does not change that the trend is ~flat over recent years. I am quite puzzled by any disagreement with the obvious. You could also say there was rapid warming in 2009 and 2010 in that data and you would be right. What is the purpose in disagreeing with a plot of the data? My recommendation is to focus on the fact that CO2 concentrations are steadily going up. By linking to the temperature trends, if it does not evolve the way the models predict, you are fueling those who conclude that CO2 is not a problem to be concerned with. By focusing on the increase in atmospheric concentration, however, which has (very incompletely known) biogeochemical effects, you would be able to build a broader consensus that this an issue to be dealt with. As it is you are exposed to the more complex response of the climate system in terms of temperatures to the wide diversity of climate forcings. This is why, in my view, you are so vigorously defending the model-predicted linear trend of the global average surface temperature when anyone presents data that conflicts, even if on a short time period. My question to you, is what is your expectation of the RSS MSU LT temperature anomalies over the next 5 and next 10 years? -
pielkesr at 11:55 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Tom Curtis - You write "As Dr Pielke believes the "flat" trend from 1998 (and 2002) is significant, perhaps he could point to the flat trend in the data once adjusted for these well known sources of noise?" First over the period ~2002 to 2011 the trend in the RSS MSU LT data is nearly flat - http://www.ssmi.com/msu/msu_data_description.html; see Fig 7. I never said it was statistically significant, but it certainly is distinct from the plots you have above. The surface and lower tropospheric trends are supposed to be in synch and they clearly are not as we reported in Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr., J.R. Christy, and R.T. McNider, 2009: An alternative explanation for differential temperature trends at the surface and in the lower troposphere. J. Geophys. Res., 114, D21102, doi:10.1029/2009JD011841. http://pielkeclimatesci.wordpress.com/files/2009/11/r-345.pdf Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr., J.R. Christy, and R.T. McNider, 2010: Correction to: "An alternative explanation for differential temperature trends at the surface and in the lower troposphere. J. Geophys. Res., 114, D21102, doi:10.1029/2009JD011841", J. Geophys. Res., 115, D1, doi:10.1029/2009JD013655. http://pielkeclimatesci.wordpress.com/files/2010/03/r-345a.pdf In terms of the "well known sources of noise" these are not noise but part of the climate system. -
Bibliovermis at 11:23 AM on 13 October 2011Understanding climate denial
"Denier" isn't an insult either. It's a basic definition straight out of a dictionary. -
muoncounter at 10:26 AM on 13 October 2011Understanding climate denial
warmist: A person who believes that the current global warming trend is the result of man-made factors. Among climatologists, global warming is just one scenario for the unusual atmospheric changes that have been observed throughout the world. Those who accept the global-warming theory are said to take the warmist position. ... —Howard Rheingold, "On Language; Succinctly Spoken," The New York Times, August 27, 1989 This has somehow morphed into an insult? Is that the best you've got? -
Tom Curtis at 10:22 AM on 13 October 2011Greenland ice loss continues to accelerate
mspelto @29, I had in mind specifically the reduction of permafrost in the inhabited areas of Greenland in terms of increase of arable land. However, I bow to your much greater knowledge in this area. -
skywatcher at 10:15 AM on 13 October 2011Understanding climate denial
#235 Jonathon, debunking what you said in #214 is not diversion. I focused on something you said 'for the record', and showed it was wrong. You brought up 'catastrophic' and you brought up 'strawman' (I never mentioned the word), maybe trying to divert from your prior errors? In fact, you're now providing a nice case study for this thread. See Is there a consensus for an on-topic comment on consensus occuring in the presence of a large range of values. -
Tom Curtis at 10:13 AM on 13 October 2011Pielke Sr. and SkS Warming Estimates
EliRabbet @78, you have quoted my comments, and I must say that I reject your comments. IMO, given the large scale motion of air due to the global circulation, specifically the Hadley and Ferrel cells, the effect of "purely local" forcings is more analogous to holding a magnifying glass to a stream of water than to a piece of paper. This is true even of non-dispersing radiative forcings (such as LC/LUC). It is certainly true of dispersing forcing agents such as aerosols, tropospheric ozone and BC which can disperse up to 12,000 km east/west, and 3,500 km north/south. -
skywatcher at 10:13 AM on 13 October 2011There is no consensus
From a debate on another thread where Jonathon argued: "For the record, I do not believe that a large range of values (whether it be climate sensitivity, projected warming, etc.) indicates that there is a consensus on the issue. On the contrary, it argues the opposite." I do think 'consensus' that some variable is changing can apply to a wide range of estimated values so long as that range does not include zero. There has been for many years a large range on estimated climate sensitivity (e.g. the oft-quoted 2C-4.5C per doubling CO2). I want to give another example where there was, for a great many years, a lot of uncertainty in the magnitude of a value, yet the existence of the change it implied was not questioned. For many years, there was a large range for estimated values of H0, the expansion rate of the Universe, which only recently has been narrowed down considerably.
As recently as 1996, there were estimates as low as 40km/s/Mpc and as high as 100km/s/Mpc, it is now closer to 74km/s/Mpc. Edwin Hubble's initial estimate in 1929, after he first measured the redshift of spectral lines in Cepheid variables, was 500km/s/Mpc. Was there consensus in 1996 that the Universe is expanding? There certainly was. Was that based on a tightly-constrained value for the expansion rate? Absolutely not.
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Michael Hauber at 10:11 AM on 13 October 2011The Earth continues to build up heat
From section 5: This more negative aerosol (or other) forcing is required for energy balance, as there was little surface warming over the last decade even though greenhouse gas concentrations continued to increase (with a small decrease in solar input) and the ocean continued to warm and sea level continued to rise. If I understand this correctly then the 'missing heat' is still missing. Deniers have seriously mis-represented the issue of missing heat. It is not that there is less heat in the ocean than the models predict. The missing heat arises if we total all the heat that we can track going into and out of the climate system; it doesn't agree with the total heat being accumulated in the system. Hence the 'more negative (or other)' forcing required to balance the heat budget. Finally as far as I can tell the total heat content of the ocean is not directly measured in this paper, but inferred from sea level rise, correcting for factors such as ice sheet melt, ground aquifer depletion, and then assuming the rest of the sea level rise is thermal expansion. The advance of this paper over previous studies is that the sea level budget has been balanced (as per introduction), although I haven't yet figured out what that actually means. -
Daniel Bailey at 10:10 AM on 13 October 2011Understanding climate denial
Ah, I see. Since "denier" is used to refer to those who deny climate science, "warmist" is thus used by deniers to refer to those who affirm climate science. Got it. -
Jonathon at 09:57 AM on 13 October 2011Understanding climate denial
Probably true Lloyd. Warmist appears similar, but opposite to denier. -
Albatross at 09:27 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Hello Dr. Pielke, The discussion is getting side tracked. Let us recall that the topic at issue here is the choice of 1998 as a start date to support the claim (made on your blog) that there has been little or no warming for 13 years. Do you agree that it was perhaps an inappropriate start date and is without statistical significance? I'm sure that Lucia and Tamino would concur. Further, the choice of 1998 (and more recently 2002) is also puzzling given that you said on your blog that "I agree with Santer et al that “[m]inimal warming over a single decade does not disprove the existence of a slowly-evolving anthropogenic warming signal". Your arguments against using linear trends are also puzzling, especially given that in a recent paper that you co-authored with Christy et al. (2010), you used linear trends extensively. In fact, Adobe tells me that the word "trend" appears 126 times in your paper. Additionally, why is using a linear trend acceptable to suggest that there has been no warming for 13 years, but using a linear trend to challenge that assertion is not? -
muoncounter at 09:14 AM on 13 October 2011Greenland ice loss continues to accelerate
adriansmits#31: Not cherry picking? You've picked 3 years of sea level data and concluded 'go back 60 or 70 years there is very little warming'? If I look in the dictionary under 'cherry picking,' I'd see this type of analysis. Wake up and look at some real data. And find the right thread for sea level rise or 'its not happening.' -
Lloyd Flack at 09:09 AM on 13 October 2011Understanding climate denial
I think "warmist" is an attempt to attribute belief that AGW is real to political ideology. Those who use it are ideologically motivated and tend to see and opposition to them as also being ideologically motivated. They find it hard to see that there are people for whom science trumps ideology. They want to win and don't understand those who are more interested in understanding than in beating opponents. -
adrian smits at 09:07 AM on 13 October 2011Greenland ice loss continues to accelerate
Hasn't anyone looked at sea level rise for the last 3 years? It is not happening. Ergo either the ice is not melting or the ocean is not warming make your pick but right now.If we go back 60 or 70 years there is very little warming maybe 2 or 3 tenths of a degree in the unadjusted record. This is not cherry picking folks it's the period of time over the last 150 years when we have spewed over 90% of the man made carbon dioxide produced over that period.Response:[DB] "Hasn't anyone looked at sea level rise for the last 3 years? It is not happening."
Adrian, 3 years is far, far too short of a period in time to be meaningful. On such a short scale of time the noise in the data series drowns out the underlying signal. Typically about 17 years of data is the minimum needed to deduce even a linear trend.
[Source]
For further reading, I suggest Tamino's excellent piece on sea level trends, So What?
"This is not cherry picking folks"
Yes, I'm afraid it is. Unless you're looking at a long enough record, say the whole record, your short period has no meaning:
Yup, still happening...
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skywatcher at 08:54 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Dr Pielke, it is funny you should ask about a return to an 'upturn, when we are presently above the long-term trend in the UAH data, as shown in my post at #58. We have been above the 30-year trend for most of the time since 2001. What gives you cause for thinking the trend has stopped? Did you think it had stopped in 1992? -
Tom Curtis at 08:54 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Dr Pielke @70, with respect, linking to a list of posts, at least one of which has nothing to do with temperatures is not very useful. Which post did you have in mind? And in what way does it support your position? -
Jeffrey Davis at 08:44 AM on 13 October 2011Pielke Sr. and SkS Warming Estimates
re: 80 and the efficacy of clean air acts and AGW It's one of the ironies of life that filthy poisonous air dampens global warming. Were there only the one consequence of burning carbon energy -- an increase in global temperature -- then the devil's bargain of filthy air might seem almost worth it. But ocean acidification is another -- and just as serious -- consequence to carbon burning. -
Tom Curtis at 08:43 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
It seems to me that two graphs by Tamino would help illustrate this discussion. The first shows the statistical significance of linear trends in Gistemp from the start year to June, 2011:
Although Tamino uses a different temperature index (because he is responding to Steve Goddard, not Dr Pielke, the point remains the same. In the case of Gistemp, the trend since 2002 has insufficient data to distinguish between an underlying trend of between +/- 0.24 degrees C per decade. That is, consistent with the data, from 2002 to June, 2011, the temperature data could reflect a long term warming or cooling of 0.24 degrees per decade plus noise. (Please note the confidence interval is estimated by eyeball, so it could be +/-0.02 from indicated value.) It is likely that UAH or RSS will constrain the trend even less over such short intervals in that they react much more strongly to ENSO events than does the surface temperature data.
For completeness, the Gistemp data from 1998 to June, 2011 is consistent with long term trends between +0.27 degrees per decaded and -0.03 degrees per decade.
In contrast, the trend since 1994 (17 years ago) could lie between +0.08 and +0.28 degrees per decade. That from 1981 could lie between +0.13 and +0.23 per decade.
The possible range of the trend increases from 0.1 degrees per decade for 30 years data to 0.2 for 17, 0.3 for 13 (1998) and 0.48 for 9 (2002). As the temperature data itself never varies by more than 0.023 over the period shown, or by more than 0.01 degree in a single year, decadal trends with uncertainties greater than ten times those values are clearly useless.
Fortunately we are not in a situation in which we do not know the major sources of noise in the global means surface temperature. The three strongest sources of noise are, in order of strength, ENSO, volcanic eruptions and the eleven year solar cycle. Because these sources of noise are well known, and their strength quantified, their influence can be removed from the temperature data:
(Click on image to read accompanying article.)
As Dr Pielke believes the "flat" trend from 1998 (and 2002) is significant, perhaps he could point to the flat trend in the data once adjusted for these well known sources of noise?
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pielkesr at 08:13 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Dikran Marsupial - I recommend you and other readers read Lucia's discussion of this issue on her weblog post; e.g. see http://rankexploits.com/musings/category/global-climate-change/gcms/ and other related posts. She has statistically looked at this issue. The short time period does raise the issue as to when you expect the upturn to recommence. -
pielkesr at 08:10 AM on 13 October 2011Pielke Sr. and SkS Warming Estimates
Rob Honeycutt - I do not accept that the global average radiative forcing is the primary climate metric to define first-order climate forcings. I have concluded that, while important, it is not the one we should place most of the emphasis. In my view, and from our analyses in our papers, it is the regional/local scale that matters much more to society and the environment. This includes the extent that heterogeneous climate forcings are altering atmospheric/ocean circulations. -
scaddenp at 07:55 AM on 13 October 2011Understanding climate denial
I came across an interesting historical case of denial - Pellagra. Caveat, my source is "52 loaves" which could hardly be described as an authoritative history text. Despite Goldberger's experiments, (which you couldnt do today) giving strong evidence for Pellagra being a diet deficiency, the "infectionists" continued in denial. It is postulated that the roots of denial were again within deeply held political values. In the US, Pellagra was most prevalent in the South. 50 years after the civil war, the message that sounded like "the South cant feed itself properly" (especially when there was obviously a lot of food) was not going to sell. I would add a 6th characteristic to denial - accepting the message would challenge deeply held values. -
Dikran Marsupial at 07:52 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Prof. Pielke wrote "I look at the figure and see lots of ups and downs. A linear line only explains a small part of the observed pattern. " The "ups and downs" are essentially noise, not signal. They are caused by internal variability, e.g. ENSO and say nothing about the underlying signal (i.e. the forced climate change). I am rather concerned that an experienced scientist should draw conclusions by "looking" at data, rather then performing a proper statistical analysis of the data. Human beings are all too good at detecting patterns in data where no pattern exists, which is why scientists use statistics. -
JosHagelaars at 07:46 AM on 13 October 2011The Earth continues to build up heat
@Kevin C For the ocean part of surface of the world (70.8%) it would be 0.76 / 1.14 = 0.67 W/m2. You can calculate other interesting trends from the period from 2003 up to now, which is the period some 'skeptics' use to indicate that the rise in OHC has flattened, e.g. : http://bobtisdale.wordpress.com/2011/09/08/2nd-quarter-2011-nodc-global-ohc-anomalies/ Trends I obtained from the ohc-levitus monthly data for 2003 - now: 0 - 2000 m = 0.42 x 10^22 J/yr 0 - 700 m = 0.05 x 10^22 J/yr It seems to me that 0.42 x 10^22 J/yr is not the same as flattened. -
Dikran Marsupial at 07:42 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Prof. Pielke writes "You can claim it is too short of a time, but you leave yourself vulnerable to the same type of cherrypicking that you accuse others of doing by not including more recent years." This is not correct, I explicitly said that I would not base a serious argument on such short term trends, precisely becuase they are not robust and statistically meaningless. The additional trends over even shorter periods are even less robust, and even more statistically meaningless. I asked you for evidence that the underlying signal (i.e. the forced climate change) is significantly non-linear over the sort of timescales we are discussing and you have presented none. Of course the climate system has non-linearities, but that does not mean that a linear approximation is not entirely reasonable in this situation. I do not wish to divert the discussion onto CO2 or any other cause of the trend. The concern is with your use of trends computed over too short a period to have any statistical robustness. -
Rob Honeycutt at 07:22 AM on 13 October 2011Pielke Sr. and SkS Warming Estimates
Dr Pielke said... "Finally, while we agree that the radiative forcing of added CO2 is "A" first order climate forcing, it is not "THE" only first order climate forcing." It rather seems to me that this is the very point of the blog post Dana has done here. In your comment at #4 I believe you accepted Dana's correction which, if I'm not mistaken, would make CO2 "the" first order forcing. If we accept AR4 or Skeie 2011 numbers then CO2 is clearly the first order forcing. I don't say this to suggest that other issues shouldn't be addressed. Clearly they should, but as Eli points out policy would suggest that the largest problem should have priority. -
Kevin C at 07:00 AM on 13 October 2011The Earth continues to build up heat
Interesting gradient JosHag. Divide by s/yr (3x10^7) and surface area of the earth (5*10^14 m^2) and you get a flux of 0.5W/m^2. Which is a plausible number of energy imbalance. -
Albatross at 06:58 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Hello Dr. Pielke @64, Sorry, there has been a miscommunication. I provided the wrong link. I requested that further discussion of the land use forcing be continued on the following thread. This thread is now dedicated to discussing the curious and puzzling choice by you to select 1998 as the start point for your trend. -
pielkesr at 06:56 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
I have asked a simple question and you have only partially answered. What is the trend since 2000, 2001, 2002 etc. I realize these are shorter time periods. My point is that if you would to convince people that human's are causing global warming, there are going to ask where the warming has been in the lower troposphere since 2002? Dikran Marsupial - You can claim it is too short of a time, but you leave yourself vulnerable to the same type of cherrypicking that you accuse others of doing by not including more recent years. If you want a convincing analysis for CO2, use the Mauna Loa Observatory plot of CO2 concentrations over time. By bringing in your expected long-term linear trend in lower tropospheric temperature but which is reality is embedded in a nonlinear system, you weaken your argument. In fact, it illustrates that the real climate system is significantly more complicated than presented by the climate models. Why not just stay with the risks of the added atmospheric concentration of CO2 as one of the climate concerns? -
JosHagelaars at 06:52 AM on 13 October 2011The Earth continues to build up heat
Sorry, the trends i gave in #5 are from 1990 to now based on the monthly data. -
Jeffrey Davis at 06:51 AM on 13 October 2011Pielke Sr. and SkS Warming Estimates
"Having said that, must of these emissions come from China and India (now), and will dissipate in any event when increased prosperity leads to pressure for clean air acts." Since the pressure in the US is actually on to gut clean air acts and neuter the Environmental Protection Agency, I think the idea that clean air acts and good environmental stewardship are historical necessities is quaint. And wrong. -
pielkesr at 06:48 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Dikran Marsupial - I look at the figure and see lots of ups and downs. A linear line only explains a small part of the observed pattern. -
pielkesr at 06:47 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Hi Albatross - You said to move the dicussion over here. With respect to the global average surface temperature trend, the land portion makes up a significant portion of it. Even more importantly, we need to dissect into regions as that is the spatial scale of major atmospheric circulation features. Land is also where most people live. -
Andy Skuce at 06:23 AM on 13 October 2011True Cost of Coal Power - Muller, Mendelsohn, and Nordhaus
There's a book review in the New York Review of Books by William Nordhaus (one of the authors of the MMN11 paper) that has further discussion on fossil fuel externalities and Pigovian taxes. -
Dikran Marsupial at 06:09 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Albatross@62 Indeed, I am somewhat puzzled that Prof. Pielke asks us to "Let [him] know the trends you see starting in different years since 1998.", given that both dana and skywatcher had already done so! Along with statistical significance, if you want to suggest there hasn't been any warming, then you also need to estimate the statistical power of the test. If there isn't enough data to reliably reject the null hypothesis when it actually is false, then the lack of statistical significance really isn't saying much! -
Albatross at 05:54 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Dikran @60, Dana also calculated the trends using different start dates. Here are some more using the UAH data (which is considered by "skeptics" to be a superior dataset): If one starts in 2000: the slope is 0.14 C per decade. If one starts in 1996: the slope is 0.13 C per decade. Spot the outlier: If one starts in 1996: the slope is 0.13 C per decade. If one starts in 1997: the slope is 0.10 C per decade. If one starts in 1998: the slope is 0.06 C per decade. If one starts in 1999: the slope is 0.18 C per decade. If one starts in 2000: the slope is 0.14 C per decade. As Dana showed above, if one uses at least 17 years of data as the research suggests is required (e.g., Santer et al. 2011) one gets 0.14 C per decade. Using the 1998 start date to claim that there has been little or no warming (for 13 years) as Dr. Pielke did is grossly misleading, is a poor choice for obvious reasons, and is simply too short a window to calculate a statistically significant trend, and as such is simply not justifiable or defensible. -
Pielke Sr. and SkS Disagreements and Open Questions
Dr. Pielke - "...focusing on a linear trend with respect to a actual nonlinear signal is a substantial oversimplication..." Absolutely correct. However, given the inherent noise in the system and measurements, as well presented by Santer et al 2011, a linear trend is is the only marginally justifiable extraction from such a short time period - any more complex fit would simply be statistically unsupportable given the limited evidence. And shown the 3x variations in linear trend with just a year variation in start point, 13 years isn't enough for a robust linear fit, either - it's not enough data. -
Dikran Marsupial at 05:28 AM on 13 October 2011Pielke Sr. and SkS Disagreements and Open Questions
Prof. Pielke what evidence do you have that the underlying signal (i.e. the forced climate change) is significantly non-linear over such a short timescale? Indeed lets look at trends starting in different years around 1998.If you start a year earlier, you get a trend of 0.103 degrees C per decade, starting in 1998 it is 0.060 degrees per decade, starting a year later in 1999 it is a whopping 0.183 degrees per decade (which is actually higher than the trend since the start of the UAH dataset, which is 0.138 degrees per decade). In other words, you need to pick 1998 to minimise the trend and the result isn't robust to changing the start date by a year in either direction. Please explain to me why we should be looking at the lack of warming since 1998, rather than looking at the trend since 1999, which gives the impression* that warming is accelerating as the post 1999 trend is steeper than the overall trend)? I suspect the problem is that the eye is deceived by the El-Nino excursion, computing the statistical trends gives a different picture that is not so heavily biased by that feature. *Of course I wouldn't try to make such an argument as a serious point because such short term trends are not robust and hence statistically almost meaningless. This is true whether the trend is large or small.
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EliRabett at 05:23 AM on 13 October 2011Pielke Sr. and SkS Warming Estimates
Eli is not so sure that just leaving it at that is a good policy. If someone keeps trying to shove nonsense into a discussion, that someone should not be told, ok, we disagree. This is not a debate with a fool that one can simply walk away from. Something stronger is required. The obdurate cynical ploy of never admitting the obvious is a major tactic of rejectionism and it works because it tires people out. The 28 vs 50 whatever stuff is important for policy, because policy says that the largest problem should have priority, the attempt to belittle the carbon forcing is simply another tactic. -
EliRabett at 05:18 AM on 13 October 2011Pielke Sr. and SkS Warming Estimates
It is interesting that 'Industrial pollutants (tropospheric ozone and BC) constitute 22.8% of all forcings (Skeie et al), or 24.9% (Pielke corrected). In any terms, these are a substantive proportion and I agree with Hansen that we should target these "low hanging fruit". Having said that, must of these emissions come from China and India (now), and will dissipate in any event when increased prosperity leads to pressure for clean air acts. " The implication being scince black carbon and ozone (mostly from NOx chemistry) are local/regional, the local/regional effects are much larger. -
Albatross at 05:18 AM on 13 October 2011Pielke Sr. and SkS Warming Estimates
Hello Dr. Pielke @76, I was clearly referring to the global mean temperature, and that is what is at issue here, not the land temperature only. It has been shown repeatedly that one cannot model the global mean temperature accurately without including both natural and anthropogenic forcings, and that includes land use change. My point still stands. If you wish to discuss this matter further, I encourage you to post future comments on the appropriate thread (here). Thank you. And yet another request for participants to please move the discussion forward to our next point. Here is the link. I look forward to hearing Dr. Pielke's thoughts on that particular issue.
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