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  • El Wall Street Journal sobre el consenso científico en el cambio climático « RealClimate
    purpose of the paper the methods the data definitions the data their observations on the proxies and their link between an anomaly and LIA MWP However I disagree with the conclusions for the following statistical reasons Soon and Baliunas try to show by asking the following questions in respect of the individual proxies using 50 years average that an indication of the LIA and the MWP can be found in most proxies and that the 20th century is not the warmest period of time over the last 1000 years A summary of their findings is given in the following lines Question A Is 20th century warmer than the previous 900 years Out of 104 proxy data they have found a yes in 22 cases and no in 82 cases Question B An anomaly is identified during 800 1300 Out of 125 proxy data they have found a yes in 123 cases and no in 2 cases Question C An anomaly is identified during 1300 1900 Out of 115 proxy data they have found a yes in 108 cases and no in 7 cases Without any statistical judgment these results looks at firsthand as at confirmation of their conclusion However in all three cases it is a matter of misusing the maximum or the minimum of series of measurements with different length and not defining a null hypothesis and not testing it at all Please note that an anomaly in a statistical sense is an observation which is smaller than the p percentile or larger than the 1 p percentiles where p 50 In a given data set an anomaly is found by finding the maximum or the minimum of the observations over a given number of years This is the key to understand the methods used by Soon and Baliunas In respect of question A is possible to show under very general condition in theory and by simulations that if there is no trend in the temperature then the probability of observing a higher temperature during the period 1000 1850 compared to the period 1900 1950 are close to 94 4 850 50 850 Using the binomial distribution with 104 trials and p 0 944 it follows that the probability of observing no in 82 out of 104 trials is less then 0 0001 This means that we have observed significant fewer no s than expected The 95 confidence interval for p equals 70 5 81 1 This indicates that the 20th century is the warmest during the last 1000 years In respect of question B and C it follows from simulation experiments using a 1 percentile to define an anomaly and a red noise with coefficient 0 2 that the probability of observing an anomaly for one proxy during 450 and 550 years respectively is round about 98 Using the binomial distribution it follows that the observed values under question B and C are as expected and in no way significant There is no basis to support their conclusion from a statistical point of view in the data they have used However their conclusion might be correct but for other reasons than they have presented in SB2003 Its is unbelievably that WSJ and others are using this paper as an argument against global warming when it actually is in favor of global warming I have worked this analysis out in more details but have no access to a webblog to publish it on Writing a scientific paper about is not relevant since SB2003 previously have been discredited However as an educational example within statistics and probability theory the SB2003 paper might be useful Reference Willie Soon Sallie Baliunas Proxy climatic and environmental changes of the past 1000 years Climate Research 23 89 110 2003 Mike Mann et al On Past Temperatures and Anomalous late 20th Century Warmth EOS Vol 84 No 27 page 256 8 july 2003 Julius Solnes Stochastic Processes and Random Vibration Theory and Practice page 34 Wiley 1977 Thomas Mikosch et al Modeling Extremal Events page 307 Springer 1999 114 SteveF says 1 Jul 2005 at 4 47 PM Interesting letter on the politics side of things http www democrats reform house gov Documents 20050701123028 71010 pdf 115 Hans Erren says 1 Jul 2005 at 6 16 PM re 106 Response The three main types of sceptics are called trend sceptics attribution sceptics and impact sceptics I discuss these three types and their main arguments in this article stefan Stefan it s intriguing you quote a climate sensitivity of 3K as central value whereas radiative equilibrium comes no further than 1K Climate models have a range of 1K to 3K for CO2 doubling the 1 5 to 4 5 K range is completely depending on the assumed slowness of the system with equilibrium times of several centuries The CSM model as used recently by CKO in the Dutch Challenge Project has an reported sensitivity of 1K for CO2 doubling Response S B is only valid for black bodies Since the Earth is not a black body it isn t a good estimate for the surface air temperature This has been discussed here The model range for the current IPCC round is from 2 7 to 4 1 deg C for a doubling of CO2 gavin 116 dave says 1 Jul 2005 at 7 30 PM Re 100 106 Stefan s comments Stefan s comments and the linked in paper are very informative The subject of natural variability deserves a separate post and comment thread all by itself Invariably no matter what the subject there are comments citing some unspecified natural variability hypothesis to explain the current warming Part of the official climate change language of the current government is climate variability I hope RC will address the issue directly and ask those skeptics to put their money where their mouth is so to speak 117 Mike Doran says 2 Jul 2005 at 12 33 AM Two main responses One the idea that cosmic ray flux is s source of climate variability doesn t mean that CO2 doesn t equally have an electrical meaning It does CO2 impacts conductivity w surface lows and gas exchanges which occur as a result Two complexity strongly suggests responsive design Which brings us back to gaia to ecology to stewardship 118 David Wojick says 2 Jul 2005 at 1 59 PM Re 109 et al I am not saying we know nothing quite the opposite We now have 40 billion worth of new knowledge This is a lot given that the US cancer research program is about 5 billion per year The point is that in science new knowledge often increases uncertainty among competing theories Astronomy and cosmology are in just that boat right now Results from Hubble and other new instruments have called much of the theoretical framework into question so hypotheses have blossomed By far the biggest result from the 15 year climate research program is the discovery of natural variability When the program started along with the FCCC treaty it was believed that climate was relatively stable and so anthro GHGs must be causing the warming in the surface record That stability assumption was found not to be true and the research has become quite complex as a result Below are two quotes that make the point nicely These two reports are good studies in the research issues even today They can be read online They are much better than the 1995 and 2001 IPCC reports because the latter are really arguments for the anthro GHG dangerous warming theory The evidence of natural variations in the climate system which was once assumed to be relatively stable clearly reveals that climate has changed is changing and will continue to do so with or without anthropogenic influences Dec Cen Variability Summary Decade to Century Scale Climate Variability and Change A Science Strategy 1998 160 pages Usually referred to as Dec Cen Variability http www nap edu catalog 6129 html Climate research on decade to century dec cen timescales is relatively new Only recently have we obtained sufficient high resolution paleoclimate records and acquired faster computers and improved models allowing long term simulations to examine past change on these timescales This research has led to genuinely novel insights most notably that the past assumption of a relatively stable climate state on dec cen timescales since the last glaciation is no longer a viable tenant The paleorecords reveal considerable variability occurring over all timescales while modeling and theoretical studies indicate modes of internal and coupled variability driving variations over dec cen timescales as well Thus dec cen climate research is only at the beginning of its learning curve with dramatic findings appearing at an impressive rate In this area even the most fundamental scientific issues are evolving rapidly Adaptability to new directions and opportunities is therefore imperative to advance understanding of climate variability and change on these timescales Pathways p 129 Global Environmental Change Research Pathways for the Next Decade 1999 621 pages Called Pathways http www nap edu catalog 5992 html 119 Dano says 2 Jul 2005 at 2 56 PM I heartily agree with Klaus the first comment is this thread is my proof o S B didn t bother to mention the multiproxy studies they just cherry picked the local studies that supported their contention Plus using a 50 year time frame effectively narrows the warming episodes Best D 120 David Wojick says 2 Jul 2005 at 3 58 PM Re 101 and part of the 100 Response To see where solar climate research is going here are two fairly recent workshops Some of the presentations provide references The basic point is that we do not understand the sun climate link certainly not enough to rule it out as the main driver of the 20th Century surface temperature record The first workshop is Solar Variability on Decadal to Millennial Timescales Influences on Earth Climate Change and Prediction hosted by the Universities Space Research Association USRA includes 95 universities that do space research mostly from the National Aeronautics and Space Administration USRA says it has launched an initiative to develop the means to increase understanding and improve prediction of solar variability and its effects on Earth especially its climate http www usra edu hq meetings scw According to USRA the research issues are broad They say This multi disciplinary workshop was designed to open communication and forge collaborations between the disparate realms of policy and science and to provide a platform for scientists of varied fields climatology paleoclimatology atmospheric chemistry solar and stellar astrophysics etc to present their measurements and models in an effort to more precisely define problems scientists face when trying to show the causal link of multi decadal variability of the Sunâs output and Earthâs climate Uncertainties remain not only regarding the solar measurements but also on the climate response to solar changes by virtue of the complexities of the climate system Another major workshop is Decadal Variability in the Sun and Climate the annual meeting of the Solar Radiation and Climate Experiment SORCE is a NASA sponsored satellite mission that provides new measurements of incoming x ray ultraviolet visible near infrared and total solar radiation http lasp colorado edu sorce 2004ScienceMeeting Meeting Review html SORCE explains the research issue this way Discerning the role of the Sun in climate variations on time scales of decades is a challenging task That climate forcing is well correlated with variations in the Sunâs energy output is now relatively well established for total and UV irradiance using high precision space based solar measurements spanning more than two decades When the Sun is near the maximum of its activity cycle it is about 0 1 percent brighter overall with much greater changes at UV wavelengths SORCE measures these variations with unprecedented accuracy precision and spectral coverage across the UV visible and IR But the climate response to these measured solar variations presents a major puzzle Response We all agree that there are interesting issues in solar climate links and there is a large uncertainty in how to calibrate solar activity to climate forcings However there is no evidence for a large role for solar forcing over the last 50 years or so No indices related to solar activity show any significant rise over this period gavin 121 Stephen Berg says 3 Jul 2005 at 11 21 PM Re 114 Thanks for the link What an exceptional letter cutting to the heart of what is going on in the US Government What is really occurring is a sort of inquisition trying to smear and destroy the careers of outstanding scientists perpetrated by the fossil fuel industry Ross Gelbspan s The Heat is On and Boiling Point provide even more evidence of this crime taking place as Mr Gelbspan says so succinctly As far as I m concerned the debate is pretty much over Climate change is happening The numerous threads on RealClimate and scientific reports that seem to be a daily occurrence are stacking the evidence heavily in favour of this conclusion Therefore the time for action is now before our existence on this planet is put in jeopardy 122 Ethan says 5 Jul 2005 at 8 56 AM Re comment 118 Results from Hubble and other new instruments have called much of the theoretical framework into question so hypotheses have blossomed This is off topic but this claim is wrong These results have vastly narrowed the uncertainties in the parameters used in the theoretical framework and spawned a large number of further directions for research They did not cast the previous theoretical framework into doubt On the contrary they allowed us to rule out many previously viable alternatives If this is your best analogy then your argument is in trouble 123 Hans Erren says 5 Jul 2005 at 4 26 PM re 115 Gavin I am a bit puzzled about your response Firstly the Stefan Boltzmann equation contains an emissivity term which has been accounted for see eg http hanserren cwhoutwijk nl co2 sb htm Secondly the CSM model used by Dutch climatologists has a proven sensitivity of 1 K 2xCO2 why is this model not considered state of the art Thirdly the analysis of CGM models by Lawrence Livermore has a range of 1 to 3 deg C for a doubling of CO2 Response First SB even using an emissivity still doesn t account for any feedbacks which we know exist Secondly CSM is not state of the art because it was superceded by CSM2 and now by CSM3 And thirdly and most importantly you confuse the transient climate response TCR at time of CO2 doubling in the 1 increasing CO2 CMIP runs with the equilibrium climate response to CO2 doubling which is always larger You should assume that it is the equilibrium sensitivity IPCC likely range 1 5 4 5 current models for the IPCC AR4 range 2 7 4 1 that people are talking about unless they specifically state that they aren t gavin 124 David H says 6 Jul 2005 at 7 56 AM Here are a couple of quotes from a peer reviewed report published a few hours ago para 22 We sought evidence that refuted the claims of McIntyre and McKitrick but have not come across any detailed rebuttal Para 23 We are in no position to determine who is right and who is wrong in the growing debate on the hockey stick If there are historical periods of marked temperature increase it seems to us it is important to know why these occurred Overall we can only urge that the issue is pursued in the next IPCC Assessment I say peer reviewed because it is a committee report from the UK s House of Lords i e Peers gavin at http www publications parliament uk pa ld200506 ldselect ldeconaf 12 12i pdf 125 David Wojick says 6 Jul 2005 at 8 58 AM Re 120 you say However there is no evidence for a large role for solar forcing over the last 50 years or so No indices related to solar activity show any significant rise over this period I am surprised you would attempt to dismiss an entire scientific community with a simple formula like this but I notice they appear frequently on these pages Response I have no idea what you mean here I have published a number of papers on solar climate connections and am involved in a number of ongoing related projects Presumably I am therefore part of the community that I am dismissing You confuse interest in solar connections with a dismissal of anthropogenic forcings These things are actually independent gavin First the surface temperature record has not increased for the last 50 years only half of that before which it cooled while CO2 levels went up Second the solar parameter need not increase with warming We are looking for an indirect mechanism which could as easily be driven by a solar parameter decrease such as a reduced solar wind Third since an indirect effect by definition involves other parameters this is not a simple correlation exercise Any more than CO2 forcing is since CO2 levels do not correlate with the globally averaged surface temperature record The reason we are looking is because there is lots of strong long term statistical evidence for a sun climate link Since we do not understand the mechanism we do not know what to look for over the recent decadal timescale This is not a lack of evidence it is a lack of understanding It is probably the biggest uncertainty is climate science today As far as there not being any correlation over the last 50 years I am quite sure that is not true However I do not follow the literature that closely because I am tracking the whole of the science But I recently came across this Finally our indices and solar irradiance co vary with long term averages in global

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