Death knell for AGW
- Thread starter Walter
- Start date
So far, anything that humans have come up with haven't been able to match nature. And I think the time when humans can do that is an awful long time away yet.
He has a good point.
One has to be naively realist to speak of nature like if it was not an image produced by human culture.
You have missed the lesson of quantum physics: the observer determines what is observed.
Strictly speaking, nature is a word presently written on this screen. Our reality is structured by human symbols. We may find scary that human disparage nature recklessly but what is scarier still is that truth is to be found in pure subjectivity.
http://www.quodlibet.net/articles/johnson-truth.shtml
http://www.quodlibet.net/articles/johnson-truth.shtml
Not to me. Nature to me is a concept as well as a word. An undescribably huge concept encompassing an undescribably huge fact. The universe exists, I exist in it with my concept of it and it's counterpart - nothing. It Simply is.
Truth as fact is not subjective.
Anyway, the subjective part for me is that I like the way nature is supposed to be considering the way I think it should be. That makes me think that humans are quite foolish animals to "crap in our own crib", so to speak. I am fairly confident that life will survive whatever we manage to inflict on it, but I like life as is. I like seeing the variety of it. From amoeba to guar tree to stork to zingelfish. And that stems from my love of life in general. I simply despise seeing life wasted because of foolishness like greed.
Has Climate Change had its "Ten Minutes of Fame"?
Written by James Murray Sunday, 25 October 2009 08:32
THUNDER BAY - Yesterday was the International Day of Action on Climate Change. In Ottawa, cold weather kept the crowd from hitting the 5,000 people that organizers hoped. About 500 people showed up. In Calgary, a snowstorm dumped wet heavy snow on the city. On Google, unlike past climate change events, there was not a special logo created. On the front pages of major newspapers across Canada the major stories were not about the looming climate crisis.
In Winnipeg, about 200 people made it to a rally at the Manitoba Legislature. In Vancouver, a city steeped in protest, the crowd was estimated at 5000. Across Canada interest in the day of action appeared less than ever.
Could it be that the fire is smoldering out on the issue of climate change? Maybe in an era where ever shorter attention spans want to shift to other topics the climate issue has had its "ten minutes of fame"?
On the popular news site www.bourque.com the climate issue is not mentioned. This morning, on Google News, there isn't a mention of the day of protest on the top stories either. The front page of the Toronto Star is void of climate change stories too.
Over on www.wattsupwiththat.com a website that over the past several years has dug into the issue, the comment is that global warming and climate change are "urban legends". Roy W. Spencer, Ph. D. writes, "I contend that the belief in human-caused global warming as a dangerous event, either now or in the future, has most of the characteristics of an urban legend. Like other urban legends, it is based upon an element of truth. Carbon dioxide is a greenhouse gas whose concentration in the atmosphere is increasing, and since greenhouse gases warm the lower atmosphere, more CO2 can be expected, at least theoretically, to result in some level of warming".
It is, perhaps causing some in the movement to ramp up their rhetoric to try to gain more attention. Elizabeth May and the Green Party recently took the approach that the only way to get the message out is to state, "Your Parents F*cked Up The Planet". May's justification is that "Our culture is steeped in the F-word".
In some cases, media saturation might be one issue. In others it might be people are looking outside and seeing the weather and deciding that the alarm over global warming is not worth all of the attention it has garnered. Over the past ten years, each time it has warmed up, news readers have explained to people that it is "global warming" or "climate change".
Part of it could be explained by a young teen yesterday who stated, "recycling is boring".
That is a telling, and in many ways a scary comment. In a world where teens expect excitement, and where a music video longer than three minutes is seen as "too long" it could well be that many teens are tuning out, just like teens did in the 1960s when they tuned out of the values pressed upon them by society. If you are one who is convinced that teens are convinced that saving the planet is a top priority, all you have to do is take a walk around a local high school and witness the litter. Then ask yourself, "does that look like a generation dedicated to the environment?"
The Pew Media Research Centre's latest poll reports, "There has been a sharp decline over the past year in the percentage of Americans who say there is solid evidence that global temperatures are rising. And fewer also see global warming as a very serious problem – 35% say that today, down from 44% in April 2008.
Written by James Murray Sunday, 25 October 2009 08:32
THUNDER BAY - Yesterday was the International Day of Action on Climate Change. In Ottawa, cold weather kept the crowd from hitting the 5,000 people that organizers hoped. About 500 people showed up. In Calgary, a snowstorm dumped wet heavy snow on the city. On Google, unlike past climate change events, there was not a special logo created. On the front pages of major newspapers across Canada the major stories were not about the looming climate crisis.
In Winnipeg, about 200 people made it to a rally at the Manitoba Legislature. In Vancouver, a city steeped in protest, the crowd was estimated at 5000. Across Canada interest in the day of action appeared less than ever.
Could it be that the fire is smoldering out on the issue of climate change? Maybe in an era where ever shorter attention spans want to shift to other topics the climate issue has had its "ten minutes of fame"?
On the popular news site www.bourque.com the climate issue is not mentioned. This morning, on Google News, there isn't a mention of the day of protest on the top stories either. The front page of the Toronto Star is void of climate change stories too.
Over on www.wattsupwiththat.com a website that over the past several years has dug into the issue, the comment is that global warming and climate change are "urban legends". Roy W. Spencer, Ph. D. writes, "I contend that the belief in human-caused global warming as a dangerous event, either now or in the future, has most of the characteristics of an urban legend. Like other urban legends, it is based upon an element of truth. Carbon dioxide is a greenhouse gas whose concentration in the atmosphere is increasing, and since greenhouse gases warm the lower atmosphere, more CO2 can be expected, at least theoretically, to result in some level of warming".
It is, perhaps causing some in the movement to ramp up their rhetoric to try to gain more attention. Elizabeth May and the Green Party recently took the approach that the only way to get the message out is to state, "Your Parents F*cked Up The Planet". May's justification is that "Our culture is steeped in the F-word".
In some cases, media saturation might be one issue. In others it might be people are looking outside and seeing the weather and deciding that the alarm over global warming is not worth all of the attention it has garnered. Over the past ten years, each time it has warmed up, news readers have explained to people that it is "global warming" or "climate change".
Part of it could be explained by a young teen yesterday who stated, "recycling is boring".
That is a telling, and in many ways a scary comment. In a world where teens expect excitement, and where a music video longer than three minutes is seen as "too long" it could well be that many teens are tuning out, just like teens did in the 1960s when they tuned out of the values pressed upon them by society. If you are one who is convinced that teens are convinced that saving the planet is a top priority, all you have to do is take a walk around a local high school and witness the litter. Then ask yourself, "does that look like a generation dedicated to the environment?"
The Pew Media Research Centre's latest poll reports, "There has been a sharp decline over the past year in the percentage of Americans who say there is solid evidence that global temperatures are rising. And fewer also see global warming as a very serious problem – 35% say that today, down from 44% in April 2008.
The title of this article could just have been: climate change sadly takes more than ten minutes.
Perhaps James Murray's local high school is surrounded by litter but the one near here isn't. And the kids are definitely more environmentally responsible than kids in my days of school.
Anyway, Murray has an opinion ..... whoopee It can join the thousands of other opinions.
Anyway, Murray has an opinion ..... whoopee It can join the thousands of other opinions.
More on the climate auditor...will the media discuss the response like they did with the original implications of bias and fraud? So far, notta. What follows is a response from Keith Briffa and colleagues, to Steve McIntyre's postings at Climate Audit on their supposed smashing of another hockey stick...
Examining the validity of the published RCS Yamal tree-ring chronology
b Laboratory Of Dendrochronology, Institute of Plant and Animal Ecology, Ural Branch of Russian Academy of Sciences, 8 Marta St., Ekaterinburg, 620144, Russia
c Dendroecology Department, Sukachev Institute of Forest, Siberian Branch of Russian Academy of Sciences, Akademgorodok St., Krasnoyarsk, 660036, Russia
d IT and Math. Modelling Department, Krasnoyarsk State Trade-Economical Institute, L. Prushinskoi St., Krasnoyarsk, 660075, Russia
[/SIZE]Abstract
At http://www.climateaudit.org/?p=7168, Steve McIntyre reports an analysis he undertook to test the "sensitivity" of the "Regional Curve Standardised" tree-ring chronology (Briffa, 2000; Briffa at al., 2008) to the selection of measurement data intended to provide evidence of long-term changes of tree growth, and, ultimately inferred temperature variation through two millennia in the Yamal region of northern Russia. It would be a mistake to conclude that McIntyre's sensitivity analysis provides evidence to refute our current interpretation of relatively high tree growth and summer warmth in the 20th century in this region. A reworked chronology, based on additional data, including those used in McIntyre's analysis, is similar to our previously published chronologies. Our earlier work thus provides a defensible and reasonable indication of tree growth changes during the 20th century and in the context of long-term changes reconstructed over the last two millennia in the vicinity of the larch tree line in southern Yamal. McIntyre's use of the data from a single, more spatially restricted site, to represent recent tree growth over the wider region, and his exclusion of the data from the other available sites, likely represents a biased reconstruction of tree growth. McIntyre's sensitivity analysis has little implication, either for the interpretation of the Yamal chronology or for other proxy studies that make use of it.
Background
Briffa (2000) published a version of the Yamal chronology as part of a general review of dendroclimatological research. This chronology was constructed using a data processing approach (Regional Curve Standardisation, RCS) that has the potential to show centennial and even longer timescale changes in tree growth, to a greater extent than some other chronology building methods used at that time. Subsequently, a slightly different version of the RCS Yamal chronology was produced using the same data set but processed using an improved implementation of the RCS technique (Briffa et al. 2008). However, the difference between the 2000 and 2008 versions of the chronology is small.
The data set used in the above-cited work was assembled and supplied by our colleagues Ra$hit Hantemirov and Stepan Shiyatov (Institute of Plant and Animal Ecology, Ekaterinburg, Russia) who also published a version of this chronology (Hantemirov and Shiyatov 2002) based on a different processing method (corridor standardisation).
The AD portion of the data set, common to these three analyses consisted of measurements from 235 sub-fossil larch samples collected at numerous sites (see map) adjacent to the Porzayakha, Yadayakhodyyakha, Tanlovayakha and Khadytayakha rivers (Hantemirov and Shiyatov, 2002) and samples from 17 living trees growing at 5 sites in the vicinity of the sub-fossil trees.
McIntyre's analysis involved removing the measurement data for 12 trees (from 3 of these sites POR, YAD and JAH), data that make up the most recent part of our chronology, and replacing them with measurements from 18 trees growing at a different single site (KHAD), slightly to the south of the locations of the removed trees and originating from a different source. This alternative "modern" set was not considered or used by Hantemirov and Shiyatov or in the previous analyses (Briffa, 2000; Briffa at al., 2008).
McIntyre produced two alternative versions of his chronology, both constructed using a simple RCS technique similar to that employed in Briffa (2000). Both versions retained all of the sub-fossil material and the measurements from 5 'living' trees (from two sites) sampled in or before 1983. In one version of the chronology McIntyre included recent data only from the KHAD site. In the second version he retained the data from the 12 trees used in the original versions of the RCS chronology as well as the data from KHAD. The two versions of his chronology exhibit different patterns of tree growth over the 20th century: one with a positive trend and one (that with only the KHAD data) indicating a clear negative trend in tree growth after 1950. If one accepts that in this area, warmer temperatures are associated with enhanced tree growth, the "KHAD only" version could be interpreted as indicating generally reducing tree growth or a general cooling during the last 40 years. Both of these interpretations are largely at odds with the inference we have drawn from our published analyses.
We wish to stress that McIntyre himself has made no such assertions. At no time does he suggest that either of his versions of the chronology represents general Yamal tree-growth changes "more realistically" than in our earlier work. However, his original posting has been interpreted in this way by others, both on the Climate Audit website and elsewhere. Some postings on Climate Audit, notably that by Ross McKitrick (comment no. 7), strongly imply that the data used in the published versions of the Yamal chronology were deliberately selected in order to manufacture misleading evidence of a recent tree-growth increase in this region. Subsequent reports of McIntyre's blog (e.g. in The Telegraph, The Register and The Spectator) amount to hysterical, even defamatory misrepresentations, not only of our work but also of the content of the original McIntyre blog, by using words such as 'scam', 'scandal', 'lie', and 'fraudulent' with respect to our work.
Our current practice when selecting data to incorporate in a regional chronology, is to include data exhibiting high levels of common high-frequency variability (i.e. on the basis of high inter-site correlations, where these are calculated using high-pass filtered data). Judged according to this criterion it is entirely appropriate to include the data from the KHAD site (used in McIntyre's sensitivity test) when constructing a regional chronology for the area. However, we simply did not consider these data at the time, focussing only on the data used in the companion study by Hantemirov and Shiyatov and supplied to us by them.
We would never select or manipulate data in order to arrive at some preconceived or regionally unrepresentative result. However, as we will show here, the fact that we did not incorporate the KHAD data has no serious implications for the general validity of our published work.
A more extensive sensitivity test
Our original data set included data from a spread of modern tree sites in the vicinity of the northern larch treeline, though each was represented by measurements from only a small number of trees. In his implementation that included recent data from only the single KHAD site, McIntyre produces a chronology whose recent character is dominated by the growth behaviour of trees observed in a narrower region slightly to the south of the original sites.
We have now undertaken a more extensive sensitivity test, using the RCS approach, to examine the relative growth rates of trees at each of the 3 original locations removed by McIntyre, as well as the KHAD site. We have also taken the opportunity to acquire and incorporate additional data from the 3 original sites, in this analysis.
The rates of recent tree growth differ somewhat between the sites (see figure C and figure D). When compared to average growth during the previous century, each site chronology exhibits greater ring growth after 1920, noticeably in the mid 1920s, during the late 1930s/early 1940s, during the mid 1950s and the mid 1960s. The relative increase in tree growth, above the long-term mean, during the 20th century is greatest at the POR and YAD sites. The mean level of growth is also clearly above the long-term mean at JAH. The relative level of growth is lowest at KHAD. While trees at each of the sites that we originally used show high average growth after 1970, the KHAD trees upon which McIntyre focused exhibit anomalously low growth, below the long-term mean, at this time.
This reveals that exclusive use of the KHAD data (i.e. the most 'extreme' of McIntyre's alternative chronologies) likely provides an atypical representation of the more general long-term course of changing tree growth, as represented by the data from the other sites.
A reworked Yamal Chronology
So what is the "best" indication of relative ring-width changes in this Yamal region? One approach is to judge this by making use of all the data to hand. A chronology using only the recent data from either POR or YAD will exhibit a greater 20th century increase in growth than one based on JAH, but one based only on KHAD, as in McIntyre's experiment, is the most anomalous and, therefore, arguably the least defensible. With no additional information with which to justify the exclusion of any of these data, we have produced a chronology using the measurements from all 4 sites (see Figure E and Figure F).
When this Yamal_All chronology is plotted alongside the Briffa et al. (2008) chronology and the McIntyre versions (i.e. using the data selected by McIntyre but produced using our current implementation of the RCS), the "KHAD-only" chronology is clearly anomalous in the recent period compared to the other series and is very unlikely to present a realistic indication of comparative tree-growth changes representative of the wider region in a way that is consistent through time. The 'living' chronologies, at POR, JAH and YAD and the alternative McIntyre version (where the KHAD data are included along with the original Hantemirov and Shiyatov data), all show similar notably increasing growth around the beginning of the 20th century and relatively high growth maintained thereafter.
We note that in the previously published Yamal chronologies, the last 2 years (1995 and 1996) were made up of data from only 5 trees, all from the YAD site. The previous 6 years (1989 to 1994) were based on data from only 10 trees, originating from the POR and YAD sites. Therefore, the most recent section of the chronology was somewhat biased by the proportionately greater growth shown at these two sites compared to that at JAH which ended in 1988. The reworked chronology now contains data from 20 trees up to 1994 and 10 trees in 1995 and 1996, but again for the last 5 years they come only from the POR and YAD sites which show higher growth rates in recent decades compared with JAH (which now ends 1991) and, particularly, KHAD. The slower-growth KHAD site data end in 1990, so that our published and new versions of the chronology (the latter containing KHAD data) are directly comparable only up until 1990. This does not mean that our published or reworked Yamal_All versions of the chronology present an incorrect impression of relatively high tree growth after 1990. It means that the only available evidence comes from the (faster growing) POR and YAD sites, so the magnitude of the post-1990 increase may be slightly elevated.
[SIZE=-1]Comparison of published and reworked Yamal chronologies.
This Figure shows the two earlier versions of the Yamal RCS larch chronology in red (published in Briffa, 2000) and blue (Briffa et al., 200[/SIZE]8)[SIZE=-1] compared to the new version, based on all of the currently available data (Yamal_All) for the original (POR, YAD and JAH) sites and including the additional data from the KHAD site (in black). Tree sample counts for this 'new' chronology are shown by the grey shading. The upper panel shows the data smoothed with a 40-year low-pass cubic smoothing spline. The lower panel shows the yearly data from 1800 onwards. All series have been scaled so the yearly data have the same mean and standard deviation as the Yamal_All series over the period 1-1600.
[/SIZE]
The new chronology based on all of the available data up until 1990 can be considered as a more 'conservative' indicator of the likely history of wider-regional tree growth in the southern Yamal area. This new Yamal_All series exhibits a slightly lower level of mean tree growth over the 20th century than is shown in previously published series (see Figure above). It nevertheless provides essentially the same picture of relatively high tree growth in the 20th century in the context of the last two millennia. A number of other studies have also reported enhanced germination and growth of larch trees during the 20th century in north central Russia (Devi et al. 2008, MacDonald et al. 2008, Shiyatov 2009).
If one accepts a link between enhanced tree-growth and warmer summers in this region, the re-examined evidence indicates that the "20th century was unusually warm" as was concluded in our previous publications (e.g. Briffa et al. 2008, p2281).
Conclusions
So what can we conclude on the basis of this and McIntyre's sensitivity tests? Does either version of the Yamal chronology as presented in Briffa (2000) and Briffa et al. (2008) present a misleading indication of the likely history of tree-growth changes near the tree line in the Yamal region over the last two millennia, or can McIntyre's "sensitivity analysis" be taken as evidence that tree growth has not increased in this region in the second half of the 20th century as is clearly implied by the "extreme" version of the Yamal chronology he produced? On the basis of the evidence we report here, the answer is very likely "NO" on both counts. McIntyre states "If the non-robustness observed here prove out .. this will have an important impact on many multiproxy studies ...". We have shown here that the "KHAD only" example constructed by McIntyre itself represents a biased chronology, contradicted by the evidence of other chronologies constructed using additional and more representative site data. The evidence does not support a conclusion that our previous work was in any way seriously flawed. The last 8 years of our chronology ARE based on data from a decreasing number of sites and trees and this smaller available sample does emphasise the faster growing trees, so this section of the chronology should be used cautiously. The reworked chronology, based on all of the currently available data is similar to our previously published versions of the Yamal chronology demonstrating that our earlier work presents a defensible and reasonable indication of tree growth changes during the 20th century, and in the context of long-term changes reconstructed over the last two millennia in the vicinity of the larch treeline in southern Yamal.
This does not mean that these chronologies will not change as additional data become available and as the RCS processing technique evolves, but the results we show here do suggest that McIntyre's sensitivity analysis has little implication for those other proxy studies that make use of the published Yamal chronology data.
When using the RCS technique, it is important to examine the robustness of RCS chronologies, involving the type of sensitivity testing that McIntyre has undertaken and that we have shown in this example. Indeed, we have said so before and stressed in our published work that possible chronology biases can come about when the data used to build a regional chronology originate from inhomogeneous sources (i.e. sources that would indicate different growth levels under the same climate forcing). In the case of the Yamal chronology. However, such tests (i.e. those described here) do not change the interpretation that tree growth has been unusually high and summers warm during the 20th century compared to the evidence of the previous two millennia.
While we re-emphasise that further experimentation with the RCS technique is warranted we would also stress that it is imperative that much more sub-fossil and recent data are collected in this and other high-latitude and high-elevation (near tree-line) sites to facilitate more detailed research into the character and causes of tree growth changes. The IPCC Fourth Assessment Report has also emphasised this: "... this assessment would be improved with extensive networks of proxy data that run right up to the present day. This would help measure how the proxies responded to the rapid global warming observed in the last 20 years and it would also improve the ability to investigate the extent to which other, non-temperature, environmental changes may have biased the climate response of proxies in recent decades." (Jansen et al. 2007, page 483)
Raw Data Availability
Briffa has also been attacked by McIntyre for not releasing the original ring-width measurement records from which the various chronologies discussed in Briffa (2000) and Briffa et al. (2008) were made. We would like to reiterate that these data were never "owned" by the Climatic Research Unit (CRU) and we have never had the right to distribute them. These data were acquired in the context of collaborative research with colleagues who developed them. Requests for these data have been redirected towards the appropriate institutions and individuals. When the Briffa (2000) paper was published, release of these data was specifically embargoed by our colleagues who were still working towards further publications using them. Following publication of the 2008 paper, at the request of the Royal Society, Briffa approached colleagues in Sweden, Ekaterinburg and Krasnoyarsk and their permission was given to release the data. This was done in 2008 and 2009.
Incidentally, we understand that Ra$hit Hantemirov sent McIntyre the Yamal data used in the papers cited above at his request as early as 2nd February, 2004. The Climatic Research Unit has never been a prolific producer of tree-ring records, focussing mainly on the collaborative analysis of data generously provided by other institutions. We will continue to respect restrictions placed upon the dissemination of data by those colleagues who provide them. All of the data produced at CRU (sampled from living oaks or pines at various sites around the UK and Scandinavia) have been provided on request. (All of the data used or produced in the analysis described here are provided on the Data page.)
Source: Examining the validity of the published RCS Yamal tree-ring chronology
Examining the validity of the published RCS Yamal tree-ring chronology
Keith R. Briffaa and Thomas M. Melvina
With thanks to Timothy J. Osborna, Philip D. Jonesa, Ra$hit M. Hantemirovb, Stepan Shiyatovb and Vladimir V. Shishovc,d.
[SIZE=-2] a Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K. b Laboratory Of Dendrochronology, Institute of Plant and Animal Ecology, Ural Branch of Russian Academy of Sciences, 8 Marta St., Ekaterinburg, 620144, Russia
c Dendroecology Department, Sukachev Institute of Forest, Siberian Branch of Russian Academy of Sciences, Akademgorodok St., Krasnoyarsk, 660036, Russia
d IT and Math. Modelling Department, Krasnoyarsk State Trade-Economical Institute, L. Prushinskoi St., Krasnoyarsk, 660075, Russia
[/SIZE]Abstract
At http://www.climateaudit.org/?p=7168, Steve McIntyre reports an analysis he undertook to test the "sensitivity" of the "Regional Curve Standardised" tree-ring chronology (Briffa, 2000; Briffa at al., 2008) to the selection of measurement data intended to provide evidence of long-term changes of tree growth, and, ultimately inferred temperature variation through two millennia in the Yamal region of northern Russia. It would be a mistake to conclude that McIntyre's sensitivity analysis provides evidence to refute our current interpretation of relatively high tree growth and summer warmth in the 20th century in this region. A reworked chronology, based on additional data, including those used in McIntyre's analysis, is similar to our previously published chronologies. Our earlier work thus provides a defensible and reasonable indication of tree growth changes during the 20th century and in the context of long-term changes reconstructed over the last two millennia in the vicinity of the larch tree line in southern Yamal. McIntyre's use of the data from a single, more spatially restricted site, to represent recent tree growth over the wider region, and his exclusion of the data from the other available sites, likely represents a biased reconstruction of tree growth. McIntyre's sensitivity analysis has little implication, either for the interpretation of the Yamal chronology or for other proxy studies that make use of it.
Background
Briffa (2000) published a version of the Yamal chronology as part of a general review of dendroclimatological research. This chronology was constructed using a data processing approach (Regional Curve Standardisation, RCS) that has the potential to show centennial and even longer timescale changes in tree growth, to a greater extent than some other chronology building methods used at that time. Subsequently, a slightly different version of the RCS Yamal chronology was produced using the same data set but processed using an improved implementation of the RCS technique (Briffa et al. 2008). However, the difference between the 2000 and 2008 versions of the chronology is small.
The data set used in the above-cited work was assembled and supplied by our colleagues Ra$hit Hantemirov and Stepan Shiyatov (Institute of Plant and Animal Ecology, Ekaterinburg, Russia) who also published a version of this chronology (Hantemirov and Shiyatov 2002) based on a different processing method (corridor standardisation).
The AD portion of the data set, common to these three analyses consisted of measurements from 235 sub-fossil larch samples collected at numerous sites (see map) adjacent to the Porzayakha, Yadayakhodyyakha, Tanlovayakha and Khadytayakha rivers (Hantemirov and Shiyatov, 2002) and samples from 17 living trees growing at 5 sites in the vicinity of the sub-fossil trees.
McIntyre's analysis involved removing the measurement data for 12 trees (from 3 of these sites POR, YAD and JAH), data that make up the most recent part of our chronology, and replacing them with measurements from 18 trees growing at a different single site (KHAD), slightly to the south of the locations of the removed trees and originating from a different source. This alternative "modern" set was not considered or used by Hantemirov and Shiyatov or in the previous analyses (Briffa, 2000; Briffa at al., 2008).
McIntyre produced two alternative versions of his chronology, both constructed using a simple RCS technique similar to that employed in Briffa (2000). Both versions retained all of the sub-fossil material and the measurements from 5 'living' trees (from two sites) sampled in or before 1983. In one version of the chronology McIntyre included recent data only from the KHAD site. In the second version he retained the data from the 12 trees used in the original versions of the RCS chronology as well as the data from KHAD. The two versions of his chronology exhibit different patterns of tree growth over the 20th century: one with a positive trend and one (that with only the KHAD data) indicating a clear negative trend in tree growth after 1950. If one accepts that in this area, warmer temperatures are associated with enhanced tree growth, the "KHAD only" version could be interpreted as indicating generally reducing tree growth or a general cooling during the last 40 years. Both of these interpretations are largely at odds with the inference we have drawn from our published analyses.
We wish to stress that McIntyre himself has made no such assertions. At no time does he suggest that either of his versions of the chronology represents general Yamal tree-growth changes "more realistically" than in our earlier work. However, his original posting has been interpreted in this way by others, both on the Climate Audit website and elsewhere. Some postings on Climate Audit, notably that by Ross McKitrick (comment no. 7), strongly imply that the data used in the published versions of the Yamal chronology were deliberately selected in order to manufacture misleading evidence of a recent tree-growth increase in this region. Subsequent reports of McIntyre's blog (e.g. in The Telegraph, The Register and The Spectator) amount to hysterical, even defamatory misrepresentations, not only of our work but also of the content of the original McIntyre blog, by using words such as 'scam', 'scandal', 'lie', and 'fraudulent' with respect to our work.
Our current practice when selecting data to incorporate in a regional chronology, is to include data exhibiting high levels of common high-frequency variability (i.e. on the basis of high inter-site correlations, where these are calculated using high-pass filtered data). Judged according to this criterion it is entirely appropriate to include the data from the KHAD site (used in McIntyre's sensitivity test) when constructing a regional chronology for the area. However, we simply did not consider these data at the time, focussing only on the data used in the companion study by Hantemirov and Shiyatov and supplied to us by them.
We would never select or manipulate data in order to arrive at some preconceived or regionally unrepresentative result. However, as we will show here, the fact that we did not incorporate the KHAD data has no serious implications for the general validity of our published work.
A more extensive sensitivity test
Our original data set included data from a spread of modern tree sites in the vicinity of the northern larch treeline, though each was represented by measurements from only a small number of trees. In his implementation that included recent data from only the single KHAD site, McIntyre produces a chronology whose recent character is dominated by the growth behaviour of trees observed in a narrower region slightly to the south of the original sites.
We have now undertaken a more extensive sensitivity test, using the RCS approach, to examine the relative growth rates of trees at each of the 3 original locations removed by McIntyre, as well as the KHAD site. We have also taken the opportunity to acquire and incorporate additional data from the 3 original sites, in this analysis.
The rates of recent tree growth differ somewhat between the sites (see figure C and figure D). When compared to average growth during the previous century, each site chronology exhibits greater ring growth after 1920, noticeably in the mid 1920s, during the late 1930s/early 1940s, during the mid 1950s and the mid 1960s. The relative increase in tree growth, above the long-term mean, during the 20th century is greatest at the POR and YAD sites. The mean level of growth is also clearly above the long-term mean at JAH. The relative level of growth is lowest at KHAD. While trees at each of the sites that we originally used show high average growth after 1970, the KHAD trees upon which McIntyre focused exhibit anomalously low growth, below the long-term mean, at this time.
This reveals that exclusive use of the KHAD data (i.e. the most 'extreme' of McIntyre's alternative chronologies) likely provides an atypical representation of the more general long-term course of changing tree growth, as represented by the data from the other sites.
A reworked Yamal Chronology
So what is the "best" indication of relative ring-width changes in this Yamal region? One approach is to judge this by making use of all the data to hand. A chronology using only the recent data from either POR or YAD will exhibit a greater 20th century increase in growth than one based on JAH, but one based only on KHAD, as in McIntyre's experiment, is the most anomalous and, therefore, arguably the least defensible. With no additional information with which to justify the exclusion of any of these data, we have produced a chronology using the measurements from all 4 sites (see Figure E and Figure F).
When this Yamal_All chronology is plotted alongside the Briffa et al. (2008) chronology and the McIntyre versions (i.e. using the data selected by McIntyre but produced using our current implementation of the RCS), the "KHAD-only" chronology is clearly anomalous in the recent period compared to the other series and is very unlikely to present a realistic indication of comparative tree-growth changes representative of the wider region in a way that is consistent through time. The 'living' chronologies, at POR, JAH and YAD and the alternative McIntyre version (where the KHAD data are included along with the original Hantemirov and Shiyatov data), all show similar notably increasing growth around the beginning of the 20th century and relatively high growth maintained thereafter.
We note that in the previously published Yamal chronologies, the last 2 years (1995 and 1996) were made up of data from only 5 trees, all from the YAD site. The previous 6 years (1989 to 1994) were based on data from only 10 trees, originating from the POR and YAD sites. Therefore, the most recent section of the chronology was somewhat biased by the proportionately greater growth shown at these two sites compared to that at JAH which ended in 1988. The reworked chronology now contains data from 20 trees up to 1994 and 10 trees in 1995 and 1996, but again for the last 5 years they come only from the POR and YAD sites which show higher growth rates in recent decades compared with JAH (which now ends 1991) and, particularly, KHAD. The slower-growth KHAD site data end in 1990, so that our published and new versions of the chronology (the latter containing KHAD data) are directly comparable only up until 1990. This does not mean that our published or reworked Yamal_All versions of the chronology present an incorrect impression of relatively high tree growth after 1990. It means that the only available evidence comes from the (faster growing) POR and YAD sites, so the magnitude of the post-1990 increase may be slightly elevated.
[SIZE=-1]Comparison of published and reworked Yamal chronologies.
This Figure shows the two earlier versions of the Yamal RCS larch chronology in red (published in Briffa, 2000) and blue (Briffa et al., 200[/SIZE]8)[SIZE=-1] compared to the new version, based on all of the currently available data (Yamal_All) for the original (POR, YAD and JAH) sites and including the additional data from the KHAD site (in black). Tree sample counts for this 'new' chronology are shown by the grey shading. The upper panel shows the data smoothed with a 40-year low-pass cubic smoothing spline. The lower panel shows the yearly data from 1800 onwards. All series have been scaled so the yearly data have the same mean and standard deviation as the Yamal_All series over the period 1-1600.
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The new chronology based on all of the available data up until 1990 can be considered as a more 'conservative' indicator of the likely history of wider-regional tree growth in the southern Yamal area. This new Yamal_All series exhibits a slightly lower level of mean tree growth over the 20th century than is shown in previously published series (see Figure above). It nevertheless provides essentially the same picture of relatively high tree growth in the 20th century in the context of the last two millennia. A number of other studies have also reported enhanced germination and growth of larch trees during the 20th century in north central Russia (Devi et al. 2008, MacDonald et al. 2008, Shiyatov 2009).
If one accepts a link between enhanced tree-growth and warmer summers in this region, the re-examined evidence indicates that the "20th century was unusually warm" as was concluded in our previous publications (e.g. Briffa et al. 2008, p2281).
Conclusions
So what can we conclude on the basis of this and McIntyre's sensitivity tests? Does either version of the Yamal chronology as presented in Briffa (2000) and Briffa et al. (2008) present a misleading indication of the likely history of tree-growth changes near the tree line in the Yamal region over the last two millennia, or can McIntyre's "sensitivity analysis" be taken as evidence that tree growth has not increased in this region in the second half of the 20th century as is clearly implied by the "extreme" version of the Yamal chronology he produced? On the basis of the evidence we report here, the answer is very likely "NO" on both counts. McIntyre states "If the non-robustness observed here prove out .. this will have an important impact on many multiproxy studies ...". We have shown here that the "KHAD only" example constructed by McIntyre itself represents a biased chronology, contradicted by the evidence of other chronologies constructed using additional and more representative site data. The evidence does not support a conclusion that our previous work was in any way seriously flawed. The last 8 years of our chronology ARE based on data from a decreasing number of sites and trees and this smaller available sample does emphasise the faster growing trees, so this section of the chronology should be used cautiously. The reworked chronology, based on all of the currently available data is similar to our previously published versions of the Yamal chronology demonstrating that our earlier work presents a defensible and reasonable indication of tree growth changes during the 20th century, and in the context of long-term changes reconstructed over the last two millennia in the vicinity of the larch treeline in southern Yamal.
This does not mean that these chronologies will not change as additional data become available and as the RCS processing technique evolves, but the results we show here do suggest that McIntyre's sensitivity analysis has little implication for those other proxy studies that make use of the published Yamal chronology data.
When using the RCS technique, it is important to examine the robustness of RCS chronologies, involving the type of sensitivity testing that McIntyre has undertaken and that we have shown in this example. Indeed, we have said so before and stressed in our published work that possible chronology biases can come about when the data used to build a regional chronology originate from inhomogeneous sources (i.e. sources that would indicate different growth levels under the same climate forcing). In the case of the Yamal chronology. However, such tests (i.e. those described here) do not change the interpretation that tree growth has been unusually high and summers warm during the 20th century compared to the evidence of the previous two millennia.
While we re-emphasise that further experimentation with the RCS technique is warranted we would also stress that it is imperative that much more sub-fossil and recent data are collected in this and other high-latitude and high-elevation (near tree-line) sites to facilitate more detailed research into the character and causes of tree growth changes. The IPCC Fourth Assessment Report has also emphasised this: "... this assessment would be improved with extensive networks of proxy data that run right up to the present day. This would help measure how the proxies responded to the rapid global warming observed in the last 20 years and it would also improve the ability to investigate the extent to which other, non-temperature, environmental changes may have biased the climate response of proxies in recent decades." (Jansen et al. 2007, page 483)
Raw Data Availability
Briffa has also been attacked by McIntyre for not releasing the original ring-width measurement records from which the various chronologies discussed in Briffa (2000) and Briffa et al. (2008) were made. We would like to reiterate that these data were never "owned" by the Climatic Research Unit (CRU) and we have never had the right to distribute them. These data were acquired in the context of collaborative research with colleagues who developed them. Requests for these data have been redirected towards the appropriate institutions and individuals. When the Briffa (2000) paper was published, release of these data was specifically embargoed by our colleagues who were still working towards further publications using them. Following publication of the 2008 paper, at the request of the Royal Society, Briffa approached colleagues in Sweden, Ekaterinburg and Krasnoyarsk and their permission was given to release the data. This was done in 2008 and 2009.
Incidentally, we understand that Ra$hit Hantemirov sent McIntyre the Yamal data used in the papers cited above at his request as early as 2nd February, 2004. The Climatic Research Unit has never been a prolific producer of tree-ring records, focussing mainly on the collaborative analysis of data generously provided by other institutions. We will continue to respect restrictions placed upon the dissemination of data by those colleagues who provide them. All of the data produced at CRU (sampled from living oaks or pines at various sites around the UK and Scandinavia) have been provided on request. (All of the data used or produced in the analysis described here are provided on the Data page.)
Source: Examining the validity of the published RCS Yamal tree-ring chronology
It gets warmer, then it gets cooler, then it gets warmer.........
Why argue about it.
What is frightening is the sheer arrogance of man, to think that man can change the actions of mother nature.
Why argue about it.
What is frightening is the sheer arrogance of man, to think that man can change the actions of mother nature.
There is nothing arrogant about that. Changing hydrology and thus flood severity, creating oceanic dead zones, diverting whole rivers...there is a very long list.
It's ignorant to say that we can't change the actions of mother nature.
lmao You've never seen a dam? Beavers can change a natural action with sticks. We can do it on a massive scale with concrete.
We can't change natural actions? Yeah, the Exxon Valdez spill had no effect whatsoever.
Lol All those examples are small change. So you are saying man can alter things on a global scale?
Because temperature variations can be measured and reported only by human beings who are still alive.