More on the recent Pages2K paper

“In Europe, for example, the average temperature between AD 21 and 80 was warmer than during AD 1971-2000.”

From Northern Arizona University

Regional insights set latest study of climate history apart

As climate studies saturate scientific journals and mainstream media, with opposing viewpoints quickly squaring off in reaction and debate, new findings can easily be lost in the noise.

But in the case of Northern Arizona University Regents’ professor Darrell Kaufman and a study appearing in Nature Geoscience, obscurity is an unlikely fate.

What Kaufman—the lead co-author of “Continental-scale temperature variability during the last two millennia”—and 78 experts from 24 countries have done is to assemble the most comprehensive study to date of temperature change of Earth’s continents over the past 1,000 to 2,000 years.

By looking regionally, the researchers found considerable complexity hidden within a global average.

“We wanted a new and ambitious effort to reconstruct past climate,” Kaufman said of the PAGES 2k network of researchers. “One of the strongest aspects of the consortium study is that it relies on regional expertise.”

Members of the consortium represent eight continental-scale regions. They lent their insights about the best proxy records—such as tree-ring measurements—to use for a particular region, and how to interpret the data based on regional climatology.

While the study does not attempt to attribute temperature changes to natural or human-caused factors, Kaufman said the finding of a long-term global cooling trend that ended late in the 19th century is further evidence that increased greenhouse gasses have had an influence in later years.

“The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century, making 20th century warming more difficult to explain if not for the likely impact of increased greenhouse gasses,” Kaufman said.

While that sounds like a familiar theme, the study’s findings of regional variations are less well known. Because of extensive participation by scientists working in the Southern Hemisphere, Kaufman said, data from those regions broadened what had been a view previously centered on Europe.

“We know the most about the long-term temperature history in Europe, but we find that not every region conforms with that pattern,” Kaufman said. He noted that temperatures varied by region against the backdrop of the long-term cooling identified by the study.

The regional focus on the past 2,000 years is significant for two reasons, Kaufman said. First, climate change at that scale is more relevant to societies and ecosystems than global averages. And second, “regional scale differences help us to understand how the climate system works, and that information helps to improve the models used to project future climate.”

Kaufman’s own research team added to the strong regional input. His research in Alaska and elsewhere formed part of the dataset.

“The questions that my team hopes to address involve the larger climate system, and our research contributes one piece of the global puzzle,” he said.

Kaufman’s role as lead co-author came about partly from good timing—he was on sabbatical as a visiting scientist at the Bern, Switzerland, headquarters of Past Global Changes (PAGES) organization, as the data were being assembled, so he took the lead in writing the manuscript.

Later, as the paper underwent a substantial reworking to address the scrutiny of peer review, co-author Nick McKay, a post-doctoral researcher at NAU, “did the heavy lifting,” Kaufman said. “He analyzed the data from each of the regions to uncover the most important similarities and differences, which we needed for the synthesis.”

In another of the study’s major contributions, the entire database on which it was based has been tabulated and will be made available publicly for further analysis. Kaufman and his co-authors have posted the data along with frequently asked questions about the study on the PAGES project website.

“My co-authors and I look forward to seeing the data used by others in future analyses because science moves forward with well-informed alternative interpretations,” Kaufman said.

==============================================================

Andrew Revkin has an interview with the author.

I found this part very interesting:

We also found that temperatures in some regions were higher in the past then they were during the late 20th century and that, the longer the individual site record, the more likely it was to show prior warm intervals, which is consistent with the long-term cooling trend. In Europe, for example, the average temperature between AD 21 and 80 was warmer than during AD 1971-2000. But temperatures did not fluctuate uniformly among all regions at multi-decadal to centennial scales. For example, the transition to colder regional climates between AD 1200 and 1500 is evident earlier in the Arctic, Europe and Asia than in North America or the Southern Hemisphere.

More here: http://dotearth.blogs.nytimes.com/2013/04/22/study-charts-2000-years-of-continental-climate-changes/

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64 thoughts on “More on the recent Pages2K paper

  1. So if they show it was clearly warmer in the past, and we didn’t “tip” into a disaster, doesn’t that kind of put a hole in that whole “tipping point” idea…
    It also seems that they can’t quite accept that natural variation which worked in the past can continue to work today, and have to embrace a new cause (CO2) for modern temperatures. Just a tiny bit tacky…

  2. Climate is not global, it is not regional, it is zonal – that is why we have the Koppen-Geiger classification that reflects the impacts of temperature and precipitation interacting with altitude and geology to define areas that limit the growth of plants. Since food is the most important factor in human life, changes in the growing areas for food are the most important aspect of climate change. A look at the Koppen-Geiger maps will show that basing studies on regional data confounds the issue. Hopefully it will be possible to extract meaningful zonal data from the promised Pages2K archive and do some real climate science.

  3. “The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century, making 20th century warming more difficult to explain if not for the likely impact of increased greenhouse gasses,” Kaufman said.
    Sorry the above statement is patent nonsense this is because the end of the Little Ice Age and hence warmer temperatures kicked in well before there were large increases in CO2 emissions. Also as regards to past warming they are merely confirming what was already known.
    It seems to me they have so much data they can’t see the woods?

  4. Of course, it’s an established and accepted scientific fact that the MWP was a worldwide warm period; warmer than the present. We don’t need doubtful proxies, flawed studies or so called climate experts to tell us that. The Vikings grew potatoes on Greenland, for goodness sake!

  5. All proxy studies contain huge error margins and uncertainties and it is important that they should be considered in tandem with written historical record (to the extent that we possess written historical record of the period/place in question) to check whether they may be on the right track.
    We know from written record that, in Northern Europe, there was a Roman warm period. We know from written accounts that vines were grown around the Scottish boarder. This cannot be done today. We therefore know that it was warmer at those latitudes than it is today. For vines to grow in the Scottish boarders, the region most probably would have had to enjoy a similar temperature/climate to that enjoyed today bySouthern England, ie., about 3 to 4 degrees warmer.
    We know from archaelogical evidence that the Vikings settled in Greenland during the Viking warm period. Again, bearing in mind farming technology available, Greeenland would most probably have to have enjoyed a temperature between 3 to 6 degrees warmer than it is today to enable Viking settlements to have flourished for several centuries.
    Any proxy reconstruction of Northern Europe should show these warm periods. If they do not, then one should be particularly wary as to their accuracy.
    I suspect that much evidence of past climatic conditions around the Mediterranean can be found from Egyptian historical record at the time of the Pharoahs and when it was the bread basket of the world (during Roman times).
    We know from the thermometer record that the Southern and Northern Hemisphere do not respond similarly, no doubt 9in part) because of the differences in the distribution of land masses and that the Southern Hemisphere possesses a greater quantity of ocean (with dampening effects associated with thermal lag and thermal capacity). Indeed, even the Antarctic appears to be bahaving differently to the Arctic, possibly because the latter is only ice and has a greater response to warm water polar currents.

  6. “My co-authors and I look forward to seeing the data used by others in future analyses because science moves forward with well-informed alternative interpretations,” Kaufman said.
    Sound like an encouraging new trend. Let’s see whether this is data rather than model outpout or “reanalysis data” model output.
    In any case, if they are as good as their claims and provide all this in a useful, auditable form (unlike BEST) it should be a very useful resource.

  7. According to “Village Idiot”

    The Vikings grew potatoes on Greenland, for goodness sake!

    Living up to his name, I see – the Idiot doesn’t seem to wonder where the Vikings got potatoes from.

  8. Sure NH / SH are different. At least the poles even show opposite tendancies:
    http://climategrog.wordpress.com/?attachment_id=161
    Their regional approach is much more relevant. It’s not a degree or two in average warming/cooling that kills people and crops. 1812 was only a couple of degrees cooler in global average. But it did not feel like a couple of degrees on the russian front.

  9. How can anybody take the European reconstruction seriously ? MWP almost gone. in Europe !
    Though the South American and Australian may even be worse.

  10. “The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century, making 20th century warming more difficult to explain if not for the likely impact of increased greenhouse gasses,” Kaufman said.

    But Co2 was below the alleged safe limit of 350ppm. As a result we must NOT act now as it would be an utter waste of time.

    “A long-term global cooling trend ended in the late 19th century, a reversal in temperature that cannot be explained by natural variability alone, according to a new study.”
    http://science.nbcnews.com/_news/2013/04/22/17864735-global-warming-study-suggests-human-causes-dating-back-to-1800s?lite

  11. How much can I save on my heating bill if I enhance the CO2 content of my house to 1000ppm?

  12. The cooling trend they describe is no more valid than a late twentieth century warming trend. The longer the period looked at, the more a linear trend starts to look like part of a cycle.

  13. I will be glad when the measured temperature data set becomes longer than the paleo proxy reconstructions of temperature. I understand this will take a while yet. 🙂
    Currently the high quality temperature datasets, from satellites, are growing at a current rate of 3% per year. Though the rate is slowing down. This is similar to my sister being 50% of my age, as my father kept reminding me, and know she is , ohhh about… get the calculator out… 113%… wait, I think I did something wrong… 88%. I did a classic Mike Mann Tiljander upside down mistake 🙂
    Climate science is so fun.

  14. I hope Village Idiot meant grapes when (s)he wrote potatoes. Pretty nasty wine otherwise.
    [Vodka? Mod]

  15. Of course it’s cooler in the NH then the SH. When it’s winter in the north, it’s summer in the south. If you think the writers of this study surely know that simple fact, you forget they are “climate scientists” trained not to observe their surroundings.
    Seriously, the data base sounds interesting if they haven’t tampered with it too much.
    What happened to the like-dislike buttons?

  16. Recent archaeological digs have shown barley was grown [beer, bread etc] Seems the last ones kicked out the fires in around 1400. The heaps of discarded food/bones/rubbish were quite high and seems to prove the Viking farms were productive for some time. Spuds and grapes are a myth I think.
    Warmer than today and no ‘tipping point’ or sea level inundation. Historic records are so more accurate than stupid computer predictions eh?

  17. Manfred says:
    April 23, 2013 at 1:45 am
    How can anybody take the European reconstruction seriously ? MWP almost gone. in Europe !

    “He who controls the past controls the future. He who controls the present controls the past.”
    ― George Orwell, 1984

  18. ‘“The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century’
    The give away word is ‘likley ‘ so they don’t know what natural forces caused past cooling or indeed warming, but they know for a fact that recent warming has to be man made becasue …..?
    In reality what they know is what brings in further research grants and what it is that organisations like the IPCC need , and its not anything that suggests that current warming cannot be the fault of man .

  19. Total carbon emissions from fossil-fuels (million metric tons of C) go from 3 in 1751 to 8 in 1800 to 188 in 1875 to 534 in 1900 to 6750 in 2000 to 8749 in 2008 (end of data).
    http://cdiac.ornl.gov/ftp/ndp030/CSV-FILES/global.1751_2008.csv
    So, over the last decade or so, in spite of fossil fuel emissions running at 15-30 times the late 19thC rate, global warming has stalled. The idea put forward in this paper that “the finding of a long-term global cooling trend that ended late in the 19th century is further evidence that increased greenhouse gasses have had an influence in later years.” is completely ludicrous.

  20. “They lent their insights about the best proxy records—such as tree-ring measurements ….”
    What ?! The best proxy records are tree-ring measurements ?! Classical climate change theory says that temperature changes are most pronounced at night and during the winter. Trees grow during the daytime and in the summer. Rates of growth are influenced not only by temperature but also by sunlight (cloudiness), the availability of nutrients, competition from other trees/plants for sunlight and nutrients, precipitation, disease / fungus / insect attack and, last but definitely not least, atmospheric CO2 levels. I seriously doubt that it is possible to filter out any temperature signal from all these confounding factors. Indeed, the “hide the decline” scandal where proxies (predominantly tree-rings) indicated declining temperatures when thermometers showed temperatures were rising confirms that tree-rings are utterly useless as temperature proxies.
    There are much better proxies such as oxygen isotopes in ice cores or studies of the historical height of tree lines.
    But Richard Verney has really hit the nail on the head in his comment above, “All proxy studies contain huge error margins and uncertainties and it is important that they should be considered in tandem with written historical record…”
    http://www.co2science.org has a directory of published studies from around the world relevant to the Medieval Warm Period. These studies confirm that the MWP was global and they are roughly 4:1 in favour of the MWP being warmer than the modern warm period. I wonder how many of these studies made it into the Pages2K paper.
    “Kaufman said the finding of a long-term global cooling trend that ended late in the 19th century……” Someone ought to tell Kaufman that the low point of the Little Ice Age occurred around 1690. The world has been warming since, though with cool interludes such as the Dalton Minimum. The LIA is considered to have ended around the mid/late 19th century but the world wasn’t on a long-term cooling trend up until then.
    “The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century, making 20th century warming more difficult to explain if not for the likely impact of increased greenhouse gasses.” The upward trend in temperatures during the 20th century was pretty similar to the upward trend in the 18th and 19th centuries. Given that the natural factors continued to operate, this means the influence of an increase in greenhouse gases must be pretty small. This is being confirmed today as 21st century temperatures flatline. And with a quiet sun, we can expect another Dalton-type cooling for a couple of decades.

  21. “How can anybody take the European reconstruction seriously ? MWP almost gone. in Europe !”
    About 15 years ago I visited a vineyard in the south of England, they had a poster up showing where vineyards had historically existed, it was as far north as Leeds. It must have been significantly warmer than it is now, for a long enough period for people to have considered planting the vines, for this to have been the case.

    • @Nial
      “About 15 years ago I visited a vineyard in the south of England, they had a poster up showing where vineyards had historically existed, it was as far north as Leeds. It must have been significantly warmer than it is now, for a long enough period for people to have considered planting the vines, for this to have been the case.”
      And what is with this vineyard?
      http://www.visitleeds.co.uk/thedms.aspx?dms=13&feature=2&venue=2193741

  22. “We know the most about the long-term temperature history in Europe, but we find that not every region conforms with that pattern,” Kaufman said. He noted that temperatures varied by region against the backdrop of the long-term cooling identified by the study.”
    Well I guess that rules out calibrating and comparing high frequency regional proxies to global averages then.

  23. “The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century…”
    Show your work.

  24. Correlation cannot be used to establish causation, so the temperature rise from the late 1800s cannot be ascribed to CO2 simply because the temperatures rose.

  25. @richard verney
    “We know from written record that, in Northern Europe, there was a Roman warm period. We know from written accounts that vines were grown around the Scottish boarder. This cannot be done today. We therefore know that it was warmer at those latitudes than it is today. For vines to grow in the Scottish boarders, the region most probably would have had to enjoy a similar temperature/climate to that enjoyed today bySouthern England, ie., about 3 to 4 degrees warmer.”
    Is Cumbria close enough to the Scottish border?
    http://www.highcupwines.co.uk/site/
    “We know from archaelogical evidence that the Vikings settled in Greenland during the Viking warm period. Again, bearing in mind farming technology available, Greeenland would most probably have to have enjoyed a temperature between 3 to 6 degrees warmer than it is today to enable Viking settlements to have flourished for several centuries.”
    http://en.wikipedia.org/wiki/Economy_of_Greenland#Agriculture_and_forestry
    http://www.independent.co.uk/environment/climate-change/greenland-reaps-benefits-of-global-warming-8555241.html
    It may be that at those times and places it was warmer than it is now. However, quite some less than 3 degrees would be enough.

  26. The instructive “further study” step would be to attempt a reconstruction of the atmospheric and oceanic oscillations that could have brought about these regional trends. It would then behoove climate scientists to determine whether or not these same conditions could be present today (and they would have to prove these same conditions could not cause similar warming). The rest of the story will be written in history books about the chicken little CO2 scare.

  27. Reich.Eschhaus says:
    April 23, 2013 at 6:05 am
    /////////////////////////////
    Modern varieties of grape which have bben genetically modified through selection to be more hardy cannot be compared to those varieites available in Roman times.
    Likewise modern day farming techniques cannot be compared to the technology and facilities available to the Vikings in the Viking warm period. Not only is crop variety more hardy, sometimes grown under grass or poly-tube, but also cattle and the like are wintered in heated barns. One only has to see how much live stock was lost this winter in Wales and Scotland due to a reasonably harsh winter to see the problems that the Vikings would have faced with much harsher conditions in Greenland. No tractors or diggers to help them out and/or to distribute feed etc.
    As far as Greenland is concerned, some of the Viking homesteads are still in areas where there is permafrost such that farming is not possible.

  28. All these studies going back a few millenia are getting boring. They all have a feeling of desperation and pleading that you MUST believe that it wasn’t as warm in the past and carbon dioxide MUST be the devil incarnate. When all is said and done they simply say that it’s a tiny bit warmer today than when the Little Ice Age came to a close. None offer any solid proof that man has anything to do with the climate variations. Every time I read one of these pitiful studies my conclusion of their conclusions is always, BIG F….ING DEAL! What a waste of taxpayer dollars.

  29. As the Schnidejoch glacier in the Swiss alps recedes, it has revealed a mountain pass once used by men, forests which once grew there and evidence of human activities. Over 300 human artefacts have been found. The dating of these artefacts is interesting. There are intervals to which artefacts can be dated: neolithic, bronze age, Roman period and medieval times, interspersed with intervals with no artefacts whatsoever.
    What this tells us is that (a) current temperatures cannot be unprecedented – they have happened before, and (b) there is a cycle of warming and cooling which has occurred a number of times in the past, each time reaching current temperatures. (Or exceeding them – we don’t know what is still below the glacier.) Any proxy temperature indicator which fails to reflect these episodes is worthless.
    These earlier warming episodes occurred without any assistance from CO2 and they did not result in thermal Armageddon. On the contrary, they were beneficial to mankind. As the laws of nature have not changed, it is most likely that whatever caused these earlier warmings is the prime suspect for most of the current warming too. The alternative is to believe that these natural factors have been switched off and coincidentally (temporally and in their effect) almost exactly replaced by CO2.

  30. Arrhenius claimed that warming from a doubling of atmospheric carbon dioxide would be greatest in the north of the NH (i.e. northern Scandinavia) and that it would be most expressed in winter and at night. So we can take this area as the “canary in the coalmine” to determine whether CAGW is real or not. Looking at the Koppen-Geiger climate zone maps we see that Greenland, where all the Gore ice melt is meant to happen, is in the same zone as northern Norway, where a recent paper presented here at WUWT shows that the end of the 20th century was distinctly cooler than in the MWP. One can find similar data for other climate zones – note that the USA region used in Pages2K is made up of several climate zones so confounding proxy and temperature data. The same is true of their other regions. This study owes more to agriculture than science – picking cherries.
    http://hockeyschtick.blogspot.fi/2012/08/paper-finds-medieval-warm-period-in.html
    Medieval Warm Period in Arctic was much warmer than the present
    Divine, D., Isaksson, E., Martma, T., Meijer, H.A.J., Moore, J., Pohjola, V., van de Wal, R.S.W. and Godtliebsen, F. 2011. Thousand years of winter surface air temperature variations in Svalbard and northern Norway reconstructed from ice-core data. Polar Research 30: 10.3402/polar.v30i0.7379.
    A paper published in Polar Research finds that temperatures at two sites in the Arctic were much warmer than at the end of the 20th century. At one site, Longyearbyen, the 11-year running-mean peak winter temperature was a remarkable 9C warmer than at the end of the record in 2000. At the 2nd site, Vardo, the 11-year running-mean peak winter temperature was about 3.3C warmer than at the end of the record in 2000.

  31. Later, as the paper underwent a substantial reworking to address the scrutiny of peer review, co-author Nick McKay, a post-doctoral researcher at NAU, “did the heavy lifting,” Kaufman said. “He analyzed the data from each of the regions to uncover the most important similarities and differences, which we needed for the synthesis.”
    ###
    Yet another wet-behind-the-ears pseudo-scientist armed with the latest Marxist world-view manipulating data in defense of the agenda. NAU, might as well be Portland State. Pablo Freire would be proud!

  32. The split from natural to anthropogenic determinants, of coming out of the LIA “naturally” and then continuing the change by the contribution of anthropogenically generated CO2 is the fundamental and key component that has none, nada, zilch, zero observational evidence. It is all theoretical. Wherever or whenever the split is, it is built on argument by ignorance, by models that leave a hole to be filled by CO2 by the non-observed but intellectually argued limitations of the natural factors put into their equations.
    What will be the response when the solar cycle induced cooling kicks in strongly and the observational records fall completely from the IPCC scenarios? I’m hoping that the academic world begins to lose credibility. I know this is a blasphemy to many, but if you think of the Friedman economic theories, the stock market and money-supply theories, the DDT/GMO/Vaccination, linear-no-threshold theories, green technology and how subsidies will create new economies and wealth, and how all these peer-reviewed ideas have messed up lives in the late 20th century, when you recall how prediction of this and that from specialized, wired activists have failed to come true due to basic errors in assumptions, you wonder how much we really should be paying more than concept-service to those with more educational letters after their names than their parents gave them initials for financial paperwork.
    With more time I’d tell you what I really think about those without their feet on the ground telling me where and when to walk.

  33. Apparently history forgot that vikings used to trade with Scotland, Ireland and wales. There is actual documented accounts that the Americas were explored centuries before the Portuguese and Spanish began their relationship with Ireland and wales, by this time there were accounts of Celtic monks (holy men) who had traveled the western Atlantic, 10’s of thousands of years worth of history has always been ignored or even manipulated by later generations, the ridiculousness of history really does sink in when you objectively study it, its fascinating. What the Vikings would have grown in Greenland would have been similar to what they were growing in Scandinavia, Ireland and northern Britain, which was various swedes, turnips and a variety of hardy crops to feed cattle, but I’m open minded that exploration and trade had been advanced enough for the possibility that other exotic vegetables were farmed, Sea fearing nations have been around for 10’s of thousands of years after all.

  34. The warm historical temperatures mentioned in many posts above seem to support this paper’s conclusions, rather than show they are wrong. The paper is all about the variations across regions (continental scale). Of course specific locations, whether in Greenland, UK or wherever, should have even more variation. Some have been warm at times when other places were average or cool.
    The synthesis part is looking at all their regional data together to see what is common and what’s not. Anecdotes can’t address that, but the scientists’ analysis seems to agree with other recent studies: there was a long global cooling trend reversed by recent warming.

  35. Is there a geological reference frame in these studies related to the Earths position and precession of regional areas, I understand that glaciers which have melted have all become easterly facing during sunrise and westerly during sun set, unsheltered valleys surrounded by mountains and hills, where as if they were northerly facing during sun rise and southerly facing during sun set they would be sufficiently sheltered to accumulate. A curious scientific fact.

  36. Chuck Nolan says:
    April 23, 2013 at 5:31 am
    I liked the like button

    Me too. Two positive qualities: It could allow readers to express appreciation for quiet, sensible, but otherwise unremarkable comments. And it could indicate the absence of general WUWT support for wackier comments, undermining their usefulness as horrible examples of our thinking to be cited by alarmists.

  37. fredd says:
    April 23, 2013 at 9:42 am
    there was a long global cooling trend reversed by recent warming.

    OTC:

    dcfl51 says:
    April 23, 2013 at 4:00 am
    “Kaufman said the finding of a long-term global cooling trend that ended late in the 19th century……” Someone ought to tell Kaufman that the low point of the Little Ice Age occurred around 1690. The world has been warming since, though with cool interludes such as the Dalton Minimum. The LIA is considered to have ended around the mid/late 19th century but the world wasn’t on a long-term cooling trend up until then.

  38. Roger, do you think those two quotations contradict? I mentioned a global trend and dcfl51mentioned one glacier in Switzerland. The PAGES 2k paper graphs four different NH reconstructions (along with their own semi-global) showing where the LIA fits. All but Hegerl (2006) show cooling since at least 1000 AD. Globally, Marcott (2013) does too.
    A lot of confusion seems to come from mixing up local, regional and global descriptions.

  39. ‘“The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century, making 20th century warming more difficult to explain if not for the likely impact of increased greenhouse gasses,” Kaufman said.’
    The quotation above contains what is very likely the best example of horrendous reasoning by a scientist that I have encountered.
    The first howler is that he confuses natural variability with drivers of climate. Natural variability is the range, from top to bottom, of all of our data points for temperature or whatever we are measuring. Natural variability is not a driver of climate or of anything. It is simply a range of numbers. So, in reality, to say that the “natural factors continued to operate through the 20th century” is to say that our range of temperatures remained the same. It is nonsense based upon a confusion that is crucial to AGW climate dogma.
    The second howler is that he treats natural variation as on a par with his favorite causative agent, increased greenhouse gases. As he sees it, because the pre-industrial causes continued to operate then a new cause, increased GHGs, is needed to explain rising temperatures. But natural variation is not a cause or a system of causes. It is simply our record of temperatures from top to bottom.
    We do not know all the causes that make up natural variation. To pretend that we do is foolishness beyond belief. Treating natural variation as a set of causes introduces an ambiguity into the phrase ‘natural variation’ that makes nonsense of all claims about natural variation.
    At the bottom of all the nonsense coming from AGW climate scientists is the assumption that all discussion of climate must be a discussion of one or more causes of climate change. Take away that assumption, as skeptics have done by insisting on the importance of natural variation (which is not a cause), and the whole global warming/…/climate extremes edifice crumbles.

  40. To fredd:
    You’re not looking at the bigger picture. Yes, there may have been a global
    cooling trend, but the point is that it was warmer, possibly by 1-2 deg. C., in
    the past, with NO APPARENT ILL EFFECTS. That is, there was no catastrophic
    “tipping point” passed when heating caused a massive release of methane
    from the Arctic, carbon dioxide from the oceans, etc. A number of climate
    scientists, James Hansen prominent among them, have argued that such
    a “tipping point” is near. These proxies illustrate that that fear, at least, is
    overblown.

  41. Chris R. says:
    You’re not looking at the bigger picture. Yes, there may have been a global
    cooling trend, but the point is that it was warmer, possibly by 1-2 deg. C., in
    the past, with NO APPARENT ILL EFFECTS. That is, there was no catastrophic
    “tipping point” passed when heating caused a massive release of methane
    from the Arctic, carbon dioxide from the oceans, etc. A number of climate
    scientists, James Hansen prominent among them, have argued that such
    a “tipping point” is near. These proxies illustrate that that fear, at least, is
    overblown.

    No, I was trying to look at the bigger picture and distinguish local or regional from hemispheric or global. The latter being what many scientists are worried about, but the former being what many posts above mention.
    As for tipping points, methane etc., isn’t that a concern about what could happen if warming (or CO2) goes to higher levels than today? So noting that 1400 years ago it was as warm as 1970-2000, without a big methane release, is arguing against a point I don’t think Hansen has made.
    Where is your 1-2 deg C warmer estimate from? I didn’t see that in any of the recent global or hemispheric reconstructions. Longer ago there were much warmer times, of course, and some of those apparently did have methane release, even extinction events.

  42. Quite apart from its merits, an alternative media reporting of the Kaufman et al. findings could be: “Likely human activity arrests Earth’s drifting into next Ice Age”
    But only bad news sells.

  43. ‘“The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century, making 20th century warming more difficult to explain if not for the likely impact of increased greenhouse gasses,” Kaufman said.’
    The quotation above contains what is very likely the best example of horrendous reasoning by a scientist that I have encountered.
    The first howler is that he confuses natural variability with drivers of climate.

    But he doesn’t. You confuse ‘factors’ with ‘variability’.
    Kaufman is talking about natural drivers, not weather. In this case, I believe he is referring to orbital mechanics (and possibly related slow feedbacks). Milankovitch cycles have been in a cooling phase for the last 10,000 years, with at least another 20,000 years of this phase to go.

  44. The NOAA NODC Solanki report on solar activity is very interesting and the abstract states Although the rarity of the current episode of high average sunspot numbers may indicate that the Sun has contributed to the unusual climate change during the twentieth century, we point out that solar variability is unlikely to have been the dominant cause of the strong warming during the past three decades. but doesn’t say what evidence they use to come to this conclusion. The simple fact of the correlation with known global temperatures was enough. They didn’t need to assuage themselves from the climate mafia..or did they? Is this what peer review means? You have to correct for ideological errors?
    h/t to Eric Worrall

  45. fredd says:
    The PAGES 2k paper graphs four different NH reconstructions (along with their own semi-global) showing where the LIA fits. All but Hegerl (2006) show cooling since at least 1000 AD.

    WUWT’s Paleoclimate sub-page is at http://wattsupwiththat.com/reference-pages/global-weather-climate/paleoclimate/ . In it, the graph by Ljungqvist et al. shows a warming since about 1675, as do the next six graphs or so. These are presumably what dgfl had in mind.
    I think there is at least one chart that shows a lower temperature in the late 19th century than in 1675, but the difference is small, and it wouldn’t be really accurate to say, based on it, that the period between 1675 and it was a continuation of a cooling trend of prior centuries. Rather, those 200-odd years were essentially flat, so dgfl was correct to say that the industrial period didn’t interrupt and reverse a long-term cooling trend. The interruption occurred earlier.

    Globally, Marcott (2013) does too.

    He would say that, wouldn’t he?

    A lot of confusion seems to come from mixing up local, regional and global descriptions.

    WUWT’s charts should add the word “Global” to their captions, since that is what the absence of a regional identifier seems to imply, based on its presence in regional graphs.

  46. fredd says:
    April 23, 2013 at 11:14 am
    Roger, do you think those two quotations contradict? I mentioned a global trend and dcfl51 mentioned one glacier in Switzerland.

    I cited dfcl’s 4:00 AM quote, below–it didn’t contain a mention of a glacier. He wasn’t relying on measurement of a glacier for his estimate of the date of the end of the LIA, as you imply.
    http://wattsupwiththat.com/2013/04/23/more-on-the-recent-pages2k-paper/#comment-1284737
    That glacier-mention was in his next quote:
    http://wattsupwiththat.com/2013/04/23/more-on-the-recent-pages2k-paper/#comment-1284876

  47. “This study owes more to agriculture than science – picking cherries.” [Peter Azlac 4/23/13, 0812]
    Yes, as Darrell Kaufman makes quite clear: “… the paper underwent a substantial reworking to address the scrutiny of peer review, co-author Nick McKay, a post-doctoral researcher at NAU, ‘did the heavy lifting,’ Kaufman said. ‘He ANALYZED THE DATA from each of the regions TO UNCOVER the MOST IMPORTANT similarities and differences, WHICH WE NEEDED for the synthesis [a.k.a. distortion of the already highly dubious data, jm].'”
    [Emphasis mine]
    *******************************************************************************
    Re: Cult of Climatology members attempting to refute the WUWT scientists above:
    Most of them are obviously (by their blatant disregard for engaging in genuine debate) posting here only for damage control to keep any of their cult members who might be reading from defecting. THIS IS A GOOD THING! It indicates that this site is read widely enough by the Cult that it just may do what its leaders fear most: prove that the Cult of Climatology is WRONG.
    Hurrah! Having enemies of the desperately-earnest-yet-hopelessly-specious ilk that some of the above pro-AGW posters are is always a good sign. Their minds sense how dangerously close they are to having to acknowledge that their beliefs are wrong. Their desperate tone shows that they are feeling threatened. (Remember how angry Gregory Peck gets in “Snowbound” whenever psychiatrist Ingrid Bergman gets close to the truth — the movie’s script was based on classic psychiatrist’s data from observation of many clients)
    And, no, I did not mean you, R. Eschhaus (not yet, anyway!) and, likely some others whose names I have not memorized.
    [DISCLAIMER: I am a non-scientist. Many of the other posters may consider my post to be a “wacky” post. The quality of this post is not representative.]
    Well, I tried. They’ll likely just quote something wacky I said out of context… DO LET ME KNOW, you wonderful WUWT science people, if my posts are doing more harm than good. I don’t want to do anything to hamper the battle for truth being fought so brilliantly here.

  48. Roger Knights says:
    WUWT’s Paleoclimate sub-page is at http://wattsupwiththat.com/reference-pages/global-weather-climate/paleoclimate/
    WUWT’s charts should add the word “Global” to their captions, since that is what the absence of a regional identifier seems to imply, based on its presence in regional graphs.

    I agree, captions should be clear about geography, also end dates and most importantly, link to the original scientific source (and original graphics). Few of those graphs are based on global reconstructions — most are one-site ice cores, some northern hemisphere, central England (in one case mis-labeled as global) etc. Also, few reach the late 20th century. Many end in mid-19th, leaving a visual impression they compare modern temperatures with ancient.
    The reconstructions compared in PAGES 2k (Moberg, Ljungqvist, Hegerl, and Mann 2008) are all northern hemisphere. Marcott data cover continents except Africa, and compare they compare their results with Mann 2008 global.

    • @fredd:
      I suggest that you post that comment at WUWT’s Reference Pages –> Global Temperature–Climatic –> Paleoclimate Pages. Maybe some corrections and/or elucidations will result.

  49. Roger Knights says:
    I suggest that you post that comment at WUWT’s Reference Pages –> Global Temperature–Climatic –> Paleoclimate Pages. Maybe some corrections and/or elucidations will result.
    I saw where corrections have been done with a few, keep the bad graph but add a note about an error. Others are not corrected, though, and the sourcing, dates and geography are unclear for many.
    Instead of adding notes, a cleaner solution would be to present only good graphs, direct and unedited along with captions from the original research articles (linked).
    Or keep some bad ones only if they have a particularly interesting story of how they got to be that way.

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