A 2485-year record shows current warming is a natural cycle

Chinese and Swedish researchers examined a 2,485-year record of tree ring data from the eastern Tibetan Plateau.  The researchers say:

The results showed that extreme climatic events on the Plateau, such as the Medieval Warm Period,  Little Ice Age and 20th Century Warming appeared synchronously with those in other places worldwide. The largest amplitude and rate of temperature change occurred during the Eastern Jin Event (343–425 AD), and not in the late 20th century. There were significant cycles of 1324 years, 800 years, 199 years, 110 years, and 2–3 years in the 2485-year temperature series. The 1324-year, 800-year, 199-year, and 110-year cycles are associated with solar activity, which greatly affects the Earth surface temperature. The long-term trends (>1000 years) of temperature were controlled by the millennium-scale cycle, and amplitudes were dominated by multi-century cycles. Moreover, cold intervals corresponded to sunspot minimums.

The graph below shows their temperature reconstruction and their prediction for the next 120 years.

Lu-tibet

The researchers say that there are few records long enough to recognize millennium-scale variations.  This particular record is well-correlated with seven other records in the northern hemisphere.

The researchers calculated the rate of temperature change for 10-year intervals.   They found that the highest rate was 0.77°C/decade between 362-390 AD. The next highest rate was 0.35°C/decade between 881–908 AD.  “In general, the calculations showed that the warming rate in the 20th century was not the highest in the past 2485 years.”

The global climatic system  is greatly affected by the millennium-scale cycles. There has been much geological evidence of millennium-scale cycles, from North America to Europe and from the Middle East to East Asia.

There is evidence worldwide indicating that millennium-scale cycles are the dominant factors for climatic fluctuation during the Holocene, and the exact periodicity of the millennium-scale cycle was modified as 1374 ± 502 years by Bond et al. The inducement mechanism of these cycles may be associated with solar activity, and perhaps, the inherent solar cycle.

The researchers say that “two century-scale cycles (199 years and 110 years) have dominantly affected the amplitude of the temperature variations.”  We experience temperature extremes through “constructive overlapping of multiple cycles” which, in the past 2,485 years appear to have produced 600-year cycles of general increases and decreases in temperature.

tibet-600

These tree-ring proxies agree with results of interpretations from ice cores, corals, speleothems, lacustrine deposits, and historical documents.  The authors say there is still uncertainty in climate change but solar activity appears to have had a great effect on the Tibetan Plateau. The implication is that 20th Century warming is not unprecedented in either rate or magnitude.  The authors say, “This moderate millennium-scale cycle [600 years] has lasted for such a long time that there is no reason for it to disappear in the last 2000 years.

The paper: Liu Y, Cai Q F, Song H M, et al., 2011, Amplitudes, rates, periodicities and causes of temperature variations in the past 2485 years and future trends over the central-eastern Tibetan Plateau. Chinese Sci Bull, 56: 2986 2994, doi: 10.1007/s11434-011-4713-7.

The full paper may be downloaded here.

 

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15 comments

  1. Here comes the endless Parsons comments. Thought I would get my comment in early.
    How does this data connect with tree ring. sun activity etc??

    1. “Here comes the endless Parsons comments.”

      You can always be counted on for the “feel-good” message of the day, fraser.  Your endless efforts to spread good cheer and uplift your fellow man must have you exhausted.  Merry Christmas, fraser. 

  2. Here we have a excellent example of how Jon and many denialists work. The authors of this study suggest that the driver of the warming periods they refer to is the sun. For example: “Moreover, cold intervals corresponded to sunspot minimums.” But the current historically high GST has occurred during the lowest solar minimum in 300 years.

    Here’s a comment about this study by one of the more respected climate.skeptics: “Their use of cycles to predict coming years and explain the long term behavior of the climate are, in my view, quite speculative, but the interpretation of their proxy data will add to the discussion of this metric.” Roger Pielke

    And here’s a couple of comments from a true denialist, Anthony Watts: “Now some will argue that skeptics scoff at tree rings, and we do- ”
    “Some will also, rightly, point out this is just Tibet, not a global average. True.” With friends like that, who needs enemies.
    The authors say this: “This moderate millennium-scale cycle [600 years] has lasted for such a long time that there is no reason for it to disappear in the last 2000 years.”.   The ” reason for it to disappear” is the changes we humans have made with CO2 and land use. A reason that is corroborated by not one study, but multiple voluminous lines of evidence.
    The authors also say this: “The largest amplitude and rate of temperature change occurred during the Eastern Jin Event (343–425 AD), and not in the late 20th century.”  “The results showed that extreme climatic events on the Plateau, such as the Medieval Warm Period,  Little Ice Age and 20th Century Warming appeared synchronously with those in other places worldwide.” These changes are not inconsistent with AGW Theory. These events occurred, but are not all recognized as Global Climate Events.
    Here’s a comment from Jon:  “This particular record is well-correlated with seven other records in the northern hemisphere.”. Now here is what the authors say: “…from seven stations on the central-eastern Tibetan Plateau (seven stations: Delingha, Dulan, Golmud, Lhasa, Nagqu, Dachaidan and Bange).” Jon continually spins the information as being in reference to Global Climate. It’s not. Here again:  “In general, the calculations showed that the warming rate in the 20th century was not the highest in the past 2485 years.”, but Jon conveniently leaves out “on the Tibetan Plateau”, making it appear that they are referencing Global Climate warming. That’s incorrect. I just wanted to point out a few quick facts. I haven’t had an opportunity to look at the entire study ( a link Jon?) or the review by the climate science community.

    I don’t want Fraser’s head to explode, so I’ll leave it at that. JP

      1. Matt, Jon has described himself as a denialist. Godwin’s “Law”, humorous as it is, has no application here. If one denies something, a strong case can be made that that person is a denialist. If you, or anyone for that matter, take some offense at the word; I have no problem avoiding its use in their company, once I know that’s the case. JP

  3. Who is doing the spinning? The full quote from the authors was: “In general, the calculations
    showed that the warming rate in the 20th century was not the highest in the past 2485 years.” They did not add “on the Tibetan Plateau.
    And the complete Anthony Watts quote (which actually came from Jo Nova): “Now some will argue that skeptics scoff at tree rings, and we do — sometimes — especially ones based on the wrong kind of tree (like the bristlecone) or ones based on small samples (like Yamal), ones with aberrant statistical tricks that produce the same curve regardless of the data (Mann’s hockey-stick), and especially ones that truncate data because it doesn’t agree with thermometers placed near air-conditioner outlets and in carparks (Mann again). Only time will tell if this analysis has nailed it, but, yes, it is worthy of our attention.”
    “Correlated with seven other records” I should have written several other records because I meant not just the ones in Tibet.
    The solar minimum you keep talking about is a phenomenon of just the last 10 years or so, a time when the temperature has not risen.
    The bottom line: Natural cycles can explain the observed behavior of the climate including the recent warming.
    For Frazer: Solar cycles vary the solar irradiance the earth receives. The longer cycles have to do also with the position of the earth relative to the sun in its tilt and position on an elliptical orbit. But the much bigger control is the variation in the Sun’s magnetic field which affects the amount of cosmic rays impinging on the atmosphere. The more cosmic rays, the more clouds, so it gets cooler.

  4. Jon, The solar minimum should have caused GST to drop. They didn’t. The author’s did add “…on the Tibetan Plateau”. They did so several times. I can only comment on what you write, Jon, not what you “should have written”. Watts wrote: “Some will also, rightly, point out this is just Tibet, not a global average. True.” Anthony Watts has been denigrating proxy tree ring data for years. Now that he sees an opportunity to spin a tree ring study his way, he’s backtracking.
    The Bottom line: This is a study about tree ring data on the Tibetan Plateau.

  5. As regards Jon’s comment to Fraser, many studies have been done on the effects of cosmic rays on climate. The results: Cosmic ray effects are too short lived, too small in magnitude, or in other ways incapable of altering cloud behavior on a large enough scale to drive significant climatic change [2008, Erlykin 2009, Erlykin 2009a, Pierce 2009, Calogovic 2010, Snow-Kropla 2011, Erlykin 2011; after Cook and Romm]. As usual, Jon has vastly oversimplified the actual mechanisms involved. Among many other complicating factors, it matters where the clouds are formed. Low thick clouds reflect the sun’s radiation and cool the earth’s surface but; high, thin clouds primarily transmit incoming solar radiation; at the same time, they trap some of the outgoing infrared radiation emitted by the Earth and radiate it back downward, thereby warming the surface of the Earth (see NASA’s Earth Observatory). I can only hope somebody asks me about the CERN studies. JP

  6. As I write this, I am letting my diesel truck idle outside just because I feel like  it.
    Also,  I turned up the thermostat in my 3000 Sq Ft poorly insulated home here in the chilly SF Bay Area.
    I plan on having a nice outside fire tomorrow in my fire pit and burn a couple cords of imported Ironwood logs that are nicely seasoned.
    Is it wrong that I am exhaling CO2 as I turn my home Compost pile which is giving off CO2?    What about all the rest of the plant and tree materials that are decomposing and expiring CO2 as well?   Last night I watched a segment on the TV about the 100s of volcanoes across the planet spewing out millions of tonnes of CO2 so I figure I hardly make a dent. 

    1. Rick, Sorry to rain on your barbecue, but here are the actual statistics on Anthropogenic versus volcanic CO2: Gas studies at volcanoes worldwide have helped volcanologists tally up a global volcanic CO2 budget in the same way that nations around the globe have cooperated to determine how much CO2 is released by human activity through the burning of fossil fuels. USGS studies show that globally, volcanoes on land and under the sea release a total of about 200 million tonnes of CO2 annually.

      This seems like a huge amount of CO2, but a visit to the U.S. Department of Energy’s Carbon Dioxide Information Analysis Center (CDIAC) website (http://cdiac.ornl.gov/) helps anyone armed with a handheld calculator and a high school chemistry text put the volcanic CO2 tally into perspective. Because while 200 million tonnes of CO2 is large, the global fossil fuel CO2 emissions for 2003 tipped the scales at 26.8 billion tonnes. Thus, not only does volcanic CO2 not dwarf that of human activity, it actually comprises less than 1 percent of that value. Your welcome. JP

  7. Will all the deniers fill a greater comfort in the grave, believing that it was not a human hand that turned our planet dark ? So it was volcanos that led to extinction, ruined our crops, acidified the oceans, and covered our shores.  Its not my train, so I dont have to get off the tracks. How about a delicious drink of Wyoming frack water. How does this conclusion help our children ?

      1. Matt, If you think there has been a lack of thoughtful attention here; you either haven’t been here much, or you haven’t been paying attention. JP

  8. Still waiting for the ” Parsons Climate Change Blogsite.” How do you have time for this as well as working for your employer.

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