Posted on 12/08/2011 9:18:50 PM PST by Ernest_at_the_Beach
In Tibet, it was about the same temperature on at least four occasions — back in late Roman times (those chariots!), then again in the dark ages (blame the collapse of industry), then in the middle ages (the Vikings?), then in modern times (blame the rise of industry).
Clearly, these climate cycles have nothing to with human civilization. Their team finds natural cycles of many different lengths are at work: 2-3 years, 100 years, 199 years, 800 years, and 1,324 years. The cold periods are associated with sunspot cycles. What we are not used to seeing are brave scientists willing to publish exact predictions of future temperatures for 100 years that include rises and falls. Apparently, it will cool til 2068, then warm again, though not to the same warmth as 2006 levels.
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.
Some will also, rightly, point out this is just Tibet, not a global average. True. But the results agree reasonably well with hundreds of other studies from all around the world (from Medieval times, Roman times, the Greenland cores). Why can’t we do solid tree-ring analysis like this from many locations?
Jo
Figure 5 Prediction of temperature trends on the central-eastern Tibetan Plateau for the next 120 years. Blue line, initial series; orange line, calibration series, 464 BC–834 AD; purple line, verification series, 835–1980 AD; red line, forecasting series, 1980–2134 AD. (Click to enlarge)
Amplitudes, rates, periodicities and causes of temperature variations in the past 2,485 years and future trends over the central-eastern Tibetan Plateau
Amplitudes, rates, periodicities, causes and future trends of temperature variations based on tree rings for the past 2485 years on the central-eastern Tibetan Plateau were analyzed. 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 a, 800 a, 199 a, 110 a and 2–3 a in the 2485-year temperature series. The 1324 a, 800 a, 199 a and 110 a cycles are associated with solar activity, which greatly affects the Earth surface temperature. The long-term trends (>1000 a) 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 prediction indicated that the temperature will decrease in the future until to 2068 AD and then increase again.
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Figure 1 Tree-ring-based temperature reconstruction for the central-eastern Tibetan Plateau during the past 2485 years (gray line), the 40-year moving average (thick black line) and the 40-year running standard deviation (thin black line); the horizontal line is the mean temperature for the 2485 years. (Click to enlarge)
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Figure 2 Power spectrum analysis of the 2485-year temperature series. (Click to enlarge)
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Figure 3 Millennium-scale cycle in the temperature variation during the last 2485 years. (Click to enlarge)
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Figure 4 Decomposition of the main cycles of the 2485-year temperature series on the Tibetan Plateau and periodic function simulation. Top: Gray line,original series; red line, 1324 a cycle; green line, 199 a cycle; blue line, 110 a cycle. Bottom: Three sine functions for different timescales. 1324 a, red dashed line (y = 0.848 sin(0.005 t + 0.23)); 199 a, green line (y = 1.40 sin(0.032 t – 0.369)); 110 a, blue line (y = 1.875 sin(0.057 t + 2.846)); time t is the year from 484 BC to 2000 AD. (Click to enlarge)
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Climate events worldwide, such as the MWP and LIA, were seen in a 2,485-year temperature series. The largest Figure 6 Temperature comparison between the forecast and observation data taken from seven stations on the central-eastern Tibetan Plateau (seven stations: Delingha, Dulan, Golmud, Lhasa, Nagqu, Dachaidan and Bange). amplitude and rate of temperature both occurred during the EJE, but not in the late 20th century. The millennium-scale cycle of solar activity determined the long-term temperature variation trends, while century-scale cycles controlled the amplitudes of temperature. Sunspot minimum events were associated with cold periods. The prediction results obtained using caterpillar-SSA showed that the temperature would increase until 2006 AD on the central-eastern Plateau, and then decrease until 2068 AD, and then increase again. The regularity of 600-year temperature increases and 600-year decreases (Figure 3) suggest that the temperature will continue to increase for another 200 years, since it has only been about 400 years since the LIA. However, a decrease in temperature for a short period controlled by century- scale cycles cannot be excluded. Obviously, solar activity has greatly affected temperature on the central-eastern Plateau. However, there are still uncertainties in our understanding of climate change, and the concentration of CO2 affects the climate. Further investigations are thus needed. -
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Liu Y, Cai Q F, Song H M, et al. 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, 2011, 56: 29862994, doi: 10.1007/s11434-011-4713-7 [ Climate Change over the Past Millennium in China.] … Hat Tip: Geoffrey Gold.
fyi
Clearly, Joanne fails to understand the relationship between Tibetans driving SUVs 2,500 years ago and the devastating effect that had on the climate back then. The human race was completely WIPED OUT as the result of those irresponsible ancient Tibetans and, today, it’s the computers conducting all of these online discussions!!!
The main reason this is important is because of the degree to which Mann relies upon (tweaked) tree ring studies to “support” his claims.
LOL!
What I think this means is that a Chinese scientist applied an advanced form of differential calculus to multiple gradients of change in tree rings from 2500 year old tress and published his derivative predictions.
And they prove correct by observation.
Is that correct?
Also found that WUWT has this Story up :
In China, there are no hockey sticks
There are 223 comments.
There always good comments ot WUWT.
Will try to look thru them.
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crosspatch says:
Please keep in mind that tree rings will only show trends in summer temperatures and then it will only show early summer — June and July. The main factors in tree rings are the onset of summer growth and June/July temperatures. The onset of growth is generally constrained by when the snow melts. So a late slow melt can delay initiation of growth for the year and reduce the overall size of the annual ring for that year.
http://academic.engr.arizona.edu/HWR/Brooks/GC572-2004/readings/vaganov-nature-siberia-tree-snow.pdf
But generally, summer temperatures will trend with general climate, though not always. Since 1998 in the continental US, for example, summer temperatures are flat while winter temperatures have been plummeting. Overall annual temperatures are in decline but summer temperatures are flat. Tree rings in North America probably do not show the decline that the instrument record does in annual average temperature observations show (NCDC’s website).
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Kasuha says:
Fourier analysis on time series may be a lot of fun but until physical background of identified cycles is demonstrated it’s not more than just playing with numbers with zero predictive potential.
Never mind what actual trees say, we have computer models.
bump tree rings and weather trends
Break out the extra blankets and rum mateys.... Hmmmmm. now where is the wonder boy from Penn State on this......
Did anyone e-mail this to Al Gore yet? I am still seeking his answer to my question of ‘What caused the ice age?’, but he didn’t answer me.
Tree ring Climate ping!
We must be having global warming, it’s not freezing down here today!
Couple of points:
1. cooling going on until 2068 we really need to drill. More and more drilling. Drill until you drop.
2. The natural gas fields that have bee found are a real blessing as we are going to be burning it fast in our homes.
[ Couple of points:
1. cooling going on until 2068 we really need to drill. More and more drilling. Drill until you drop.
2. The natural gas fields that have bee found are a real blessing as we are going to be burning it fast in our homes. ]
To Heck with that, Build a Thorium LFTR reactor for every 100,000 people in the world and dump the excess energy that is unused into acres upon acre of plugged electric space heaters....
And we can build them here. I like the way you think.
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