By passing over the ongoing scientific squabbling over global warming as per the item here it is time to again address the thousand year cycle that appears to have prevailed during the Holocene. The first image is of a graph based on over 6000 boreholes and represents a convincing proxy.
http://www.c3headlines.com/2010/05/peerreviewed-research-unprecedented-global-warming-during-medieval-period-boreholes-reveal.html
The prime source for these graphs is the C3 Headlines site:
http://www.c3headlines.com/temperature-charts-historical-proxies.html
We see a decisive envelope that shows us an apparently natural thousand year cycle that has recently returned to the natural axis and is presently preparing to slowly rise above that axis and stay there for several hundred years or so. Whether this effect or cycle is real depends largely on repeatability. In previous posts I was able to see enough data to make the thousand year cycle rather creditable.
Now we have the following graph:
http://www.c3headlines.com/2010/01/extreme-cool-warm.html
This pretty well removes any further doubts over the validity of the cycle itself and also eliminates any need for a special contribution from the deforestation of the Sahara that I had relied on for earlier interpretation.
The only remaining question to answer is what drives the cycle itself. My best answer appears to be that during the cold part of the cycle, an excess of cold water from the Southern hemisphere is increasingly shifted into north Atlantic by way of the deep ocean conveyer belts. It actually appears to be a natural corrective system that keeps the two hemispheres in balance.
In summary, we now have compelling historical evidence of a thousand year long climate cycle that has been maintained throughout the Holocene that clearly overrides imagined short term phenomena. The magnitude is strong and specific as to timing and must be understood as the dominant relationship. This means that climate for the next two centuries will have an upward bias for a net of at least one degree.
This also means that the CO2 hypothesis which barely made it as noise sinks even lower in terms of likelihoods. We can now call it rubbish. And the Arctic is getting warmer because it is absorbing more warm surface water and beginning to assist in the warming of the Northern Hemisphere. Those surface temperatures have barely begun to climb and will add two degrees over the next two centuries.
Peer-Reviewed Research: Unprecedented Global Warming During Medieval Period, Boreholes Reveal
http://www.c3headlines.com/2010/05/peerreviewed-research-unprecedented-global-warming-during-medieval-period-boreholes-reveal.html
http://c3headlines.typepad.com/.a/6a010536b58035970c0133ed7097ba970b-pi
Read here, PDF, here, here and here. Way back in 1997, researchers published a paper that was based on data from 6,000 plus borehole sites from all the continents. The reconstructed temperatures clearly showed a Medieval Period warming that was, and is, unprecedented. The data also makes clear that subsequent warming began well before the growth of human CO2 emissions and this natural rebound would obviously lead to temperatures similar to the Medieval Period.
A year later, the infamous Mann hockey-stick temperature chart was published to wild acclaim by the IPCC and AGW-centric activists. So popular did the Mann chart become, the 6,000+ borehole chart was completely ignored since its data refuted the Mann study. The borehole scientists then decided to re-publish their study with primarily only the blue-side (the typical AGW-favored data cherry-picking) of the chart below. This repackaged borehole study became accepted by the AGW-centric scientists as it seemed to support their cause and the Mann's hockey-stick. (click on image to enlarge)
"The authors searched the large database of terrestrial heat flow measurements compiled by the International Heat Flow Commission of the International Association of Seismology and Physics of the Earth's Interior for measurements suitable for reconstructing an average ground surface temperature history...Based on a total of 6,144 qualifying sets of heat flow measurements obtained from every continent of the globe, they produced a global climate reconstruction, which, they state, is "independent of other proxy interpretations [and] of any preconceptions or biases as to the nature of the actual climate history."...From their reconstruction of "a global climate history from worldwide observations," the authors found strong evidence that the Medieval Warm Period was indeed warmer than it is now."
"Quite suddenly, the same borehole authors - Pollack, Huang, Shen published a new, two-page-long paper in Nature: it appeared in October 1998. The paper contained a rather different graph than the graph from 1997...The new paper was using temperatures and 358 sites only instead of the 6000 sites used in 1997 (94 percent of sites eliminated) and it has erased 19,500 years out of 20,000 years (97.5 percent of the time interval eliminated) from the paper written in 1997 in order not to contradict Mann et al....That's what they call "independence". Moreover, if someone wanted to extend the record as far as possible while avoiding any hints of a warmer period in the past such as the medieval warm period, he would have made the same cut: 500 years ago. What a coincidence."
More historical charts here. Other climate history postings here. Modern temperature charts.
