beyond the normal variations that have occurred in the last 8,000 years

Tree Ring data is often cited as evidence of global warming. The data is available on various web pages, but not usually in a useful presentation. Where they have graphed data, I present their graph here. If the data is available and the graphs are not, then I have taken the data and simply graphed it in MS Excel. You can do the same with the data files which are referenced and can be easily downloaded.

When viewed as graphs, it is apparent that the minor increases in temperatures of the last 100 years are not as large as temperature increases and decreases that have occurred many times in the last few thousand years. Global Warming implies that present temperatures are higher than ever before, and that is simply not true.

Of the 92 sets of tree ring data in the file, I have only done a few so far. It takes about an hour to get each graph converted to .jpg images for the web. I have limited time to do this. So I will keep adding more as time passes, but for now I have selected those with a lot of years and from different parts of the world to give a fair representation. If there is no evidence of global warming in Tasmania, Siberia, or Idaho then there can not be any global warming. If the graph shows a long period of time, it is a better comparison to show if the recent changes in climate are unusual. It does not mean anything to say the climate is "extreme" or "warming" if you only look at a few years. How can it be extreme or unusual if it has been worse many times in the past?

The first example is from Finland. It covers the northern Hemisphere climate and is a clear example of long term trends.
Finnish Tree ring data from 1500 to 2000 and data from 11,000 years

This graph from the bottom of the page of Finnish Tree Ring Data shows the highs and lows of the past 7,500 years were much higher and lower than the present ones.
Clicking on any of the following images will give you a full scale version - Full size is the only way to see all the details and just how many hot and cold periods there have been.

7500 years

A good source of data is at the US National Oceanic and Atmospheric Administration - Satellite and Information Service:

The Excel data file of 92 sets of Paleoclimate Network temperature reconstructions from tree rings and ice cores is from:
With the excel spreadsheet of 92 sets of data at:
Excell Data Sheet of 92 paleo temperature reconstructions

NOTE that the now famous "hockey stick" graph of excessive global warming showing a rapid rise in temperatures recently is NOT included with the NOAA data sets, even though it is displayed on their web page. It seems to not be accepted as valid data by NOAA.

The first graph is from Cook, E.R., B.M. Buckley, R.D. D'Arrigo, and M.J. Peterson. 2000: Warm-season temperatures since 1600 BC reconstructed from Tasmanian tree rings and their relationship to large-scale sea surface temperature anomalies. Climate Dynamics 16(2-3):79-91

3600 years in Tasmania

Note that the temperature has been much higher than present times, and lower than the recent cold spell of the early 1900s. If global warming from CO2 was real, there would not have been a cold spell lasting from 1900 - 1950.

This graph is from: Hantemirov, R.M. and S.G. Shiyatov. 2002. A continuous multimillennial ring-width chronology in Yamal, northwestern Siberia. Holocene 12(6):717-726. Note that there have been many ups and downs, and nothing unusual in the last 200 years.

4100 years in Siberia

This graph is from: Biondi, F., D.L. Perkins, D.R. Cayan, and M.K. Hughes. 1999. July Temperature during the second millennium reconstructed from Idaho tree rings. Chart shows temperature variations from average. Geophysical Research Letters 26(10):1445-1448.

900 years in Idaho

This graph is from: Briffa, K.R., P.D. Jones, F.H. Schweingruber and T.J. Osborn. 1998. Influence of volcanic eruptions on Northern Hemisphere summer temperature over the past 600 years. Nature 393:450-455.

600 years in the Northern Hemisphere

This graph is from: D'Arrigo, R., R. Wilson, and G. Jacoby. 2006. On the long-term context for late twentieth century warming. Journal of Geophysical Research 111:D03103. This graph shows anomalous variations from an average. Note that this graph DOES show warming from 1900 to 1950 that is greater than the earlier years. However, it also shows that the temperatures have been decreasing since 1950, which should not be possible if CO2 levels were causing temperature increases.

1300 years in North America and Eurasia