Oh gee, you got me. I was not sure what the baseline average they used for the anomaly chart zero line and you found out. Good for you Guess what nitwit. It doesn't matter. It is a departure from average chart. We could have used any time period at all. The chart would still look like it does with the same uptrend. You can't grasp this simple concept but yet you presume to know better than the world's climate scientists.
And what are you arguing anyhow? That the world is not rapidly warming? If so, you are even more deluded than I thought. You have no clue as to the actual science going on.
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An independent assessment of Mann's hockey stick was conducted by the National Center for Atmospheric Research (Wahl 2007). They reconstructed temperatures employing a variety of statistical techniques (with and without principal components analysis). Their results found slightly different temperatures in the early 15th Century. However, they confirmed the principal results of the original hockey stick - that the warming trend and temperatures over the last few decades are unprecedented over at least the last 600 years
While many continue to fixate on Mann's early work on proxy records, the science of paleoclimatology has moved on. Since 1999, there have been many independentreconstructions of past temperatures, using a variety of proxy data and a number of different methodologies. All find the same result - that the last few decades are the hottest in the last 500 to 2000 years (depending on how far back the reconstruction goes). What are some of the proxies that are used to determine past temperature?
Changes in surface temperature send thermal waves underground, cooling or warming the subterranean rock. To track these changes, underground temperature measurements were examined from over 350 bore holes in North America, Europe, Southern Africa and Australia (Huang 2000). Borehole reconstructions aren't able to give short term variation, yielding only century-scale trends. What they find is that the 20th century is the warmest of the past five centuries with the strongest warming trend in 500 years.
Stalagmites (or speleothems) are formed from groundwater within underground caverns. As they're annually banded, the thickness of the layers can be used as climate proxies. Areconstruction of Northern Hemisphere temperature from stalagmites shows that while theuncertainty range (grey area) is significant, the temperature in the latter 20th Century exceeds the maximum estimate over the past 500 years (Smith 2006).
Historical records of glacier length can be used as a proxy for temperature. As the number of monitored glaciers diminishes in the past, the uncertainty grows accordingly. Nevertheless, temperatures in recent decades exceed the uncertainty range over the past 400 years (Oerlemans 2005).
Of course, these examples only go back around 500 years - this doesn't even cover theMedieval Warm Period. When you combine all the various proxies, including ice cores, coral, lake sediments, glaciers, boreholes & stalagmites, it's possible to reconstruct Northern Hemisphere temperatures without tree-ring proxies going back 1,300 years (Mann 2008). The result is that temperatures in recent decades exceed the maximum proxyestimate (including uncertainty range) for the past 1,300 years. When you include tree-ring data, the same result holds for the past 1,700 years.
