ANOTHER MAN(N)-MADE CLIMATE CHANGE. In 2001 the Intergovernmental Committee on climate Change IPCC used a graph originally produced by Michael Mann of the University of Virginia and colleagues showing temperature trends for the last 1000 years to drive home their message of man-made global warming. The graph showed temperatures remaining fairly static with a slight downward trend for about 900 years until the 20th century when there was a dramatic rise. The dramatic rise was attributed to the rapid increase in carbon dioxide emissions associated with industrialisation.
As thermometers have only been used to record temperatures since the mid 1800s the graph was based on “tree rings, ice cores and historical records.” However, historical records did not fit a story of a static cool climate for 900 years over the last millenium. A thousand years ago the earth was going through the Medieval Warm Period and then in the 1300s the temperatures started decreasing and the earth descended into a cold period known as the Little Ice Age which reached its nadir in the late 1600’s and early 1700s. Since then the earth has be warming up. Mann’s graph had somehow eliminated these natural cycles of heat and cold resulting in an overall straight line for 900 years, instead of a double curve that history indicated should be there. For this reason the graph has been referred to as the “Hockey Stick Graph” because its shape resembles an ice hockey stick lying on it back.
Since 2001 a number of scientists have re-analysed the data from various temperature indicators and have found problems with Mann’s team’s analysis. When these have been corrected they have produce graphs that include both the Medieval Warm Period and Little Ice Age, making the recent warming appear much less dramatic. For examples of how this analysis was done (and references) see Hockey Stick, 1998-2005, R.I.P. on World Climate Report 3 Mar 2005. Their article comments: “Had the original reconstruction by Mann and colleagues looked like the latest reconstruction by Moberg et al. (one of the re-analyses), no one would have paid it much attention, because it would have fit nicely with the expectations given all of the prior research on the climate history of the past millennium. It would have been nothing remarkable. But, the ‘hockey stick’ was remarkable. And as such, it will be remembered as a remarkable lesson in how fanaticism can temporarily blind a large part of the scientific community and allow unproven results to become mainstream thought overnight. The embarrassment that it caused to many scientists working in the field of climatology will not be soon forgotten. Hopefully, new findings to come, as remarkable and enticing as they may first appear, will be greeted with a bit more caution and thorough investigation before they are widely accepted as representing the scientific consensus.”
ED. COM. If you put the increase in temperature over the 20th century into an even longer historical analysis, it certainly looks for less dramatic and confirms that it is just another variation in a long history of temperature cycles that has included other warm periods, such as during the Roman Empire. The IPCC has quietly disposed of the hockey stick graph, but without learning any lessons on “how fanaticism can temporarily blind a large part of the scientific community and allow unproven results to become mainstream thought overnight.” The IPCC and its followers have become even more fanatical and intolerant of any criticism, and has continued to promote man-made climate change, as revealed in the e-mail and data leak from the Climate Research Unit at University of East Anglia. (Ref. climategate, propaganda)