Global Warming - Mann's discredited 'Hockey Stick'

 The Geophysical Research Letters paper of Mann, et al, of 1999 masked the then accepted Medieval Warming Period and the Little Ice Age climatic events. Mann chose to only use tree ring density data as a proxy for temperature in the first part of the graph's millinium and actual instrumental temperatures in the 20th Century part of the graph. Not only by using two different data sets to "bias" his graph, he also discounted the well demonstrated Solar Oscilliation effect as determined by 14C and 18Be isotope temperature proxies, 400 years of sun spot activity, sea/lake level core data, and historical data through their omissions. Missing from Mann's graph is the Maunder Minimum, the 70 year period of almost no sun spot activity leading into the Little Ice Age, and the Sporer Minimum of non-periodic irregular sun spot activity preceeding the Maunder Minumum. Both events producing colder climates that have been attributed to Solar variability and spectral change.

The following article is an extensive review of the various proxies used to determine temperature in the distant past when there is little or no instrumental data. It explains the problems of using improperly calibrated tree ring data, especially as shown by Cook using the two distinct climaticological areas of hisTasmanian tree ring data. In addition, Mann's paper is further discrdited by the omission (truncation) of Briffa's 20th Century tree ring data that does not indicate recent climatic warming.

The document below is well worth reading to get a better understanding of the scientific methods used to study the Earth's climate. It also ends with a excerpt from the National Academy of Science stating the need of a healthy skeptic attitude in the scientific community in order to support the peer review process. I hope you will find this document very informative.

Link to Article: http://www.john-daly.com/hockey/hockey.htm