Breaking hockey sticks over their heads!

Well, I couldn't come up with any other clever titles for this post but I did post these polar bears playing hockey, so you have to cut me some slack.

Anyone that has been following the climate change debate knows the hockey stick theory. For those that do not, I've posted the graph that depicts the estimated temperature variation globally for the past 1,000 years. Around here, we call it "Lie #1."

As the article states, inconvenietly missing from the timeline is "the widely recognized Medieval Warm Period (about A.D. 800 to 1400) and the Little Ice Age (A.D. 1600 to 1850)." If such crucial data is absent from the chart, then how can an entire social movement be built upon a chart with incomplete data?! I'll have the answer to that question in tomorrow's post!

The article starts with the shaft and goes right to the blade of the IPCC's most coveted possession, the "Hockey Stick" theory, the "tip of the spear," if you will, of the IPCC's argument that my '97 F150 is creating ocean front property opportunities in Ohio. The author, David Legates, puts that tip to a grinding stone.

Starting at the shaft....

They contend that Mann and his colleagues in their 1998 and 1999 papers unjustifiably truncated or extrapolated trends from source data, used obsolete data, made incorrect calculations, and associated data sets with incorrect geographical locations.

The broken blade...

Mann’s warming estimate has grown substantially over the last couple of years, apparently to accommodate his continuing claim that the 1990s were the warmest decade of the last two millennia, but we found that the blade of the hockey stick could not be reproduced using either the same techniques as Mann and Jones or other common statistical techniques.

The uncertainy factor...

Mann and Jones’ uncertainty assessment — the estimate of how much warmer or cooler than their reconstruction the temperature could actually have been — is based solely on how well the proxy records match the observed data. However, their assessment fails to account for several significant forms of error, including:

• Biases in hemispheric air temperatures estimates
• Reconstructions based on a small number of trees
• The inability of a proxy record to represent regional air temperatures
  

The stick is broken....

Consider that if 1) the amount of uncertainty is doubled (an appropriate representation of the “sheath”), 2) appropriate 20th century increases in observed air temperature are applied (a correct representation of the “blade”), or 3) the period from A.D. 200 to 1900 correctly reproduces millennial-scale variability (a reliable representation of the “shaft”), then one can have no confidence in the claim that the 1990s are the warmest decade of the last two millennia. The assertions of Mann and his colleagues — and, consequently, the IPCC — are open to question if even one component of their temperature reconstruction is in error, let alone all three!

'Nuff said!

Breaking the “Hockey Stick”
by David R. Legates