Although VP Al Gore has had no direct part in the recent Climategate controversy, it was his 2006 movie An Inconvenient Truth that most activated the ALARMISTs, outraged the DENIERs, and animated the reaction by the Skeptics.
When I watched Gore's impressive movie several years ago, I was most struck by the scene in the above photo [Click it for a larger version - The base photo is from the movie, the annotations are mine.]
Gore displayed some 600,000 years of ice core proxy data that shows the remarkable correlation between Temperature and CO2. When one goes up, so does the other, and vice-versa for down. Gore then shows the rapid build-up of CO2 in recent years, due, he says, to human activities. He uses a platform to lift himself high up where he shows what will happen to CO2 levels in a few decades unless we humans drastically cut our CO2 emissions!
Very impressive! The implication is that such a dramatic rise in CO2 will cause an equally impressive rise in temperature, melt the sea ice, and lead to a vicious cycle of flooding and further warming until the Earth burns up and all life with it!
THE UNFORTUNATE TRUTH (FOR GORE'S POINT)
Well, as everyone (except for Gore's science advisor) knew, the ice core data clearly shows that CO2 does not cause the initial Temperature rise because, in each ice age, TEMPERATURE has gone up 800 to 1200 years BEFORE CO2 rises! As I pointed out in 2007, the CAUSAL link goes the other way. Please look at the inset graph in the above figure that magnifies the time scale for one of the ice ages and shows the temporal causality.
Even the well-respected Warmist site Real Climate admitted the lag between Temperature and CO2. In 2004, a couple years before Gore's movie, Real Climate says: "CO2 does not initiate the warmings, ..."
WHAT GORE COULD HAVE SAID
Of course, from the well-known "greenhouse" effect, everyone but the DENIERs agrees that, once CO2 rises, it will have the effect of increasing the warming by some amount. Gore could have said that and he could have added that the current rapid rise in CO2 levels, due to human activities, is unprecendented, so the direction of the causal effect of the ice core proxy data is not applicable to the current situation. If the ice core data is not applicable, why did Gore show it, if not to confuse the audience?
OTHER PROBLEMS WITH GORE'S GRAPHIC
The graphic has other problems. While the most recent CO2 and Temperature data is from actual measurements taken over the past 50 to 150 years, all the rest of the graphic is based on PROXY data that has been calibrated. As I discussed in an earlier posting, as demonstrated by "Mike's Nature trick" which is at the heart of Climategate, the process of calibration of proxy data can result in scaling errors or purposeful exaggeration.
For example, we cannot be sure current Temperatures or CO2 levels are higher than ever. Indeed, even Gore's graphic shows Temperatures were considerably higher 130,000 years ago. We also know Temperatures were higher during the Medieval Warm Period, only 800 to 1000 years ago! Gore's graphic was generated several years after "Mike's Nature trick" and the IPCC 2001 report that used faulty calibration of proxy data. Therefore, Gore's graphic almost certainly suffers from similar scaling errors.
All we know for sure from the cyclic ups and downs of the ice core data is that Something caused Temperature to rise and rising Temperature caused CO2 to rise. After both reached their peaks and stayed up for a few thousand years, Something caused Temperature to drop and dropping Temperature caused CO2 to drop. Note that, according to the ice core data, every case of rapid Temperature drop occurred when CO2 levels were at their peak and they stayed at their peak for 800 - 1200 years while Temperature continued to drop!
What is the Something? Well, since these repeated warming and ice age periods occurred well before humans evolved on Earth (around 100,000 years ago) and way before the industrial age, that Something could not have been human activities! The unavoidable conclusion is that that Something must have been Natural Cycles of the Sun and multi-decadal ocean currents and other things not under human control.
If Natural Cycles were undoubtedly responsible for great periods of warming in the past, far greater than anything we are seeing now, how can the Warmists be so sure it is mainy human activities causing the current warming period?