BP,
The writer trots out the same old arguments that have been used for years now, and discredited. No one--and certainly not Mann--does this, for example: "The Mediaeval Warming had simply been wiped from the record." No one denies natural variability. No one says that ocean currents aren't an extremely important factor in climate. See realclimate.org for more on the Hockey Stick. The real questions aren't whether or not there has been natural variability, it is what is causing the current warming trend. There is no question at all that atmospheric CO2 measurements are today higher than they have been for at least hundreds of thousands of years--evidence from ice cores, ocean sediments and soil samples establish this. Less well established but still fairly well established is that it is higher than it has been for at least several million years--the evidence for that is still being compiled. And there is no other source for CO2 over the past few hundred years other than human activities that can account for this rise. CO2 is a greenhouse gas--it is transparent to incoming solar radiation, but opaque to outgoing infrared radiation. Therefore, it traps heat. See en.wikipedia.org for a reasonable explanation if you wish. It is a matter of physics, not politics.
Honestly, I have zero desire to rehash this argument--been there, done that, am very very tired of it. The arguments have been refuted dozens of times before, you can find all of the arguments against and answers to them here, nicely indexed: gristmill.grist.org |
