With all the hoopla over the two documentaries The Great Global Warming Swindle and An Inconvenient Truth, you would think that greenhouse-gas emissions and solar activity were the only two possible explanations for climate change. Not true.
In fact, if I had to wager, I would bet on a small change in cloudiness to explain at least part of our current warmth. (Yes, I know there is a solar-modulation-of-cosmic-rays-causing-cloud-changes theory, but here I’m talking about internal variability of the climate system.)
Everyone in climate circles agrees that clouds are complex beasts. Yet, it seems like most climate scientists assume that the total amount of clouds remains the same from year to year. Indeed, satellite observations
(of marginal quality) over the last 20 years seem to indicate a remarkable yearly consistency.
But we also know that it wouldn’t take much of a change to make a big difference. For instance, it has been calculated that about a one-percent increase in low clouds could offset the warming from a doubling of the carbon-dioxide concentration.
Of course, it works the other way, too. A decrease in low clouds with warming would enhance the warming.
But when I mention this possibility to other climate researchers, the response is usually, “what would cause such a change in clouds?” You see, in climate research, if we can’t think of a causative mechanism, then it obviously doesn’t exist. And if we can’t measure cloud variations accurately enough to know if there has been a 0.5-percent change in the last 30 years, then we’ll just assume it hasn’t happened.
They call this science, but I call it faith.