- Scientists and the media have been alternating from publicizing global cooling to publicizing global warming for over a hundred years. If it isn't one possible ecological disaster it is another.
- Climate change is a fact. The climate changes. In 900-1300, the climate was warmer than it is now. When the Vikings first came to Greenland, it was actually green. From 1500-1850 we had the little ice age. Since then we have warmed up a bit with some hotter and some cooler years. Global temperature shifts are nothing new and are nothing to get overly excited about.
- Most of the public discourse on this topic is badly oversensationalized. There are a lot of downright lies. This is true for Al Gore's movie and a lot of other work.
It is current about 20 C (67 F) at my desk. Which is a little cooler than I'd like. Lets say it goes up by a couple of degrees. Now I'm more comfortable. How much did it change? Well 22 degrees from 20 degrees is a 10% increase right? That's a lot, right? Well yes and no. I'm a lot more comfortable, but in actuality it didn't get that much warmer in the grand scheme of things. You see when doing thermodynamic and heat transfer calculations, especially using radiative heat transfer (like we get from the sun) you do not use the Celsius or Fahrenheit temperature scales. You use absolute temperature in Kelvin. So it is actually 293K in my office. That 2 degree difference is actually a 0.7% absolute temperature change. A lot smaller than you probably thought.
Now we can easily track down the reason for that temperature shift in my office, because it is a simple closed system. But global climate? As a system, the global inputs and outputs are fairly well characterized (in terms of energy in and out), but simple? Not on your life. With global climate change, we're still talking about temperature shifts of perhaps a percentage point or two in average absolute temperature. Which makes analyzing these changes very difficult because a lot of individual phenomenon or groups of phenomena can actually produce such a small shift.
So I'm not saying that we don't have global warming or anything like that. What I'm saying is that this issue is something that the academics like to call "a non-trivial problem." It is a toughie and anyone that says they have it completely figured out (especially when extrapolating their conclusions into the future) deserves to receive a skeptical reception in my opinion.