That's because the scientific consensus is fairly limited, at least where there is nearly complete agreement among scientists. That consensus includes the following:
- Humans are extracting and burning carbon sequestered below the earth's surface in the form of coal and oil which causes CO2 to be released into the atmosphere.
- CO2 is a greenhouse gas - it absorbs infrared radiation from the Earth's surface and therefore slows the radiation of that energy into outer space.
- All other factors being equal, larger amounts of CO2 in the atmosphere would lead to higher average global temperatures.
- Assuming the temperature measurements are accurate and correctly calibrated, global warming has occurred during the last century.
A whole different level of the AGW debate is the risk of whether or not global warming will be catastrophic. Here the scientific consensus is far less overwhelming. Indeed, there's not even a consensus on the definition of "catastrophic". For some it means economic burdens. For others it means human misery and death. For still others it means increased extinction rates for various species.
I'm completely skeptical of the concept of Catastrophic Global Warming (CGW) for several reasons including the following:
- The earth's climate system has been adequately stable for the past billion years to support life even through meteor strikes, tectonic upheavals, etc. It seems extraordinarily unlikely to me that the re-addition of CO2 from fossil fuels to the atmosphere poses any significant risk of extinction of all life or even significant hardship to humans through climate instability. If the climate had the capacity for such instability from such a small change, it would've happened many times in the last billion years and we wouldn't be here to have this discussion.
- My observations lead me to believe that warming is better than cooling. Land based life at the equator, on average, is far denser and more diverse than life at the poles. Humans are also more successful at inhabiting warming climates than colder climates. Therefore, while warming has costs, my guess is that the benefits of warming will end up outweighing the costs by a wide margin. Especially since the bulk of warming is predicted to occur away from the equator and over a long period of time which will enable us to easily adapt.
1 It's questionable whether it's correct to use "scientific" and "consensus" together, but since many scientists do it, who am I to argue?