re: The 4 Positions
Having spent some time trying to understand things from a data driven perspective, I tend to be a 4-ist too although I might modify that to being a 5-ist:
5-ism: We're doing something, so is nature, but what we're doing might not be mainly because of CO2.
Sure. we're doing something, but how much and is it within Mothar Nature's/Gaia's capability to compensate. Apparently around 95% of the carbon cycling through out atmosphere is just natural carbon cycle processes and just 5% are due to us. It only needs a slight change in Mother Nature to make a difference and soak it up.
A lot of what we're doing to the planet is through other mechanisms (land use for cities and agriculture, landfills, changing water flows,...).
Blaming global warming for every possible ill is not only wrong, it is also lazy science. If you are worried about frogs, polar bears or anything else then just link them to global warming and QED they're under threat.
Unfortunately this laziness also slams the door shut on other lines of research (eg. blaming pesticides or swampland drainage).
Often it is a toss up as to how we impact the planet. We can reduce fossil fuel usage by covering New Mexico in algae farms. The obsession with global warming makes it very difficult to have rational discussions about trade offs: Is it better to save the polar bears by building infrastructure in the desert that wipes out the desert dwellers? Is a coyote less valuable than a polar bear?
Here in NZ tuatara are apparently under threat from global warming. Unless we fix global warming the tuatara are doomed because a 4degree change in temperature will destroy their breeding. What a shame. These guys have been around since dinosaur times and we're going to kill them with a 4 degree temperature change. C'mon people: surely if they've survived countless ice ages, meteorites and other happenings that have caused all kinds of extinctions they can survive 4 degrees.