Stewart Brand classifies the viewpoints on climate change into four groups: denialists, skeptics, warners, and calamatists. I fall somewhere between the second and third:
SKEPTICS This group is most interested in the limitations of climate science so far: they like to examine in detail the contradictions and shortcomings in climate data and models, and they are wary about any “consensus” in science. To the skeptics’ discomfort, their arguments are frequently quoted by the denialists.
In this mode, Roger Pielke, a climate scientist at the University of Colorado, argues that the scenarios presented by the United Nations Intergovernmental Panel on Climate Change are overstated and underpredictive. Another prominent skeptic is the physicist Freeman Dyson, who wrote in 2007: “I am opposing the holy brotherhood of climate model experts and the crowd of deluded citizens who believe the numbers predicted by the computer models .… I have studied the climate models and I know what they can do. The models solve the equations of fluid dynamics, and they do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields and farms and forests.”
WARNERS These are the climatologists who see the trends in climate headed toward planetary disaster, and they blame human production of greenhouse gases as the primary culprit. Leaders in this category are the scientists James Hansen, Stephen Schneider and James Lovelock. (This is the group that most persuades me and whose views I promote.)
“If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on earth is adapted,” Mr. Hansen wrote as the lead author of an influential 2008 paper, then the concentration of carbon dioxide in the atmosphere would have to be reduced from 395 parts per million to “at most 350 p.p.m.”
When I see charts like the one posted above, it seems clear that both sunspot activity and increasing levels of carbon dioxide in the atmosphere can affect global temperature. But, paradoxically, the recognizable correlations occur at different times. Between 1910 and 1960, the temperature rise paralleled that of increasing sunspots. However, the increased temperatures from 1960 to 2000 corresponded to the rise in CO2.
The core question, then, is: Which variable has a great effect? (If there are any statistics experts out there, I wonder whether a measurement of the rates of change corresponding to temperature would reveal that either sunspots or carbon dioxide have a greater correlation to global temperature.) If it is sunspot activity, then humanity can do nothing, and the entire issue is a non-starter. If it is CO2, then the world can do something to prevent some global warming.
Regardless, it is always a good idea to decrease the level of carbon-dioxide in the atmosphere simply because pollution is unhealthy. However, the only way to make a drastic difference would be for the world to revert to pre-Industrial Revolution lifestyles. So, a balance needs to be struck until so-called sources of “green” energy are developed: How can the world reduce CO2 levels without suffering economic harm?
