Legitimate Concerns

In science, it’s important to be skeptical—it’s what drives discovery. Furthermore, there seems to be a major problem in the public discourse with bipolarity: either you are a ”proponent” who “believes” or a “skeptic” who does not. In reality, once can question aspects of a theory while still supporting it. And in the case of anthopogenic global warming, there are still concerns with some of the science despite claims of universal consensus. However, this does not mean that the science is wrong; rather it places impetus upon the public to be well-informed in order to make proper decisions.

These concerns tend to be associated not with the physics of global warming itself, but with prediction of the climate future:

Climate Models: see Climate Models
Recent Historical Data:
There are major concerns with extrapolating trends in hurricane activity, severe weather, and other small-scale extreme weather events because the data that exists depends strongly on the technology available. For example, before the satellite era began in the 1970s, our only means of detecting hurricanes in the middle of the ocean was via ships, which did not cover the entire ocean. Thus, the number of hurricanes that formed is not known; only landfalling hurricanes and others near shipping lanes were detected. With such a short time frame with good data (post-1970), it’s almost impossible to distinguish an observed trend from a natural variation.
Unknown Influences:
We feel we have gained a solid understanding of the Earth (although not necessarily how internal aspects of the Earth’s system interact). However, there are still influences that we don’t understand, especially those of the solar system. While it seems logical that CO₂ is forcing these changes and there is plenty of supporting evidence, other unknown forcings may exist, such as the “cosmic ray” theory or undetected solar shifts, that we simply don’t understand.

We like to think that our incredible technological advances mean that “we now know everything,” but we simply do not. We have a very reasonable theory, but it’s a theory and a science that is still worthy of questioning, if nothing else simply for the purposes of self-enlightenment. However, being skeptical does not imply that we can ignore its possible consequences.