Objection: Current warming is just part of a natural cycle.
Answer: While it is undoubtedly true that there are natural cycles and variations in global climate, those who insist that current warming is purely natural or even mostly natural have two challenges.
First, they need to identify the mechanism behind this alleged natural cycle. Absent a forcing of some sort, there will be no change in global energy balance. The balance is changing, so natural or otherwise, we need to find this mysterious cause.
Second, they need to come up with an explanation for why a 35% increase in the second most important greenhouse gas does not affect the global temperature. Theory predicts temperature will rise given an enhanced greenhouse effect, so how or why is it not happening?
The mainstream climate science community has provided a well-developed, internally consistent theory that accounts for the effects we are now observing. It provides explanations and makes predictions. Where is the skeptic communitys model or theory whereby CO2 does not affect the temperature? Where is the evidence of some other natural forcing, like the Milankovich cycles that controlled the ice ages (a fine historical example of a dramatic and regular climate cycle that can be read in the ice core records taken both in Greenland and in the Antarctic)?[\quote]
How to Talk to a Climate Skeptic: Responses to the most common skeptical arguments on global warming | Grist
Again, I ask ONE AND ONLY PLANET EARTH why risk it?