In order to fear climate change, there are several beliefs you must hold.
1. CO2 drives temperature change
This is a the central belief of the AGW theory. If you don’t believe CO2 controls temperature, then the increase in mankind’s emission poses no threat.
2. Strong positive feedbacks exist
Even if you believe that CO2 drives temperature change, this isn’t enough. Without strong positive feedbacks the temperature increase is minimal. The fear from future climate change arises from the belief that the slight temperature increase will lead to positive feedbacks (such as water vapor) that will further increase the temperature.
3. The temperature record is reliable
The .7c degree increase over the last century is usually considered proof of the AGW theory. After all, CO2 emission have risen quite a bit in the last 50 years, so temperature should have risen as well. To use this evidence, the temperature record must be taken as valid.
4. Life on earth is not very adaptable
If you fear climate change, then you must believe that it will negatively affect life on the planet. This assumes that life will be unable to adequately adapt to the future change in temperature.
This isn’t an exhaustive list and there may be some who fear climate change who don’t hold all four of these tenets. However, if you throw out any one point then fearing climate change makes little sense. If CO2 doesn’t drive temperature change, then increasing CO2 isn’t a problem. If there are no positive feedbacks, then the minimal rise in temperature from CO2 isn’t a threat. If you don’t believe the temperature record, then there is absolutely no observational evidence for the AGW theory. If you believe that life on planet earth is sufficiently adaptable, then an increase in temperature isn’t something to fear.
I would simply point out that CO2 hasn’t driven temperaturesin the past, positive feedbacks are completely theoretical and very controversial, the temperature record is notoriously unreliable, and planet earth has already shown its incredible adaptivity in the past through several ice ages and other temperature fluxes.
Don’t fear climate change.