How do we know that it is man that is causing the increased CO2 levels?

If the earth is in a natural climate [warming] change, wouldn't a warmer earth and a warmer ocean naturally lead to increased CO2 levels?

How do we know which is driving which? To me, it sounds like the age-old question of which came first, the chicken or the egg.

Isn't climate too complex, too dynamic a system for one small component, like CO2 levels, to have that much of an effect?

I have listened to two leading limate scientists, Dr. David Legates and Dr. Willie Soon, explain why the current warming trend is probably natural and the result of solar cycles and is therefore unstoppable, so I am just skeptical of any attempts by man to have an impact in trying to change it.

These two scientists point to evidence in Greenland -- which was much warmer at the height of the last natural warming cycle than it is today -- and elsewhere.

Certainly, the impact of the climate change on our lives is significant and important. But also significant and important would be the cost of measures aimed at reducing human greenhouse gas emissions. It is important, therefore, to get the science right before raising taxes or adopting expensive government mandates.

Barbara