I have. So have lots of economists and climatologists who aren't leftwing wackos. The evidence points to a strong possibility that human-generated CO2 is causing at least some warming.
There are no serious climatologists who will deny that there is at least some non-negligible probability that global warming is at least partially being generated by humans. All the dissenters have done is show that there is considerable uncertainty regarding that proability. But no one can say with any confidence that that probability is zero.
Others will object that human caused global warming isn't proven. True, but that's beside the point. It can't be proven that human activies aren't causing global warming, either.
We live in the world of uncertainty, so it is simply irrational to wait until we have absolute proof before taking action. The fact is, if human caused global warming is real, it can hurt us regardless of whether it can be proven or not. Hence it is irrational to demand proof before taking action, just as it would be irrational for a doctor to wait for absolute proof before operating on a patient whom he strongly suspects of having a life-threatening condition.
Once you admit that there is some sigificant chance that global warming has a human cause (which everyone admits), it becomes an optimization problem. There are some expected costs associated with warming, and there are costs associated with measures we can take to reduce it. Like with most tradeoffs, neither extreme is likely the optimal solution (corner solutions tend to be rare in the real world). Rather, the optimum is most likely somewhere in between: to take some measures to curtail global warming, but not do everything possible. There are reputable, conservative economists working on this problem as we speak.
Besides, there are certain things that would help reduce global warming that we should be doing anyway for security reasons, such as building more nuclear power plants and start reprocessing nuclear fuel.
Of course, the hysteria of Algore and the rest of the extreme left engage is in equally irrational, but that doesn't mean the opposite extreme is any better.
Consensus is not science, but I think that you will have to admit that most economists state that given the unsettled science of global warming, the economic trade off that would be required to prevent it, are not worth it. Even the UN report stated that the steps that the radical environmentalists are advocating would leave the average person around the world 30% poorer and much less able to cope with any effects of global warming that might occur.
If the left were really serious about green house gases, they would be advocating nuclear power plants and windmills. But the fact remains that as long as China and India are not subjected to the same controls that the socialists want to put on the US, any steps that we would take would be meaningless.
No, everyone does not admit anything about climate change, except that it changes. Here is a statement from a professor at the University of Pennsylvania:
The Earth has been warming for abut 20,000 years. We've only been collecting data on that trend for about 200 years. For most of Earth history, the globe has been warmer than it has been for the last 200 years. It has only rarely been cooler. Those cooler periods have meant things like two miles of ice piled over much of what is now North America. Nothing to be nostalgic for.
The cause of global warming that the Penn prof. supports was developed by a Serbian scientist, and it explains the cyclical nature of the global warming and cooling. The Earth's orbit around the sun is more or less circular, but when other planets align in certain ways and their gravitational forces tug at the Earth, the orbit stretches into a more elliptical shape. Combined with the tilt of the Earth on its axis as it spins, that greater or lesser distance from the sun, plus the consequent difference in solar radiation that reaches our planet, is responsible for longterm climate change.
The prof also suggests that CO2 levels could be influenced by climate change, not the other way around.
I have a whole file of these professors who believe that global warming is a socialist meta narrative aimed at bringing about world socialism.
Before I'll listen to anyone even express an opinion on anthropogenic (human-caused) global warming, I've been asking them to take a simple, 3-question quiz for the past five years or so:
1. What gas is responsible for approximately 95% of the "greenhouse effect" on planet Earth?
2. Are the United States a net A) Emitter, or B) Absorber of carbon dioxide?
3. Is the global climate now A) Warmer, or B) Cooler than it was approximately 1,000 to 1,100 years ago?