I'm going to take a very unpopular position in the name of rational discussion in the hopes that this forum can hear the message.

For the record, I am of the opinion that anthropogenic warming is real. However, I think it's wise and even scientific to be skeptical of solutions implemented primarily because "we have to do something" in the absence of diligent logical and cost-benefit analysis, which I'm not sure has always been communicated to the public.

Here are the assumptions you must accept in order to go from "hey, it appears the Earth is warming and it looks like it's mankind's fault" (a statement I think most everyone can agree with) to "here is the plan for action."

Some of these assumptions are fairly solid, others maybe not so much. Some are quite controversial, intentionally, to stimulate discussion. I will reiterate my intent here is not to be a denialist but to present the argument of a stone-cold realist.

1. Assumption: we can accurately measure whether the earth is getting warmer or not.

This requires us to accept that the proxy data (ice core samples, tree rings, etc.) are sufficiently reliable to provide a good baseline for comparison on geologic scales, and that the timeline of climate change data that these sources provide is adequately large to be meaningful. (1,000 years versus 1 billion, for example)

I think most people here will agree that the proxy data are good.

Now that you’ve proven that the Earth is in fact getting warmer, we have to ask if

2. We can accurately assess the cost and benefit of global warming

Perhaps global warming produces net long term benefits to humankind. Humans tend to alwayss adopt a "change is bad" posture - however, with climate, "change is inevitable."

I know this is a very controversial hypothesis - most people wouldn't dare to ask the question - but we must. Why should we assume that the current global temperature is optimal for life on Earth or even human habitability? We might find that a warmer planet is quite beneficial. If so, we need not bother with solutions, as there is no problem. It's my opinion that the science to date seems content with "any change is bad" but in my opinion that is weak science.

But that's not my axe to grind. Let's assume the analysis is correct, and that global warming produces a net cost to society in general. Now, we need to determine if

3. We can accurately assess man’s contributions to global warming

Here is a significant problem for science to solve. It is likely that at least some of the warming we are experiencing is due to non-anthropogenic forces. Should policies be put into place that try to offset these as well as the anthropogenic sources of warming? We ought to have at least some good idea by how much is mankind warming the planet before we put in place policies to offset it.

I'm not sure we really understand that, but let's say we do. Now the question becomes how well...

4. We can accurately model and predict how changes to man’s behavior will affect the warming trend

Many changes have been proposed with obvious economic and social consequences. How will those changes affect global warming? Is it conceivable that we might overshoot? Or perhaps the combined effect of available changes is completely negligible. If we don’t know the impact of a particular change, then we’re really just shooting in the dark.

Let’s assume we can, in fact, measure the impact of particular changes on the climate. Now, we must presume

5. That we can meaningfully lower man’s impact on the climate through a coordinated global effort

Perhaps we discover a few changes that, if made, would reduce or eliminate man’s effect on the climate. Could these changes be implemented globally? It is unlikely that a few local changes would have significant impact, and global changes are very hard to implement.

Let’s assume #1 through #5 are demonstrable. We have now demonstrated that global warming is real, that it is bad, that man is causing it, that there are a set of changes which will result in a meaningful solution, and that these changes are globally feasible. I don't think we know all of those things, and that's a problem, but let's say we do know them.

Now we need to demonstrate to some degree of satisfaction:

6. That the global efforts at combating anthropogenic global warming have a net quality of life and economic benefit around the globe. In other words, the costs of remediation are outweighed by the benefits.

It is entirely possible that humanity could embark on a set of policy changes that would have very bad consequences for humanity while having negligible consequences on climate change. This possibility is greatly increased by a "we have to do something!" mentality.

Again - my argument is not intended to present a denialist story. I actually think that anthropogenic warming is real, I personally support some of the policies to combat it, and I personally try to minimize my impact on the planet in my own small way. My argument is only intended to provoke discussion about the difficulty in responsibly getting from "we have a problem" to "here is the solution."