>Expert opinion is pretty unanimous about what is likely causing climate change

Actually it isn't. I submit that most scientists do not believe in AGW. Want me to prove it? I can't. I submit that most glaciers are expanding, rather than retreating. Want me to prove it? I can't, and for the same reason.

There are an uncounted number of glaciers out there. Nobody has even counted them-- I meant that literally-- certainly nobody is doing a survey of a statistically significant number (a number we don't know because nobody has counted them, glaciers are really common) to determine whether they are expanding or contracting.

However, it is very common to hear from AGW proponents that glaciers are shrinking. Why? Because every chance they get, proponents of AGW, who are politicians, highlight glaciers shrinking. "There are no more snows of kilimanjaro" being a very famous example.

Same thing with scientists. Do you have a census of scientists? Have you surveyed them all? Can you provide me a statistically significant sample of the scientists who have looked into AGW and given a scientific argument on it one way or the other?

You can't. What you're doing here is repeating a political claim. A political claim that has the very convenient feature of excluding from any debate the very possibility of science.

Thus every AGW debate ends up being about politics and not science, because once someone tries to introduce some science, they are immediately shut down by AGW supporters asserting that all the scientists are unanimous.

Have you ever met a scientist? Find two scientists married to each other and they're not unanimous about anything. Hell, find an honest scientist by himself, and he isn't unanimous.

Ask 12 scientists for their theories on something and you'll get 18 theories.

The idea that scientific opinion is unanimous about AGW is really quite absurd, if you think about it.

FWIW, I can disprove AGW really easily. Mars is getting hotter. The IR absorption of CO2 is lower than water vapor. CO2 is a tiny fraction of the atmosphere. The planet is actually getting cooler since the solar maximum on the short end (despite CO2 going up) but getting warmer since the last ice age-- as it has always done. Mainstream perception of AGW is that there's some CO2 level that will result in runaway temperature increases-- this is historically false, as CO2 has, in the past, been vastly higher than it is today without any runaway effect. Pluto and Mars have been getting warmer exactly during the time of the rise in popularity of the AGW theory, they have no cars on them. (its the sun that is driving it.)

Did you know that the earth started out with a CO2 atmosphere with very little oxygen? The rise of algeal and plant life started converting that CO2 to oxygen and terraformed the planet into the oxygen atmosphere we have now.

BTW, CO2 tends to rise as the temperature rises, but unlike the graphs Al Gore showed in his movie (Which had been offset in time for "dramatic effect", this rise actually happens after the temperature increases.)

All of the above are basic scientific facts, many are not in dispute, though you can find lots of AGW propaganda sites "debunking" these "denier myths". (if AGW is so scientific, why the need to call people names?) I've followed hundreds of links to these blogs over the years, the vast majority assert they are "myths" and don't defend the assertion, a lot of them make up magical excuses (the most amusing was the claim that the effects of human created CO2 are different from naturally occurring CO2) ... and the ones that cite actual "peer reviewed research" almost always misrepresent it, or flat out lie about what the papers actually say.

They're pretty much completely relying on people giving up their hands and not doing any research and "believing the experts".

>there are no serious reasons to suppose bias.

Of course there are. The advocates of AGW are not scientists but politicians. And what are they pushing legislatively? The ability to control CO2. Since CO2 is produced by everything from beer and bread making to the very act of breathing, the power to control CO2 is the power over everybody. They have a vested interest in this control. The IPCC is a wing of the UN, the UN has been lobbying for years for the power to institute a global tax. A global tax on CO2 would go a long way towards making the UN a global government, which is what they want. Al Gore-- the primary spokesman for the movement in the USA-- is not a scientist, but does own a carbon credits trading firm and stands to make billions if Cap & Trade passes.

There have been numerous incidents of scientists being coerced into publishing results only if they conform to the AGW hypothesis. APL started refusing to publish any letters that questioned the issue-- tantamount to a rejection of science itself. And naturally, government funding goes to labs to prove AGW, not to objectively research the question.

I've worked in a national lab, including on a controversial question, and been thru the peer review process. The idea that there's no bias is silly. Even in non-controversial things, there's always bias. Peer review is often about not stepping on the toes of someone whose long held theory is undermined by your results.

Science involves bias at every level all the time.