"But don't an equal number of opportunities exist for the contrary side?"
Sure there is. Thus why a large part of "science" is publishing your data and your methodologies. That removes most of those opportunities from *either* side.
"Wouldn't a researcher who proved AGW was a hoax be bathed in media attention, career opportunities, etc.? With good enough research, couldn't journals be shamed into publishing?"
In this case, no. As it turns out the community is so insular that the very people cooking the numbers (go read some of the published source code and data - whole parts of it are simply made up because they didn't have any raw data) are the gatekeepers of who gets published it is near impossible to publish otherwise. We can clearly see from the e-mails that when something *did* get published - and therefore supposedly made it through even that level of collusion in the peer review process - that group successfully got those editors fired. Nor can one "prove" it either way. Basically the AGW people got there first and won, not through science but through manipulating the system better.
"Anyone foolish enough to think they'll advance their careers with false science will be caught out soon enough."
True enough - see these released papers for that happening. There ought to be some felony cases (FOIA deletions, especially given that they were intentional to avoid them) and it should have a number of careers killed. It would have killed mine to do this type of stuff and I'm was supposedly in one of the "soft sciences" (Computer Science) as far as methodology is concerned.
Sadly the so called wagons are circling - too many have too much riding on the models to be accurate (money, careers, belief system). It is a combination of a failure of our edumacational system (I refuse to call it an educational system) to teach proper research methodologies and the politicization of science. It has become a "belief" instead of going where the research shows. It doesn't even need some insidious plot, I've known some of the people involved here (not the main people but recipients and colleagues at ORNL) and their level of belief was VERY strong (some long stories there, in short an example is one of them decided that Linux was wrong and he was not getting the cache miss rate reported because he had calculated differently - couldn't have been a bug in his code). Of the ones that were not Believers this is the story I got from them about the state of the climatology world, though it has been a lonely world in that knowledge.
These systems should have *never* been allowed to get to where this is a bombshell. The circular reasoning with the reliance on the models as the primary tool for outcomes (that is models trumped raw data - see said e-mails and much of the public raw data for the last 10 or so years), the secrecy of the data and models, and the structured used to peer review articles (you do not even need the e-mails again, though now they offer inside proof of what was obvious from the outside). Further so much of the work outside of this group uses data they did release (along with no ability to research how they arrived at it - from the leaked information we know some of it was simply made up because they didn't have it) and it is all based on garbage.
As is we simply just *do not know* it could be no AGW, it could be *worse*, it could be exactly as they said. You can't put garbage in, process it with bad procedures, and get gold out. Heck you can't even put gold in, improperly process it, and get gold out! None of this takes one to be an expert in climatology - it only takes one to note that the procedures being used are incapable of creating a conclusion with a high degree of likelihood of being correct. That is they used a Garbage in Garbage Out method and said we had Gold Out. You hit it exactly (though I do not think you meant it this way) in that there are equal opportunities to do something similar on the other side - if things were working as they are supposed too that would *not* be the case.
There are a lot of things I am afraid of coming down the line in the next 20 years for both the western countries in specific and the world in general - for me one of the largest is the sever decline in basic science education. Two generations ago you had people who understood and followed a scientific process, the current teachers learned from them but "played the game", and our up and coming scientists have never even really seen good science. They see the scientific method the way I was taught (but later on was lucky enough to be in a group that was a hard stickler for what it *is* both in college and professionally), an outline that if you put stuff in that slot - WIN!! We are building an entire world view on something that probably is incorrect - and sadly AGW isn't even some of the worst cases I've seen of it, it is so endemic in the universities and labs to be disheartening. There are still isolated pockets of really good science going on, but it is getting farther and farther apart. I have to look no further than one of the biggest responses is "Eh, we do it all the time too" - yes and that is how the Cold Fusion scandal at ORNL a few years back made it through so many peer reviews, though at least the openness of the project let it get caught.