That is why the event looks like it’s going to turn into a victory for the sceptics after all. It’s not that the leaked data and emails does all that much damage to the alarmists’ arguments. It didn’t need to: they weren’t that strong to begin with.
The case for global warming depends on positive feedback – in more ways than one. First, because the actual temperature change due to increased CO2 concentration is not worth worrying about, and can only be a problem if it produces weather changes that themselves create more warming – positive feedback. And secondly, because the electorate, reasonably, takes the scientists’ word about the seriousness of the problem, and responds by demanding that politicians demonstrate their concern about the problem, which they do by creating more opportunities for alarmist scientists, who then persuade the public even more of the need to demand more from the politicians…
So a key element in the forming of the AGW political consensus has been that people just accept what they’re told. That’s what anyone would expect – you’ve got to be a bit odd to start to delve into the details of atmospheric physics, weather station siting, dendrochronology, Regularized Expectation-Maximization calculations, just to check up the conclusions of the people who are actually qualified to talk about these things. If someone starts challenging the conventional wisdom by referring to all these technicalities, the only sensible thing is to ignore the technicalities and make a judgment based on the the trustworthiness and qualification of the competing authorities.
The leaked emails change that – not because the man in the street will say – “Oh my! There’s a perhaps somewhat disturbing compensation between indirect aerosol forcing and sensitivity across the CMIP3 models that defies the assumption of independence!”, but because he will see that the argument is not between robot white-coated paragons and a few scruffy nutters, but between two groups of real people, at least one of which must be wrong. That doesn’t change his mind, but it takes the pressure off, so that politicians who have not previously dared to express contrary opinions feel able to make themselves known. That in turn will stir up more doubt, and the positive feedback will move the issue back to being a legitimate debate, as it belongs to be.