Hello, Andre and Anna,
You may well be right about Alex, but I hope not.
As for me, I would rather think of myself as well-informed (thanks, Anna) than as 'clinging to views' or closed-minded and incapable of learning - but that's what we all like to think about ourselves, isn't it?
How can we tell?
The tests in the Kalamasutta, adapted to the modern scientific environment, might be handy.
More generally, I know how the science 'industry' works - peer-review and all that - and have identified the groups whose work passes all the tests and is respected inside and outside the field. When you get such broad agreement from peak bodies, from NOAA and the AAAS to the IPCC, I think it's pretty solid. When you see smart, expertly advised non-specialists taking notice and taking serious $$$$ action against their own short-term interests - e.g. the governments of China and most European countries - you've got to figure that it must be getting serious. When you see pro-business leaders like Bush (!) and Rupert Murdoch (!!) joining them, you probably should be looking for some safe place, like a Swiss mountain-top, to hide.
But I also do know the science, as much as a lay person can, and it all makes worryingly good sense. If I had to point to one thing that convinced me we were in trouble, it would be the Keeling curve . That one graph, plus the knowledge that CO2 traps heat, is all you need to know to be aware that business as usual in not an option.