Too much advocacy? Scientists and public policy

James Hansen (not to pick on him, but he's handy) is a climate scientist, but that's no reason to think he knows much about the economics of the carbon tax he has advocated. (Instead, one might look to an economist such as William Nordhaus, whose research has indeed supported the efficacy of a carbon tax, among other measures.)

Not to say that advocacy on the part of scientists is the sole cause of the nation's skepticism toward science in general and climate change in particular. More influential by far has been the terrific sum invested by fossil-fuel industries and their allies in challenging any science that the Earth is warming.

Can we see some details of this alleged "terrific sum"?  How much money, specifically, and how, specifically, was this money allegedly spent?