chris horner was formerly a registered lobbyist for oil, gas and chemical companies.limatologist pat michaels of the cato institute has estimated 40% of his funding has come from fossil fuel interests. >> ...of politics getting into science. >> hockenberry: exxon at one time was one of heartland's most generous donors. >> there were a lot of corporations, including oil companies, that objected to the kyoto accords in 1997. but most of them lobbied against the treaty on economic and fairness grounds. but exxon did something that i think was fairly radical, which was that they chose to go after the science. >> and as for carbon dioxide, it isn't smog or smoke; it's what we breathe out and plants breathe in. >> hockenberry: borrowing tactics used on behalf of the tobacco industry, advocacy groups were enlisted to confuse the issue and shut down new federal regulations. >> they call it pollution, we call it life. >> a lot of these groups were run by economists, litigators, lawyers and public policy specialists-- people who specialized in getting a message out. >> hockenbe