I think this is the one that has caused the more recent uproar:
http://insideclimatenews.org/sites/d...e%20Effect.pdf (from 1982)
Part of this story:
http://insideclimatenews.org/news/15...global-warming
which quotes someone claimed to have given a presentation on the topic in 1977.
The most controversial thing is that Exxon carried out private studies on CO2 levels through the 80's until they stopped that and started funding what is now the basis of the "denier" movement.