There are many companies that have intentionally ignored and supressed evidence of climate change. Exxon Mobile is just one of them. They are more interested in their bottom line, in making the big bucks, than preserving our planet for future generations. These industrial companies don't want to admit that climate change is real as that means they would likely see less profit in their pockets.
Oil companies have probably intentionally ignored and suppressed evidence of climate change. Why wouldn't they? The government is doing anything possible to destroy the business. Exxon would be utter morons to cooperate in its own destruction. The sad parts is that the government is doing this without having a complete scientific basis for doing it.
You don't have to look very deeply to find evidence that the earth is changing. Take, for instance, the big chunk of ice that just fell off the coast of Antartica.
I don't see how people can still dispute it, but it would only be to Exxon's advantage to perpetuate the denial.
Large oil corporations such as ExxonMobile are not exactly known for their good ethics, it is all about the big profits. The BP Deepwater Horizon accident was a good example of how these companies go about their business. For this reason I expect they have been intentionally ignoring evidence. I feel there is no smoke without fire in this story.