ExxonMobil is under investigation by New York Attorney General Eric Schneiderman over whether it lied to the public about the risks of climate change, the oil giant said Thursday.

Ken Cohen, a vice president for public affairs at ExxonMobil, described the demand for documents as a "broad subpoena," and said the company was still reviewing how to respond to it. A person familiar with Schneiderman's thinking said he believes ExxonMobil knowingly understated the risks of climate change to consumers and shareholders.

Schneiderman's subpoena demands documents dating back to 1977 on ExxonMobil's climate science, its marketing and advertising materials that discuss climate change and its funding of climate science inside and outside the company, said a person familiar with Schneiderman's probe.

The probe comes on the heels of investigative stories by the website Inside Climate News and the Los Angeles Times that recounted how scientists at the oil giant as early as the 1970s recognized climate change as a potentially grave problem caused by fossil fuel use.

Even so, the stories showed, ExxonMobil in the 1990s and early 2000s campaigned against that idea as well as fought the Kyoto Protocol and other major policy efforts to regulate carbon emissions. It also funded lobby groups that questioned the link between fossil fuel emissions and climate change. Some ExxonMobil critics have likened the oil giant's conduct to that of tobacco companies that suppressed evidence linking tobacco use to cancer.