For the last few years, climate hysterics have demanded that government prosecute those who disagree with their notions of climate change. The New York Times is reporting that New York's attorney general has opened an investigation into ExxonMobil, accusing the oil company of making false statements about climate change to its investors while its scientists were telling company officials of the dangers of global warming.

“We unequivocally reject the allegations that Exxon Mobil has suppressed climate change research,” Mr. Cohen said, adding that the company had funded mainstream climate science since the 1970s, had published dozens of scientific papers on the topic and had disclosed climate risks to investors.

Mr. Schneiderman’s decision to scrutinize the fossil fuel companies may well open a new legal front in the climate change battle.

The people with knowledge of the New York case also said on Thursday that, in a separate inquiry, Peabody Energy, the nation’s largest coal producer, had been under investigation by the attorney general for two years over whether it properly disclosed financial risks related to climate change. That investigation was not previously reported, and has not resulted in any charges or other legal action against Peabody.

Vic Svec, a Peabody senior vice president, said in a statement, “Peabody continues to work with the New York attorney general’s office regarding our disclosures, which have evolved over the years.”

The Exxon inquiry might expand further to encompass other oil companies, according to the people with knowledge of the case, though no additional subpoenas have been issued to date.

The people spoke on the condition of anonymity, saying they were not authorized to speak publicly about investigations that could produce civil or criminal charges. The Martin Act, a New York state law, confers on the attorney general broad powers to investigate financial fraud.

To date, lawsuits trying to hold fuel companies accountable for damage they are causing to the climate have failed in the courts, but most of those have been pursued by private plaintiffs.

Attorneys general for other states could join in Mr. Schneiderman’s efforts, bringing far greater investigative and legal resources to bear on the issue. Some experts see the potential for a legal assault on fossil fuel companies similar to the lawsuits against tobacco companies in recent decades, which cost those companies tens of billions of dollars in penalties.