California’s attorney general is investigating Exxon Mobil on whether the company lied to the public and shareholders about the risks of climate change, and whether the company’s statements over the years constitute violations of securities laws and other statutes.

The investigation is similar to one started in November by the New York attorney general, Eric T. Schneiderman, for which the company has already produced thousands of documents.

Mr. Schneiderman, calling climate change “the defining issue of our time,” applauded the action taken by Kamala D. Harris, the attorney general.

“Just like any other publicly traded company, these energy giants have an obligation to ensure that their disclosures to investors of known and reasonably likely risks are truthful and not misleading, and to disclose to the public the risks associated with their products,” he said.