Last week, in a historic first, the former CEO of a major oil company took the witness stand in a New York City courtroom and spent four hours defending his company against charges that it misled investors about the potential impact of global warming on its viability as a business. 

Rex Tillerson, who led ExxonMobil from 2006 until the end of 2016 when he became U.S. secretary of state, was grilled by an attorney for the New York State attorney general for allegedly participating in a “longstanding fraudulent scheme” by Exxon to fool investors. More specifically, the company is charged with exaggerating the stringency of its financial safeguards in pricing risks from regulations restricting greenhouse gas emissions, according to the complaint filed last year in New York state court.    

But Tillerson’s appearance was just one of several recent watershed moments for efforts to hold the fossil fuel industry accountable for its dominant role in causing climate change.

These included a former Exxon scientist giving first-ever oil industry whistleblower testimony before Congress, a Senate hearing on how dark money blocks climate change action, the Supreme Court allowing three major climate liability suits to proceed, Maui and Honolulu announcing they will sue the fossil fuel industry, and, perhaps most significant, the Massachusetts attorney general filing suit against Exxon.