Environmental leaders delivered a petition with more than 350,000 signatures to U.S. Attorney General Loretta Lynch Thursday afternoon calling on her to launch an investigation into whether ExxonMobil misled the American public on global warming.

"Exxon has known about the threat of climate change since the 1970s and 80s," the letter says. "But Exxon chose to protect their profits over the planet, and proceeded to cover up their findings for nearly forty years...Decades later, we're in the midst of a rapidly-unraveling crisis—one that we could have been well on our way toward solving, had we acted much sooner."

The 350,000-plus signees join dozens of activist groups and politicians in calling for a Justice Department probe into what Exxon knew about climate change and when, including the Democratic presidential field, Hillary Clinton, Bernie Sanders and Martin O'Malley. New York State Attorney General Eric Schneiderman subpoenaed ExxonMobil earlier this month for any documents related to its climate science research and communications to shareholders and the public as part of a year-long investigation into the company.

"As we learned yesterday, we have just come through the hottest month ever recorded in human history," said Bill McKibben, a climate activist and co-founder of 350.org, on a call with reporters Thursday. "It is time to turn up the heat on Exxon."

House Democrats, led by Reps. Ted Lieu of California and Peter Welch of Vermont, also announced Thursday they are planning a broader probe into when other energy companies first understood that fossil fuels drive climate change, what they did with that information and whether they funded or participated in sowing doubt about the matter. The companies include Chevron Corp., ExxonMobil, ConocoPhillips Co., BP, Royal Dutch Shell and Peabody Energy Corp.



"The American people deserve answers from the fossil fuel corporations about their actions to massively deceive the public in regards to climate science," Lieu and Welch wrote in a letter to their House colleagues asking for their support. So far, more than 20 Democrats have signed the letter, Lieu told reporters. They plan to send their requests to the companies "in a few weeks," he said.

The calls for the probes follow separate investigative news reports by InsideClimate News and the Los Angeles Times. InsideClimate News found that Exxon scientists conducted rigorous climate research from the late-1970s to mid-1980s and warned top company executives about how global warming posed a threat to Exxon's core business. The company later led a decades-long campaign to create doubt about the scientific evidence for man-made climate change.

The petition was organized by more than a dozen environmental and activist groups, including CREDO, Climate Hawks Vote, MoveOn, Sierra Club, Avaaz and 350.org. Many green leaders see the fight against ExxonMobil as a new target for the climate movement following its win against the Keystone XL pipeline, which President Obama rejected earlier this month.

"All fifty states are now suffering damages from Exxon Mobil's greenhouse pollution, from sea level rise to wildfires, floods, and drought," RL Miller, president of the political advocacy group Climate Hawks Vote, said in a statement. "The Department of Justice must investigate Exxon knew and what Exxon did, and then prosecute Exxon's deliberate climate denial. And if Attorney General Loretta Lynch fails to act, then our state attorneys general must step up to protect the American people."