In a move that could reshape the worldwide environmental debate, a Massachusetts advocacy group is suing ExxonMobil for what it calls "a decades-long campaign to discredit climate change."

Conservation Law Foundation President Brad Campbell said Tuesday the company's strategy of publicly denying the risks that its own scientists have known about for decades has harmed local communities, including neighborhoods near its Everett facility.

“ExxonMobil’s strategy of publicly denying the very risks its scientists have known for decades has direct impact on Greater Boston communities,” Campbell said. “ExxonMobil knowingly and unlawfully misled regulators about whether its Everett facility can withstand rising seas, more intense precipitation, and other climate impacts without spewing oil and other toxic pollutants into adjoining neighborhoods, the Mystic River, and the Boston Harbor."

ExxonMobil, a direct descendant of John D. Rockefeller's Standard Oil, is the world's largest oil company.

In a nutsell, CLF alleges that scientists working for the oil giant developed hard science pointing to the fact that global warming was real, and that ExxonMobil dismissed this evidence of climate change and failed to translate it into operational guidelines for its far flung enterprises.

In practical terms, ExxonMobile's Everett facility is more of a trigger than a target. If the CLF lawsuit is successful, the assumption is that other legal assaults would be mounted in other markets.

ExxonMobil spokesman Alan Jeffers calls the lawsuit part of a "well-publicized, coordinated assault on ExxonMobil's reputation" that he says includes deliberately inaccurate reporting on the company's nearly 40 years of publicly conducted climate research.

Jeffers says the Everett terminal complies with federal and state environmental standards, including monitoring and treating ground water.

In March, state Attorney General Maura Healey said she was investigating whether ExxonMobil deceived the public and investors about the effects of climate change. Sixteen other state's attorneys general are pursuing similar probes.

After announcing their intent to file the lawsuit, representatives of CLF hopped on a water taxi on the Mystic River. In an effort to dramatize their effort, they wanted to get a closer look at the company’s oil terminal they say is vulnerable to climate change.

“If we had a confluence of a storm surge and high tide, even now, this facility would be underwater," CLF staff attorney Chris Killian told people on the boat. "And it’s just a matter of time.”

CLF says that failure to protect the terminal is in violation of federal law.

“Our facilities are designed and operated to withstand a variety of extreme conditions, including those associated with potential climate change impacts,” Jeffers said.

CLF also points to the more than 70 times the terminal has exceeded pollution limits in the Mystic and Island End Rivers.

Jeffers says the terminal complies with all federal and state environmental standards.

By law, ExxonMobil has 90 days to address the issues before the Conservation Law Foundation files their lawsuit.

WGBH News reporter Craig LeMoult and the Associated Press contributed to this report.