A rare coalition of 19 state attorneys general plus the attorney general from the U.S. Virgin Islands announced Tuesday they are joining forces to pursue investigations related to global warming, including looking into whether companies such as Exxon Mobil misled shareholders and the public about the risks of climate change.

The new coalition signals an escalation in the battle against companies that have played a central role in funding climate denying think tanks to help sow public confusion over the reality of human-caused global warming.

See also: New York launches investigation into whether Exxon lied about global warming

At a news conference in Manhattan, the attorneys general of Vermont, Connecticut, Maryland, Massachusetts, Virginia, the Virgin Islands and New York were joined by former vice president Al Gore at the outset of a daylong conference on climate change. Other attorneys general are also involved in the coalition, including those of California, Washington, D.C., Iowa, Illinois, Maine, Minnesota, New Mexico, Oregon and Washington.

While only two concrete developments in climate investigations were announced during the press conference, the “coalition of the willing,” as one state official called it, is likely to lead to more cases brought against fossil fuel firms or utilities that are suspected of deceiving stockholders or the public about the reality and risks of human-caused global warming.

Massachusetts Attorney General Maura Healey announced that her state is joining New York and California’s investigation into whether Exxon committed fraud by misleading investors and the public about the very existence of human-caused global warming, despite having conducted its own in-house research that confirmed mainstream scientists' findings.

“Fossil fuel companies that deceived investors and consumers about the dangers of climate change should be, must be, held accountable. That’s why I too have joined in investigating the practices of Exxon Mobil," Healey said. "We can all see today the troubling disconnect between what Exxon knew, what industry folks knew and what the company and industry chose to share with investors and with the American public.”

Former U.S. Vice President Al Gore addresses participants during a three-day climate change training and workshop on how best to address the effects of global climate change Monday, March 14, 2016 in suburban Pasay city, south of Manila, Philippines. Image: Bullit Marquez/Associated Press

Claude Walker, the attorney general for the U.S. Virgin Islands, said his office is also pursuing an investigation into a company for misleading the public and investors about climate change risks, though he did not specify whether that is Exxon or a different entity. Other sources told Mashable the investigation is into Exxon, however.

The Exxon investigations began after a series of investigative reporting published by Inside Climate News, the Los Angeles Times and other outlets during the past year showed that Exxon scientists told the company about the dangers of fossil fuel burning, but that the company chose instead to fund a vast network of climate denial think tanks to sow confusion about the science.

New York Attorney General Schneiderman called the gathering of top law enforcement officers from several states, “A significant milestone in our collective efforts to deal with the problem of climate change.”

Gore, for his part, hailed the possibility of more state-initiated investigations of fraud and other violations to finally bring to justice those who for years smeared climate scientists, and him personally, by arguing that global warming is a hoax or some sort of liberal conspiracy.

“I really believe that years from now this convening by attorney general Schneiderman and his colleagues may well be looked back upon as a real turning point in the effort to hold account those commercial interests who have been deceiving the American people,” Gore said.

Gore, who heads up the nonprofit Climate Reality Project and helps lead an investment firm built around principles of sustainability, likened the prospect of state-sponsored lawsuits against fossil fuel companies, utilities and others as similar to the state challenges that ultimately helped break the grip of the tobacco companies that refused to acknowledge the ties between their products and lung cancer.

This historic coalition will do all it can to push for even more aggressive action in defending our climate: https://t.co/xE9n0iSj4M — Eric Schneiderman (@AGSchneiderman) March 29, 2016

When pressed to clarify whether the gathering of so many state attorneys general meant a major expansion in the Exxon case or other specific cases, Schneiderman demurred, noting that different states have various statutes that affect how they can take legal action, and that many investigations are not announced at the outset or even while they are in progress.

“We are here today because we’re all committed to pursuing what you might call an ‘all levers approach.’ Every state has different laws, different statutes, different ways of going about this. The bottom line is simple. Climate change is real; it is a threat to all the people we represent,” he said.

“If there are companies, whether they’re utilities or they’re fossil fuel companies committing fraud in an effort to maximize their short-term profits at the expense of the people we represent, we want to find out about it, we want to expose it and we want to pursue it to the furthest extent of the law.”

Environmentalists greeted the news positively, saying it provides new momentum to the push to hold Exxon accountable.

"This creates a huge sense of momentum. Exxon may have been able to brush aside a few isolated inquiries, but with more states jumping on board, these investigations are sure to generate some serious waves," said Mary Boeve, the executive director of 350.org, in a statement.

"The Exxon revelations may turn out to be the largest corporate scandal in history. We'll be looking for the Department of Justice and many more cities and states to get involved. Everyone is impacted by climate change, which means everyone has a stake in these investigations. A trial of ExxonMobil and the fossil fuel industry would be even bigger than the cases against Big Tobacco."

Kathryn Mulvey, climate accountability campaign manager for the Union of Concerned Scientists, said in a statement: "Evidence shows that ExxonMobil and other fossil fuel companies have known about the risks posed by climate change for decades, but still chose to fund a multi-million dollar disinformation campaign against climate science and solutions. This pattern of deception continues today."

"We would applaud any move by the attorneys general of other states to join those of New York and California in seeking to hold fossil fuel companies accountable for decades of deception about the harm caused by their product.”

Democratic presidential candidates Sen. Bernie Sanders and former Secretary of State Hillary Clinton have both said federal investigations of Exxon are necessary in light of what has already been revealed in media accounts. None of the Republican candidates have endorsed such investigations.