Big Oil on Thursday launched what amounts to a legal fight against little kids.

The unusual case began back in August when a group of “youth plaintiffs” (ages 8 to 19) sued the federal government, arguing that weak action on climate change is a violation of their right to life, liberty and property. They demanded that President Obama act more swiftly to slash the emissions that cause global warming. They sued for themselves but also for “future generations,” a group whose “guardian” is listed as James Hansen, the former chief climate scientist for NASA.

The case is seen as an unlikely winner, long on symbolism and short on precedent. But the fossil fuel industry isn’t taking any chances.

On Thursday, representatives of ExxonMobil, BP, Shell, Koch Industries, and hundreds of other users, producers and refiners of fossil fuel filed a joint motion to intervene. Fearing “massive societal changes” and an “unprecedented restructuring of the economy,” they asked a district judge in Eugene, Oregon to let them join the Obama administration in fighting the lawsuit.

RELATED: Meet the kids suing Obama

The trade groups involved include the National Association of Manufacturers (NAM), American Fuel & Petrochemical Manufacuters (AFPM) and the American Petroleum Institute (API). Collectively these groups provide most of the nation’s energy and, directly or indirectly, produce most of America’s carbon pollution. The trade groups did not immediately respond to a request for comment.

“The impacts [of this lawsuit] could impair the interests of virtually the entire swatch of the NAM, AFPM, and API’s members,” the motion reads, according to a copy obtained by MSNBC. “For all these reasons, it is critical that they have the opportunity to intervene.”

The motion goes on to describe the children’s lawsuit as “a direct threat” that could constrain “the sale of the product they have specialized in developing and selling.”

It argues that the court should take economic factors into account, claiming that while a reduction in carbon emissions would ”abate some of the future risks of climate change, those reductions would nevertheless not be ‘appropriate’ if the future potential benefits would be outweighed by, for instance, enormous losses in productivity and economic development.”

The plaintiffs were organized by Our Children’s Trust, an Oregon-based nonprofit that has spearheaded climate-related lawsuits in all 50 states. The action was filed by Earth Guardians, a Colorado-based nonprofit that hopes to bring atmospheric carbon levels down to 350 parts per million, the maximum level that scientists consider to be safe. The current level is close to 400 p.p.m.

“The science is clear,” Hansen, a climate researcher who headed NASA’s Goddard’s Institute for Space Studies for more than 30 years, said in a statement Thursday. He first warned Congress of global warming in 1988 and now his granddaughter is one of the plaintiffs. In an earlier interview with MSNBC, he called Obama’s climate change policies “practically worthless”—and in the statement Thursday he called for the rapid phase out of all fossil fuels.

“I am not surprised that fossil fuel corporations seek to derail this case, but the fundamental rights of my granddaughter and future generations to life, liberty and pursuit of happiness must prevail,” he said.

Some of the young people’s complaints are lofty and intellectual, and others reflect basic childhood interests like the health of a local swimming hole. They span childhoods in Oregon, Colorado, Florida, Arizona, Washington state, Hawaii, New York, Alaska, Pennsylvania and Louisiana. All are treated as equal violations of the U.S. government’s fundamental responsibility to protect its citizens today, and provide for a healthy tomorrow.

RELATED: Is the Exxon investigation a witch hunt?

“The purpose of the case is to protect our rights,” Tia Marie Hatton, an 18-year-old plaintiff from Oregon, told MSNBC in August. “They depend on a healthy climate and right now that healthy climate is being negatively impacted by the government allowing and promoting the use of fossil fuel.”

“Different rivers and creeks are drying up, and having them get warmer, it gets more algae into them. So it’s like really gross to swim in them,” added Avery McCrae, an 11-year-old who’s also from Oregon.

“This case presents the opportunity for a landmark decision like Brown v. Board of Education (on racial equality) or Obergefell v. Hodges (on marriage equality),” Julia Olson, one of the kids’ lawyers, wrote in a briefing sent to MSNBC in August. It asks the court to decide whether children have a constitutional right to protection from fossil fuel policies that “knowingly create dangerous climate change.”

The White House has declined to comment on the case. A spokesperson for the EPA declined to address the specific merits of the lawsuit, but agreed that the government has “a moral obligation to leave a healthy planet for future generations.” The agency pointed to the White House’s Climate Action Plan – and the EPA’s controversial Clean Power Plan – as examples of remedies already underway.

But the lawsuit portrays these efforts as “ineffectual” and “demonstrably short of what is needed.”

Correction: This article originally reported that the motion was filed Monday.