The overhaul comes at time when U.N. scientists are warning that up to 1 million plant and animal species are facing an "imminent risk" of extinction because of human activity.
The Trump Administration took steps on Monday to significantly weaken the U.S. Endangered Species Act, prompting state attorneys general and conservation groups to threaten legal action to protect at-risk species.
The 1970s-era Act is credited with bringing back from the brink of extinction species such as bald eagles, gray whales and grizzly bears, setting limits for drilling and mining companies, and other industries with new listings of vast areas of land off-limits to development.
The weakening of the Act's protections is one of many moves by U.S. President Donald Trump to roll back existing regulations to hasten oil, gas and coal production, as well as grazing, ranching and logging on federal land.
"These changes crash a bulldozer through the Endangered Species Act's lifesaving protections for America's most vulnerable wildlife," Noah Greenwald, the Center for Biological Diversity's endangered species director, said in a statement. "For animals like wolverines and monarch butterflies, this could be the beginning of the end."
Trump finalizes disastrous rollbacks to the Endangered Species Act that will have profound effects on our nation’s rarest animals and plants. Disgusting and disturbing. We’re fighting back.— Center for Bio Div (@CenterForBioDiv) 12 de agosto de 2019
Read: https://t.co/K7a4keVWZH pic.twitter.com/xUQiuI7Mtd
The changes would end a practice that automatically conveys the same protections for threatened species as for endangered species, and would strike language that guides officials to ignore economic impacts of how animals should be safeguarded.
The original Act protected species regardless of the economic considerations.
Massachusetts and California will lead a multi-state lawsuit joined by conservation groups once the final rule is published in the Federal Register in the coming weeks, challenging what they say was an "illegal" process to revise it.
"By gutting key components of the Endangered Species Act, one of our country's most successful environmental laws, the Trump Administration is putting our most imperiled species and our vibrant local tourism and recreation industries at risk," said Massachusetts Attorney General Maura Healey.
"We will be taking the Administration to court to defend federal law and protect our rare animals, plants, and the environment," she added on a call with reporters.
According to the revision, the Fish and Wildlife Service would need to write separate rules for each threatened species, slowing their protection until conditions worsen. Previously, threatened species, which account for 20 percent of listed species under the Act, would receive the same automatic protections as endangered species, according to the liberal Center for American Progress policy research organization.
"Ending this practice ... would strain the resources of USFWS and NMFS, costing managers valuable time before they can take action to protect a species," said Kate Kelly, the organization's public lands director.
The revised rules will also prohibit designation of critical habitat for species threatened by climate change, the impacts of which tend to be felt in the future, the Center for Biological Diversity said.
Environmental groups said the overhaul comes at time when U.N. scientists are warning that up to 1 million plant and animal species are facing an "imminent risk" of extinction because of human activity.
But Trump rejects mainstream climate science and agencies such as the Interior Department have stopped weighing climate impacts in their regulations.
"Instead of undercutting the Endangered Species Act and other bedrock environmental laws, we should be strengthening these laws to improve their effectiveness for people and wildlife," said Jamie Rappaport Clark, president and CEO of Defenders of Wildlife.
"We are in the midst of an unprecedented extinction crisis, yet the Trump administration is steamrolling our most effective wildlife protection law," Rebecca Riley, legal director of the nature program at the Natural Resources Defense Council, said in a statement. "This administration seems set on damaging fragile ecosystems by prioritizing industry interests over science."