The US government is making drastic changes to how the Endangered Species Act (ESA) is applied. The revisions weaken protections for threatened species, and will allow federal agencies to conduct economic analyses when deciding whether to protect a species.

The changes, finalized by the Fish and Wildlife Service (FWS) and the National Marine Fisheries Service on 12 August, are among the most sweeping alterations to the law since it was enacted in 1973.

President Donald Trump’s administration says that these updates will ease the burden of regulations and increase transparency into decisions on whether a species warrants protections. But critics say that the revisions cripple the ESA’s ability to protect species under increased threat from human development and climate change.

“These changes tip the scales way in favour of industry,” says Brett Hartl, government-affairs director for the Center for Biological Diversity, an environmental advocacy group in Washington DC. “They threaten to undermine the last 40 years of progress.”

The attorneys general of California and Massachusetts have already announced their intention to sue the Trump administration over the changes, which they call unlawful.

Limits to protections

Chief among the changes is the removal of blanket protections for threatened animals and plants.

Until now, any species deemed threatened — a category for organisms at risk of becoming endangered — by the FWS automatically has received the same protections as endangered species. They include bans on killing threatened and endangered species. Now, those protections will be determined on a case-by-case basis, a move which will likely reduce overall protections for species that are added to the threatened list, says Hartl.

The revisions also narrow the scope of those protections. Previously, government officials considered threats that would affect a species in the “foreseeable future”, such as climate change. Now, they have leeway to determine the time period meant by the foreseeable future, and can only consider threats that are “likely” to occur in that time frame. Critics say that this weaker language could allow regulators to ignore threats from climate change, such as rising sea levels, because their effects might not be felt for decades.

And in a third change to the ESA, the Trump administration removed language explicitly prohibiting the consideration of the economic impacts of listing a species. However, the FWS will continue to rely only on the best available science when determining whether a species should be listed, said Gary Frazer, the assistant director for endangered species at FWS, in a press call.

The changes to the ESA are expected to be published in the US government's Federal Register this week. They will take effect 30 days after publication.