We live in the age of extinction, a quiet catastrophe that surely ranks as one of the great ecological and moral crises of our time. The best tool for saving America’s imperiled animals and plants is the Endangered Species Act, first passed by Congress in 1973. But you wouldn’t know it from what’s been happening recently in the nation’s capital.

Last week, the Trump administration proposed major changes to the law. Although some offered welcome clarifications and efficiencies, others would strike at the core of the law that now protects more than 2,000 threatened and endangered species, from the largest animal on the planet, the blue whale, to the Florida perforate cladonia, a two-inch lichen found only in the state.

Among the most worrisome is a proposal that would allow cost considerations to influence whether a species qualifies for protection or should be left to its fate. Decisions are now based on the best available science, and references to economic impacts are prohibited. Introducing cost criteria would circumvent the science that keeps the listing process honest. The plan also would give the administration the discretion to scale back protections for some species listed as threatened in future determinations.

The administration’s proposal joins legislative efforts to retool the law. In examining them, we should ask two questions: Will these changes increase populations of endangered species, or at least slow their decline? And will they advance cooperation and reduce conflicts between the federal government and states, industries and landowners? Almost none of these recent proposals pass this test.