It’s no secret that the Trump administration is attacking science. From scrubbing the words “climate change” from federal agency websites to cutting public health programs in the Environmental Protection Agency to burying its own climate report involving more than 300 leading climate scientists, President Donald Trump and his appointees take well-established scientific facts and treat them like science fiction. One environmental attack is particularly appalling, but headlines have focused more on its political theatrics than on its catastrophic consequences for North American biodiversity: building the wall along the U.S.-Mexico border. As a scientist who understands the implications of this decision for wildlife, I am astounded and outraged that such a precious biological treasure is being sacrificed for political gain. And I am not alone.

Earlier this year, my colleagues at Defenders of Wildlife and I led more than 2,500 scientists from around the world in declaring consensus over the impending consequences of the border wall on North America’s biodiversity in a synthesis study published in BioScience. In an exceptional moment of unity, we scientists agree with the irrefutable evidence that the border wall is a rampant ecological disaster. This is notable because consensus is rare among scientists. When scientific consensus does exist—as with climate change—it’s a wake-up call that business as usual is likely to result in catastrophe.

While the border wall has critical implications for human migration and international relations, this physical barrier is also an ecological nightmare. As it divides communities where millions of people live, the border wall also cuts through the habitats of over 1,500 wildlife species. As they evolved through time, these species developed specific characteristics to thrive in the ecologically diverse landscapes along the border, ranging from extreme desert scrublands to rain-heavy wetlands. Many eked out a living by tracking rare resources along north-south migratory routes by land and air. The breadth of species that thrive in this ecological marvel make the borderlands one of the most biologically rich regions in the world, and an internationally acclaimed conservation hotspot.

While campaigning for office, Trump riled up his supporters with promises of a “great, great wall on our southern border,” one that will divide the complex biological mosaic of the Southwest. But large parts of our border with Mexico are already walled off. The Department of Homeland Security (DHS) has already constructed 600 miles of blockades without regard for impacts to the region’s previous biodiversity, using the 2005 Real ID Act to sidestep bedrock environmental protection laws like the Endangered Species Act (ESA) with no chance for public engagement.

This 600-mile stretch of wall is an unclimbable barricade for 346 nonflying animal species, not to mention flighted species like the endangered Quino checkerspot butterfly and the threatened and endangered ferruginous pygmy-owl that cannot fly high enough to surmount the wall. Without passage, animals cannot disperse to new populations to spread their genes, potentially leading to genetic inbreeding akin to the plight of the African cheetah. During natural seasonal flooding, the wall traps flood waters and kills wildlife and vegetation. During natural disasters like heat waves, when water or food on one side of the wall is not available, those species will be left to perish, unable to access resources on the other side.

But the border wall is much more than just a physical wall. Massive construction vehicles drag building supplies through delicate habitat, and light and noise pollution disturb and displace diurnal and nocturnal species. Once built, security vehicles patrol along miles of paved and unpaved roads and extensive networks of undesignated off-road paths, all of which expand the barren footprint of the wall.

These pervasive impacts will not be recognized, assessed or addressed, because the Trump administration has waived dozens of laws in New Mexico, Texas and California designed to protect plants, animals and humans. These are laws that Congress passed, and which the American people wholeheartedly support to safeguard our environmental and public health. With these laws ignored, wall construction proceeds—at this very moment—without environmental impact analysis, mitigation, public input or protection of legal action.

Besides the 600 miles installed, there may be 1,953 miles of border wall yet to come. In one generation, humans will have successfully disintegrated an extraordinary biodiversity web that evolved over millions of years. It is a legacy of which we should not be proud. Building the border wall sacrifices the ancient biodiversity of North America for the momentary political gain of one president. Our biodiversity is less flexible, requiring millions of years to evolve to its intricate state of ecological intactness. Further construction of the U.S.-Mexico border wall will undoubtedly lead to the death of countless species in the process—adding to the 10 million species marching towards extinction worldwide as a result of the broader human footprint.

But there is hope. Biodiversity is resilient, and we can reverse this biodiversity crisis if we act now. Congress can still defund the wall, support flexible barriers or technology measures that consider the needs of biodiversity, and require the DHS to comply with U.S. laws to assess and address environmental impacts. We live in an age with technological capabilities to keep people safe without sacrificing wildlife, wild places and fellow humans. Let us apply our innovative minds to this worthwhile task.

Let us not compromise thousands of species and a rare biodiversity hotspot, alongside the identity of millions of people along the border, for reprehensible campaign promises and political theatrics that will only further divide us.