More than 2,500 scientists from 43 countries are joining together as signatories to a scientific paper warning about the environmental impacts of President Donald Trump’s proposed wall along the border between the United States and Mexico. This includes more than 1,400 U.S. scientists and 616 scientists from Mexico.

“Fences and walls erected along international boundaries in the name of national security have unintended but significant consequences for biodiversity,” states the study published in the scientific journal BioScience, authored by 16 scientists and signed onto by thousands of others.

The paper echoes concerns raised ever since the border wall was first introduced by Trump. In January, the administration waived dozens of environmental rules in order to accelerate building parts of the wall in New Mexico. The following month, a judge in California rejected environmental groups’ arguments that the administration’s plans violated environmental laws and the state’s right to protect its resources.

In the paper released Tuesday, scientists issue a call for action. They “urgently advise” that all future budget appropriations for construction of the wall require key environmental laws be followed, such as Endangered Species Act (ESA) and the National Environmental Policy Act (NEPA). Two different bills before Congress have also sought to expedite the border wall by allowing authorities to circumvent 36 different environmental laws — one of these failed to pass the House last month.


There is one hopeful development in recent legislation regarding Trump’s border wall, however: Contained within the spending bill passed in March by Congress is the stipulation that none of the more than $1 billion allocated for the wall could be used for construction in the Santa Ana Wildlife Refuge. The refuge is home to at least 400 species of birds, 450 types of plants, and half of the butterfly species found in North America.

But as the authors of the paper explain, the wall will “threaten some of the continent’s most biologically diverse regions” — even if in some areas it’s a fence rather than a solid barrier. This is because the U.S.-Mexico border spans a variety of different regions, from desert and grasslands to temperate forests, which include conservation hot spots. The border currently bisects land home to 62 species listed as either critically endangered, endangered, or vulnerable.

Before any future construction happens, the scientists ask that the Department of Homeland Security (DHS) do pre-planning surveys to identify species, habitats, and ecological resources at risk. Scientific research along the border should also be allowed to continue unhindered, the study states, which could help assist environmental assessments and mitigation efforts.

As of 2017, the paper states, over 650 miles of “primary” barriers along the border have been constructed. According to the scientists, building a continuous border wall could disconnect more than a third of U.S. “non-flying” land and water species from more than half of their habitat that extends south of the border. This includes jaguar and ocelot — while neither are endangered, their populations are both decreasing. Low-flying animals such as the pygmy-owl and the endangered Quino checkerspot butterfly could also be impacted.

By fragmenting these habitats with a wall, along with the requisite roads, lights, and operating bases, a slew of detrimental environmental impacts will follow, write the scientists. This includes degrading vegetation, soil erosion, changes in fire patterns, and the potential for more flooding. Wildlife will see their homes degraded and will suffer as a result.


In addition, “physical barriers prevent or discourage animals from accessing food, water, mates, and other critical resources by disrupting annual or seasonal migration and dispersal routes.”

The endangered Peninsular bighorn sheep, for instance, would be less able to move between California and Mexico to access water and birthing sites. And it will be “likely impossible” for other endangered animals, such as the Mexican gray wolf or the Sonoran pronghorn, to help reestablish smaller populations across the border, the scientists say.

In the long term, a separation of a species’ habitat could potentially drive genetic differences in plants and animals. “Fragmented populations may also suffer from reduced genetic diversity and face greater extinction risks,” according to the paper.

Added to all of this are the the protracted impacts of climate change. With increasingly warm, dry conditions, habitats could shift or resources may be redistributed, the scientists write. Animals may not be able to respond to these changes if a wall blocks off access to more hospitable areas.

While many factors are at play that may determine how a specific species is impacted, the scientists are clear that a wall will prove an impenetrable barrier for many species.

“We urge the U.S. government to recognize and give high priority to conserving the ecological, economic, political, and cultural value of the U.S.-Mexico borderlands,” they conclude. “National security can and must be pursued with an approach that preserves our natural heritage.”