Often lost in discussions of efficacy and payment relating to the proposed U.S.-Mexico border wall is what would happen to the environment if a concrete divider were placed across a nearly-2,000 mile swath of habitat. While wall-like barriers already stand on hundreds of miles of the U.S.-Mexico border, expanding to a full-border wall would constitute a massive transformation of the rest of the United States’ southern borderlands, posing substantial threats to the wildlife that roam the area.
The U.S.-Mexico border region has some of the highest levels of biodiversity in the continental United States, and is home to a variety of endangered species. A tall, continuous concrete structure would fragment the habitats of the charismatic animals living in the region, such as bighorn sheep, roadrunners, and mountain lions. Fragmentation limits an animal’s movement, reducing their access to food and water sources, and separating breeding populations. Cutting down the habitat range can be particularly destructive for already-sensitive animals, imposing an additional burden on endangered species—like the jaguar, Mexican gray wolf, and the ocelot—that call the Southwest home. A U.S. Fish and Wildlife Service provisional report from last year estimated that a full-border wall has the potential to impact 111 endangered species.
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The impacts of the wall are particularly worrisome in the context of climate change, which is causing many species to shift their ranges pole-ward due to warming temperatures. Not only would a wall hinder these adaptive habitat changes, but it also would amplify the causes of climate change. The massive amount of concrete needed for a wall spanning over 1,000 miles and up to 50 feet high would contribute substantially to carbon emissions. The cement industry is already responsible for about 5% of the world’s annual carbon dioxide emissions, and engineers from New York University and University College London estimate the wall would require double the amount of concrete as is in the Hoover Dam. A researcher at the Earth Institute of Columbia University estimated that a 1,000-mile wall would generate about 1.9 million metric tons of CO2. This would be about the same as adding over 400,000 cars to the road every year. Impacts on carbon emissions means the wall would not only harm its local environment, but also ecosystems across the globe.
In addition, a large-scale construction project such as a border wall can degrade the surrounding land and cause harmful flooding events. In Israel, where a barrier wall already stands at the border of the West Bank, environmental impacts such as erosion, soil compaction, ecosystem fragmentation, and flooding were seen after the wall’s construction. We don’t have to speculate entirely about what such a wall would do to the surrounding ecosystems; wall-like fencing already stands on several hundred miles of the U.S.-Mexico border. Nogales, Arizona, and Nogales, Sonora (Mexico), felt these impacts in 2008, when the border wall acted as a dam, causing a flood that killed two people and cost millions in damages.
While its political future is still undetermined, a border wall of the size and magnitude as envisioned by President Trump would almost unavoidably harm wildlife and border communities.
To learn more about how environmental legislation will or won't affect the wall, see Environmental Law and the Border Wall.