Donald Trump’s border wall doesn’t make financial sense. But it’s also a disaster in terms of the environment.
We’ve already shown that the wall could cost as much as $40 billion to build. But the materials required to build it would take their toll on the environment. A 1,000-mile wall that's 50 feet tall with 15 feet underground and one-foot thick would require 9.7 million cubic meters of concrete and 2.3 billion kilograms of (presumably American) steel.
According to figures from the Institute for Sustainable Energy and the Environment at University of Bath, there are about 380 kilograms of carbon dioxide emissions for every cubic meter of concrete poured. So the wall’s concrete could produce up to 3.7 million tons of CO2. (Some of that will actually be absorbed by the concrete over time, but only slowly.)
Then, depending on the quantity of recycled metal within it, there are around 1.8 kilograms of carbon dioxide emissions embodied within a kilogram of steel. That means the steel would contribute a further 4.1 million metric tons of CO2.
All told, the wall will tally 7.8 million metric tons of carbon dioxide.
For some context, that’s the same as the emissions from 823,654 homes over the course of a year. And that’s on the low end: ongoing maintenance, re-routing of traffic, and other unforeseen consequences could all push the figure far higher.
The wall also poses a large ecological threat. As Motherboard points out, a report created last year based on U.S. Fish and Wildlife Service data explained that its construction could have a negative impact on "111 endangered species, 108 species of migratory birds, four wildlife refuges and fish hatcheries, and an unknown number of protected wetlands."
There could be an environmental benefit to the wall—but it is a repercussion that might not sit well with with the president. One suggestion for funding the structure is to place a levy on imports from Mexico. But according to Bloomberg, a 20 percent import tax on Mexican crude oil could push U.S. gas prices up by as much as 30 cents per gallon. When gas prices go up people drive less, so in theory the wall could lead to lower carbon emissions from transportation.
Given the damage it could cause, though, building the wall would be unquestionably wasteful. Speaking to Scientific American, Bryan Lee Jr., the place and civic design director for the Arts Council of New Orleans, just about sums up the situation: "The embodied energy in thousands and thousands of miles of wall is insane and useless in so many ways. The embodied energy of creation is one thing … but also the embodied energy from the social perspective.”