During his first week in office, Donald Trump, as we’re all aware, wasted no time in acting on several of the egregious promises he made during his presidential campaign. Among the executive orders he signed was one to build a 1,300-mile-long concrete wall — and as high as 55 feet — between the borders of the United States and Mexico.

There are many reasons why this wall is a terrible idea. As Care2 writer Cody Fenwick pointed out back in August of 2015, the wall is an insult to Mexico, an important trading partner with the US There is little evidence that a wall will actually prevent people from entering the United States. Furthermore, it would be very expensive to build – an estimated $40 billion, according to M.I.T. researchers.

Of course, back then Trump promised that Mexico would pay for the construction of this “great, great wall,” but we know now — and could have guessed then – there’s no way that’s going to happen.

Trump’s recent proposal of a 20-percent tariff on Mexican imports would raise the prices of everything from the food we eat to the cars we drive. The irony, as William Gale, co-director of the Tax Policy Center, told USA TODAY, is that “consumers will be paying for the wall, not Mexican producers.”

Now that this terrible idea could actually become a reality, scientists and conservationists have also voiced their concerns. In addition to allegedly blocking people from entering the US, a concrete wall along the border with Mexico would obstruct important wildlife migration routes for jaguars, ocelots, mountain lions, deer and other animals.

Of these animals, the wall would be the most harmful to highly endangered jaguars, according to the Center for Biological Diversity. If the small population remaining in northern Mexico becomes blocked off, the US population will never be reestablished.

“We already know that walls don’t stop people from crossing the border, but Trump’s plan would end any chance of recovery for endangered jaguars, ocelots, and wolves in the border region,” said Kierán Suckling, the Center’s executive director. The border region, Suckling explained, “is the only place in the world where jaguars and black bears live side by side. It’s this diversity that makes us strong — not some wasteful, immoral wall.”

“Disruptive, Artificial Boundary”

Jamie Rappoport Clark, president and CEO of Defenders of Wildlife, similarly called the wall “a disruptive, artificial boundary in the natural world” in a Jan. 25 statement.

Dan Millis, a program manager with the Sierra Club’s Borderlands project, also opposes the wall. “In terms of climate adaptation, building a border wall is an act of self-sabotage,” Millis told E&E News. “And the reason I say that is we’re already seeing wildlife migrations blocked with the current walls and fences that have already been built.”

Those 670 miles of fences and barriers along Mexico’s border with California, Arizona, New Mexico and Texas were erected after the passage of the Secure Fence Act of 2006. In Texas, the wall blocks both people and animals from accessing the Rio Grande River, “an iconic and vital water source for communities and wildlife alike,” according to the Defenders of Wildlife.

“At the border wall, people have found large mammals confounded and not knowing what to do,” Jesse Lasky, an assistant professor of biology at Penn State University, told the Washington Post.

In addition to the possible extinction of some species, the production of cement used to build Trump’s wall would be a major source of greenhouse gas emissions.

Many of the existing walls were built “without dozens of environmental protections,” according to Millis. It’s highly unlikely that Trump’s wall will undergo any environmental review process. In a controversial 2008 announcement, the Department of Homeland Security said it would waive environmental reviews for the fences built along the border.

Protesting the Wall

In November 2016, leaders of the Tohono O’odham Nation, whose reservation sits on the US-Mexico border, said they would refuse to allow the wall to be built on their land, which is the size of Connecticut. Among their reasons was that the wall would be devastating for wildlife.