Please take a few minutes to skim through this article posted by Scientific American. I really try not to take too much of a political stance in my posts, but I am very much against the building of a Mexico-US Border for several reasons, and environmental concerns is one of them.
Humans have defined the borders of our towns, states, and countries for the past few centuries in order to claim territory. However, the lines that we draw in the sand are only recognized by people- not animals. Their migratory patterns are based off of their needs and instincts. A wall at the border would disrupt animals’ migration as well as the water flow that much of the wildlife relies upon.
Additionally, the process of making concrete and building the wall creates an enormous amount of CO2 emissions. The border wall currently in place already looks over the needs of the environment, and replacing it with a bigger one will do massive amounts of damage.