It doesn't seem like this is a problem solved by trying to put up walls and pay for more law enforcement officers and military equipment.

It's not. This is a problem solved by reforming the immigration system. I'll let you try to figure out which of the two parties in power has stonewalled progress on that front for the last 30 years.

It's a problem where regulating the number of people coming into the country today can help substantially. That very well may mean putting up walls and paying for enforcement officers, but at a minimum is must mean monitoring the rate of people entering the US and being able to keep our cities from being overwhelmed by economic migrants so that we're able to accommodate as many of the climate refugees as we can in a way that doesn't cause the same problem or further destroy the environment creating even more climate refugees and further displacement within US borders as our remaining resources grow increasingly strained.