I would agree that achieving all of what is suggested in the Green New Deal is, certainly currently, out of reach. However wasting billions on a wall to solve a problem which we know doesn't really exist, would be a lot stupider than spending the same amount for at least some small steps toward dealing with a problem which we know actually does exist.
Yes the Wall is ridiculous. However, there is only one way to battle GHG and Global Warming- War.
You see, human beings are selfish and will wait until most mammals are extinct, and it threatens their way of life. Humans will kill each other off. Anyone who thinks we will all join hands, and play fair is naive. The USA is moving backward on the issue, and China and India are emitting more and more pollutants as they become more industrialized. There is no hope for us.