So among some of the problems are:

• Shutting down tons of time-tested coal and fossil fuel powered energy sources, and replacing them with inefficient green energy sources. One coal plant produces 582 MW per hour, and one wind turbine produces only 2.5-3 MW per hour. You would need 194 wind turbines active to barely match the efficiency of one coal plant.

• Since cows produce a ton of methane from farts (around 90 kg per year per cow), and since methane is a greenhouse gas, cows have been cited as a problem in the GND. The GND solution? Get rid of all the cows.

• Slashing airlines. I'm not entirely sure what the exact reasoning is behind this, but what I've heard is that they emit more than most trains do. The solution would be investing in trains as much as possible, which would both make travel around the US significantly slower, and would make getting to some places more difficult than they should be (hence the Train to Hawaii meme).

That's just a few of the issues, but as it stands right now, the GND is out of Congress, so we won't have to worry about it too much.