Declare War on Climate Change

What is stopping the President of the United States from waging war on climate change?

I’m seriously asking.

Is there anything to keep him from declaring a state of emergency and mobilizing the National Guard to plant trees?

How much Defense Department funding could be moved into R&D for renewable energy and disaster mitigation?

I’m just spitballing. But how do we take the rumbling┬ámachine that is the US Military and turn it away from the genocide of the differently-indoctrinated–to take up arms instead against the universal enemy of all humankind?