....... I'm curious how you come to your 50% savings of GDP.
BS rectal extraction. Assumed getting off the carbon cycle which will greatly improve our productivity and keep the US/ world out of wars in the Mid-East over oil resources. And factored in the increased likelihood that the human race doesn't destroy itself. The major powers will let the people in the Mid-East kill each other like they do in Africa where money isn't an issue. I answered facetiously since there is no way to know future "savings" since you can't hold everything constant in the world except for one change. And there are so many massive unexpected changes; look at the accuracy of any long term projection. Read "The Singularity is Near" about how artificial intelligence is going to surpass human intelligence within many of our lifetimes.
As to defense spending, there has been no change I have seen under Trump. Nor do I expect any as long as a defense build-up is foreseen. The barriers to entry are so high in much of the defense industry that they charge what they want and employ practices which ensure higher profits as well as erect barriers to others competing. The companies are much more motivated to increase profits than the Government side is to resist; to me it's not political party ideology but insolvable with our current form of government. And having Government organizations do the work has it's own problems and inefficiencies. Trump's simplistic approach to bluster without deep understanding or factual basis won't solve the problem.
Anyway, back to global warming. In my opinion, it's real and a large portion of the temperature increase is due to man-made CO2. But I don't think we'll do much to prevent the acceleration of it unless we break the carbon cycle; so that's my opinion and basis for 50% of the Gross Global Product. Your opinion is as good as mine on the benefits ......
https://www.nrlmry.navy.mil/tc-bin/.../www/atlantic/tropics/microvap/dmsp&TYPE=ssmi
