Donald Trump called climate change a "Chinese hoax" and vowed to undue Obama Administration's efforts to rein in US greenhouse gas emissions. He might have had an "interesting" meeting with Al Gore but Trump's choice to head the Environmental Protection Agency is clear indication that he will keep his promise. Oklahoma Attorney General Scott Pruitt is a long-time foe of the EPA and a strong supporter of the fossil fuels industry who has challenged EPA regulations intended to promote US compliance with the Paris climate change agreement. Pruit is by no means alone; Trump's short list for environmental and energy positions tilts heavily toward industry and climate change deniers.
So when Trump says that climate change is a Chinese hoax, I will take him at his word (Rule No. 1 for survival in an autocracy) and expect him to turn the US into a festival of fossil fuel folly. I do not expect the US government to make any appreciable effort to contain US greenhouse gas emissions during a Trump Administration. I think it likely that we will backslide.
Since the US is the second largest greenhouse gas emitter after China, our lack of progress in the next four or eight years will be a serious barrier to the world's efforts to halt climate change. Given the threat climate change poses to the the world, I would not think it unreasonable for future generations to view the United States as a rogue nation whose policies threaten other nations. Would they be able to invoke the right of self-defense against the US?
Beacon on the hill? A model for other nations? No so much anymore, I'm afraid.