Remember "reserve currency" is mostly a description of a phenomenon, not a legal construct. There no point in a country like the State of Venezuela holding dollars if it has almost nothing to trade for them. That doesn't mean that individual Venezuelans don't hold dollars. They probably hold more than ever. What else would they hold? What currency would you store long-term value in, in South America?

Talk of the Dollar losing reserve status is type of boycott talk. No matter ho much you may agree with the sentiment, boycotts almost never last.

If there is no path to owning property free and clear in a country that country's currency will never be a reserve currency to you. Even wealthy Chinese are moving to Singapore, Thailand and everywhere else they feel their money is safer.

As far as the climate, if you tie these two together you get a grim picture indeed. If the U.S. is allowing dollars to keep going into fossil fuels, and it remains the "reserve currency" then it become a de facto currency for people to avoid de-carbonization costs.