The United States. The conventional wisdom is that what the US gets in return is outsized influence in the internal politics of basically every country within that protection sphere, plus the petro-dollar. I don't totally agree with the second part, but that's what you'd find in an "explainer" from Vox or the pages of The Economist.
The United States, despite inventing the thing and using it first, has done more to get rid of nukes than anyone.
It’s essentially a prisoner’s dilemma where individual countries are better off defecting.
The thing is people and countries don’t all benefit equally from buying into the existing system. It’s the same basic reason people continue to run scams and steal stuff on land etc.
The US has not been the majority player in policing pirates in a long time and piracy is at an all time low - China and Europe handle the majority of the piracy actions around Africa today, the largest source of modern piracy. Even if the US were to withdraw, and it's just Europe and Asia trading with each other, what navy is going to magic into existence to threaten those trade routes? The 5th fleet is in theory always around to back things up, but even if you look at CTF-151 the USA hasn't had the comm since 2009, and basically all of the anti-piracy actions today are small potatoes and easily handled by coalition members.
Yes, the US navy is the best in the world. Yes, without it, there is less ability to protect these trade routes. But if the people that are doing the remaining trade are the people with the next 20 biggest navies, where in the world is the threat going to come from?
If globalization ends it's not going to be because the US navy took their ball and went home, because you have to go really far down the list of naval might to find people who wouldn't want to still be trading with each other.
Container ships produce a lot of emissions, but they also move a lot of cargo. On a CO2 per kilogram per mile basis, containers ships vastly beat out automobiles.
Automobiles are the worst and least efficient mode of transportation, and should be severely curtailed.
But yes, on the whole it's correct that common assumption that the distance freight travels equates to the overall carbon intensity of transit is incorrect.
A more effective change would be to make transportation emit less greenhouse gases. Get hydrogen powered container ships and electric vehicles. This would reduce greenhouse gases significantly more, and wouldn't involve destroying the global economy.
Do you think ammonia or hydrogen is more likely to be used for ships? At this time, I am leaning towards ammonia because storage and infrastructure is simpler.
Funny side note: While writing this post, I was doing a bunch of Google searches about ammonia, hydrogen, and blue vs green. Every single search returned a single ad from Saudi Aramco touting their blue ammonia and hydrogen capabilities. Incredibly depressing. The non-petro states need to hurry up and cover the center 80% of Australia with solar panels (Chilean Andes and North Africa too) to produce whatever green industrial inputs we need from "thin air". Maybe we can run a bunch of carbon sequestration machines too. In parallel, we can drive up carbon taxes.
Per the source above, rail is most efficient at 128k, then ships at 97.3k, then road at 10.8k, where units are in tonne-kilometers shipped per tonne of CO2 emitted.
If Country A can produce 100Mt of raw material by digging up 10000ha of already-destroyed farmland, and Country B would need to clear 100000ha of pristine untouched forest for the same amount of raw material extraction, wouldn't it be better to source from Country A? At least up to some point where the environmental impact of oil used to ship 100Mt of material from Country A is worse than clearing 100000ha of pristine untouched forest.