Not every international agreement is a treaty. You're right, though; this is merely an agreement in principle and has no force whatsoever. That doesn't mean it won't lead to actual legal changes, but this article is misleading.
> this is merely an agreement in principle and has no force whatsoever
You mean that it's unenforceable in a court, but that doesn't mean at all that it lacks force:
Court enforcement isn't the the only force. If your boss, client, spouse, etc. pressures you to do something, it can't be enforced in a court, but it can have great force. We all are subject to great social pressure in our behavior, conduct, life choices, etc. - we all generally speak the same language, dress the same, follow the same life and career paths, avoid socially unacceptable things (even those that are unfairly discriminated against), etc. HN mods have great influence here, even though they have no means of court enforcement (in any practical sense).
International relations in particular has no law, in the sense of a court that can make enforceable decisions. In a sovereign legal sense, it's anarchy. There is no international sovereign government (the UN is a conference of sovereign governments). But obviously a great deal is done which has real force. It's actually very interesting to see the creative ways in which 'international law' (again, not the same as a sovereign government's law) is crafted, given that very significant constraint, in order to give it force and effectiveness. Note that the G7 is exceptionally influential despite having no legal power - why do you think these very powerful, busy people are spending their time there?
The President controls the Executive Branch of the U.S. government. Their decisions have great legal force. Politically, those decisions mostly carry forward to future presidents.
