Second I want to mention there aren’t “Democratic” states or “Republican” states. Just states. Each state is full of Americans. Sometimes they vote for one party and sometimes they vote for another. For example I used to vote Republican and then the party has diverged from what I value. I live in the same state and that hasn’t changed.
To answer your question though which is why can’t states with supposed Democrat leadership or control create legislation for their own states - they can and often do. For example [1].
It’s important to note that Congress can take action at the federal level, and state legislatures can also take action at the state level and they’ll probably be able to do some very precise legislation that the federal government would have trouble with, but then the federal government can use its much greater power (and budget) to do things that any single state or group of states cannot.
[1] https://www.cnn.com/2022/09/06/business/california-emissions...
The US military labelled climate change as a natsecurity threat [1], unfortunately NATO is only concerned with other countries invading or waging a war against the member states and thus such problems can't be addressed even though they are directly related to national security.
[1] https://www.defense.gov/News/News-Stories/Article/Article/27...
I also don’t think invasion of member states is the only thing NATO is concerned with. For instance, NATO allies are coordinating and providing direct military support to Ukraine which isn’t a member state.
For the US climate change policy completely falls at the feet of one group of people, and that’s Republicans. Period. End of story. No possible narrative otherwise exists.
“Can’t the President issue executive orders?”
Yes but the Supreme Court has been striking down and limiting the EPA from executing on executive orders or other mandates that the agency has. For example last year [1]
[1] https://www.npr.org/2022/06/30/1103595898/supreme-court-epa-...-Edit in response to OP edit-
Biden actually has addressed the UN at least once [2] and discussed climate change. He wouldn’t address NATO on this topic because NATO is a defensive military alliance and most NATO members are well aware of climate change risks.
He doesn’t need to explain to other political leaders that his “hands are tied” because they already know and understand how the U.S. political landscape works.
[2] https://abcnews.go.com/Politics/biden-challenges-act-pandemi...