No they could be socialists, anarchists, anarcho-syndicalists, communists.
Much of leftist political theory is coming at libertarianism from the view that liberalism provides necessary but not sufficient conditions for freedom. We have to go further than classical liberalism to get more freedom.
Capital L Libertarian is a very right-wing political faction in the USA, but libertarianism is not that.
They would be broadly similar to the liberal democracy solution, with perhaps the implementation of cooperative ownership of production so that the owners, being ordinary people, are vulnerable to climate change. But certainly some kind of legislative solution would be needed, though the government structure would be different.
Much of leftist political theory is coming at libertarianism from the view that liberalism provides necessary but not sufficient conditions for freedom. We have to go further than classical liberalism to get more freedom.
Capital L Libertarian is a very right-wing political faction in the USA, but libertarianism is not that.