Australia's rulers know that the imperialist tensions between the US and China could lead to war. They could also force Australia to act even more directly as an imperailist power in its own right. That's why Australia's accelerating its spending on military hardware.
When it comes to rising sea levels, it's already too late. Even if we stop all carbon pollution tomorrow, rising sea levels will destroy coastal communities around the world. The only solution to that will be international cooperation of a kind that capitalism can't deliver.