Of the many threats and challenges confronting the world, two stand out: the deteriorating relationship between the world’s two most consequential powers, and the looming reality of climate-induced catastrophe. Both require goodwill and real cooperation between the United States and China if they are to be addressed.

The odds are still against it, but there is one way in which the two problems could be addressed in combination to bring about the sort of ‘win–win’ outcome Chinese President Xi Jinping says he favours. It’s unlikely that US President Donald Trump will be sympathetic, especially in the midst of an election campaign, but if Democratic challenger Joe Biden wins he just might be interested in resetting relations with China.

Given the current rhetoric about the beginning of a ‘new cold war’, it’s worth remembering that at the height of the last cold war the US and the Soviet Union managed to negotiate a series of arms-control agreements that not only reduced the immediate danger of nuclear apocalypse, but opened up the possibility of reducing arms expenditure in the process.

The fact that such opportunities weren’t always embraced, and that the US in particular was determined to maintain its strategic dominance at all costs, shouldn’t blind us to the possibility that arms-control agreements offer a way of overcoming the notorious ‘security dilemma’, when states become caught up in futile arms races as they act on the assumption that their notional foes are just as paranoid and untrustworthy as they are themselves.

The intensifying rivalry and ill-feeling that has developed between the US and China is clearly damaging for them—not to mention the rest of us, as we impotently watch from the sidelines and try to conjure up plausible-looking foreign and strategic policies. One of the things Australia could do, however, is to encourage the ‘G2’, China and the US, to take a more constructive approach to their own bilateral relationship and concentrate on common challenges.

In this regard, no problem looms larger than unmitigated climate change. Despite being the world’s largest investor in renewable energy, China in particular is being badly affected by environmental degradation and climate change. Indeed, if there is one thing that really threatens the authority, legitimacy and even continuity of the Chinese Communist Party, it is unhappiness among the middle class about the environmental consequences of rapid development.

Consequently, China just might be interested in an arms-control agreement with the US, particularly if it were based on the assumption that both countries would use the money they saved by not buying new weapons to retrofit their domestic economies along more sustainable lines. This would, after all, allow China’s leaders to claim that they were playing a suitably pivotal role in global affairs while simultaneously addressing the greatest threat to their domestic legitimacy.

Plainly, Trump is unlikely to countenance such an idea, especially as it is designed to address a problem he doesn’t seem to think is real and probably doesn’t even understand. Whatever you may think about Xi’s authoritarianism and incipient megalomania, he does seem to get the basic science around climate change and recognise the threat it poses for any regime that fails to deliver promised improvements in the lives of the masses.

Plenty of people in the US understand the urgency of addressing climate change, too. Unfortunately, they’re not in the Trump administration, which makes the coming election perhaps the most important in the history of America—and perhaps the world. That may sound hyperbolic, but the scientifically informed jury on climate change is unambiguously in, and much of our planet may soon become uninhabitable if action is not taken quickly.

Given the scale of the changes that are needed to ward off the worst effects of even 2°C of warming (which now looks like a best-case scenario), a negotiated arms-control agreement that involves a commitment to drastically and immediately reduce emissions doesn’t look that outlandish. Indeed, if we can’t even collectively agree that this sort of relatively modest and unambiguously rational basis for cooperation is worthwhile, then there’s next to no chance of addressing the even bigger challenges that lie ahead.

It’s vital to recognise that the most immediate danger and ‘enemy’ that the US and China face is not each other but the common challenge of addressing climate change, which many now think threatens the very basis of human civilisation. The good news is that we really have no choice other than to cooperate on a hitherto unprecedented and unimaginable scale if we’re to get out of the hole we have dug ourselves into.

The bad news is that history suggests that international cooperation is not our collective strong suit—especially if the people who are supposed to be leading us don’t even recognise the nature of the problems we face.