Looking back, it is hard to believe that in the Obama era there were serious discussions about whether a “G2” could emerge – with the US and China coming together, never easily but earnestly, and in good faith, to tackle the world’s great problems. The costs of mutual hostility are now greater and clearer than they were back then: the risk of global economic recession, a failure to tackle the climate crisis, and even of military conflict in the future. Yet far from strengthening, bilateral relations have nosedived. The relationship…