Chinese media sang the praises of 10 achievements, but commitments to growth, greater economic openness, trade, promoting the digital economy, encouraging entrepreneurship and employment, while defeating corruption, all rank as good things – like motherhood and apple pie. But the last two don’t involve a collision between global and national interests.

China could congratulate itself on a well-organised summit, but Beijing above all insists that global demands must not trespass on domestic necessities, however Xi and his colleagues define them.

North Korea immediately tested international resolve after leaders left Hangzhou by carrying out its fifth nuclear test, almost as if Pyongyang was deliberately thumbing its nose at any idea of a global order. Beijing joined the chorus of condemnation, but stopped there.

Everyone except Kim Jong-un and his colleagues agree that North Korea’s nuclear weapons imperil world peace, but no one has a practical solution to resolve the issue. North Korea’s graduation to a nuclear state is only one aspect of nuclear dangers facing the world.

The nuclear issue is only one multiple-warheaded threat among a galaxy of others endangering the peace and safety of the world.

Summer is supposed to be the silly season when politicians go on holiday, but this year has seen the four horsemen of the Apocalypse galloping across media prime time.

These include death and destruction in Aleppo, an episode in a cruel war waged by proxies of great powers; the continuing flight of refugees now numbering 66 million; the dangerous polarisation of the US election; Brexit’s threat to the post-war order and stability in Europe; increasing hostility to immigrants in the West, and indifference in Asia; and terrorist threats that appear as if in some live whack-a-mole game.

All these have driven from the front pages myriad other potential flashpoints, including territorial claims in the China seas, the unresolvable Arab-Israeli conflict, dictatorship and lack of civil rights in too many countries, and the environmental threat to the planet. But all are alive and dangerous.

All the immediate problems also have medium- and long-term knock-on effects, potentially even more damaging than the original crisis. This is true of North Korea’s nuclear games, of potential conflict in the China seas, the US election or Brexit.

Pope Francis visits Nazi death camp of Auschwitz; implores God to forgive “so much cruelty”

What is truly troubling about the modern world during these weeks of the G20, the UN General Assembly and the annual financial summits of the International Monetary Fund and World Bank, is the inability of so-called “leaders” to comprehend an international dimension in their decision-making.

The only person who does have a global vision is Pope Francis, who has many times spoken out in defence of the poor and vulnerable and the protection of the planet. But how many battalions does the pope have? Or perhaps we should ask how many clicks does he have? – because modern politicians are increasingly driven by the trivia of soap operas that enchant social media.

That is a major factor driving leaders in the West to short-term and nationalist positions without giving a damn for consequences for the rest of the world. That their promises and policies may be based on slogans, half-truths, rumours or outright lies – think Brexit or Donald Trump – does not seem to worry them.

US President Barack Obama, normally a most thoughtful man, was driven to short-termism when he pushed for World Bank president Jim Yong Kim to be approved for a second term this month, even though his existing term still has 10 months to run. You can see why Obama did it – because he feared leaving the nomination to his successor if Trump wins.

Obama’s haste was a betrayal of the promise that the leaders of the global financial system would be chosen on merit, not according to the post-war old boys’ club rules that the US gets to pick the World Bank head and Europe the IMF’s.

Over at the UN, the choice of a successor to Ban Ki-moon led to question-and-answer sessions with the candidates, and leaked secret ballots of the voting intentions of Security Council members. But with only months before Ban’s term ends, secretive debate is still going on. The original old boys’ club, the veto-wielding five permanent members of the council, have made no promises about letting the best person win.

That’s why China’s leadership of the G20 was critical and ultimately disappointing. Xi is increasingly driven by how he sees his domestic agenda, on which critical voices are unwanted.

Professors of realpolitik are writing books about the impending decline of the West and arguing when China will be the world’s top dog, as soon as 2020 or as late as 2040. It is natural, they say, that the top economic power should also rule the global political and military roost.

A president Trump might hasten China’s rise if he pulls US troops back from Asia, as key supporters are urging.

But the fragile and battered planet needs to get beyond old realpolitik of war and conquest and top dogs. Any new war involving the US, China or Japan would have disastrous consequences for all.

Beijing would show its real 21st-century wisdom when it uses its soft power – to listen to and accommodate people outside the Middle Kingdom and to understand that we all have to live together in some kind of harmony if mankind is to survive.

Kevin Rafferty is a political commentator