UNITED NATIONS — Under a global cloud of wars and bitter divisions, world leaders meet at the United Nations this week facing new fears that runaway artificial intelligence could threaten humanity even as climate shocks and escalating prices are already making life much tougher for hundreds of millions of people.The annual high-level gathering at the U.N. General Assembly will also be consumed with major wars in Iran, Gaza, Ukraine,Sudan, Congo and Myanmar and a persisting question: Can the leaders do anything to end them?And what can they do about the relentless rise of global warming threatening the future of the…