Jubilant crowds bid farewell on Sunday to the hottest year on record, closing a turbulent 12 months marked by clever chatbots, climate crises and devastating wars in Gaza and Ukraine.

Much of the world's population — now more than 8 billion — is hoping to shake off high living costs and global tumult in 2024, which will bring elections concerning half the world's population and the Paris Olympics.

In Sydney, the self-proclaimed "New Year's capital of the world," more than a million partygoers packed around the harbor, with city officials and police warning that all vantage points were full.