NEW YORK (AFP) - A "once-in-a-generation" music event circled the world last Saturday (Sept 26), with a slew of megastars taking the stage in New York and beyond for Global Citizen Live - 24 hours of shows across the planet to raise awareness on climate change, vaccine equality and famine.

Between star-studded sets of some of the biggest names in music - including Elton John, BTS, Coldplay, Lizzo, Jennifer Lopez and Billie Eilish - actors, politicians, company executives, royals, actors and activists made appeals or announced donations to tackle major global challenges.

NGO Global Citizen wants one billion trees planted, two billion vaccines delivered to the poorest countries and meals for 41 million people on the brink of starvation.

After the show ended in Paris and handed off to New York, Britain's Prince Harry and his wife, Meghan Markle, took to the stage to advocate for Covid-19 vaccine access to be treated "as a basic human right".

The Duke and Duchess of Sussex followed pop veteran Cyndi Lauper with a rendition of her Girls Just Want to Have Fun dedicated to Afghan women.

As night fell, the crowd swelled and attendees roared for shows from headliners, including Eilish.

Between sets, funding announcements poured in and calls to action were hammered home, even from the International Space Station.

The show moved on from New York to Los Angeles, opened by pop band 5 Seconds of Summer at the Greek Theatre in Los Angeles, with Demi Lovato, Adam Lambert and Stevie Wonder, among others, also billed.

The broadcast on social media opened with a pre-recorded performance by pop superstars BTS in Seoul before the show kicked off in Paris with Elton John.

Pre-recorded performances were also delivered by Green Day in Los Angeles, DJ superstar Alok in Rio, Kylie Minogue in London and Andrea Bocelli in Tuscany.