richard roth explains what to expect. >> much of the world comes together for a global summit. u.n.ficials want the emergency of the climate to be the number one issue despite other confrontations now under way. a new devastating u.n. report on climate change serves as a backdrop to all the talking and speeches. the secretary-general wants action, though and has called on world leaders to speak for only three minutes and he wants concrete bold transformative proposals from world leaders. he doesn't want the usual speeches wherein people stand at the rostrum, leaves town and nobody remembers what he or she said. that's easier said than done since donald trump won't appear or the leader of japan or any other high officials from brazil. the u.n. doesn't have a global climate change army and can't punish those not living up to commitments. the u.n. officials it's time to regather momentum and they're counting on what happened in the streets around the world from the young people, the demonstrations on behalf of thousands of people in dozens of cities. greta thunberg is expected to make