listen. there were some pretty sizeable crowds of students walking out of their schools to demand changes with climate change across the country. not just the country, but around the world. there were huge turnouts in new york, berlin. they say it's the biggest they've had so far. >> what most of these students want is a reduction in greenhouse gas emissions. the 16-year-old climate activist greta thunberg organized the day of demonstrations. >> our nina dos santos is taking look at the rallies around the globe for us. ♪ >> reporter: in australia they gathered in hundreds of thousands, determining to make their voice heard. >> it seems that the only people standing on the wrong side of