About 150 people have gathered for a rally in Times Square as part of a series of demonstrations around the world calling for action on global warming.

The focus of Saturday's rallies was the number 350.

Some scientists say that's the level to which atmospheric carbon dioxide emissions, measured in parts per million, should be lowered to prevent dangerous climate change.

To drive the point home, the Times Square rally included a slideshow of photographs of similar events from across the globe, some showing human formations of the number 350. The pictures were displayed on Times Square billboards.