Heads of state from nearly 150 countries met in Paris Monday in a show of support for a strong agreement to combat climate change. The speeches and bilateral meetings offered plenty of rhetoric highlighting the urgency of addressing climate change and little in actual substance. Nonetheless, the star power helped give the start of the conference, formally known as the 21st Conference of Parties (COP 21), the momentum experts say it needs to motivate a strong agreement. A marathon of speeches by world leaders in attendance marked the highlight of the opening session.