WASHINGTON (AP) — More than 120 world leaders will convene for a U.N. climate summit. Environmentalists will take to the streets in what is being billed as the largest march ever on global warming. Celebrities, CEOs and climatologists will appear at a string of events and press conferences.

Despite the hoopla in New York this week, little action is expected on saving the planet.

The hope is to recapture the momentum lost after the disappointing 2009 climate summit in Copenhagen. But few decisions are expected beyond galvanizing political will for a new global climate treaty by the end of 2015.

Whatever emerges from the one-day summit Tuesday is unlikely to bring the world closer to a goal set in 2009: Preventing Earth's temperature from rising 2 degrees Fahrenheit from where it is now.