A record number of countries and territories participated in this year's event.
The initiative involves 7,000 cities across 172 countries.
We are often told that the United States is more divided now than at almost any time in our history. If you're following the presidential election, it's easy to see what they mean. And it's not just in America.
Switch off on Study Abroad for the places we love. Shine a light on Climate Action this Earth Hour, March 19.
Those negotiations are important, but the games really begin next week. March 31st is the first checkpoint when several countries, including the United States, will announce new targets to reduce climate pollution and other commitments to support climate action.