LOS ANGELES (CBSLA.com) — Officials from the United States and China — the world’s top two sources of greenhouse gas – gathered in downtown Tuesday for a two-day summit to fight climate change.

Gov. Jerry Brown, Los Angeles Mayor Eric Garcetti and other U.S. city and state officials joined their Chinese counterparts at the JW Marriott Hotel L.A. Live to sign agreements to set verifiable goals and chart a course to limit greenhouse gas emissions in the two nations.

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“Today, the most important players in determining whether the world makes it are the United States and China,” said Gov. Brown, who was the keynote speaker.

Mayor Garcetti, who hosted the event, said global warming, if unchecked, could lead to more of the kinds of weather extremes we have witnessed in California over the past few years.

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“We see it in the fires that are raging up and down the state. We feel it in the hot days that we’ve had and the new records that we’re setting,” Garcetti said. “We feel it even on a rainy day like today, and the drought that is the new normal for the state. We all have to take action.”

The Mayor said the biggest accomplishment on Tuesday was the fact that two biggest greenhouse-gas contributors agreed to take action to tackle environmental issues.

“And together when two nations, great nations, step up not to point fingers, not to ask questions, but to commit to life-saving changes, we can deliver this not just for our nations but to inspire the world,” Garcetti said.

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Vice President Joe Biden is scheduled to deliver closing remarks on the second day of the conference Wednesday afternoon following a visit to a solar energy trade show in Anaheim.