This story was originally published by Mother Jones and is reproduced here as part of the Climate Desk collaboration.

A major two-week summit on climate change opened on Monday in Paris, and President Barack Obama was there to urge world leaders to push for a strong international agreement to slow global warming.

In his speech (video above), the president also offered a rebuke to the terrorists behind the Nov. 13 attacks in the French capital that left 130 people dead.

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The summit, he said, is “an act of defiance that proves nothing will deter us from building the future we want for our children.”

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Obama acknowledged America’s unique responsibility for ensuring success at the talks, which are designed to produce an unprecedented agreement between nearly 200 nations to reduce greenhouse gas emissions and prepare for the impacts of climate change. It’s the first time nations have tried to reach that goal since the last major climate summit, in 2009 in Copenhagen, crumbled over disagreements between the U.S., China, and developing nations.

In his second term, Obama has sought to make action on climate change a central part of his legacy; a strong agreement in Paris would be a vital component to that. “I’ve come here personally, as the leader of the world’s largest economy and the second-largest emitter,” Obama said, “to say that the United States of America not only recognizes our role in creating this problem, we embrace our responsibility to do something about it.”

Prior the speech, Obama met privately with Chinese President Xi Jinping. The two leaders have worked closely over the last year to advance a joint climate agenda. President Xi also gave a speech, in which he said it was “very important for China and the United States to be firmly committed to the right direction of building a new model of major country relations.”

Obama’s remarks come a day after the White House announced a sweeping initiative to double public-sector investment in clean energy research and development from $5 billion to $10 billion by 2020. That new program, known as Mission Innovation, also includes over a dozen major private-sector investors, including Bill Gates, Richard Branson, and Mark Zuckerberg.

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Finance for clean energy and for climate change adaptation is likely to be a major issue at the talks, as vulnerable nations in Africa, Southeast Asia, and elsewhere urge the U.S. and other major emitters to pony up more cash. At the last major climate summit, in 2009 in Copenhagen, countries agreed to raise $100 billion per year for a U.N.-administered climate adaptation fund. That goal is only about two-thirds met.