About 150 world leaders joined U.N. Secretary-General Ban Ki-moon Monday to kick off a two-week climate summit near Paris.
Each leader will speak about what their country is doing to reduce emissions and slow climate change, according to NBC News.
President Barack Obama on Monday called the global talks an "act of defiance" against terrorism, saluting the people of Paris for "insisting this crucial conference go on" just two weeks after attacks that killed 130.
He urged leaders to "rise to this moment" and fight the enemy of cynicism — "the notion we can't do anything" about the warming of the planet."
All members of the G-20 submitted their own plans for addressing global warming. Activists expect the plan that emerges from the Paris summit will address a decrease in fossil fuel emissions.
Efforts to agree on a climate deal have been delayed by a disagreement on whether developing nations share the same burden as industrialized nations that have polluted a lot more. The U.S. and other nations have said hat all countries chip in under the new agreement.