President Barack Obama said Tuesday the world needs to tackle climate change now.
"This one trend — climate change — affects all trends. If we let the world keep warming as fast as it is, and sea levels rising as fast as they are ... then before long we're going to have to devote more and more of our economic and military resources ... to adapting to the various consequences of a changing planet," Obama said. "This is an economic and security imperative that we have to tackle now."
Speaking at the COP21 Climate Change Summit in Paris, Obama urged other countries to agree on lower greenhouse gas emissions.
"Now, all of this will be hard. Getting 200 nations to agree on anything is hard," he said. "But I'm convinced we're going to get big things done here."
Obama also discussed the ongoing situation in Syria, saying Russian President Vladimir Putin sees no military answer to the devastating civil war.
"Now, where we continue to have ongoing difference, is not on the need for political settlement. It's the issue of whether Mr. Assad can continue to serve as president while still bringing that civil war to an end," he said. "It's been my estimation for five years now that that is not possible."
He also said he does not expect to see a 180 degree turn soon on Russia's strategy regarding its support of Syrian President Bashar Assad. "They have invested for years now in keeping Assad in power. Their presence there is predicated on propping him up."
Obama also said he has seen progress on Turkey's efforts to close its southern border with Syria, but added that there are some gaps. "In particular, there are still some 98 kilometers that are still used as a transit point for foreign fighters."
— Reuters contributed to this report.
Correction: An earlier version misstated the location of Turkey's border with Syria.