It was the gum-smacking heard 'round the world.

President Obama raised eyebrows (and ire, among some in China) when he was spotted chewing gum while entering an economic summit this week in Beijing.  But according to homeland security expert JulietteKayyem, we should look beyond the social faux pas when evaluating the President's recent trip to China, which, it was announced today, has produced a major greenhouse emissions reduction agreement. 

"President Obama was chewing gum and apparently that's our takeaway from his trip to China, not that he managed quite secretly to get the Chinese, the number one global emissions polluter, to sign an agreement with us, the number two global emissions polluter, to reduce emissions over the next twenty or thirty years," she said.

The agreement, which would reduce U.S. emissions by 26 percent by 2025 and peak Chinese emissions by 2030, is one of the first and most significant climate change commitments from both countries to date. Why so significant? The U.S. and China have two of the most robust economies in the world, and where they go, Kayyem predicted, the rest of the world will follow.

"There's no way you can get third world countries or other countries to sign on to global emissions reductions unless you have China and the U.S. publicly committing to it," she said.

More broadly, Kayyem warned, the world should be looking at climate change not just as an environmental challenge, but as a matter of national security.

"It is probably the one issue that poses an existential threat to the livelihood of so many people, whether it's in the U.S. or island nations in the South Pacific or China," she said.

"It is causing a fight and competition for resources, for clean resources. That's when wars get started. That's when mass migrations occur. That's when people fight over limited goods."

It's also a force, Kayyem noted, that propels people to radicalize. "When people feel like they cannot give to their children, that there's no future for them, radicalization occurs," she explained.

"This is why people fight," she said.

To hear more from homeland security expert Juliette Kayyem, tune in to the full interview on Boston Public Radio above.