The three main greenhouse gases hit record high levels in the atmosphere last year, the U.N. weather agency said Wednesday, calling it an ominous sign.

The U.S. plans to reduce greenhouse gas emissions dramatically in the next decade. Scientists say it's crucial that the U.S. succeed. Still, many of the positive effects won't arrive for decades.

With surgical care on the rise globally, researchers worry the energy-consuming procedures will have a negative impact on the climate. But they say there are ways to make them more energy efficient.