The U.S. target looks like it’s going to be really tough to meet without new laws.The United States promised to cut emissions 26 percent below 2005 levels by 2025 and to try to get to a 28 percent cut. (Notice a pattern – baseline and stretch goals – between the United States and China?) If the United States hits its current target – 17 percent below 2005 levels by 2020 – on the head, it will need to cut emissions by 2.3-2.8 percent annually between 2020 and 2025, a much faster pace than what’s being targeted through 2020. That is a mighty demanding goal. It will be particularly challenging to meet using existing legal authority – which the administration says can be done.