Next Back in 2009, for example, the US led the global effort to achieve the Copenhagen Accord at the COP15 climate-change summit, which was attended by more than 100 world leaders. But hopes of a meaningful US contribution were subsequently killed by bipartisan opposition in Congress, which balked at the perceived cost of reducing emissions. Biden, who was then vice president, faces a similar problem today: how to make good on his pledges while knowing that Congress will not approve any serious climate measure. He has therefore chosen the path of least political resistance, which is why Biden’s climate plan carefully avoids notions such as a “carbon tax” or a “cap-and-trade” emissions scheme, both of which are politically toxic in the US.