Political upsets could stall coordinated international mitigation action, but emissions and investments over the next few years will have long-term consequences. Any delays to mitigation or cuts to renewable energy research by the US will likely render the 2 °C target unachievable if a global precedent is set.
Benjamin M. Sanderson,Reto Knutti. Delays in US mitigation could rule out Paris targets[J]. Nature Climate Change,2016-12-26,Volume:7:Pages:92;94 (2017).