根据国际能源署2014年发表的报告和我们根据美国在全球二氧化碳排放量中所占的份额进行的计算，向清洁能源系统转换将额外花费6.6万亿美元。
And, according to a 2014 International Energy Agency (IEA) report and our own calculations based on the US share of global CO2 emissions, transitioning to a clean-energy system will cost an additional $6.6 trillion.