Although China will soon be emitting total emissions at levels twice as much as the United States, the following chart demonstrates that the US will still lead even China in per capita emissions.
To make sense of the performance on greenhouse gas emissions of any nation one must understand the magnitude of greenhouse gas emissions reductions necessary to prevent catastrophic warming.
The international community has agreed that future warming should be limited to 2 degrees C because greater warming is believed to create a risk of passing tipping points in the climate system that will trigger rapid increased warming with devastating consequences. Given this there is now a strong scientific consensus that the entire global community must limit its greenhouse gas emissions by as much as 25% to 40 % below 1990 emissions levels by 2020 to have any reasonable chance of avoiding dangerous climate change and that global emissions are still increasing between 2% and 3% per year, the challenge to the international community in regard to magnitude of emissions reductions needed is staggering. And so any national commitment to reduce greenhouse gas emissions must now be evaluated by examining whether the commitment is ambitious enough to prevent dangerous climate change given what is the nation’s fair share of safe global emissions. A simple comparison of the US commitment with needed global emissions reductions clearly reveals that the US promise is woefully and utterly inadequate. That is, the US commitment of 17% below 2005 emissions is only a 4% reduction below 1990 emissions levels making it among the weakest of the developed nations’ promises to reduce emissions and far below of global emissions reductions needed to prevent rapid climate change.