The just released BP Statistical Review includes an updated historical record of CO2 emissions across the world, through 2013.
While China's CO2 emissions have almost tripled since the Kyoto Protocol of 1997, the U.S. emissions have decreased about 2%.
That U.S. reduction actually is superior to all the world's major regions and entities, as identified by the BP research report. This U.S. reduction (see adjacent chart) took place even though the U.S. was one of the few countries not to sign the 'Protocol.'
With that said, any CO2 emission reduction by the U.S. is being immediately offset by the huge increases happening in other parts of the world. As a result, neither U.S. citizens, nor the world's, are benefiting from any U.S. CO2 reduction efforts.
To make the U.S. CO2 reduction aspirations even more bleak, if America could slash its emissions by 50% for each of the next 85 years, the net impact on global temperatures by 2100AD, at best, might be all of a measly -0.09°C.
That type of impact would require U.S. emissions to drop by some 3 billion metric tonnes per year, which based on today's technology, would likely amount to at least an annual $1 trillion expense (assumes a ludicrously low $400 per tonne cost to immediately replace all the lost fossil fuel utilization, needed new infrastructure, replacement transportation vehicles and g*d knows what else to survive).