As stated by Noah Smith in The Atlantic last fall.
U.S. CO2 emissions are declining rapidly with a shift from coal to natural gas. Down over 10% since 2007, and continuing to decline even as the U.S. economy has grown back since the financial crisis. Shift from coal to gas is made possible as a result of the shale gas boom and massive new gas supplies coming on line.
2. Solar (and other renewables)
Solar PV pricing is following its own sort of "Moore's Law" -- 7% annual decline in costs annually for MANY years past, and likely to continue at the same rate for the next 20 years at least. Increasingly available and cheaper electricity from renewables will allow a transition to electric vehicles and gradual shift away from oil and coal entirely.
Short term -- shift from coal to gas.
Longer term -- shift entirely to renewables.