The Clean Power Plan proposed by the President is a very important step forward for climate change. According to the Energy Information Administration, the American power sector will emit almost half a gigaton less carbon into the atmosphere by 2024 than otherwise would have been the case. That is almost a quarter of all power-sector emissions!
Globally, the picture looks like this through 2021:
To be fair, the graph misses a full third of the reduction, which will happen in 2022-24. I guess that makes it better?
The problem is that electricity generation produces only 40% of the carbon dioxide emitted in the United States. 24% × 40% = 9.6%, which does not look as impressive. (And only 7.2% by 2021.) Add to that the fact that the United States is not the only country on the planet and things look even less impressive.
A start is better than nothing. But it is only a start.