“Whether it’s a carbon tax or a cap-in-trade, that’s the mechanism,” she said. “This whole conversation is about reducing greenhouse gas emissions and we each have to find a way in our provinces to do that.”
In 2003 Ontario had about 7600 MW of coal power. Today it has been replaced by 10000 MW of nat.gas  with a additional 1200 MW to be added. Burning nat.gas vs. coal produces about half the CO2 emissions. We routinely export the amount of wind and solar produced due to the excess power produced in Ontario
making it pointless
So we have picked the low hanging fruit. But at what cost? It will have no measurable effect on the climate or weather going forward, no saving in health care.
see:  http://www.ieso.ca/Pages/Ontario%27s-Power-System/Supply-Mix/default.aspx#NaturalGas
http://www.cns-snc.ca/media/media/CNS_Position_Papers/Ontario_coal.pdf
http://www.theglobeandmail.com/news/national/ontarians-paid-37-billion-above-market-price-for-electricity-over-eight-years-ag/article27560753/