Canada has the third largest natural gas production after USA and Russia . Total production according to Environment Canada, was about 202 GW in 2012.
A quick math: 202 Gw is 202*8670 =1,771,333 MWh per year and 1 GWh = 3,600 GJ, thus 202 GW = 6,377,000,000 GJ per year
According to NRCcan, burning natural gas produces is 56 kg of CO2 per GJ. Thus total emission of Canadian Natural Gas from combustion is 6,376,000,000 x 56 = 357,000,000,000 kgCO2eq/year or 357 Mt CO2Eq/yr. On top of that, Environment “Canada 2012 emission trends” estimates that GHG emission for Natural gas extraction only was 46 Mt/yr.
357 Mt combustion + 46 Mt extraction = about 400 Mt of CO2 eq. per year. Total CO2 for Canada is about 720 MtCO2/yr (2011). Thus ‘Natural’ gas generates the equivalent of more than half of total Canadian greenhouse gas emissions.
In addition, US EPA estimates that 3.2% of global gas production leaks into the atmosphere. (Well heads, valves, pipelines, etc,…- some other sources indicates 9% worldwide) For Canada, it would be the equivalent of 6.46 GW or 200,000,000 GJ leaked per year. The gas emitted is not CO2 but Methane (NH$) with a GHG factor 20 times more potent than CO2. Therefore, total GHG emission, including leakage, is: 357*(1-0.032+0.032*20) + 46 = 630 Mt CO2 eq !
Almost the entire Canadian inventoried emissions !
The bottom line: Natural Gas is definitely not green contrary to what industry and some governments want us to believe.
One may argue that a significant portion of the gas is exported to the US thus becoming US problem. But it does not make any difference as far as climate change is concerned.
On another note, Canada NG production is only 1/1,000,000 (one millionth) of total solar energy intercepted by earth. Would it be not smarter to develop solar energy rather than more shale gas?