Maybe
http://www.madsci.org/posts/archives/1997-03/8 53558324.Ph.r.html
1500 watts per squre meter
at 510 million square kilometers I make that 6.6 x 10�� joules per day.
Thats about 2 trillion tonnes of coal
But remember it's not the heat that's important here - it's not what's heating it up, it's the insulation effect.
And small amounts of insulation can have a real big effect.
If you don't believe me take off that fraction of an inch of clothes your wearing and go stand outside for an hour or two!
Remember the Ozone hole (now thankfully closing since we stopped using certain aerosoles)
How many fridges and deodorants did it take to make that?
Small things can have big effects!