Take a look at these numbers from the link I gave above:
The first number is the deficit for FY2009. FY2009 is October 1, 2008 to September 20, 2009.
That's Bush's deficit. 1,412.7 billion dollars.
You can see Obama has hacked away at that deficit ever since. But because his starting line was so unbelievably high thanks to Bush, the debt was going to keep climbing at an alarming rate until we get our deficits back to "normal".
This is why Republicans keep voting to raise the debt ceiling, but make a lot of noise about it for the rubes.