A few days ago, I was roaming around Wikipedia and came across something, this comet came extremely close to Mars for astronomical standards recently.
I'm also working on a science fiction universe and was wondering what would happen if this comet collided with Mars. From Wikipedia, it would have released 24 billion megatons of TNT.
Would this be enough to release the carbon dioxide on Mars and start a runaway greenhouse effect? Also, how would this comet be tweaked to collide with Mars, if even possible?