An asteroid just made a near miss of Earth, after being discovered 3 days ago. Had it hit us, though, it would not have been the end of the world, since this rock is only about 100 feet across. But traveling at 40k MPH, it would have done some regional damage, similar to the 1918 hit in Siberia. Earth was actually hit by an asteroid last October, but that rock was only the size of a car, and exploded in the atmosphere before it had a chance to hit the ground.
Nope, no world coming to an end here, but it is something to think about, and having a way to destroy or deflect near Earth objects would make me feel a lot safer. You never know when a civilization changing object might be discovered, maybe only hours before civilization does change due to its hitting Earth. IMHO - This is a project that the whole world should get behind, no matter what differences we have. If we put them aside for something this important, then the human race as we know it will deserve to continue.
Now lets go nuke each other out of existence.