Asteroid impacts on Earth are an unfortunate inevitability. And while devastating impacts are extremely rare in terms of a human lifespan, the destruction they can potentially cause is far greater than more familiar natural disasters.
International efforts have rallied to address threats such as global warming, earthquakes, hurricanes, and the like, but if a 45-meter-wide chunk of rock comes to pay Earth a visit, humanity really doesn't have a cohesive response plan.
More: http://www.theregister.co.uk/2008/09/25/ase_asteroid_report_to_un/