The chance of another Tunguska-size impact somewhere on Earth this century is about 30%. That isn’t the likelihood that you will be killed by an asteroid, but rather the odds that you will read a news headline about an asteroid impact of this size somewhere on Earth. Unfortunately, that headline could be about the destruction of a city, as opposed to an unpopulated region of Siberia.
The chance in your lifetime of an even bigger asteroid impact on Earth—with explosive energy of 100 megatons of TNT—is about 1%. Such an impact would deliver many times the explosive energy of all the munitions used in World War II, including the atomic bombs. This risk to humanity is similar to an individual’s odds of dying in a car accident. That risk is small, but would you drive a car without air bags and seat belts? The question is apt because our society is effectively doing so with regard to the risk of a devastating asteroid strike.
I’ve been concerned about this for years (actually decades, ever since Alvarez first came up with his dinosaur theory, which seems to have been recently confirmed).