Meteors hit Earth every day. 70% of Earth is covered by water so any sizeable incoming meteors over that area are unlikely to be noticed, unless they're spotted by ships and/or satellites. While there is the possibility of a Tsunami event in the event of an ocean impact, a impact on land or a detonation over a populated area are what really concerns people.

The two major events of the last 109 years are the Tunguska event (1908) and the Chelyabinsk Meteor in 2013 (see my post here for a bit more info on these).

That's roughly one major event per century. We track thousands of Near Earth Objects but, of course, we can't track everything and it's the rogue incoming object we have to worry about as by the time we detect it, it's probably too late to do anything about it.

There's speculation that the Mega Fauna - all the large animals - in North America were wiped out and became extinct following the effects, and after-effects of a large object that broke up on entry to the Earth's atmosphere.

They might be rare events (I'd like to see Fitzsimmons research that supports an impact "soon" hypothesis) but when they occur, they are devastating.

"Soon" is a relative term. For humans, it means a year or two, maybe ten if you stretch it. In geological terms, it means anything from 100-10,000 years. The tabloids love playing up doomsday scenarios, so unless Fitzsimmons gives a more concrete timeframe than "soon", I wouldn't give much credence to their prognostications.

Here's one doomsday scenario that seldom gets talked about: a meteor comes in and explodes over northern India or Pakistan, or maybe North Korea. Knee-jerk reactions kick in and the affected nation assumes it's been attacked with a nuclear bomb and retaliates because, if they are under attack and they don't retaliate fast enough, they could get wiped out. So they launch their own nuclear missiles at their perceived enemy...