What kind of problem is 34,000 pieces of space junk circling the Earth?

National Public Radio program Weekend Edition featured the expertise of John Crassidis for a report on how a four-ton section of a SpaceX rocket recently hit the moon, as well as the growing problem of space debris. In a Q&A with the program’s host, Crassidis noted “As far as a scale, a lot of people like to say that space is very big, and I keep saying it's getting smaller every day. So right now, we currently track about 54,000 objects that are greater than about a softball size. And we haven't had that many instances of collisions, but the big one we'd had was in 2009 when two big satellites, Iridium and Cosmos, collided even though we thought we had tracked them well.”