Since humans started traveling to space, we’ve left a lot of stuff up there. Sometimes that’s good (communications satellites, the space station, ETC), but sometimes not so much (spent rocket parts, satellites that we’re not using anymore, random garbage, ETC). And just like here at home, all of that junk is becoming a problem. In fact it’s becoming such a problem that if just a couple of wrong things happen, modern life as we know it is no longer going to be modern life as we know it. Here’s an interesting, not at all concerning video that explains the situation in understandable terms.
Thankfully it ends with the news that science is aware of the issue and already working on ways to fix it, which will hopefully be met with a better reception than climate change has gotten when it comes time to actually start acting.