This probably happens to everyone who goes somewhere relatively pristine as a tourist: I've come home thinking tourism to Antarctica should be tightly constrained. Maybe I shouldn't have gone?

There's a limited number of places where you can take a diversely aged and enabled group of people to experience the Antarctic Peninsula. Most of the tour operators do a very good job of limiting their impact. I don't recall ever seeing trash. But, anywhere there was snow, it was easy to find evidence of someone who was there within the last few days, especially if it was good hill for sledding on your waterproof pants.

Where's the line that lets us know when too many people are visiting? History lets us know that we'll know the number after it's too late to turn back the damage.