Hi Joe and others
I am pleased to read that other hams are concerned, as I am, about the garbage problem to which disposable radio balloons contribute. Thank you, Joe, for raising the issue.
Yes, it's unlikely that a human will encounter one of 29% the radio balloons that falls on land. However, that doesn't mean it's not garbage or not bad. Humans are not the only creatures on this planet who are harmed by humans' garbage. Furthermore, I do not discount the other 71% of the balloons that become garbage in the ocean either. Yes, the components of the circuit will decompose in perhaps hundreds of years, but only the exposed metals will decompose within the first few years in the ocean. The circuit board, ICs, and other components will probably last longer than we will. The mylar balloon will not decompose rapidly in the ocean. It will last a long time and would probably kill a creature if ingested. It will become part of the ocean plastic crisis. See http://plastic-pollution.org/ for an introduction and links to other articles describing various facets of the crisis.
To me, launching a radio balloon is equivalent to throwing the equivalent amount of garbage into the sea or forest. Rationalizing it as a tiny amount of garbage relative to the enormity of the global garbage problem doesn't satisfy me. On the other hand, I am eager to participate in this part of the ham radio hobby once I learn a bit more and Hans introduces the U3B.
When I accidentally lose a piece of garbage to the wind while hiking and am unable to retrieve it, I make a special effort to pick up at least that much trash on my way back. Similarly, I have considered coupling a personal effort to pick up ocean trash or a donation to https://www.theoceancleanup.com/ or https://oceanconservancy.org/ to a future balloon launch. Still, I'm not quite comfortable with this either, as it reeks of "emissions trading".
I would welcome further discussion and exploration on how we can continue these high-altitude propagation and metrology experiments while contributing to environmental solutions rather than being part of the problem.