One thing the public seems completely oblivious of is the situation regarding helium. Currently, we are experiencing a supply shortage, and although suppliers may be able to increase output somewhat, it is a rapidly depleting resource. Supplies will ratchet down rapidly over time.
Certainly, I suggest that everybody seriously consider not wasting helium on party balloons. As a matter of principle, my family have strictly avoided using helium in such a wasteful manner.
At one time Helium was produced as a byproduct of the nuclear weapons industry. Today it comes from certain natural gas deposits. However, they are projected to run dry in the coming decades.
We have all heard of shortages of resources that will in time cause problems for our civilization. Oil and other fossil fuels are one problem; we all hope renewable energy will replace them by the time they run out (i.e. the remaining supplies become excessively expensive). Metals are another problem: Mines are running out. We all hope that recycling and advanced materials will solve that problem.
The trouble with helium though is that it is small and light. It leaks out of all but the most elaborate, and hence expensive, containers. And when it leaks, it goes up, to the top of the atmosphere, where recovery would seem essentially impossible. It can't be collected in recycling depots like junk metal or electronics, and can't be manufactured (since it is an element) other than through nuclear reactions. We have a small supply so it is absolutely critical not to squander it.
I was aware of the shortage from reading articles over the past decade, however it really hit home this past summer when we received a bulletin at the university telling us that our contractual supply of helium for scientific work likely could not be met.
Helium is needed in various industries. It used in extreme cooling, and hence in modern medical devices like MRI machines. It is hard to cool things as low as helium can. It is used in radiation detection, hence is important for nuclear security. It is also used in other areas of medicine. And in the future it may extremely valuable as a fusion fuel. Our decedents will curse us if we have wasted it all. We should be thinking in terms of the supply needed for centuries or millennia. The current shortage is nothing compared to what is to come.
Here is a very interesting article at Wired on the Helium shortage. It points out that there is likely a plentiful supply on the moon. However, sending spacecraft to retrieve it will be staggeringly expensive.