Sorry if I say it was an uneducated comment...
Of course Global warming and energy usage are definitely important issues, and I won't sidetrack the entire thread to debate this issue. But it's worth considering that the energy spent folding is going to be spent somewhere by someone - even if it's done by supercomputers in laboratories. The search for curing certain diseases and understanding the human body better is a very important one which is going to continue unabated, and by distributing the work it simply speeds it up.
It should also be considered that we waste an inordinate amount of physical and human resources - and hence add a lot more to global warming - in the continuing treatment of diseases which could otherwise be cured for good. Imagine how much less energy could be used in the future if we find cures or simple treatments for major long-term diseases like Cancers, Alzheimers, Parkinsons, AIDS and so forth. The amount of energy used to produce the medicines, machines and treatments for these diseases is huge, so folding could be a potential way to prevent even larger energy wastage in the future.