One pop climate/eco song crossed over and made the charts by Hudson/Ford in 1974..'burn baby burn', written before anyone knew about carbon emissions etc. It's catchy pop, with a bit of environmental conscience thrown in. Some on-line lyric databases have slaughtered the lyrics with cloth eared transcription mistakes, so I won't reproduce them here. Not folk music, but Hudson/Ford came out of the Strawbs.. so kind of protest music in a lighter form.