Read the January issue of 'Nature reports Climate Change' the conclusion of several of the reports is that things are more complex then had been previously recognized. Lots of information on geo-engineering - more of trading the old problems for newer more intractable problems. Links led me to an article on the envirnmental problems that had been noted when horses were the prime means of transportation.

One the the first replacements for horses was the electric trolley. Too bad private vehicles suplantted the trolley so quickly in so many places. I think Calgary even had trolleys way back when; but they were all gone before I moved here.