Can we really power civilization with just hydro, solar and wind power? Scientist Ken Caldeira says almost, but not quite, in a new study. But we’ve already dumped too many greenhouse gases into the atmosphere. From the UK, scientist David Beerling explains a big new solution: laying down carbon-grabbing rock as fertilizer in the world’s fields. James Hansen is a co-author. Environmental journalist Stephen Leahy reports the good and bad news as cities lead the way. This is Radio Ecoshock 180314