Saving the planet from ecological disaster is all very laudable, but be careful what you wish for. In this two-part Anglo-Canadian production of John Wyndham's 1951 sci-fi novel, the voracious man-eating plants called triffids had been artificially cultivated as a fuel source, so successfully that triffid oil had enabled the world to wean itself off fossil fuels and thus curtail global warming. The story didn’t bother itself with those pesky climate change deniers.