Mercury: MOTOR vehicles, aircraft, power stations — we all know about those bogeymen of climate change that pollute the atmosphere and cause temperatures to rise. But there’s another, less talked-about element in the mix. "Non-energy" activities, mainly to do with land use, account for a third of all human-induced greenhouse gas emissions. Most of it comes from livestock production. Livestock and crops are our main sources of sustenance. And despite growing populations in …