It's almost a year since Barry Brook, Professor of Climate Change at Adelaide University, posted a piece on his blog about Australia's most powerful global warming agent. That piece, co-authored with Peter Singer and I, showed that Australia's livestock cause more warming than all our coal-fired power stations.

It wasn't a defence of coal, it was a plea for people to understand the role of methane as a potent climate forcing and to understand that cattle methane is no laughing matter.