Mark Maslin of the Environmental Change Research Centre at University College, London, believes that the spike was caused mainly by emissions from tropical wetlands and peat bogs that formed as the ice retreated.

ECONOMIST: Methane and climate change

University College London (UCL) climatologist Mark Maslin called it "the Stern report for medics", referring to the 2006 review that outlined the future impacts of the climate change situation in economic terms and advocated comprehensive, early-stage action to address it.

BBC: Climate 'biggest health threat'