The annual UCL–Lancet Lecture was delivered on 29 November 2009 by Professor Lord (Robert) May, former Government Chief Science Adviser and former President of the Royal Society. Professor Lord May’s lecture was entitled 'Climate Change: The biggest global threat of the 21st century?' The event was organised by the UCL Institute for Global Health, the hub which brings together UCL’s multidisciplinary wealth of intellectual capital and international collaborations to provide innovative, workable solutions at scale to address the Grand Challenge of Global Health.