Introduction: This document is written as a high level background brief to inform discussions of the Citizen’s Assembly. The paper draws on the work of the Intergovernmental Panel on Climate Change (IPCC) – especially the Fifth Assessment Report (AR5), which represents the latest consensus view of the scientific community. These reports are compiled by hundreds of scientists from across the world, who summarise developments and insights from the scientific literature published in peer reviewed journals. The report is signed off by all countries. The IPCC thus provide an authoritative assessment of our state of knowledge on all aspects of climate change. The subsequent sections of this brief are organised around the key questions that I was requested to cover.