Some 28 trillion tonnes of ice have disappeared from the surface of the Earth since 1994: enough to cover the entire surface of the UK to 100 metres thick. That's the stunning conclusion of a new report by scientists. The consequence could be sea level rises of a metre by the end of the century. To put that into perspective, every centimetre of sea level rise displaces around a million people from low-lying homelands. We speak to Professor Andrew Shepherd, director of the Centre for Polar Observation and Modelling at the University of Leeds, who worked on the report.