Scientists believe they have found the world's oldest ice sheet, which will provide information on future climate change. The discovery, made in eastern Antarctica, is 1.5 million years old, almost twice the age of the previous oldest sample. Dr Tas van Ommen, from the Australian Antarctic Division, says airborne radars were used to shine light through the ice and reveal its thickness. The ice sheet is about three kilometres thick. Dr van Ommen says an ice core taken from the sheet could hold valuable information about the earth's climate and greenhouse gases.