Scratching the surface

During the last 500,000 years the British ice sheet grew and decayed several times. During ice ages, ice masses grew in the mountains of northern Britain, spread out and met up to form ice sheets that covered the lowland landscape, including parts of the continental shelf that are now underwater. The position of the ice sheet’s farthest reaches on land are reasonably well known, particularly for when the ice was last at its greatest, during the last glacial maximum between 25,000 and 18,000 years ago. But no one is sure how far the ice reached under today’s sea. Conflicting models argue for scenarios ranging from ice advancing to where the continental shelf plunges to the deep, to ice terminating only a short way offshore. If we can reconstruct the volume of the ice-sheet, the corresponding drops and rises in sea level and how the melt-water affected the major current in the North Atlantic (the thermohaline circulation), we will better understand how the oceans, atmosphere and frozen environment interact as a system, and so better understand worldwide environmental change.