Willem van der Bilt

While warming at rates that far exceed the global average, Arctic climate is also becoming much wetter. This intensification of the hydrological cycle is closely linked to the dramatic loss of regional sea ice. As larger areas are covered by open water for longer periods, moisture fluxes to theatmosphere increase sharply. A wetter Arctic will have global impacts: for example, when falling as snow, precipitation increases can partially offset melt of the region`s ice caps – major contributors to global sea-level rise. Despite the consequences for millions of people living in low-lying areas, the future response of the Arctic water cycle remains poorly constrained. This is best-illustrated by a worrying mismatch between instrumental data and projections. Simulations under-estimate observed changes and exhibit considerable seasonal variability, while predicted increases differ by up to a factor four between models. Our ability to constrain future change is severely hampered by a lack of baseline data. Predictions remain uncertain,because climate models are calibrated to instrumental data while future change exceeds this range. I propose to close this pressing knowledge gap by taking full advantage of key geological windows into near-future Arctic climate: lake sediments from the warmer-than-present Early Holocene (EH) period. Concretely, this project aims to quantify linkages between hydrological intensification and glacial evolution in a warmer Arctic.