Regional climate change around Greenland - from sea-ice to permafrost and ice sheets. Results from a transient climate simulation at 25km for 1950 - 2050

Simulations with global climate models (GCMs) clearly indicate that major climate changes are expected within the next 100 years. Current observations suggest substantial changes in sea ice. The extent, thickness and seasonality of seaice have been varying over the last several decades with a recent clear declining trend, which has occurred along with steady increase in (air) temperature along the coast of Greenland. The implications for the vulnerable wild life, ecosystems and society in Greenland are complicated and often difficult to assess. One reason for this is the coarse resolution of global climate models, which prevents a detailed assessment of the role of a changing climate near Greenland. In the existing models the Greenland ice sheet is poorly represented, without any dynamics. Following the recommendations from the ACIA assessment, high resolution regional/local climate simulations coupled with ice sheet dynamics should be performed in order to test whether more detailed predictions of climate change can be provided for the Arctic region. Here we present results from a transient climate change experiment with the regional climate model HIRHAM representing the period 1950 - 2050, where the model was used at 25 km horizontal resolution. Results from simple mass balance calculations of changes in the Greenland Ice Sheet and permafrost dynamics based on the simulated atmospheric forcing will be presented. In addition we present a further nesting experiment, in which a full 3D coupled ocean-sea ice model is forced by the regional atmospheric model. This model has a resolution of 20km, which allows the impacts of the changes in the climate on near-shore ocean circulation and stratification to be addressed.