The climate modelling part of ice2ice had a very productive meeting in Copenhagen in September with an opportunity to both hear about progress in the simulations and discuss problems, potential pitfalls and the potential results. The science part of the programme commenced with a good overview of the representation of sea ice in CMIP5 models and how this is likely to change presented by Shuting Yang. These results showed that even in a 2°C world, Arctic sea ice is likely to be gone in September. We also considered the EC-Earth – PISM results for the extended RCP8.5 scenario. Shuting showed a linear relationship between sea ice and surface mass balance in this run and there was much discussion on the implications of Arctic ocean stratification and salinity in the models and how this anaylsis can be both used for ice2ice and extended with other models, output and datasets.

Mats Bentsen gave an interesting overview of the NorESM model, the updates since CMIP5 that will be used in CMIP6 and the configuration for the palaeo-simulations. The run-time is impressive and there has been a significant improvement in model performance in the North Atlantic.

Rasmus Pedersen presented a detailed overview of his PhD work using the CESM model to identify the atmospheric response to regional sea ice change, where sensitivity experiments in different sectors of the Arctic Ocean were carried out, with some rigorous questioning afterwards, which he acquitted well.

Peter Langen presented some statistical work on the CMIP5 model outputs and ways to better define uncertainties in projections which is relevant for the way we will analyse the ice2ice datasets.

We also managed to set up some remote participation with Norwegian colleagues not able to join us; Lu Li updated us from Bergen on the challenges and progress in setting up WRF to model the Greenland domain. A couple of issues were identified and the future strategy for both regional models (WRF and HIRHAM5) was firmed up.

Finally there was a wide-ranging discussion session that dealt with coordination of the modelling programme, the planned palaeo-runs and sensitivity experiments and how to synthesise the data and analysis together.

 

Author Ruth Mottram