The reflectivity (albedo) of snow and ice is significantly influencing the evolution of the Antarctic and Greenlandic ice sheets, due to the positive melt-albedo feedback. Therefore, a wavelength dependent description of the albedo is embedded in our polar regional climate model, which now take all relevant aspects of albedo into account. The updated model has been applied for both ice sheet. Evaluation against satellite observations reveals an improved representation of albedo compared to its predecessor. A remarkable result is that the Antarctic summer climate is extremely sensitive to snow metamorphism; minor overestimations of the metamorphism lead to substantial higher temperatures.

Worldwide excess fishing capacity, steadily increasing demand for fish products, and declining catches in marine fisheries are all expected to lead to increased interest in new or under-utilized fishing opportunities. The polar regions may present such opportunities due to, among other things, impacts of climate change and lack of alternative, commercially viable, fishing opportunities. Expansion of existing polar fisheries and commencement of new polar fisheries are constrained by a considerable lack of scientific knowledge and data on target species as well as on impacts of fisheries on non-target species and the broader ecosystem. The abovementioned socio-economic considerations, however, may lead to less strict adherence to the ecosystem approach to fisheries (EAF). If polar fisheries are allowed to expand in existing fishing areas or commence in new areas, access must be strictly regulated to avoid over-exploitation. This can be achieved by making access to high seas fisheries conditional on participation in the relevant regional fisheries management bodies and by allocating fishing opportunities within them. In light of these potential developments and challenges, the envisaged research will examine the formal rules and practices of polar fisheries management bodies in the context of relevant international law, focusing on three main areas: (i) participation in polar fisheries management bodies; (ii) allocation of fishing opportunities in polar regions; and (iii) the EAF in polar fisheries. The research will, among other things, verify the consistency of polar rules and practices with overarching international law, develop recommendations to strengthen international law, and ascertain entitlements of the Netherlands.

In this project we address the centennial evolution of surface mass balance and in particular meltwater runoff from the Greenland ice sheet (GrIS). GrIS mass loss increased from ~150 Gt yr-1 in 2000-2005, to ~265 Gt yr-1 in 2005-2009 and ~380 Gt yr-1 in 2009-2012, contributing 20-30% to total global average sea level rise over the last decade. An increasingly large fraction of the mass loss (from ~55% in 2000-2005 to ~70% in 2009-2012) is caused by enhanced meltwater runoff. The rapidity of these recent developments is alarming, and we urgently need to address the following questions: how exceptional are recent GrIS surface melt events when viewed in a century-long perspective? What fraction can be ascribed to anthropogenic climate change, and what fraction to natural (decadal) variability? What is the role of transient firn processes and the albedo-melt feedback on meltwater runoff, and how does uncertainty in their representation affect the results? We address these issues by using the ECMWF 20th century global atmospheric re-analysis product, to be released in the summer of 2014, to force -in a fully transient fashion- the coupled regional climate/snow model RACMO2.3. This effort will provide a time series of GrIS surface mass balance, melt and runoff for the period 1900-2014, nearly doubling the length of the currently available time series and enabling us to provide physically-based answers to these pressing questions.

The basic question addressed by this proposal is: what will be the influence of future Arctic climate changes on the Netherlands and how will this impact Dutch policy? The first part is subdivided into two (interrelated) questions: 1) how does Arctic climate change affect the climate of Western Europe (WE) and the Netherlands (NL), 2) to what extent does Arctic climate change provide opportunities for Dutch socio-economic activities in the Arctic (e.g. oil/gas exploration and exploitation, fishery, shipping and transport, tourism), and how does this pose challenges for potentially vulnerable ecosystems with possible impacts on biodiversity. Both issues will impact Dutch policy: 1) WE/NL climate change, affected by specific changes in the Arctic, will directly affect climate scenarios used for Dutch adaptation/mitigation policies. Recent studies suggest that Arctic-induced changes (both in means and extremes) on WE/NL climate might be substantial. However, significant uncertainties remain, which warrants a thorough quantification including uncertainty estimates. 2) Since the Arctic currently undergoes rapid climate changes that may lead to an ice-free summer Arctic possibly within one or two decades, policy measures related to rapid socio-economic and ecological changes in the Arctic, in terms of their desirability and sustainable nature, will probably need to be amended quickly. This study will provide climatological boundary conditions to forthcoming Arctic activities and influences by using a variety of existing high-quality climate model output, state-of-the-art climate models and novel modeling techniques, to accurately quantify Arctic climate change and its impacts on WE/NL climate relevant to Arctic policy measures.

This project studies the dynamics in the structure of an Arctic terrestrial food web and the genetic structure of a population of geese. Geese play a central role in this food web. Historical patterns of habitat distribution will be analysed to recognize the effect of local and global anthropogenic drivers of change. Observations over a time-series of 23 years on three trophic levels with details on food availability, diet selection, intake rate, plant-animal interaction, habitat use, reproductive success and timing of marked individuals (plants, geese and foxes) are combined with predator abundance, predation pressure and disturbance into a spatial model of resource utilisation, habitat distribution and population dynamics. Information on the genetic structure of the barnacle goose population will provide novel insight in contemporary patterns of divergence, population size and gene flow. While studying species-specific plant-animal interaction and immunological parameters we hope to understand historical changes in species distribution. All elements combined should enable the prediction of future scenarios of anthropogenic impact on species interaction within the food web.