An estimated 60% of the presently observed sea level rise is attributed to melting glaciers, ice caps and ice sheets. The contribution of Arctic glaciers and especially the Greenland ice sheet (GrIS) has more than doubled over the period 1961-2008, and is likely to increase further when global temperature increases over the coming century. A first order effect of increasing temperatures on the glacier mass budget is an increase in surface melt. However, not all melt contributes to mass loss via runoff, because part of the meltwater refreezes in the cold snow. For the GrIS, an estimated 30-50% of all meltwater refreezes. Infiltration of water and subsequent refreezing is not well included in existing mass balance models, and estimates of refreezing are not well validated due to a lack of observations. Given the importance of refreezing for the mass budget of Arctic glaciers, in this proposal we focus on improving refreezing estimates for the GrIS and therewith other Arctic ice masses, by using a combined observational and modelling approach. Existing satellite and in-situ observations, complemented with detailed snow temperature observations to be carried out in western Greenland (K-transect), will be used to evaluate the mass balance terms and refreezing modelled with the regional climate model RACMO2, which includes a multi-layer snow model. After improvements to the snow model have been implemented and evaluated, RACMO2 will be run for the period 1958-present-2100 in order to study the role of refreezing in the mass balance of the GrIS in a changing climate.

Up to now most sea level projection where mainly for the global scale and did not consider the probability density functions in much detail. This is not sufficient for coastal management where projections for local rise are needed. Moreover for risk analyses it is important to study the extreme values, which may have only a small probability. Recent work indicates that in particular the changes in the dynamics of ice sheets may lead to skewed distributions, which need to be taken into account in total local projections of sea level. New developments in sea level research enable the start of the construction of probability density functions for the North-Sea region based on CMIP5 ensemble results. Updated calculations of the contribution of thermal expansion, glaciers and ice sheets, groundwater depletion, air pressure differences and changing wind and wave patterns will be combined in a sea level equation model that accounts for gravitational and rotational effects of the changes in mass in the ocean. Results will be validated with local data for the North-Sea region, corrected for tidal effects in order to attribute sea level changes and increase the reliability of future projections. The end result are trends and the variability in the trend of local sea level rise including a probability density function, which can be used for coastal management purposes.

Wildfires impact ecosystems, air quality, and the climate, with human activities and climate change making them more intense. The INFLAMES project takes an interdisciplinary approach, combining Dutch atmospheric satellite data, computer models, and field research to understand how wildfires evolve and affect the environment around the world. Experts from climate science, ecology, and social sciences work together to study how fire emissions influence air pollution, vegetation, and future climate patterns. By integrating these perspectives, INFLAMES aims to improve wildfire predictions and inform strategies to manage their risks in a changing world.

How do we prepare for increasingly extreme weather conditions? The answer to this question is hidden in an essential part of our climate system: clouds. Researchers will develop a new type of radar that can observe the whole sky in a matter of seconds. It is designed to both reveal how particles grow inside clouds and precipitation and to track large-scale movements of weather systems. The transportable radar will contribute to breakthroughs in climate and atmospheric research, more precise weather forecasts (crucial for water management) and further (radar) innovations.