The widely reported impacts of climate change on ecosystems and biodiversity pose a threat also to the supply of ecosystem services. Ecosystem services (ES) arise when ecological structures or functions contribute toward meeting a human demand. Global change is impacting biodiversity and ecosystems properties and is therefore likely to affect the supply of ES and, consequently, human well-being. Assessing the possible bio-physical impacts of the ongoing and future changes in climate is relevant for designing mitigation and adaptation policies. Yet undergoing a comprehensive climate impact assessment continues to be a demanding research challenge due to the large knowledge gaps, for instance on impact areas such as the consequences on ecosystem services.<br> Here we present a preliminary assessment of the changes in ES supply as a function of projected changes in climate and land use / land cover (LULC). The assessment is carried out for the mainland of the 28 Member States (MS) of the European Union (EU-28). The focus of the analysis is on regulating ecosystem services, which are directly dependent on the proper functioning of ecosystems, they are not traded on markets so that their contribution to human well-being is more difficult to assess. We present an assessment of changes in ES supply for three regulating services: air quality regulation, soil erosion control, and water flow regulation. The assessment was carried out under the IPCC SRES A1B climate change scenario. Changes were expressed as a positive or negative percentage variation, relative to the present situation. Land conversion was found to have a much stronger impact on ES provision than climate change. When considering both climate change and LULC change the expected variation ranged between -100% and +100%. These results are explained by the key role that LULC plays in the delivery of regulating ES. The sensitivity of ES to climate change is smaller than that to LULC change, with variations ranging at the most between -27% and +27%. However, these changes are the most relevant to assess, for instance, potential economic impacts of climate change on the provision of ES. There are clearly major challenges to address within the area of climate-change impacts, yet the scale of global change requires prompt actions to mitigate or adapt to the new conditions. This work, therefore, represents perforce a preliminary spatially explicit assessment. Further research is needed not only to expand the analysis to other ES, but also to incorporate processes and scaling properties of the systems considered as they become available, and to account for spatial dependencies.
