A B S T R A C T Temperature, precipitation and wind extremes over Europe are examined in an ensemble of RCA3 regional climate model simulations driven by six different global climate models (ECHAM5, CCSM3, HadCM3, CNRM, BCM and IPSL) under the SRES A1B emission scenario. The extremes are expressed in terms of the 20-yr return values of annual temperature and wind extremes and seasonal precipitation extremes.The ensemble shows reduction of recurrence time of warm extremes from 20 yr in 1961-1990 (CTL) to 1-2 yr over southern Europe and to 5 yr over Scandinavia in 2071-2100 (SCN) while cold extremes, defined for CTL, almost disappear in the future. The recurrence time of intense precipitation reduces from 20 yr in CTL to 6-10 yr in SCN over northern and central Europe in summer and even more to 2-4 yr in Scandinavia in winter. The projected changes in wind extremes have a large spread among the six simulations with a disperse tendency (1-2 m s −1 ) of strengthening north of 45 • N and weakening south of it which is sensitive to the number of simulations in the ensemble. Changes in temperature extremes are more robust compared to those in precipitation extremes while there is less confidence on changes in wind extremes.

Published by Copernicus Publications on behalf of the European Geosciences Union. 484M.-J. Gaillard et al.: Holocene land-cover reconstructions for studies on land cover-climate feedbacks Abstract. The major objectives of this paper are: (1) to review the pros and cons of the scenarios of past anthropogenic land cover change (ALCC) developed during the last ten years, (2) to discuss issues related to pollen-based reconstruction of the past land-cover and introduce a new method, REVEALS (Regional Estimates of VEgetation Abundance from Large Sites), to infer long-term records of past landcover from pollen data, (3) to present a new project (LAND-CLIM: LAND cover -CLIMate interactions in NW Europe during the Holocene) currently underway, and show preliminary results of REVEALS reconstructions of the regional land-cover in the Czech Republic for five selected time windows of the Holocene, and (4) to discuss the implications and future directions in climate and vegetation/land-cover modeling, and in the assessment of the effects of human-induced changes in land-cover on the regional climate through altered feedbacks. The existing ALCC scenarios show large discrepancies between them, and few cover time periods older than AD 800. When these scenarios are used to assess the impact of human land-use on climate, contrasting results are obtained. It emphasizes the need for methods such as the REVEALS model-based land-cover reconstructions. They might help to fine-tune descriptions of past landcover and lead to a better understanding of how long-term changes in ALCC might have influenced climate. The RE-VEALS model is demonstrated to provide better estimates of the regional vegetation/land-cover changes than the traditional use of pollen percentages. This will achieve a robust assessment of land cover at regional-to continental-spatial scale throughout the Holocene. We present maps of RE-VEALS estimates for the percentage cover of 10 plant functional types (PFTs) at 200 BP and 6000 BP, and of the two open-land PFTs "grassland" and "agricultural land" at five time-windows from 6000 BP to recent time. The LAND-CLIM results are expected to provide crucial data to reassess ALCC estimates for a better understanding of the land suface-atmosphere interactions.

A B S T R A C T Seasonal mean temperature, precipitation and wind speed over Europe are analysed in an ensemble of 16 regional climate model (RCM) simulations for 1961-2100. The RCM takes boundary conditions from seven global climate models (GCMs) under four emission scenarios. One GCM was run three times under one emission scenario differing only in initial conditions. The ensemble is used to; (i) evaluate the simulated climate for 1961-1990, (ii) assess future climate change and (iii) illustrate uncertainties in future climate change related to natural variability, boundary conditions and emissions. Biases in the 1961-1990 period are strongly related to errors in the large-scale circulation in the GCMs. Significant temperature increases are seen for all of Europe already in the next decades. Precipitation increases in northern and decreases in southern Europe with a zone in between where the sign of change is uncertain. Wind speed decreases in many areas with exceptions in the northern seas and in parts of the Mediterranean in summer. Uncertainty largely depends on choice of GCM and their representation of changes in the large-scale circulation. The uncertainty related to forcing is most important by the end of the century while natural variability sometimes dominates the uncertainty in the nearest few decades.

Abstract. The Land Use and Climate Across Scales Flagship Pilot Study (LUCAS FPS) is a coordinated community effort to improve the integration of land use change (LUC) in regional climate models (RCMs) and to quantify the biogeophysical effects of LUC on local to regional climate in Europe. In the first phase of LUCAS, nine RCMs are used to explore the biogeophysical impacts of re-/afforestation over Europe: two idealized experiments representing respectively a non-forested and a maximally forested Europe are compared in order to quantify spatial and temporal variations in the regional climate sensitivity to forestation. We find some robust features in the simulated response to forestation. In particular, all models indicate a year-round decrease in surface albedo, which is most pronounced in winter and spring at high latitudes. This results in a winter warming effect, with values ranging from +0.2 to +1 K on average over Scandinavia depending on models. However, there are also a number of strongly diverging responses. For instance, there is no agreement on the sign of temperature changes in summer with some RCMs predicting a widespread cooling from forestation (well below −2 K in most regions), a widespread warming (around +2 K or above in most regions) or a mixed response. A large part of the inter-model spread is attributed to the representation of land processes. In particular, differences in the partitioning of sensible and latent heat are identified as a key source of uncertainty in summer. Atmospheric processes, such as changes in incoming radiation due to cloud cover feedbacks, also influence the simulated response in most seasons. In conclusion, the multi-model approach we use here has the potential to deliver more robust and reliable information to stakeholders involved in land use planning, as compared to results based on single models. However, given the contradictory responses identified, our results also show that there are still fundamental uncertainties that need to be tackled to better anticipate the possible intended or unintended consequences of LUC on regional climates.

Abstract. This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, ∼ 6 and ∼ 0.2 k BP in Europe. We apply We apply the Rossby Centre regional climate model RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three G. Strandberg et al.: Sensitivity to changes in anthropogenic deforestationfrom the KK10 scenario (V + KK10). The climate model results show that the simulated effects of deforestation depend on both local/regional climate and vegetation characteristics. At ∼ 6 k BP the extent of simulated deforestation in Europe is generally small, but there are areas where deforestation is large enough to produce significant differences in summer temperatures of 0.5-1 • C. At ∼ 0.2 k BP, extensive deforestation, particularly according to the KK10 model, leads to significant temperature differences in large parts of Europe in both winter and summer. In winter, deforestation leads to lower temperatures because of the differences in albedo between forested and unforested areas, particularly in the snow-covered regions. In summer, deforestation leads to higher temperatures in central and eastern Europe because evapotranspiration from unforested areas is lower than from forests. Summer evaporation is already limited in the southernmost parts of Europe under potential vegetation conditions and, therefore, cannot become much lower. Accordingly, the albedo effect dominates in southern Europe also in summer, which implies that deforestation causes a decrease in temperatures. Differences in summer temperature due to deforestation range from −1 • C in south-western Europe to +1 • C in eastern Europe. The choice of anthropogenic landcover scenario has a significant influence on the simulated climate, but uncertainties in palaeoclimate proxy data for the two time periods do not allow for a definitive discrimination among climate model results.

A B S T R A C TA fully coupled atmosphere-ocean general circulation model is used to simulate climate conditions during the last glacial maximum (LGM). Forcing conditions include astronomical parameters, greenhouse gases, ice sheets and vegetation. A 50-yr period of the global simulation is dynamically downscaled to 50 km horizontal resolution over Europe with a regional climate model (RCM). A dynamic vegetation model is used to produce vegetation that is consistent with the climate simulated by the RCM. This vegetation is used in a final simulation with the RCM. The resulting climate is 5-10 • C colder than the recent past climate (representative of year 1990) over ice-free parts of Europe as an annual average; over the ice-sheet up to 40 • C colder in winter. The average model-proxy error is about the same for summer and winter, for pollen-based proxies. The RCM results are within (outside) the uncertainty limits for winter (summer). Sensitivity studies performed with the RCM indicate that the simulated climate is sensitive to changes in vegetation, whereas the location of the ice sheet only affects the climate around the ice sheet. The RCM-simulated interannual variability in near surface temperature is significantly larger at LGM than in the recent past climate.

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Abstract. We investigate European regional climate change for time periods when the global mean temperature has increased by 1.5 and 2 • C compared to pre-industrial conditions. Results are based on regional downscaling of transient climate change simulations for the 21st century with global climate models (GCMs) from the fifth-phase Coupled Model Intercomparison Project (CMIP5). We use an ensemble of EURO-CORDEX highresolution regional climate model (RCM) simulations undertaken at a computational grid of 12.5 km horizontal resolution covering Europe. The ensemble consists of a range of RCMs that have been used for downscaling different GCMs under the RCP8.5 forcing scenario. The results indicate considerable near-surface warming already at the lower 1.5 • C of warming. Regional warming exceeds that of the global mean in most parts of Europe, being the strongest in the northernmost parts of Europe in winter and in the southernmost parts of Europe together with parts of Scandinavia in summer. Changes in precipitation, which are less robust than the ones in temperature, include increases in the north and decreases in the south with a borderline that migrates from a northerly position in summer to a southerly one in winter. Some of these changes are already seen at 1.5 • C of warming but are larger and more robust at 2 • C. Changes in near-surface wind speed are associated with a large spread among individual ensemble members at both warming levels. Relatively large areas over the North Atlantic and some parts of the continent show decreasing wind speed while some ocean areas in the far north show increasing wind speed. The changes in temperature, precipitation and wind speed are shown to be modified by changes in mean sea level pressure, indicating a strong relationship with the large-scale circulation and its internal variability on decade-long timescales. By comparing to a larger ensemble of CMIP5 GCMs we find that the RCMs can alter the results, leading either to attenuation or amplification of the climate change signal in the underlying GCMs. We find that the RCMs tend to produce less warming and more precipitation (or less drying) in many areas in both winter and summer.