• Energy Research

AbstractThis study investigates the impact of increased global warming on heat stress changes and the potential number of people exposed to heat risks over Africa. For this purpose a heat index has been computed based on an ensemble‐mean of high‐resolution regional climate model simulations from the Coordinated Output for Regional Evaluations embedded in the COordinated Regional Climate Downscaling EXperiment, under two Representative Concentration Pathways (RCPs) scenarios (RCP2.6 and RCP8.5), combined with projections of population growth developed based on the Shared Socioeconomic Pathways (SSPs) scenarios (SSP1 and SSP5). Results show that by the late 21st century, the increased global warming is expected to induce a 12‐fold increase in the area extent affected by heat stress of high‐risk level. This would result in an increase of about 10%–30% in the number of days with high‐risk heat conditions, as well as about 6%–20% in their magnitude throughout the seasonal cycle over West, Central, and North‐East Africa. Therefore, and because of the lack of adaptation and mitigation policies, the exacerbation of ambient heat conditions could contribute to the exposure of about 2–8.5 million person‐events to heat stress of high‐risk level over Burkina Faso, Ghana, Niger, and Nigeria. Furthermore, it was found that the interaction effect between the climate change and population growth seems to be the most dominant in explaining the total changes in exposure due to moderate and high heat‐related risks over all subregions of the African continent.

In order to meet a stringent carbon budget, shared socioeconomic pathways (SSPs) aligned with the Paris Agreement typically require substantial land-use changes (LUC), such as large-scale forestation and bioenergy crop plantations. What if such a low-emission, intense-LUC scenario actually materialized? In this contribution, we quantify the biophysical effects of LUC under SSP1-2.6 using an ensemble of regional climate simulations over Europe. We find that LUC projected over the 21st century, primarily broadleaf-tree forestation at the expense of grasslands, reduce summertime heat extremes significantly over large swaths of continental Europe. In fact, cooling from LUC trumps warming by greenhouse gas (GHG) emissions, resulting in milder heat extremes by 2100 for about half of the European population. Forestation brings heat relief by shifting the partition of turbulent energy fluxes away from sensible and towards latent heat fluxes. Impacts on the water cycle are then assessed. Forestation enhances precipitation recycling over continental Europe, but not enough to match the boost of evapotranspiration (green water flux). Run-off (blue water flux) is reduced as a consequence. Some regions experience severe drying in response. In other words, forestation turns blue water green, bringing heat relief but compromising water availability in some already-dry regions.

A high resolution (1 km × 1 km) data set of monthly wind velocities over Germany for the time period 1951-2001 is provided. The data have been reduced to a reference level using a so called 'relative altitude' scheme, interpolated using a simple Inverse Distance Weighting approach and retransformed to the actual topography. However, no parametrization of land use or surface roughness has been integrated in the modelling process of this data and therefore the data is not suitable to serve as criteria for planning wind energy sites. A Cross-Validation scheme applied to this data set yields a mean error of 0.1 m/s for the time period 1951-2001. Regarding the area mean of wind velocities a linear trend of −0.05 m/s is obvious for this period. This negative linear trend changes to a positive one when shorter time scales are considered, e.g. +0.3 m/s for the 1981-2001 period. However, all these temporal trends are not significant. Thus, they could be the result of random features within the dataset and are not further interpreted. These monthly derived wind velocities serve as a reference data set for regional climate model evaluations. The climate models used are two different versions of the hydrostatic regional climate model REMO as well as the nonhydrostatic CLM and MM5 models. All models are capable to reproduce the temporal and spatial variability of the observations to a great extent. Projections of changes in wind velocity have been carried out with these regional climate models. All of these projections show a significant increase in wind velocities over the full model domain, especially over the Baltic Sea and the North Sea, during winter and a decrease during summer. Regarding changes in annual means an increase of up to 1.0 m/s for the Baltic Sea and a decrease in wind velocitites of the same magnitude for the Mediterranean is projected as an average for the 2070-2099 period.

AbstractThe European CORDEX (EURO-CORDEX) initiative is a large voluntary effort that seeks to advance regional climate and Earth system science in Europe. As part of the World Climate Research Programme (WCRP) - Coordinated Regional Downscaling Experiment (CORDEX), it shares the broader goals of providing a model evaluation and climate projection framework and improving communication with both the General Circulation Model (GCM) and climate data user communities. EURO-CORDEX oversees the design and coordination of ongoing ensembles of regional climate projections of unprecedented size and resolution (0.11° EUR-11 and 0.44° EUR-44 domains). Additionally, the inclusion of empirical-statistical downscaling allows investigation of much larger multi-model ensembles. These complementary approaches provide a foundation for scientific studies within the climate research community and others. The value of the EURO-CORDEX ensemble is shown via numerous peer-reviewed studies and its use in the development of climate services. Evaluations of the EUR-44 and EUR-11 ensembles also show the benefits of higher resolution. However, significant challenges remain. To further advance scientific understanding, two flagship pilot studies (FPS) were initiated. The first investigates local-regional phenomena at convection-permitting scales over central Europe and the Mediterranean in collaboration with the Med-CORDEX community. The second investigates the impacts of land cover changes on European climate across spatial and temporal scales. Over the coming years, the EURO-CORDEX community looks forward to closer collaboration with other communities, new advances, supporting international initiatives such as the IPCC reports, and continuing to provide the basis for research on regional climate impacts and adaptation in Europe.

Abstract Climate change has increasingly adverse effects on global crop yields through the occurrence of heat waves, water stress, and other weather-related extremes. Besides losses of average yields, a decrease in yield stability—i.e. an increase in variability of yields from year to year—poses economic risks and threatens food security. Here we investigate a number of climate indices related to adverse weather events during the flowering of wheat, maize and rapeseed, in the current cultivation areas as well as the main European producer countries. In 52 projections from regional climate models, we identify robust increases in the interannual variability of temperature, precipitation and soil moisture by ∼+20% in standard deviation in the model median. We find that winter wheat is most exposed to variability increases, whereas rapeseed flowering escapes the largest increases due to the early flowering time and the northern locations of cultivation areas, while the opposite (escape due to southern locations and late flowering) is true for maize to some extent. Considering the timing of crop development stages, we also find a robust increase in the variability of the temporal occurrence of flowering, which suggests a decreased reliability in the timing of crop stages, hampering management steps like fertilization, irrigation or harvesting. Our study raises concerns for European crop yield stability in a warmer climate and highlights the need for risk diversification strategies in agricultural adaptation.