Regional Climate Model: Climate Scenarios for Europe

Do we understand the present climate over Europe and can we predict its changes in the future? Which tools are available to investigate the complex relationships between natural systems and human activities? Are we able to predict the impacts of the changing climate on the environment (floods/droughts, agriculture, etc.)?

Nowadays, there is a growing demand from decision-makers for detailed information on future climate. Only with such information it becomes possible to quantify the risks of a changing climate. In order to formulate and implement realistic adaptation and mitigation strategies, quantitative and reliable predictions of future climate scenarios are absolutely necessary. These scenarios are developed by means of a Regional Climate Model (RCM), a highly complex, state-of-the-art numerical tool able to make detailed, high-resolution forecasts for a given limited area of interest (e.g. Europe), given appropriate initial and boundary conditions (i.e., from a Global Circulation Model).

The Regional Climate Model

The model implemented and used at JRC is the Cosmo model in Climate Mode (Cosmo-CLM), a state-of-the-art non-hydrostatic, high-resolution weather/climate model originally developed by the DWD (German Weather Service) for operational weather forecast. Continuous development of the model is provided by members of the Cosmo-CLM Community.

To enable for long-term simulations, the Cosmo-CLM community implemented several new features in the original model. In particular, main changes include the introduction of a multi-layer soil model, for describing the thermal and hydrological processes in a deep soil; dynamical boundary conditions for vegetation parameters; and the specification of CO2 concentration following A1B and A2 SRES scenarios.

The non-hydrostatic formulation of the dynamical core of Cosmo-CLM without any scale assumption makes it eligible for use at horizontal grid resolutions of about 20 Km and less, coming closer to the spatial scales requested by modellers of climate impacts, especially in regions of complex topography.

Normalized Difference Vegetation Index, Europe, 01 to 10 July 2002

Research activities:

1. Impact assessment of future climate change in Europe

The Action IPCA-EEI (Integrated Climate Policy Assessment: Emissions and Environmental Impacts) aims to make an integrated assessment of climate change mitigation and adaptation options with focus being on linking global emissions of greenhouse gases to their impacts on climate and the environment.

By using the regional climate model Cosmo-CLM, climate change scenarios for Europe will be developed to be used as input to a range of JRC impact models, such as:

• The hydrological model LISFLOOD, to make an assessment of changes in flood and drought hazards in Europe under climate change (NAHA action LMNH Unit, IES).

• The analysis of remote sensing data, the application of numerical hydrodynamic and bio-geochemical models for monitoring the functioning of marine ecosystems (PROCAS Action, GEM Unit, IES).

• The Mars Crop Yield Forecasting System (MCYFS), an ensemble of methodologies and tools to provide agricultural season quality indicators, such as extreme temperatures maps at a given crop stage (MARS-STAT Action, AGRIFISH Unit, IPSC).

Change in the 99th percentile of exceedance of precipitation for July-August-September from 1961-1990 to 2071-2100, i.e., the change in the average precipitation on the 1% of days with highest precipitation during this season (Prudence Project)

2. Study of the land-atmosphere interaction and the role of the C and N cycle on the climate

Projections of future climate change based on global atmosphere-ocean general circulation models remain deficient both in regional detail and in the characterization of their uncertainty, as AOGCMs do not resolve spatial scales of less than approx. 150km and, consequently, do not provide information on the spatial structure of temperature and precipitation in areas of complex topography and land use distribution (e.g. the Alps, the Mediterranean, Scandinavia).

Regional climate Models (RCMs) can more accurately represent spatial variations of climate forcing such as topography, lakes, land-sea contrast, etc. There is currently a significant on-going effort in developing regional climate modelling systems where RCMs are coupled with other earth system components like hydrological models, ocean and sea-ice models, and terrestrial ecosystem models.

Due to the complexity of the various feedbacks, and often mismatch of temporal and spatial scales, still much needs to be done in the successful integration of these different model components.

Our goal is to couple two state-of-the-art models (a RCM and a geobiochemical land-surface model) in order to perform high resolution regional climate modelling coupled with a detailed description of the C and N cycle in the biosphere. The coupled version of the two models will be used to perform scenario analysis of the impact of climate change on the European ecosystems and to test alternative adaptation strategies.