WP3b - EXTREMES

Impact on extreme events

WP coordination: Max Planck Institute for Meteorology (Susanne Pfeifer)

Observational records show that the global climate is changing and ongoing changes are also visible in Central Eastern Europe. About 64% of all catastrophic events in Europe since 1980 can directly be attributed to weather and climate extremes. Climate change projections show even an increasing likelihood of extremes (i.e. Voigt et al., 2004).

The following objectives will be addressed by WP3b:

  • Assessment of the impact of climate change on extreme events.
    Past and future trends of extreme events in the Central and Eastern European region will be analyzed using the indices of extreme events defined in WP2. The analysis will be based on existing Regional Climate Model (RCM) Simulations from MPI-M and CNRS and will be evaluated using the validation data obtained in WP3a.
  • Assessment of the impact of the summer drying problem (SDP) on the simulation of extreme events.
    The SDP is a systematic bias in the simulation of today’s mean climate and is a model feature that is typical for many RCMs, and to a less extent is visible in some general circulation models (GCMs). The SDP is the too dry and too warm simulation of climate over central and eastern Europe during the summer (RAACS project; Machenhauer et al., 1998).
    The SDP is still an open issue strongly influencing the uncertainty related to climate change projections in CEEC.
    Although WP1 aims to detect, understand and solve the summer drying problem for the new regional climate change simulations, which will be carried out within WP1, MPI-M and CNRS will analyse the impact of SDP on extremes. This will deliver important information about the quality of already existing climate simulations like those being carried out within PRUDENCE and ENSEMBLES.
  • Analysis of the impact of different climate model resolutions on the representation of extreme events.
    It is generally expected within the climate research community that extreme events will increase under climate change conditions, that extreme events will occur more often and will become more intense. Such events could be heavy extra-tropical storms as well as heavy precipitation events. In order to investigate the projected future behavior of extreme events using climate models, the corresponding model must be able to adequately simulate the extreme events, which shall be considered. Here, not only the choice of the climate model and its dynamical and physical parameterizations is important but also the resolution of the model grid. Previous climate modeling studies using model resolutions ranging from 250 km down to 18 km have shown (e.g. Iorio, 2004) that simulated extremes become more intense/extreme with increasing resolution. This raises the following questions:
    What is the resolution that is necessary to adequately resolve CEE extreme events and the dynamics of the corresponding deep pressure cyclonic systems?
    Is it possible to identify resolution thresholds, which are decisive whether an extreme event can be represented by the climate model or not?
    A newly developed method using a cascade of RCMs with different horizontal resolution will be utilized by MPI-M to address this issue.
  • Assessment of the potential impacts of climate change on forestry and water management, soil and agriculture on specific hydrological basins which could be affected by extreme events.
    A better approach to different climate change scenarios and models, as well as the potential impacts of climate change on forest ecosystems, especially wetlands, and water management, soil and agriculture on specific hydrographical basins will be developed with focus on the impact of extreme events (VITUKI, EiC, NIMH, IG).

Results of WP3b

Status of WP3b Tasks (internal)