Leading scientists participating at the workshop EPRECOT (effects of precipitation change on terrestrial ecosystems), hosted by the Risoe National Laboratory in Denmark, and co-sponsored by the European Commission’s 6th Framework Program. Scientists agreed in principle on certain future climatic changes.

Climate models forecast that climatic changes due to increased emissions of greenhouses gasses (CO2) and the consequent increase in surface temperatures, will amplify the hydrological cycle with an increase in the evaporation of water from the earth surfaces.

This will probably lead to a wetter world with longer dry periods separating intensified periods of rain. This tendency toward more extreme precipitation is larger the higher the projected global surface temperature. For Europe droughts will likely be more frequent in the summer and heavy rainstorms will occur more often in the winter. That changes in rainfall patterns and seasonality can have strong effects on ecosystem processes even with no change in annual rainfall amounts. Signs of this are already being seen in Italy.

Data from Europe and the US show that such changes have already started and severe droughts have become significantly more frequent in the eastern Mediterranean area. If continued this could become a serious threat to the dominant vegetation of these and similar habitats in this region.

In average or medium-dry regions increased drought will affect many key ecosystem processes and will potentially lead to adverse effects, e.g. reduced growth, changes in nutrient availability and uptake, long term changes in soil structure and the development of new ecological niches beneficial to some plants at the expense of others with long term consequences for biodiversity.

The suppression by the excess precipitation in relatively wet ecosystems where excess water limits biological processes, increased rates of biological processes e.g. increased growth and long-term increased loss of soil carbon.

Model predictions show that future rainfall changes will have a stronger effect on some ecosystems compared to changes in temperature and CO2. “AlphaGalileo” Risoe Laborartory, E-mail: epricot@risoe.dk www.climaite.dk/epricot/epricot.html