The Role of Land and Vegetation for Climate Variability and Climate Change

Sonia I. Seneviratne, ETH Zurich

This presentation provides an overview on recent results investigating the role of land-atmosphere interactions for European summer climate variability in the context of climate change.

Increasing greenhouse gas concentrations are expected to enhance the variability of summer climate in Europe and other mid-latitude regions, potentially causing more frequent heatwaves and heavy precipitation events. Several new investigations show that these projected changes are very much impacted by interactions between land and the atmosphere. In particular, a recent study (Seneviratne et al. 2006, Nature) identified that land-atmosphere coupling is relevant for summer temperature variability in present climate in the Mediterranean region, and in Central and Eastern Europe in the future climate (end of 21st century) conditions. The geographical shift in soil moisture-temperature coupling is associated with a shift of climatic regimes on the continent, creating a new transitional climate zone in Central and Eastern Europe. Moreover, a further investigation (in preparation) shows that soil moisture also strongly constrains precipitation in the future climate conditions. Finally, other processes relevant for land-climate interactions, in particular linked with vegetation functioning (such as CO2 assimilation), may be relevant in this context.

These findings highlight the need for a better understanding and monitoring of land surface processes on the European continent, and open new perspectives in the fields of climate, hydrological and ecosystem modeling, as well as for short-term and seasonal forecasting.