Volcanoes

Contact: Claudia Timmreck

Volcanic eruptions affect climate if they are strong enough to inject sulfur rich gases into the stratosphere. From sulfuric gases, sulfate aerosols form and reflect sunlight back into space. Thus, the surface of the Earth is cooling considerably. At the same time, sulfate aerosols trap the energy of thermal radiation coming from the Earth's surface. This leads to a pronounced warming of the stratosphere. These two effects lead to changes in the atmospheric and ocean circulation and alter the hydrological and carbon cycle.

Together with the varying solar activity and astronomical variations, strong volcanic eruptions are a major factor driving climate variability over the last millennium. In the context of decadal climate prediction, the possibility of a large volcanic eruption provides arguably the largest uncertainty concerning the evolution of the climate system and has to be taken into account once a strong eruption occurs. A sound knowledge of the impact of volcanic eruptions is therefore essential to understand both historical and possible future climate evolution.

A key issue of our research is to study the climate impact of volcanic
eruptions depending on location, source strength and season of the eruption, and on the ocean state. Special attention is given to the impact of the volcanic aerosol on stratospheric dynamics and a possible coupling with tropospheric dynamics.

Another important motivation for our research is that volcanic eruptions are natural experiments revealing the sensitivity of the climate system to perturbations. Their simulation with coupled stratosphere-troposphere-ocean models provides more insight in the origin of climate sensitivity of our models. Such studies can therefore greatly improve our confidence in climate predictions with complex coupled models.

• Super volcano project
• Millennium project

 Selected presentations