Abstract

Volcanic eruptions have a significant potential to affect the climate system, the environment and society. I will summarize my work on volcanic sulfur emissions from volcanic eruptions of different styles, magnitudes, and durations. I will first discuss how volcanic sulphur emissions into the troposphere and effusive Icelandic volcanism can alter the microphysical properties of low-level clouds and serve as a “natural lab” to better understand and quantify aerosol-cloud interactions. A prime example is the most recent Icelandic eruption at Holuhraun (Bárðarbunga volcano). Starting in August 2014, Holuhraun erupted effusively for 6 months and emitted up to nine times as much sulfur dioxide per day as all European industry combined, which led to a measurable episodic degradation of air quality across Northern Europe in September and October 2014. Holuhraun was the first so-called flood lava eruption in Iceland since the much bigger 1783-1784 CE Laki eruption. Laki had substantial effects on northern hemisphere climate and the environment across Europe. Using a global aerosol microphysics model to simulate the effects of a future Laki-type eruption, I show that such an eruption could have the potential to degrade air quality and affect human health in Europe. Lastly, I will present results from aerosol-climate model simulations of volcanic eruptions and their radiative effects since 1979, highlighting the role of small-magnitude explosive eruptions in frequently reducing the transparency of the stratosphere.