Abstract
Explosive volcanic eruptions are magnificent events that in many ways affect the Earth's natural processes and climate. They cause sporadic perturbations of the planet's energy balance, activating complex climate feedbacks and providing unique opportunities to better quantify those processes. We know that explosive eruptions cause cooling in the atmosphere for a few years, but we have just recently realized that they affect the major climate variability modes and volcanic signals can be seen in the subsurface ocean for decades. The volcanic forcing of the previous two centuries offsets the ocean heat uptake and diminishes global warming by about 30%. In the future, the explosive volcanism could slightly delay the pace of global warming and has to be accounted for in long-term climate predictions. The recent interest in dynamic, microphysical, chemical, and climate impacts of volcanic eruptions is also excited by the fact that these impacts provide a natural analog for climate geoengineering schemes involving deliberate development of an artificial aerosol layer in the lower stratosphere to counteract global warming. In this chapter, we aim at discussing these recently discovered volcanic effects and specifically pay attention to how we can learn about the hidden Earth system mechanisms activated by explosive volcanic eruptions. To demonstrate these effects, we use our own model results when possible along with available observations, as well as review closely related recent publications.