Unrest

Oscillation (cell signaling)

Atlantic multidecadal oscillation

Physics

Quasiperiodic function

Geology

Climate change

Pacific decadal oscillation

Biology

Politics

Climate model

Political science

Astrophysics

Tectonics

Volcano

Climatology

Volcanism

North Atlantic oscillation

Variation (astronomy)

Forcing (mathematics)

Condensed matter physics

Oceanography

Paleontology

Global climate

Southern oscillation

El Niño Southern Oscillation

Genetics

Science

A volcanic source of variation The Atlantic Multidecadal Oscillation (AMO), a 50- to 70-year quasiperiodic variation of climate centered in the North Atlantic region, was long thought to be an internal oscillation of the climate system. Mann et al. now show that this variation is forced externally by episodes of high-amplitude explosive volcanism. They used an ensemble of climate models to evaluate the causes of the AMO, finding that volcanos are the most important influence, and that there is no evidence to show that it has been internally generated during the last millennium. Science , this issue p. 1014

Multidecadal climate oscillations during the past millennium driven by volcanic forcing