Bidecadal North Atlantic ocean circulation variability controlled by timing of volcanic eruptions
Résumé
While bidecadal climate variability has been evidenced in several North Atlantic paleoclimate
records, its drivers remain poorly understood. Here we show that the subset of CMIP5
historical climate simulations that produce such bidecadal variability exhibits a robust
synchronization, with a maximum in Atlantic Meridional Overturning Circulation (AMOC) 15
years after the 1963 Agung eruption. The mechanisms at play involve salinity advection from
the Arctic and explain the timing of Great Salinity Anomalies observed in the 1970s and the
1990s. Simulations, as well as Greenland and Iceland paleoclimate records, indicate that
coherent bidecadal cycles were excited following five Agung-like volcanic eruptions of the last
millennium. Climate simulations and a conceptual model reveal that destructive interference
caused by the Pinatubo 1991 eruption may have damped the observed decreasing trend of the
AMOC in the 2000s. Our results imply a long-lasting climatic impact and predictability
following the next Agung-like eruption.
Domaines
Géophysique [physics.geo-ph]
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