Recent unprecedented change of Pacific decadal variability shows a
fingerprint of anthropogenic forcing
Abstract
How the Pacific Decadal Variability (PDV) would change under a warming
world remains an issue of scientific debate and societal concern. Here
we show that the PDV has been experiencing an unprecedented change in
the last two decades. The PDV has amplified along the west coast of
North America and equatorial central Pacific while weakened over the
South Pacific and Kuroshio-Oyashio Extension (KOE) region. Examination
of 33 CMIP6 models’ ensemble mean projection reveals that anthropogenic
radiative forcing may weaken the PDV variability in the South Pacific
and KOE region, suggesting part of the observed change may be attributed
to anthropogenic forcing. However, the recently increased decadal
variability over the western North American coast and equatorial central
Pacific may be part of the internal variability arising from increased
coupling between the positive Pacific Decadal Oscillation (PDO) and
negative North Pacific Gyre Oscillation (NPGO).