Drivers of Future Extratropical Sea Surface Temperature Variability
Changes in the North Pacific
Abstract
Under anthropogenic warming, future changes to climate variability
beyond specific modes such as the El Niño-Southern Oscillation (ENSO)
have not been well-characterized. In the Community Earth System Model
version 2 Large Ensemble (CESM2-LE) climate model, the future change to
sea surface temperature (SST) variability is spatially heterogeneous. We
examined these projected changes (between 1960-2000 and 2060-2100) in
the North Pacific using a local linear stochastic-deterministic model,
which allowed us to quantify the effect of changes to three drivers on
SST variability: ocean “memory” (the SST damping timescale), ENSO
teleconnections, and stochastic noise forcing. The ocean memory declines
in most areas, but lengthens in the central North Pacific. This change
is primarily due to changes in air-sea feedbacks and ocean damping, with
the shallowing mixed layer depth playing a secondary role. An eastward
shift of the ENSO teleconnection pattern is primarily responsible for
the pattern of SST variance change.