Unique Temperature Trend Pattern Associated with Internally Driven
Global Cooling and Arctic Warming during 1980-2022
Abstract
Diagnosing the role of internal variability over recent decades is
critically important for both model validation and projections of future
warming. Recent research suggests that for 1980-2022 internal
variability manifested as Global Cooling and Arctic Warming (i-GCAW),
leading to enhanced Arctic Amplification (AA) and suppressed global
warming over this period. Here we show that the observationally derived
i-GCAW is rare in CMIP6 large ensembles, but simulations that do produce
similar i-GCAW exhibit a unique and robust internally driven global
surface air temperature (SAT) trend pattern. This unique pattern of SAT
change features enhanced warming in Barents and Kara Sea and cooling in
the tropical Eastern Pacific and Southern Ocean. Given that these
features are imprinted in the observed record over recent decades, this
work suggests that internal variability makes a crucial contribution to
the discrepancy between model-simulated forced SAT trend pattern and
observations.