EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

On the forced response and decadal predictability of the North Atlantic Oscillation

Bo Christiansen1, Shuting Yang1, and Dominic Matte2,3
Bo Christiansen et al.
  • 1Danish Meteorological Institute, Climate and Arctic Research, Copenhagen, Denmark (,
  • 2Physics of Ice, Department of Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
  • 3Ouranos, 550 Rue Sherbrooke W., West Tower, 19th Floor, Montreal, QC, H3A 1B9, Canada (

We investigate the forced response of the North Atlantic Oscillation (NAO)  in large ensembles of climate models including simulations with historical  forcings and initialized decadal hindcasts.  The forced NAO in the  CMIP6 historical ensemble correlates significantly with observations after 1970. However, the forced NAO shows an apparent non-stationarity with significant correlations to observations only in the period after 1970 and in the period before 1890. We demonstrate that such apparent non-stationarity can be due to chance even when models and observations are independent. We find only weak evidence that initialization improves the skill of the NAO on decadal time-scales. Neither of the historical ensembles including only natural forcings, well-mixed greenhouse-gases, or anthropogenic aerosols show any skillful NAO. Our results question the possibility of useful decadal predictions of the NAO.

How to cite: Christiansen, B., Yang, S., and Matte, D.: On the forced response and decadal predictability of the North Atlantic Oscillation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7508,, 2022.


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