North Atlantic as a Trigger for Pacific-Wide Decadal Climate Change

The Interdecadal Pacific Oscillation (IPO) features a basin-scale horseshoe-like sea surface temperature (SST) anomaly pattern. Its cold-phase shift around 1999, implicated as a driver for the early-2000s global warming slowdown, has been potentially linked to the Atlantic warming during the positive-phase Atlantic Multidecadal Variability (AMV). However, the key mechanism for the trans-basin Atlantic-Pacific teleconnection remains debatable. Here, we show that an AMV-SST cooling can initiate a pan-Pacific response. The North Atlantic cooling induces westerly wind anomalies over the central-western equatorial Pacific as Kelvin-wave responses and easterly wind anomalies over the far-eastern equatorial Pacific as Rossby-wave responses. Additionally, anomalous lows are generated over the extratropical North and South Pacific through the midlatitude Rossby wave propagation. The tropical and midlatitude teleconnections act together to develop into a warm-phase IPO-like pattern through the wind-induced latent heat. Our results suggest a potential of advancing the predictability of IPO through a skillful simulation of AMV.

Automated summary

The study suggests that a cooling in sea surface temperature due to Atlantic Multidecadal Variability can trigger a pan-Pacific response through wind-induced anomalies, leading to the development of a warm-phase pattern similar to IPO.