This year, the Pacific Decadal Oscillation (PDO), in its cold phase, has acted as a protective force against El Niño’s typical impacts. While El Niño typically raises sea levels and increases coastal flooding risks—especially in Southern California—the PDO’s long-term dominance since several years ago has weakened these effects along the Northwest Coast. Data from Washington’s coast, including La Push and Toke Point, show sea levels remain slightly above normal, far below flood thresholds, thanks to the PDO’s opposing influence on El Niño’s Kelvin waves.
The PDO operates on a multi-year cycle, counteracting El Niño’s warming and sea-level rise effects. When in its cold phase, it tends to reduce coastal flooding risks and dampen El Niño’s overall impact on temperature and sea levels. This balance ensures that, despite El Niño’s presence, the Northwest Coast has avoided significant flooding this year.
The PDO’s role in moderating El Niño’s effects highlights the complexity of climate systems. While El Niño’s influence spans roughly 5-7 years, the PDO’s phase shifts over several years, shaping coastal resilience. This interplay means that, even during strong El Niño events, the PDO’s cold phase can mitigate risks, offering a natural buffer against flooding and sea-level changes.
The PDO’s role in moderating El Niño’s effects highlights the complexity of climate systems.
Scientists note that the PDO’s cold phase has been dominant for several years, providing a prolonged period of reduced coastal vulnerability. This natural cycle underscores the importance of understanding long-term climate patterns beyond short-term weather events like El Niño.