The 2019 Reappearance of the Northeast Pacific Marine Heatwave

Extreme positive sea surface temperature anomalies over much of the northeast Pacific during the summer of 2019 had eerie resemblance to the scale and magnitude of the 2013/14 marine heatwave known as “The Blob”. The area of ocean experiencing marine heatwave conditions has grown over the summer months to approximately 9.0x10⁷ km² extending from the Gulf of Alaska to the Hawaiian Islands with maximum temperature anomalies exceeding 4ºC above the seasonal climatology in early September. Watchful eyes are on the looming impacts from this year’s event, including harmful algal blooms and severe coral bleaching already underway. In this study, we present an update on the causes and consequences of the 2019 Northeast Pacific marine heatwave, and compare how this event stacks up to the infamous “Blob” of 2013/14. We use vertical profiles from Argo to provide context for water column changes and biogeochemistry following the event as it evolves.