Causes and Impacts of the 2014 Warm Anomaly in the NE Pacific

Remarkably high sea surface temperature anomalies developed in the NE Pacific Ocean during the winter of 2013/14. This caught the attention of Nick Bond of the University of Washington’s Joint Institute for the Study of the Atmosphere and Ocean (JISAO)—who started calling the mass of warm water the “Blob”—and Meghan Cronin of NOAA Pacific Marine Environmental Laboratory (PMEL). Their objective was to determine the relative importance of the various upper ocean temperatures that could have been responsible for this short-term climate event.

As detailed in this recent article published in Geophysical Research Letters, the warm waters of the Blob can be attributed to a reduction in the seasonal cooling of the ocean under a strong and persistent ridge of higher than normal sea level pressure that was present during the winter of 2013/14. This ridge meant fewer storms and weaker winds, and hence less heat transferred from the ocean to the atmosphere. The winds also tended to be less westerly than usual, resulting in transport of relatively warm water by upper-ocean currents into the region of interest.

The pattern of upper ocean temperature anomalies in the NE Pacific has evolved over the past year but a vast area is still dominated by large positive temperature anomalies. These conditions appear to be influencing air temperatures inland along the Pacific coast, and having major impacts on the marine ecosystem. The climate and fishery-oceanography communities are following how this event plays out from both physical and biological perspectives.