How the warm water of the northeastern Pacific persisted and whether scientists could have predicted it

  • 8 November 2016
  • Number of views: 989

A new study published in the Journal of Climate investigates the evolution and predictability of the abnormally warm water that emerged in October 2013 and persisted until June 2016 in the northeastern Pacific, colloquially known as “the Blob”. The Blob, the most prolonged warming in the northeastern Pacific since records began in 1900, devastated some native marine ecosystems of the Gulf of Alaska and left many marine mammals unable to find food. Understanding the causes and predictability of this event could help natural resource managers prepare for future extreme warming events and potential impacts on communities and ecosystems.

Previous research has suggested that the unusually warm water was caused by remarkably strong and persistent high pressure over the northeastern Pacific Ocean. However, motivated by the many significant impacts, scientists looked to uncover more details about the persistent warm water. Zeng-Zhen Hu and Arun Kumar (NOAA Climate Prediction Center) and other researchers evaluated whether unusual sea surface temperatures (SSTs) in regional and remote ocean basins affected the persistence of the abnormal atmospheric circulation associated with The Blob. They also assessed the skill of real-time forecasts and evaluated the possibility of predicting The Blob and other future extreme warm SST events.

The authors found that the long-lived abnormal atmospheric circulation over the northeastern Pacific, may have been caused in part by unusual SSTs, particularly, in the tropical Pacific. However, when assessing forecast skill, the researchers found that random atmospheric variability was likely the more important cause. Thus, the researchers concluded that The Blob would have been challenging to predict in advance based on the current state of science. This outcome motivates the need for further research on understanding, modeling, and predicting ocean temperature variations to develop a capability to anticipate the next extreme warming event.

This research was funded, in part, by the NOAA Climate Program Office’s Modeling, Analysis, Predictions, and Projections Program.

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