Jul 11, 2016

Multi-year persistence of the 2014/15 North Pacific marine heatwave

Emanuele Di Lorenzo and Nathan Mantua
Nature Climate Change

The atmospheric variability that forced the warm blob is the same that forced the drought...This atmospheric variability is increasing under greenhouse gases.

Emanuele Di Lorenzo, study co-author and ocean and climate dynamics professor at Georgia Tech

These climate patterns tend to have some influence on each other, and then El Niño is a central player in coordinating the connection... Looking at the historical record we see that similar things have happened, but never to the extreme that was observed in the last few years.

Nathan Mantua, study co-author and National Oceanic and Atmospheric Administration scientist

  • States that between the winters of 2013/14 and 2014/15 during the strong North American drought, the northeast Pacific experienced the largest marine heatwave ever recorded
  • Combines observations with an ensemble of climate model simulations to show that teleconnections between the North Pacific and the weak 2014/2015 El Niño linked the atmospheric forcing patterns of this event
  • Finds these teleconnection dynamics from the extratropics to the tropics during winter 2013/14, and then back to the extratropics during winter 2014/15, are a key source of multi-year persistence of the North Pacific atmosphere
  • Finds the corresponding ocean anomalies map onto known patterns of North Pacific decadal variability, specifically the North Pacific Gyre Oscillation (NPGO) in 2014 and the Pacific Decadal Oscillation (PDO) in 2015
  • A large ensemble of climate model simulations predicts that the winter variance of the NPGO- and PDO-like patterns increases under greenhouse forcing, consistent with other studies suggesting an increase in the atmospheric extremes that lead to drought over North America