Hi Peter,

There's not enough heat from hydrothermal sources to explain sea surface temperature anomalies like the Pacific blob, and it would be difficult to explain the three-dimensional structure of these heat anomalies through hydrothermal sources.  Regarding the long-term trend, North Pacific sea surface temperatures, including in the Gulf of Alaska, have been rising over the past 50 years or so, so such warm anomalies are becoming more common.  (By the way, this is a nice site where you can do linear trend and other calculations if you have some familiarity with the layout.)