Is a global warming signature emerging in the tropical Pacific?

The tropical pacific experienced a hitherto-unseen anomalous basinwide warming from May 2009 through April 2010 with the maximum warming to the east of the dateline, but for a weak anomalous cooling west of 140°E after early boreal fall. Our observed analysis and model experiments isolate the potential teleconnections from TP during the summer of 2009. Further, we show through an empirical orthogonal function analysis of the tropical Pacific SSTA that the anomalous conditions in TP during this period could have manifested as a canonical El Nio, but for a slowly intensifying background west-east gradient. This zonal SST gradient is subject to an increasing trend associated with global warming. A possible implication is that any further increase in global warming may result in more basinwide warm events in place of canonical El Nios, along with the occurrence of more intense La Niaños and El Nio Modokis. Copyright 2012 by the American Geophysical Union.