While the study raises more questions than it answers about human-induced impact, scientists say the shift marks a fundamental change in our understanding of climate change, and promises to complicate climate prediction orthodoxy.

Lead authors Tong Lee of Jet Propulsion Laboratory and Michael McPhaden of the National Oceanic and Atmospheric Administration spent months analyzing 30 year's worth of data - arriving at the conclusion that El Niño is becoming stronger and shifting toward the central Pacific, where it accounts for a long-term warming trend.
"Since the early 1980s, we've been collecting measurements from space for sea surface temperatures and also measuring in the ocean," said McPhaden. "Put the two data sets together and a clear trend in the tropical Pacific emerges."
Their research shows the intensity of El Niños in the central Pacific has nearly doubled in that time, with the most intense event occurring in 2009-2010.
Bill Patzert, a JPL climatologist, said the research was another unsettling chapter in a series of recent revelations about climate change.