A New Pattern Emerges

Regular changes in sea-surface temperature in the Pacific Ocean, such as , such as El Niño and La Niña, influence precipitation and storms over a wide swath of the globe. Recently, Kristopher Karnauskas and colleagues found model-based evidence for another natural cycle , the Pacific Centennial Oscillation (PCO), which repeats on 100-year timescales. In one phase of the PCO (shown here), warmer temperatures (red) predominate across the western equatorial and northeastern Pacific; cooler temperatures predominate in the other. In November, Konrad Hughen sampled coral skeletons in Micronesia looking for evidence of temperature changes caused by the PCO. If confirmed, the PCO adds to understanding of how human actions can interact with naturally occurring climate patterns.(Image created by Kris Karnauskas, Woods Hole Oceanographic Institution)