• sea level

Sea level in the western tropical Pacific Ocean has been increasing at a rate about 3 times the global average rate of sea level rise, as observed from satellite altimetry and tide gauges. Why are sea level trends so much different in this region? Previous studies have suggested that the high rate of sea level change in the western tropical Pacific is associated with the natural variation of the El Niño–Southern Oscillation. However, using a general circulation model, Merrifield and Maltrud show that western tropical Pacific sea level trends are likely due to a gradual intensification of the Pacific trade winds in the past 2 decades. They also highlight other aspects of ocean circulation that have been altered in response to the intensifying trade winds. Some previous research has suggested that the trade wind intensification is a result of global warming, although that has yet to be verified. If that is the case, the authors conclude, the western tropical Pacific sea level trends will likely continue to be anomalously high. (Geophysical Research Letters, doi:10.1029/2011GL049576, 2011)