sentence: Coauthor Malte Stuecker of the University of Hawaii Meteorology Department reports that `` Our study documents that some of the largest tropical and subtropical climate trends of the past 20 years are all linked : Strengthening of the Pacific trade winds , acceleration of sea level rise -LSB- three times faster than the global average -RSB- in the western Pacific , eastern Pacific surface cooling , the global warming hiatus , and even the massive droughts in California '' .
question: when has something accelerated _ _ _ ?
answers: the past 20 years