Background
Inspired by the Intergovernmental Panel on Climate Change (IPCC), climate alarmists contend that extreme weather events of all types should become both more frequent and intense when the world warms. Particularly is this so with respect to events having to do with precipitation. In their popular book Dire Predictions: Understanding Global Warming -- which is subtitled The Illustrated Guide to the Findings of the IPCC -- for example, Mann and Kump (2008) write that as temperatures rise "increases are to be expected in the frequency of very intense rainfall events," while stating that "individual storms will be associated with more severe downpours ... due to the greater amount of water vapor that a warmer atmosphere can hold."

But have such things truly been happening in the real world? ... especially in conjunction with the global warming of the past three decades, which climate alarmists typically describe as having been unprecedented over the past one to two millennia, and when Hawaii warmed at a rate of 0.163°C per decade, as reported by Giambelluca et al. (2008)?

What was done
In a study designed to address this question, Chu et al. write that "for the first time, five climate change indices for extreme precipitation (four related to wetness and one related to dryness) in Hawaii have been calculated," based on "daily observational records from the 1950s to 2007." These specific indices are (1) the simple daily intensity index, (2) the total number of days with precipitation ≥25.4 mm, (3) the annual maximum consecutive 5-day precipitation amount, (4) the fraction of annual total precipitation from events exceeding the 1961-1990 95th percentile, and (5) the number of consecutive dry days.

What was learned
The three University of Hawaii at Manoa scientists determined, as they describe it, that "since the 1980s, there has been a change in the types of precipitation intensity, resulting in more frequent light precipitation and less frequent moderate and heavy precipitation intensity," as well as a "shorter annual number of days with intense precipitation and smaller consecutive 5-day precipitation amounts and smaller fraction of annual precipitation due to events exceeding the 1961-1990 95th percentile in the recent epoch [1980-2007] relative to the first epoch [1950-1979]." And they add that "long-term upward trends are observed for consecutive dry days."

What it means
In almost every conceivable way the subject could possibly be analyzed, Chu et al. determined that the precipitation predictions of the IPCC had not only not been realized throughout the part of the Pacific that is home to the Hawaiian Islands, but that just the opposite had occurred there, once again demonstrating the degree to which the climate models employed by the IPCC fail to represent reality.

References
Giambelluca, T.W., Diaz, H.F. and Luke, M.S.A. 2008. Secular temperature changes in Hawaii. Geophysical Research Letters 35: 10.1029/2008GL034377.

Mann, M.E. and Kump, L.R. 2008. Dire Predictions: Understanding Global Warming. The Illustrated Guide to the Findings of the IPCC. Dorling Kindersley Limited, London, United Kingdom.