From the CO2Science archive: “One of the possible consequences of global warming,” in the words of the authors, is that “there will be more precipitation days throughout the year, where also the level of precipitation will be higher.” Loosely speaking, as they put it, “because of global warming, it rains not only more but also more heavily.” What was done: In the first stage of a planned program to evaluate this claim for many different countries, Koning and Franses “provide a detailed analysis of a century of daily precipitation levels observed at the de Bilt meteorological station in the Netherlands,” noting that they performed similar analyses for the five other stations in the country, but that they “did not find qualitatively different results.” Hence, they report in detail on just this one site.
Paper reviewed: Koning, A.J. and Franses, P.H. 2005. Are precipitation levels getting higher? Statistical evidence for the Netherlands. Journal of Climate 18: 4701-4714.
What was learned
The two Dutch researchers say that “the often-considered gamma distribution does not fit well to samples of yearly data,” and that “its incorrect use can lead to spuriously high probabilities of extreme precipitation levels.” Hence, using what they consider to be more appropriate and “more robust nonparametric techniques,” they found that “the cumulative distribution function of the annual maximum precipitation levels remains constant throughout the period 1906-2002,” concluding that “precipitation levels are not getting higher.”
What it means
Over the period of 20th-century global warming, which climate alarmists claim is unprecedented over the past two millennia, Koning and Franses find that the climate-alarmist expectation of higher levels of precipitation has not been realized in the Netherlands. Of course, the Netherlands represents just a tiny portion of the planet. Nevertheless, for a warming that was supposedly so extreme, one might have expected to see something along the lines of what has been claimed would be the case. But we don’t.
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