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An Absence of Trends in Extreme Sea Levels in the Pearl River Estuary

Paper Reviewed
Wang, W. and Zhou, W. 2017. Statistical modeling and trend detection of extreme sea level records in the Pear River Estuary. Advances in Atmospheric Sciences 34: 383-396.

Writing as background for their work, Wang and Zhou (2017) state that the Pearl River Delta "is an urban agglomeration with an extremely high population density and a fast-growing economy, and its location on the coast of China makes it vulnerable to sea level rise and extreme climate." Such vulnerability has captured the hearts of alarmists everywhere, who predict catastrophic flooding of coastal waters -- such as that of the Pearl River Estuary -- in the years and decades to come in consequence of model-based predictions of sea level rise due to global warming. But should we be all that concerned? Are sea levels rising at the rates predicted by the models?

Attempting to answer these questions, at least for the Pearl River Estuary, Wang and Zhou performed a series of statistical analyses on sea level data from two tide gauge stations within the estuary (Macau and Hong Kong). More specifically, they applied "peaks-over-threshold model of extreme value theory to statistically model and estimate secular parametric trends of extreme sea level records." Tide gauge data for Macau and Hong Kong spanned the period 1925-2010 and 1954-2014, respectively.

In describing their findings, the two Chinese researchers note that there are "evident decadal variations in the intensity and frequency of extremes in [the] sea level records," but that "none of the parameters (intensity and frequency) of daily higher high water height extremes in either Macau or Hong Kong has a significant increasing or decreasing trend." Similar results were obtained upon examination of trends of extremes in tidal residuals, where Wang and Zhou again report that "none of the parameters presents a significant trend in recent decades."

Commenting about their findings, the two researchers say that "why the extremes in [these] original sea level records show no significant trend against the background of increased mean sea level is unclear." Yet, perhaps it really is not so unclear; the models are simply wrong and there is no CO2 effect spurning increases in sea level extremes.

Posted 19 May 2017