On our popular Sea Level Check series we took CDN readers on a round-the-world tour of coastal spots where long term tide gauge data mostly revealed sea levels rising very slowly, at rates that will not cause anything but minor inconveniences over the coming century. Yes but, the alarmists say, sea level rise is now accelerating due to climate change so it’s actually going to be a catastrophe. Which if true will see the Bill Gates and Barack Obamas of the world hardest hit, what with their penchant for oceanfront mansions. But is it true? Is sea level accelerating? Many authors have looked at satellite data for the answer and argued that it is. But in a new study two Dutch researchers (Hessel Voortman and Rob de Vos) have looked at tide gauge data from around the world and found that in almost every place they looked there is no evidence of acceleration, and where acceleration appears it is usually caused by local land disruptions unconnected with climate. The seas are gently rising but not accelerating. And of all things, when proxy measures gathered by satellites need to be processed by complex algorithms before translating into real-world data, the alarmists writing the algorithms seem to have made them exaggerate.
The authors of the study begin by pointing out an enigma in the sea level data, namely that satellites suggest a rate of sea level rise that can’t be reconciled with ground-level measurements of ice melting, thermal expansion of sea water, etc. It was first pointed out 20 years ago that the satellites suggest too much sea level rise. Since then, a long list of authors have investigated and claimed to have reconciled the two accounts. But, the authors note:
“Without exception, we found papers attempting to close the budget by increasing the contributors to sea level rise”.
Given the way theory drives data in the climate field, including those infamous “adjustments”, it’s not very surprising that no one considered the common-sense explanation that the complex, mediated satellite processed “data” might be inaccurate, and instead everyone looked for problems with the ground-level actual data. Even though another problem with the surging-seas-disaster thesis is that climate models have been predicting sea level rise acceleration for a long time, but a major review of the subject in the 1990s:
“concludes that acceleration appeared to be small in comparison to expectations stemming from climate science, but also that the available data series are too short for definitive conclusions, and that corrections for inter-annual and inter-decadal variations need to be made.”
So the authors of this new study decided to examine whether the local tide gauge data supports claims of acceleration. To do so, they examined data from thousands of sites around the world and applied straightforward statistical tests for acceleration after controlling for short-term and long-term tidal cycles. And they found that (drum roll please) sea level rise around the world is proceeding very slowly.
“The long-term rate of sea level rise is mild for the majority of locations, with rates of rise less than 5 mm per year. Clusters of negative rates are found in the Baltic and along the West Coast of Canada. High rates of rise (up to 10 mm per year) are found in one location in the Pacific, in the United States along the coast of the Gulf Coast, on the West Coast of India, in Japan, in Thailand, and in Australia. High rates are often found in close proximity of stations with much lower rates, suggesting a local phenomenon affecting the observed rise. The mean rate of sea level rise is 1.4 mm/year, and the median is 1.5 mm/year. Ninety percent of the rates lie between −5.9 mm/year and 6.8 mm/year.
The metric system makes calculations easy. A mean rate of sea level rise of 1.4 mm/year means 14 cm in a century, which is easily handled with minor coastal infrastructure adjustments or additions. Except in a handful of locations there was no evidence of acceleration. And where they found evidence of acceleration, such as a station along the coast of Japan, it was likely an artifact of an earthquake-induced change in the land level.
Yeah, yeah, that’s all fine and good in reality. But what about climate model projections? Well, Voortman and de Vos compared IPCC projections at every place where long term tide gauge data were available and reported that in most places the projections are too high. They explain that in their chart:
“Where the rate in the projections is higher than the empirical rate, the point is above the line; otherwise, it is below. The graph shows the majority of locations to be above the blue line, indicating that the rate of sea level rise in the projections is too high compared to the empirical rate.... the overestimation along the Atlantic coast of North America is 4 mm/year to 5 mm/year; the highest overestimation found anywhere.”
So, overall, sea level rise is linear and slow, below climate model projections and showing no sign of acceleration. The elites with their oceanfront mansions can breathe a sigh of relief. Or not, if they are devoted to the climate crisis and its angry seas meme.
