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Rising sea levels are not to be dismissed

Sign of the times: high, high tide (Photograph by Glenn Fubler)

Dear Sir,Bermuda has this week (November 25 to 29) been experiencing a temporary increase in mean sea level that is evident in low-lying coastal areas. I urge people to take note of some resulting occurrences of seawater inundation. My colleagues at the Bermuda Institute of Ocean Sciences have previously pointed out that this itself is not a climate-change phenomenon but rather a localised oceanographic event, known as a warm eddy, which can raise the sea levels. In this case, as in the last major event in October 2017, the occurrence of an eddy is coincident with the natural monthly highest tidal ranges — called spring tides — causing a more noticeable water-level increase during high tide. I should reiterate that this is temporary, and we should see water levels go back to normal as the eddy departs our area and the tide cycle returns to more average conditions. However, it is worth having a good look at docks and coastal infrastructure in the context of both this warm eddy, and also climate change, which is resulting in accelerated sea-level rise. This event affords us a preview of what the normal high tide will likely be in as soon as 20 years. Not all areas will be adversely affected, but take note of those parts of the island that we already know are prone to coastal flooding. Instances of seawater inundation have already been pointed out in the local press and on social media, in areas such as King’s Square and Ordnance Island in St George’s, and the dock near Somerset Bridge. Existing sea-level rise projections put these places under water regularly as part of the normal high-tide cycle in two to three decades. It doesn’t take a great degree of understanding or imagination to think about the consequences of that additional foot of water during a warm-eddy or storm-surge event, with a future sea level that is now confidently expected. So I call for your readers to consider these areas, and imagine an extra foot on top of the recent flooding — this will be our reality sooner than we might anticipate. MARK GUISHARD, PhDDirector, Corporate and Community RelationsProgramme Manager, Risk Prediction InitiativeBermuda Institute of Ocean Sciences