thing is cat 5 hurricanes happen every year (and are thus not freak storms), just not here. In the parts of the world where these happen, people tend not to live below sea level so even poor islands eventually recover after being hit. Extrapolating form the current climate the probability for cat5 hurricane winds in NL is about zero, cause the mechanisms that cause these kinds of storms don't apply here. But as the climate changes, and the seas warm, you might see the general storm patterns change, and you might get into a different regime where such storms are possible. Take hurricane Lorenzo, the easternmost Category 5 Atlantic hurricane on record. What was previously unthinkable just happened last October. If you extrapolate from this trend (more frequent, more eastern hurricanes happening in the Atlantic), I think it looks a lot less unlikely that one of those monster will someday make it to the North Sea.

Same with sea level rise: the currently observed rate of change is very manageable, and even a factor 5 higher can probably be managed. But what if we reach (or have already reached) a tipping point in the climate system that causes rapid acceleration of sea level rise? The existence of these tipping points cannot be derived from historical (say last 1000 years) observations, and therefore one might conclude that they don't exist. I believe such reasoning is known as the black swan logical fallacy. But from my casual observations, we are entering uncharted territory now (greenhouse gas levels, sea temperature, changing weather patters, changing jet stream patterns), so who knows what will happen.

Last point, look at the temperature 40,7 °C reached just last summer. Until 2018 the highest recorded temperature was 38,4 °C (in 1947). Some say this was a huge outlier, I think this is the new normal. I would love to know the probability of this happening taking the weather observations from start of record until 2018, would be surprised it it in the 1:1.000.000 range.

edit: Of course someone did the math (in Dutch) https://www.knmi.nl/over-het-knmi/nieuws/hoe-bijzonder-zijn-...