This is an experiment to see what happens if the sea was one day 5m higher. The docks are all reclaimed land and are quite vulnerable, but the old city (Below Bar) is much higher up.
5m sounds like a lot, but normal tides in Southampton seem to be up to 4m variation (which I assume is +/-2). Predictions on sea level rise by 2100 range from 50cm to 200cm. One bad storm surge could render the lowlying parts of our city unusable. My back of the envelope maths is:
1m sea level rise + 2m high tide + 2m storm surge (last happened in the UK in 2013). https://noc.ac.uk/news/storm-surge-hits-uk-coastline
OK, I know that higher end of those predictions is only 1-5% chance that's not odds normal people would take of a massive disaster.
This is a very approximate model of what London would look like under 6m of water. Parliament square is only about 5 or 6m above sea level and the Thames barrier protects it.. for now. The barrier was expected to be used 2-3 times a year, but is now needed 6-7 times.
Remember with sea level rise, it's not the average that matters, it's how high high tide gets!
Source data: LIDAR from DEFRA using most recent 1m scale DTM & DSM. Map data from openstreetmap.
Inspired by Extinction Rebellion. Keep up the good work.