There has been an inventory of bathymetry data in the North Sea of before they were systematically digital. BODC was leading when this was done. (DG RTD paid a part of it). Could these not be used for the last 100 years, even if only parts of the North Sea would be covered? One should be able to get sea level rise with these? Are there no publications that have done this already and could be cited?
Temperature data in the water column and on the seafloor are an issue. Even today the resolution is low, mostly because of cost.
By the way, how do the graphs compare to similar graphs published and not necessarily or based on the same data set? How does NS042 compare to European data sets?