Understood cause of sea level rise between 1850 and 1950
SLR is thought to be caused by temperature rise, which is caused by CO2 rise and other factors. Temperature has been rising since before 1850. It could be another Question: "Why temperature does not correspond with CO2 levels since 1850".


  
  The reconstructions used, in order from oldest to most recent publication are:
  (dark blue 1000-1991): The Holocene.
  (blue 1000-1980): Geophysical Research Letters.
  (light blue 1000-1965): Ambio. Modified as published in Science.
  (lightest blue 1402-1960): J. Geophys. Res..
  (light green 831-1992): Science.
  (yellow 200-1980): Geophysical Research Letters. doi:10.1029/2003GL017814.
  (orange 200-1995): Reviews of Geophysics. doi:10.1029/2003RG000143
  (red-orange 1500-1980): Geophys. Res Lett.. doi:10.1029/2004GL019781
  (red 1-1979): Nature. doi:10.1038/nature03265
  (dark red 1600-1990): Science. doi:10.1126/science.1107046
  (black 1856-2004): Instrumental data was jointly compiled by the Climatic Research Unit and the UK Meteorological Office Hadley Centre.
  Robert A. Rohde,  Creative Commons Attribution-Share Alike 3.0 Unported