The sea level rise (SLR) maps presented in En-ROADS are risk maps of potential flooding. If you believe the 2030 maps might be unreliable, there is still good reason to consider the maps with longer time horizons. There is some uncertainty in the elevation data of the maps, but this uncertainty is swamped as the amount of SLR increases. SLR will be significantly higher in 2100, for instance, than in 2030 under any scenario. The significant amount of sea level rise by 2100 will be far larger than the uncertainty in the elevation data, making the longer-term map useful for review and discussion.

 

For instance, if the 2030 risk map for a city shows lots of “Land at risk” but that city doesn't experience lots of flooding today, this could be because of current flood protection (e.g., a levee or sea wall). Today the city has flood risk (i.e., blue area) but has mitigated the risk with protection. In the future though, that location may experience >70cm (2.3 ft) or more in sea level rise. In many cases, today's levees and other coastal protections weren't designed to handle that height of sea water. Therefore, unless action is taken to improve the protection, all the “Land at risk” in 2100, including the land protected in 2030, would be at risk of being underwater.