Global sea level (this webgis) is a simple webgis for visualizing sea level rising based on DEM data. This was created using Mapbox DEM data and simple polygon layer (rectangle 4 point polygon covering all over the world) by playing/changing the elevation a.k.a extrude polygon.

Because of Climate Change, global mean sea level has risen about 8–9 inches (21–24 centimeters) since 1880, with about a third of that coming in just the last two and a half decades. The rising water level is mostly due to a combination of melt water from glaciers and ice sheets and thermal expansion of seawater as it warms. In 2020, global mean sea level was 91.3 millimeters (3.6 inches) above the 1993 average, making it the highest annual average in the satellite record (1993-present). Source

There is still some uncertainty about the full volume of glaciers and ice caps on Earth, but if all of them were to melt, global sea level would rise approximately 70 meters (approximately 230 feet), flooding every coastal city on the planet. Source

This webgis was created using these library :

• Mapbox GL JS for map visualizing
• Bootstrap 5 for frontend design
• Suncalc JS for getting sun position in 3D view
• Disqus for adding discussion/comment section
• Google Firebase for hosting site
• Google Analytics

The data used :

• Mapbox Terrain as main DEM data
• Mapbox Styles as basemap
• World Rectangle Polygon uploaded to mapbox studio for creating vector tiles
• 3D Building from mapbox too, but based on Openstreetmap building height data

Source Code : Github
Website : GeoIT Developer

Disclaimer: Please note that this global sea level map on its own is not sufficient for analysis of flood risk since there are many other factors involved.
And because of this web data simplicity(using only extrude polygon), there will be data display error in smallest zoom number, so it is better to zoom as high as possible.