How the Sea Level Simulator Works
This interactive simulator combines high-resolution multispectral satellite imagery with Mapzen Terrarium
digital elevation models (DEMs). Terrarium encodes surface elevation in meters with millimetric precision
into RGB color channels, allowing GPU shaders to calculate bathymetric exposure and coastal flooding in real
time.
Bathtub Model Disclaimer
This is a topographic elevation visualization, not a full hydrodynamic tide model: it does not account for
local seawalls, tidal harmonics, storm surge resonance, or ground subsidence. Use it to understand
geographic exposure and scale rather than as a flood forecast.
Frequently Asked Questions
What does this sea level rise simulator show?
It overlays a sea-level threshold you choose onto terrain elevation and highlights every area that sits
below that level, so you can preview which coastlines, island nations, and low-lying regions would be
underwater at that height.
How much has sea level risen, and how much more could it rise?
Global mean sea level has risen roughly 20 cm (about 8 inches) since 1900, and the rate is accelerating
to over 4.5 mm per year. According to the IPCC Sixth Assessment Report (AR6), sea levels are projected
to rise roughly 0.38 to 0.77 metres by 2100 under moderate emissions, with up to 1.5 to 2 metres
possible under high-emissions scenarios if Antarctic ice shelves destabilize. If Greenland and the
Antarctic Ice Sheet were to melt completely, global oceans would rise by approximately 66 metres (216
feet).
Why do negative numbers (like -2582m) reveal land?
Negative heights simulate a drop in sea level, draining the ocean and revealing the submerged topography
of the ocean floor (bathymetry). At -120m, the continental shelves that formed land bridges during the
Last Ice Age (such as Beringia and Sundaland) are exposed. At -2582m, massive mid-ocean ridges (like the
Mid-Atlantic Ridge) and continental slopes become dry land.
Why do some inland areas (like the Caspian Depression or Death Valley) appear flooded?
The simulator shades any terrestrial pixel whose elevation falls below the selected threshold. Closed
inland basins that naturally sit below global mean sea level — such as the Caspian Depression
(-28m) or Death Valley (-86m) — are below zero elevation and will naturally display as submerged
in a pure elevation model.
What satellites and data sources monitor global sea level?
Global sea surface height is measured with millimetric precision by radar altimeter satellites including
Sentinel-6 Michael Freilich, Jason-3, CryoSat-2, and the SWOT (Surface Water and Ocean Topography)
mission.
