% of land area · 2015 vintage · World Bank / CIESIN · 200 countries
Land below 5 metres of elevation, as a percentage of land area — 2015 data, a static indicator. Measures potential exposure to sea-level rise, not a flood projection.
World Bank, World Development Indicators (AG.LND.EL5M.ZS) — primary source: CIESIN digital elevation model. Static rather than time-series: the source records only three data points (1990/2000/2015) with near-identical values year to year for a given country — a fixed geographic metric, not a series that genuinely evolves.
48 of the 200 countries covered sit at 0%: the metric only makes sense for coastal and delta countries.
Exposure is concentrated among small island states and deltas: the Marshall Islands (82%) and the Maldives (81%) have most of their national territory below this line, against 52% for the Netherlands — a country that, unlike the first two, has built its entire hydraulic engineering tradition around this geographic fact for centuries.