Methodology and Sources
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Metric definition:
Coral reef area (km²).

Ranking logic:
Higher values rank higher.

Methodology extracted from article:
Methodology The indicator measures mapped coral reef area in square kilometres. It is a spatial-extent measure: reef polygons or reef pixels are summed within each country, territory or reef jurisdiction. More area means more mapped reef surface — not healthier reefs. Measurement logicCoral reef area is the summed surface of shallow, warm-water reef systems. The ranking runs in descending order: the larger the mapped area, the higher the position. Snapshot yearThe page uses a 2026 publication snapshot. Reef-extent datasets are not annual censuses, so a single baseline can stay valid for area comparison even as reef condition shifts from year to year. Rounding and harmonisationValues are rounded to the nearest 10 km² or 1 km², depending on source precision. Entries at 100 km² or below are treated as maximum-estimate bands and carry more uncertainty. LimitsThe metric says nothing about live coral cover, bleaching, fish biomass, biodiversity, water quality, management effectiveness, tourism value or coastal-protection performance. The headline ranking uses World Population Review, a public compiled table, as its numeric baseline. UNEP-WCMC and the Allen Coral Atlas provide methodological context — they were not used to re-verify each row. The two traditions can diverge sharply. UNEP-WCMC's Global Distribution of Coral Reefs is a baseline map assembled from several sources, including the Millennium Coral Reef Mapping Project and the World Atlas of Coral Reefs, while the Allen Coral Atlas builds global habitat maps with satellite-based bleaching and turbidity monitoring — a different mapping logic that can yield substantially different area totals. So totals differ between datasets, driven by reef definitions, mapping resolution, depth limits and boundary-attribution rules. Next: Full Ranking → Back to chart ↑

Sources extracted from article:
Sources UNEP-WCMC — Global Distribution of Coral ReefsThe baseline global dataset for warm-water coral reef distribution, compiled with WorldFish, WRI and The Nature Conservancy.resources.unep-wcmc.org Allen Coral AtlasSatellite-based, high-resolution mapping of reef extent and coral habitat at a global scale.allencoralatlas.org Lyons et al. — New global area estimates for coral reefsPeer-reviewed context for global reef area, coral habitat area and the uncertainty in satellite mapping.sciencedirect.com World Resources Institute — Reefs at Risk RevisitedThreat and vulnerability framing for countries and territories with coral reef ecosystems.wri.org World Population Review — Countries with Coral Reefs 2026The public country-level table used for the headline figures. As a commercial compilation, its values are treated here as rounded estimates; the primary mapping sources are used for methodological context, not for row-by-row verification.worldpopulationreview.com

Limitations:
The dataset is generated from the published StatRanker article table. It inherits the limitations of the original source, metric definition, reporting period, rounding and coverage. The values should not be interpreted outside the stated unit and methodology.
