Side project
Reef explorer
Caribbean heat, 1985–now
A satellite has measured the sea around these reefs every day since 1985. Draw the years on one set of axes and you get a hill. The water is coolest in March and warmest at the end of September. Coral built its life around that curve.
NOAA draws a line one degree above the warmest month a reef normally sees. Above that line, coral starts to expel the algae living inside its tissue — the algae that supply most of its food and all of its color.
Sixteen stations from the Florida Keys to Trinidad all set their heat records in 2023 or 2024. Pick a reef. Pull a year. Or press play and watch the heat arrive.
Sources
NOAA Coral Reef Watch, 5 km virtual station time series, through 21 August 2026 (2026 is a partial year). The notebook that draws the original figures is here.
Live hard-coral cover is from GCRMN & ICRI, Status and Trends of Caribbean Coral Reefs: 1970–2024, December 2025: about 40–50% in 1970, 28% in 1985, 15% in 2024. That is the floor this heat landed on — a handful of region-wide points, not an annual series and not a station record.