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Coral Reefs

When these happened

28 dated records from 1842 to 2026. Each is drawn as wide as its date is certain — a band is a band because nobody knows the year, not because the drawing is imprecise.

18501875190019251950197520002025Darwin publishes The Structure and Distribution of Coral Reefs — 1842Drilling on Enewetak reaches volcanic basement beneath the reef — 1952Great Barrier Reef Marine Park Act creates a single managing authority — 1975The Great Barrier Reef is inscribed on the World Heritage List — 1981Caribbean-wide mass mortality of the long-spined sea urchin — 1983–1984Mass synchronous spawning described on the Great Barrier Reef — 1984The Long-Term Monitoring Program begins annual reef surveys — 1985The International Coral Reef Initiative is formed — 1994 (announced; first workshop 1995)The Belize Barrier Reef Reserve System is inscribed as World Heritage — 1996The first global mass bleaching event — 1998A published projection that reefs would bleach faster than they could recover — 1999Caribbean elkhorn and staghorn corals listed as threatened in the United States — 2006A measured decline in Great Barrier Reef coral calcification is published — 2009-01Coral Triangle Initiative Leaders' Declaration at Manado — 2009-05The second global bleaching event — 2010Twenty-seven years of monitoring show coral cover roughly halved — 2012Stony coral tissue loss disease first observed off Florida — 2014The third global bleaching event — 2014–2017Mass bleaching on the Great Barrier Reef — 2016-03 to 2016-04A second consecutive year of mass bleaching on the Great Barrier Reef — 2017Belize's reef is removed from the List of World Heritage in Danger — 2018The interval between severe bleaching events is measured, and it has collapsed — 2018-01The coral symbionts are reclassified into a family of genera — 2018Mass bleaching on the Great Barrier Reef during a La Nina — 2022-03Extreme water temperatures in the Florida Keys kill nursery and wild coral — 2023-07The fifth mass bleaching on the Great Barrier Reef since 2016 — 2024-03The fourth global bleaching event is confirmed — 2024-04The current state of the fourth global bleaching event is not established in this package — 2026-08 (state not established)
28 shown · 28 dated · 0 cannot be placed on an axis · Approximate or contested. Draw a band and do not sharpen its edges.
In order28
  1. 1842Darwin publishes The Structure and Distribution of Coral Reefs

    It happened, and the record is settled.

  2. 1952Drilling on Enewetak reaches volcanic basement beneath the reef

    It happened, and the record is settled.

  3. 1975Great Barrier Reef Marine Park Act creates a single managing authority

    It happened, and the record is settled.

  4. 1981The Great Barrier Reef is inscribed on the World Heritage List

    It happened, and the record is settled.

  5. 1983–1984Caribbean-wide mass mortality of the long-spined sea urchin

    It happened, and the record is settled.

  6. 1984Mass synchronous spawning described on the Great Barrier Reef

    It happened, and the record is settled.

  7. 1985The Long-Term Monitoring Program begins annual reef surveys

    It happened, and the record is settled.

  8. 1994 (announced; first workshop 1995)The International Coral Reef Initiative is formed

    It happened, and the record is settled.

  9. 1996The Belize Barrier Reef Reserve System is inscribed as World Heritage

    It happened, and the record is settled.

  10. 1998The first global mass bleaching event

    It happened, and the record is settled.

  11. 1999A published projection that reefs would bleach faster than they could recover

    It happened, and the record is settled.

  12. 2006Caribbean elkhorn and staghorn corals listed as threatened in the United States

    It happened, and the record is settled.

  13. 2009-01A measured decline in Great Barrier Reef coral calcification is published

    It was measured or witnessed, with the observation cited.

  14. 2009-05Coral Triangle Initiative Leaders' Declaration at Manado

    It happened, and the record is settled.

  15. 2010The second global bleaching event

    It happened, and the record is settled.

  16. 2012Twenty-seven years of monitoring show coral cover roughly halved

    It was measured or witnessed, with the observation cited.

  17. 2014Stony coral tissue loss disease first observed off Florida

    It happened, and the record is settled.

  18. 2014–2017The third global bleaching event

    It was measured or witnessed, with the observation cited.

  19. 2016-03 to 2016-04Mass bleaching on the Great Barrier Reef

    It was measured or witnessed, with the observation cited.

  20. 2017A second consecutive year of mass bleaching on the Great Barrier Reef

    It was measured or witnessed, with the observation cited.

  21. 2018Belize's reef is removed from the List of World Heritage in Danger

    It happened, and the record is settled.

  22. 2018-01The interval between severe bleaching events is measured, and it has collapsed

    It was measured or witnessed, with the observation cited.

  23. 2018The coral symbionts are reclassified into a family of genera

    It happened, and the record is settled.

  24. 2022-03Mass bleaching on the Great Barrier Reef during a La Nina

    It was measured or witnessed, with the observation cited.

  25. 2023-07Extreme water temperatures in the Florida Keys kill nursery and wild coral

    It was measured or witnessed, with the observation cited.

  26. 2024-03The fifth mass bleaching on the Great Barrier Reef since 2016

    It was measured or witnessed, with the observation cited.

  27. 2024-04The fourth global bleaching event is confirmed

    It was measured or witnessed, with the observation cited.

  28. 2026-08 (state not established)The current state of the fourth global bleaching event is not established in this package

    Sources disagree, or the dating is contested. Stated, not resolved.