Marine heatwave

Assembled from 13 blocks · 1 evidence · 16 related

1. Story
2. A prolonged period of anomalously warm water at a given location, conventionally defined relative to a local climatological percentile rather than an absolute temperature, so that the same event definition works in the Arctic and in the tropics. Marine heatwaves are the proximate agent of every mass bleaching event: the background warming trend raises the baseline, and the heatwave is the excursion above it that crosses the physiological threshold. The two combine multiplicatively rather than additively from the reef's point of view — a heatwave of a size that was survivable against a 1980 baseline crosses the bleaching threshold against a 2020 one, without the heatwave itself having become larger. This is why reef thermal risk rises faster than mean sea surface temperature does.
3. Knowledge
4. Marine heatwave
5. Connections
6. Reef-building corals (Scleractinia)
7. Coral bleaching
8. Thermal refugia
9. Coral restoration methods
10. Mass bleaching on the Great Barrier Reef during a La Nina
11. Extreme water temperatures in the Florida Keys kill nursery and wild coral
12. Evidence
13. The ocean has absorbed a large share of anthropogenic carbon dioxide emissions and surface ocean pH has declined by roughly 0.1 units since the pre-industrial period, corresponding to an increase in hydrogen ion concentration of around thirty per cent. V55 verification basis: not consulted in this session; these are standard assessed figures stated from the producing model's knowledge of the assessment, not read from the chapter, and no confidence language from the report is reproduced.