Coral Reefs and Climate Change: Bleaching, Acidification and Storms, per NOAA
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How we wrote this: A plain-English summary of NOAA's National Ocean Service page "How does climate change affect coral reefs?", checked October 29, 2026.
The biggest global threat
NOAA calls climate change the greatest global threat to coral reef ecosystems. It says the atmosphere and ocean are warming, mainly because of greenhouse gases from human activities.
How it affects reefs
| Change | Effect on reefs |
|---|---|
| Warming ocean | Thermal stress that contributes to coral bleaching and disease |
| Ocean acidification (more CO₂ absorbed) | Lower pH that slows coral growth and weakens structure |
| Sea level rise | More sediment for reefs near land, which can smother coral |
| Storm changes | Stronger, more frequent storms that can destroy reefs |
| Rainfall changes | Runoff of fresh water, sediment and pollutants that fuels algal blooms and murky water |
| Altered currents | Less food for corals and poorer dispersal of coral larvae |
Mass bleaching events and disease outbreaks are becoming more frequent as temperatures rise.
Why it matters
Together these changes alter how reefs function, and the goods and services they provide to people around the world.
What you can do
NOAA's suggestions include choosing sustainable seafood (see NOAA Fisheries on sustainable seafood). See also reading sunscreen labels.
Related: harmful algal blooms, why the ocean is blue, what is seaweed.