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Coral Reefs Turn White, Explained

The shallows look beautiful because the coral has turned white. That color is the reef dying: corals expel the algae living inside them, and what remains are skeletons, later smothered by seaweed. "And the reef turns from wonderland... to wasteland." The bleaching was a mystery until it lined up with warming seas, and with carbon released by burning fossil fuels.

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Key moments

Start here, then watch the full scene
  1. ❝ Monologue · 5 lines Beautiful White Coral Turns Tragic

    0:22–1:15
    52s
  2. The Earth Begins to Lose Balance

    1:46–2:50
    64s
  1. ❝ MonologueFrom beauty to ruin5 linesPractice page ↗

Coral Reefs Turn White, explained

What happens

In the shallows, ocean life is coming apart. A Blue Planet film crew stumbles on coral reefs turning white, a sight little known in 1998. The color comes from corals expelling the algae that live inside them. Beauty flips: the white is skeletons of dead creatures, and seaweed smothers the reef until wonderland becomes wasteland. Warming seas explain the bleaching, and the ocean has been absorbing the excess heat.

What's really going on

The white is doing two jobs. It looks like a spectacle, and it is a death. "Because what you're looking at is skeletons." Seaweed finishes the work. "And the reef turns from wonderland... to wasteland." The harder turn is the cause. Bleaching was a mystery, then it kept showing up where the ocean was warming. Climate scientists had already warned that burning fossil fuels and releasing carbon dioxide would heat the planet. A marked change in atmospheric carbon "has always been incompatible with a stable earth," and it was a feature of all five mass extinctions. Volcanoes needed up to a million years to dredge up enough carbon. Burning coal and oil did it in less than two hundred. Air temperatures looked steady into the 1990s only because the ocean was absorbing the excess heat and masking the impact. The white reef is the first indication that the earth was beginning to lose its balance.

Key lines & what they mean

“When you first see it, you think perhaps that it's beautiful, and suddenly you realize it's tragic.”
The white reef can look lovely at first glance. The same sight is then understood as a catastrophe, not a wonder.
“Because what you're looking at is skeletons.”
The white is not a living surface. It is the bare remains of creatures that have already died.
“And the reef turns from wonderland... to wasteland.”
After the corals whiten and seaweed smothers them, the reef is no longer a living marvel. It is a barren place.
“A marked change in atmospheric carbon has always been incompatible with a stable earth.”
A sharp change in atmospheric carbon cannot coexist with a stable earth. The line treats that clash as a standing fact.
“It was a feature of all five mass extinctions.”
That marked change in atmospheric carbon showed up in every one of the five mass extinctions.
“It was the first indication to me that the earth was beginning to lose its balance.”
For the speaker, this is the first sign that the earth is starting to lose its balance, after the ocean had been masking the heat.

Theme

  • Death & grief — The white coral is beautiful only until it is revealed as skeletons, and the reef turns from wonderland to wasteland.
  • Survival — A carbon change linked to all five mass extinctions is underway, and the reef's living cover is already dying into skeletons.

What this chapter teaches

Teaching points

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Questions, then the lines
Why do the coral reefs turn white?

The white color is caused by corals expelling algae that lives symbiotically within their body. The algae had been living inside the coral, and once it is expelled the reefs turn white. That is the reason given for the white itself.

Why did scientists connect the bleaching with warming seas?

At first, the cause of the bleaching was a mystery. Scientists then found that in many cases where bleaching occurred, the ocean was warming. Climate scientists had warned that the planet would get warmer as we burned fossil fuels and released carbon dioxide and other greenhouse gasses into the atmosphere.

Why did global air temperature look stable until the 1990s?

The global air temperature had been relatively stable till the '90s only because the ocean was absorbing much of the excess heat, masking our impact.

How does burning coal and oil compare with volcanoes here?

Volcanic activity took up to one million years to dredge up enough carbon from within the earth to trigger a catastrophe. Burning millions of years' worth of organisms all at once as coal and oil did that in less than 200 years.