More than half of the world’s coral reefs are under direct threat from human activities. Growth rates on some reefs have fallen by fourteen percent since the 1990s. Many scientists are concerned that global warming and ocean acidification—carbon emissions can destroy corals by dissolving their calcium carbonate structure—may doom the entire reef system before the end of the century.
In a last-ditch effort to save them, the Zoological Society of London has started its plan B: the freezer. Two-millimeter biopsies are being taken from living corals and preserved in liquid nitrogen at -200° C. Craig Downs, of the Haereticus Environmental Laboratory, has shown that these pieces can be thawed to regenerate into polyps.
The initiative follows the creation of a frozen ark in Svalbard Global Seed Vault, a Norwegian-funded program to preserve the world’s seed heritage, and a project in San Diego called the Frozen Zoo that stores the DNA of every living species.
Neither the Norwegian, San Diego, nor the Zoological Society of London efforts offer a fix, but future generations may thank scientists for taking out this insurance policy. The Global Coral Cryobank takes the long view: by preserving one thousand samples each of the 5,000 or so coral species on the planet, biologists may one day be able to replant reefs when the ocean’s health is restored. In the meantime it’s a reminder of the need to address climate change.