Coral Reefs Fight Climate Change by Impacting Weather and Forming Clouds

Coral reefs are in danger from climate change. Warmer conditions can impact the algae within corals and cause bleaching events that can, ultimately, cause vast swathes of a reef to die off. Now, though, scientists have learned that coral can fight back. It turns out that the coral animal makes an important sulphur-based molecule with properties that include the encouragement of cloud formation.

"The characteristic 'smell of the ocean' is actually derived from this compound, indicating how abundant the molecule is in the marine environment," said Cherie Motti, co-author of the new paper, in a news release. "In fact we could smell it in a single baby coral."

The compound itself is called dimethylsulphoniopropionate (DMSP). Previously, researchers had assumed that the large concentrations of DMSP emitted from coral reefs came solely from their symbiotic algae. However, that appears to not be the case. It turns out that the coral animal can also emit DMSP.

In this case, the scientists discovered that corals increased production of DMSP during warmer water temperatures that put them under stress. DMSP and its breakdown products act as antioxidants and protect the coral tissues from environmental stress. In addition, DMSP can also serve as nuclei for the formation of water droplets in the atmosphere. Essentially, this compound can help create clouds.

"Cloud production, especially in the tropics, is an important regulator of climate--because clouds shade Earth and reflect much of the sun's heat back into space," said Jean-Baptiste Raina, lead author of the new study, in a news release. "If fewer clouds are produced, less heat will be reflected--which ultimately will lead to warmer sea surface temperatures."

As coral reefs decline, in fact, there will be less DMSP. This, in turn, could help exacerbate local global warming and make conditions worse. For example, Australia's Great Barrier Reef is a major hotspot for the emissions of sulphur aerosol particles and could constitute a major source of cloud condensation nuclei along its 2,600 km length. Needless to say, this is something that should be kept in mind when it comes to preserving and protecting coral reefs across the globe.

The findings are published in the journal Nature.