Dr Graham Jones of Southern Cross University in Lismore has shown that the algae present in healthy reefs produce a volatile substance called dimethylsulphide (DMS), which oxidises in the atmosphere to produce what are known as cloud condensation nuclei. Water vapour condenses around these tiny sulphur aerosol particles, leading to the formation of clouds. 

The production of DMS is strongly tied to water temperature, with even slight increases leading to a drop in production. The resulting pattern of reduced cloud cover during periods when water temperature is increased has already been observed during El Niño years. ‘What we think happens is that during an El Niño, which can produce doldrum conditions in the Great Barrier Reef (GBR), sometimes for a couple of weeks at a time, this process shuts down,’ Jones told Mongabay.com.

Jones points out that disruption to coral reefs’ ability to promote cloud formation could have a significant impact on vegetation on adjacent land areas. ‘The best example is the rainforests of north Queensland,’ he said. They are right in the path of the southeast trade winds, which blow over the [GBR] for most of the year.’

May 2010