Atlantic In Bloom: Hope For
Global Warming
By Steve Connor
18 June 2004
The Independent
Hurricanes sweeping across the North Atlantic ocean have triggered a spectacular "bloom" of marine plants, satellite pictures have revealed.The burst of phytoplankton is caused as the hurricanes stir up deeper layers of the ocean, bringing much-needed nutrients to the surface where the microscopic plants live.
Images captured by the SeaStar satellite clearly show how the growth of phytoplankton over vast distances can be influenced by storms as they track across the Atlantic from west to east.
After the storms have passed, the phytoplankton colonies grow and multiply for up to three weeks as minerals and other nutrients - particularly iron - become more plentiful.
Phytoplankton are important because they can soak up huge amounts of carbon dioxide from the air immediately over the sea surface and deposit this carbon deep within the ocean where it can stay for thousands of years.
In the past, information on what affects the growth of phytoplankton has mainly come from ships. The satellite shows the vast areas affected by hurricanes, underlining how important these tiny marine plants could be for limiting global warming. The satellite study, funded by Nasa, measured the amount of the green plant pigment chlorophyll in the upper layers of the ocean, a direct way of assessing the amount of phytoplankton present, said Steven Babin of Johns Hopkins University in Laurel, Maryland.
"Some parts of the ocean are like deserts, because there isn't enough food for many plants to grow. A hurricane's high winds stir up the ocean waters and help bring nutrients and phytoplankton to the surface, where they get more sunlight, allowing the plants to bloom," Professor Babin said.
"This effect of hurricanes has not been seen before. We believe it is the first documented satellite observation of this phenomenon," he said.
The satellite study was carried out between 1998 and 2001, during which time 13 hurricanes crossed the Atlantic.
Some scientists have suggested that artificially fertilising the oceans with iron filings may trigger more phytoplankton to bloom and so help to offset the carbon dioxide pollution released as a result of human activities.