October 2004 Marine plankton, bubbles and sea-spray could regulate climate

An EU-funded research team lead by Professor Colin O'Dowd from the National University of Ireland, Galway and Dr. Maria Cristina Facchini from the Italian National Research Council's Institute of Atmospheric Sciences and Climate has discovered a new and dominant source of aerosol particles over the ocean which can contribute, through the formation of haze and cloud layers, to the Earth's heat shield. This in turn can partially reduce global warming driven by the increase in greenhouse gases.

These aerosol particles are mainly comprised of organic matter, produced by plankton, and concentrated at the ocean surface due to its surface-active properties. Through the formation and bursting of bubbles in oceanic whitecaps, this organic matter is ejected into the atmosphere in the form of sea-spray aerosol particles. The bubble bursting process produces sea-spray which is generally thought to comprise sea-salt (i.e. inorganic matter). However, this new research has demonstrated that during periods of plankton blooms, sea-spray comprises organic matter rather than inorganic sea-salt and that the addition of this organic matter can increase the availability of aerosol particles and cloud nuclei – both of which contribute to increasing the cooling effect of the Earth's heat shield.

Previous research had linked algae and plankton to climate change through sulphur and iodine vapours forming aerosols. This new research which has been published in the most recent edition of Nature magazine, has shown that organic matter could in fact be the most important contributor to marine aerosols. However, this source of marine aerosol is currently lacking in state-of-the-art climate modelling studies. This breakthrough, linking the marine biosphere to climate change, is expected to have an important impact on the future prediction of the Earth's response to greenhouse-gas induced global warming.

The research team is composed of scientists from the Environmental Change Institute of the National University of Ireland, Galway; the Italian National Research Council's Institute of Atmospheric Sciences and Climate; and the European Commission's Joint Research Centre, also in Italy.

This work was funded by EC FP5 projects QUEST and PHOENICS.

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