Marine algae a weapon against global warning?

July 19, 2002

Brussels, 18 July 2002

"Parforce" an EU-funded research project has discovered a new link between marine algae and climate change. Researchers working on the project found out that iodine vapours, released from algae or plankton, condense over oceans to form aerosols. These aerosols, which tend to counter "global warming", can have a significant impact on climate change as well as on precipitation patterns.

"This new discovery represents a major breakthrough in the prediction of climate change, as no current prediction model takes this fact into account", says Commissioner for research Philippe Busquin.

Aerosols have an important influence on climate regulation since they contribute to the Earth's "heat shield" through the formation of haze and cloud layers. Aerosols work in a way opposite to greenhouse gases: greenhouse gases trap heat escaping from the Earth's surface and lead to "global warming", while aerosols block heat from reaching the surface where it is absorbed, and may have a "global cooling" effect.

All aerosol types contribute to the "heat shield", but marine aerosols formed over oceans are its most important source, as oceans cover 70% of the Earth's surface.

What nobody knew until now was that algae and plankton are an important natural source of iodine-oxide aerosols. It was thought that the main source of oceanic aerosols were their emissions of sulphur compounds.

How to explain this new source of marine aerosols (iodine oxides)? Increasing oceanic biological activity (of algae or plankton) resulting from changes in ocean temperatures, can lead to increased iodine vapour emissions, which in turn, can lead to an increased abundance of aerosol particles. The iodine vapour released from algae is in the form of methyl-iodine molecules, which react with sunlight and ozone to produce iodine-oxide aerosol particles.

Thus, increasing the availability of aerosols will increase the solar blocking efficiency of the haze and cloud layers. Such a trend comprises a global cooling effect that could partially offset global warming from greenhouse gases.

Also, an increased abundance of aerosols will lead to a reduction in precipitation, and therefore longer-lived clouds further adding to the effect.

Experimental field studies into the phenomenon were made on the Irish Atlantic coast, and now the researchers are investigating whether this transformation occurs on a large oceanic-scale. In this regard, the research team (EU project PARFORCE), led by Professor Colin O'Dowd (National University of Ireland, Galway) and comprising a total of 15 research groups and dozens of scientists from Ireland, Finland, Sweden, Germany, UK and The Netherlands (see Annex), have also collaborated with US scientists from the California Institute of Technology to unravel the new process producing marine aerosols.

This research discovery has been recently reported in the scientific journal Nature (June 6).

For further information please contact:

Giovanni Angeletti, Scientific officer, Environment Programme, Biodiversity and Global Change Unit Research DG
Tel.: +32 2 295 84 32, Fax:+32 2 299 57 55
E-mail :

Julia Acevedo, Press and information officer Research DG
Tel.: +, fax: +

PARFORCE - New Particle Formation and Fate in the Coastal Environment


Main objectives

  • to elucidate and understand the processes and conditions which control and promote new aerosol particles formation in the coastal atmosphere
  • to examine the influence of man-made air parcel mixing on the production of these particles, important for their interactions with clouds and consequently their role on climate.
The production rate and fate of newly formed aerosol particles were examined by conducting experiments, both in the field and in the laboratory, for the determination of the complete aerosol size distribution.

The site of the field experiment was located at the Mace Head atmospheric monitoring station in the West Coast of Ireland.

Relevant aerosol precursors, (e.g sulphur and halogenated compounds), as well as primary gases such as ammonia, nitric acid and ozone, were measured with the high sensitivity required for this clean environment and high temporal resolution.

Among the results obtained, these may be briefly summarised here:

    Natural coastal aerosol formation events occur about 90% of days of the year;
  • Peak aerosol concentrations can exceed 1,000,000/cm3 during production events which can last from 2 to 8 hours;
  • the source of aerosol precursors is the exposed tidal zone and major production of aerosols coincide with low tide;
  • Coastal regions provide a very significant source of natural aerosol particles;
  • Halogenated compounds, in particular iodine vapours, had been observed among the most dominant emissions from various marine biota in the coastal zone


Co-ordinator: C.O'Dowd, National University of Ireland, Galway (IRL)&University of Helsinki (FIN)


  • H.C.Hansson, University of Stockholm (S)
  • J.M. Makela, University of Helsinki (FI)
  • G.Jennings, University College Galway (IRL)
  • H.Berresheim, German Weather Service (DE)
  • Leeuw, TNO The Hague (NL)
  • N.Hewitt, Lancaster University (UK)
  • R.M.Harrison, University of Birmingham (UK)
  • Y.Viisanen, Finnish Meteorological Institute (FI)

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