Oct 14 2015 Posted: 11:52 IST

Irish and Italian scientists reveal new link between oceanic plankton, viruses, clouds and climate, published today in Scientific Reports


An international team of researchers led by Professor Colin O’Dowd from NUI Galway’s School of Physics and Centre for Climate and Air Pollution Studies have found that the release of plankton-produced organic matter, which leads to a global-cooling effect that could partially off-set the warming caused by greenhouse gases, is triggered by marine virus attack. The results were published today (14 October, 2015) in leading journal Scientific Reports.

Plankton plays an important role in the global carbon budget and biogeochemical cycling of Carbon Dioxide (CO2), the dominant greenhouse gas. The ocean contains 50 times more carbon than the atmosphere, and at least half of the oxygen we breathe comes from the photosynthesis of marine plants such as plankton. Currently, 48% of the carbon emitted to the atmosphere by fossil fuel burning is sequestered into the ocean. However, the future fate of this important carbon sink is quite uncertain because of potential climate change impacts on ocean circulation, biogeochemical cycling, and ecosystem dynamics, the latter often determined by marine viruses.

Recent research has suggested a trophic predator-prey dance between phytoplankton, viruses and climate change as the growth of plankton blooms not only responds to temperature change but also acts as a Carbon Dioxide sink, ultimately leading to a reduction in global warming. This new study, led by NUI Galway, finds that the demise of the plankton blooms, or the bloom’s death disco, also has the potential to counteract global warming through the release of organic matter which becomes concentrated at the ocean surface and enters into sea-spray produced by bursting bubbles.

This spray forms haze and cloud layers that block out some of the sun’s heat, leading to a cooling effect. This cooling effect partially off-sets the warming caused by greenhouse gases. The organic matter enriched in the sea-spray effectively increases the cooling effect of the spray’s haze and cloud layers, but, to date, it has proven elusive to find the underlying reasons for the production of organic matter from the blooming plankton.

The team of Irish and Italian scientists found that the release of the organic matter is triggered by an attack from marine viruses, the most abundant biological particles in the world, leading to the demise of the bloom. And in doing so, releasing massive amounts of organic matter much more so than if the bloom was to die more naturally, leading to more abundant haze and cloud layers.

The team was led by Professor Colin O’Dowd from NUI Galway’s School of Physics and Centre for Climate and Air Pollution Studies, and included Dr Dagmar Stengel from Botany and Plant Science at the School of Natural Sciences, NUI Galway. The Italian contributions were led by Dr Maria Cristina Facchini, Institute for Studies of Atmosphere and Climate and Professor Roberto Danovaro, University of Marche.

Professor O’Dowd said: “This represents a major breakthrough in our understanding of the coupling between the climate system and the marine biosphere. The breakthrough could only have been achieved through the collaboration within a multi-disciplinary team comprising world-leaders in atmospheric physics, atmospheric chemistry, ocean chemistry and ocean biology, utilising state-of-the-art technology to quantify aerosol particles and viruses on the nano-scale, to Earth Observation satellites on the global scale.”

To view Scientific Reports paper visit: www.nature.com/articles/srep14883 

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