Phytoplankton waste in ocean spray could trigger ice formation in clouds

Marine biological materials could contribute to ice formation in clouds. Source: Flickr, CC, Jose Roberto V Moraes.

Organic waste from phytoplankton (plant life) in remote polar oceans contributes to rare airborne particles that trigger ice formation in clouds, according to an international team of researchers that includes University of British Columbia (UBC) and University of Toronto scientists.
 
Results published this week in the journal Nature show that the organic waste from life in the oceans, which is ejected into the atmosphere in sea spray from breaking waves, stimulates cloud droplets to freeze into ice particles. This affects how clouds behave and influence global climate, which is important for improved projections of future climate change.  
 
“It’s been speculated that some of this biological material may trigger the formation of ice in clouds – making them ‘ice nucleating particles’ (INPs) in the atmosphere,“ says Theo Wilson, lead author from University of Leeds.
 
“Now we have clear evidence that marine biological material such as matter exuded from phytoplankton is able to nucleate ice and could do so in the atmosphere. This could be particularly important in the polar regions.”
 
Together with Jon Abbatt at the University of Toronto, UBC atmospheric chemist Allan Bertam oversaw and organized a field campaign in Ucluelet, British Columbia to collect samples for the study. The team used specialized equipment housed in trailers—UBC’s Mobile Aerosol Characterization Facility—to facilitate collection onsite.
 
Clouds in the Earth’s atmosphere are made of liquid water droplets, ice particles or a mixture of both. Ice particles affect how long a cloud exists and how much rain, hail or snow it produces. They also help control temperature of the climate by reflecting sunlight (keeping surface temperatures cool) or trapping heat close to the Earth’s surface (keeping temperatures warmer). Climate in the polar regions is changing more rapidly than any other part of the planet, yet predictions for how it will change in future remain uncertain. This improved understanding of cloud formation is a step closer to helping reduce uncertainties in global climate modelling.

An international team of researchers investigated marine life from the biological ecosystem in the Arctic Ocean, Western Atlantic and North Pacific by collecting biological matter using a remote controlled boat launched from research ships, along with hand held sampling equipment. By combining these direct measurements with global computer modelling scenarios of the atmosphere, the team found that airborne particles from sea spray were most influential on cloud formation in the polar regions.

Now we have clear evidence that marine biological material such as matter exuded from phytoplankton is able to nucleate ice and could do so in the atmosphere. This could be particularly important in the polar regions.

Chris Balma
balma@science.ubc.ca
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