Marine life triggers atmospheric ice

Marine life in remote ocean regions can contribute to airborne particles that trigger ice formation in clouds.

Scientists at the University of Leeds used biological matter samples to discover that organic waste from marine life – ejected into the atmosphere along with sea spray from breaking waves – can stimulate the formation of ice particles in clouds.

Dr Theo Wilson, from the School of Earth and Environment at the University of Leeds, said: “Breaking waves in the ocean generate large quantities of airborne sea spray. Some sea spray particles contain biological material linked to the ocean’s ecosystem. It has been speculated in the past that some of this biological material may trigger the formation of ice in clouds – making them ‘ice nucleating particles’ (INPs) in the atmosphere.

“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.”

In the study, published in the journal Nature, the team collected biological matter from the Arctic Ocean, Western Atlantic and North Pacific by using a remote-controlled boat launched from research ships. They combined this data with computer models of the atmosphere and found that specific marine life forms such as the common species of algae Thalassiosira psuedonana release organic material – less than 0.2?m in size – that is able to nucleate ice like the INPs found in the sea.

The scientists suggest marine organic material may be an important source of INPs in remote marine environments such as the Southern Ocean, North Pacific Ocean and North Atlantic Ocean.

Also, the scientists found that airborne particles from sea spray were most influential on cloud formation in polar and other remote ocean regions.

Research leader Dr Benjamin Murray said: “Understanding where ice nucleating particles come from is critical for predicting future climate. For example, as the polar ice caps shrink – we are heading for another record Arctic minimum later this month – there will be more ocean from which these particles can be emitted, and this marine source of ice nucleating particles might become more important.”