Fertile Marine Plankton Involved in Southern Ocean Cloud Formation

A recent large-scale study suggests that fertile marine plankton may be one of the precursors of Southern Ocean could formation. Indeed, this region, considered by scientists one of the cloudiest regions on Earth, may owe the blankets of clouds overhead to tiny marine organisms called phytoplankton.

A team of researchers from the Pacific Northwest National Laboratory in collaboration with scientists from the University of Washington have investigated how the gases and particles produced by phytoplankton reach the atmosphere and become the very first seeds of clouds.

Published on July 17th in the journal Science Advances, the study postulates that phytoplankton is directly responsible for producing gases as well as organic matter which serve as the seeds of cloud droplets. In turn, these droplets contribute to the formation of brighter, more reflective clouds.

This new information may provide valuable insight into the role of such air particles play in global climate change.

Aerosols differ depending on their origin points. On land, they stem from vegetation, dust and pollution. Ocean aerosols, on the other hand, stem from sea salt being shot into the atmosphere. However, marine organisms are also responsible for producing considerable quantities of aerosols.

The team of scientists led by Susannah Burrows and Daniel McCoy from the University of Washington attempted to differentiate among the multiple types of aerosols and identify the role of organic matter in cloud formation. In order to achieve this, they used computer models and simulated the role that sulphates and organic matter, as well as sea salt, have.

With the help of satellite data on could droplets, they could observe a multitude of events occurring over the course of several months. Moreover, they were capable of studying large areas, on a scale of thousands of kilometers.

“The clouds over the Southern Ocean reflect significantly more sunlight in the summertime than they would without these huge plankton blooms,” Daniel McCoy, study co-author said.

After separately analyzing the data from the three types of aerosols, the team of researchers compared the concentrations of ocean-derived components and came up with a mathematical equation to help identify how sulfates and organic matter relates to cloud droplet concentrations.

While sea salt was a uniform contributor to the cloud droplets formed above the Southern Ocean, organic matter yielded significantly more cloud droplets during the summer. In fact, McCoy explains, during the summertime, the team identified approximately double the concentration of cloud droplets than they would have expected from a biologically dead ocean.

The researchers then concluded that the remarkable return of sunlight characteristic of summer periods relates to this flurry of phytoplankton activity. It’s this seasonality that causes increases in cloud brightness, which amounted to an increase of almost 4 watts per square meter.

Hopefully, in the future, similar research will help shed light on the role that the Southern Ocean clouds play in global climate.
Photo credits: NASA

Bio
Latest Posts

Christina Langfold

Remember that weird girl in school who never quite managed to fit in? Who was always silent and strange? That was me during my entire teenage life. A few years after finishing college (with a degree in arts) I decided that the best way to become more sociable, while also feeling safe, is to test my people skills online.