Daily Bulletin


The Conversation

  • Written by The Conversation
imageThe Southern Ocean is remote, cloudy – and full of plankton.Liam Quinn, CC BY-SA

Most life in the sea ultimately depends on photosynthetic plankton. Also known as microalgae, these tiny or microscopic organisms live near the surface and take their energy from the sun and pass it on through the marine food chain.

But these plankton have a big role to play above the surface of the sea too. In new study published in the journal Science Advances, colleagues and I found that plankton help to control clouds over remote seas far from land. These clouds in turn bounce the sun’s energy back into space, regulating the Earth’s climate and keeping temperatures cooler than they would otherwise be without them.

Clouds are made up of many tiny droplets of water that have condensed from water vapour onto microscopic particles floating in the Earth’s atmosphere. These particles are known as cloud condensation nuclei. Plankton essentially help provide clouds with these nuclei to form around.

The number of these particles in a given volume helps to determine the number of droplets in a cloud, which can have a big influence on how much sunlight a cloud reflects back into space. The more droplets a given mass of cloud water is broken up into, the more sunlight is reflected, as the overall surface area of the cloud’s droplets increases. Since a significant portion of the planet’s reflectivity, or albedo, is due to clouds, this can have a major impact on the energy balance of the Earth.

imageAssorted phytoplankton under the microscope.Gordon Taylor / NOAA

To investigate the link between plankton and clouds, we looked at the Southern Ocean. This sea, encircling Antarctica, is one of the most remote places on the planet and far from any man-made sources of particles. And yet it is also one of the cloudiest places on Earth. What then are these clouds clinging on to?

Counting cloud droplets from space

We analysed satellite cloud data in a section of the Southern Ocean spanning right around the globe between the 35th parallel south (which passes through Australia and just south of South Africa) and the 55th (which just clips the bottom of South America).

imageChlorophyll-a in the Southern Hemisphere summer – the Southern Ocean is full of productive green and yellow patches.NASA

We found that more cloud droplets tended to occur above patches of the ocean with more plankton, indicated by increased concentrations of a type of chlorophyll used in photosynthesis. This means plankton are likely to influence cloud albedo and the amount of energy from the sun that is reflected to space.

Most of this is down to plankton releasing gases either through cell ageing, or when they are broken open and eaten by their microscopic animal counterparts zooplankton. Some of this gas is then converted into new microscopic solid particles, or adds to existing particles, which act as extra condensation nuclei.

imageZooplankton like this Antarctic krill feast on phytoplankton.krill666, CC BY-SA

However, we also found that some organic material – which can come from the bodies of the plankton, other sea creatures, viruses, bacteria and so on – is emitted directly into the atmosphere through sea spray. Water can condense around these tiny particles, forming extra cloud droplets (although organic material may affect droplet numbers in other ways too – the science is still hotly debated).

Keeping the oceans cool

We also estimated how much extra solar energy was prevented from reaching the surface due to the extra cloud droplets formed by phytoplankton – up to ten watts per square metre in summer. That’s comparable to similar estimates of the annual mean effect on clouds from man-made particles downwind of highly polluted regions. Thus, in a lifeless ocean without phytoplankton it is likely that the Southern Ocean’s surface would be somewhat warmer.

imageChlorophyll in the Southern Ocean, as seen from space.NASA, Author provided

Many climate models underestimate the amount of sunlight reflected back into space by clouds in the Southern Ocean. This can lead to errors in regional sea surface temperature predictions and incorrect large-scale circulation patterns both locally and in far afield regions such as the tropics, and so it is important that they are corrected.

These biases might partly be down to an unrealistic representation of the link between phytoplankton and cloud formation. Somewhat ironically, uncertainties in our knowledge of the “baseline” effect of these natural condensation nuclei are also one of the biggest causes of uncertainties in how anthropogenic aerosols are affecting the climate.

Due to its remoteness and inhospitality there is, however, very little in-situ data available from within Southern Ocean clouds with which to study what is going on. This makes satellite data very valuable, but also emphasises the need for more direct observations in this region.

Daniel Grosvenor does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Authors: The Conversation

Read more http://theconversation.com/how-plankton-help-control-clouds-over-the-worlds-most-remote-oceans-44855

Writers Wanted

Buying A Home In Australia: How To Prepare Financially

arrow_forward

Record year of growth for Tweed based business The Electrical Co

arrow_forward

The Conversation
INTERWEBS DIGITAL AGENCY

Politics

Prime Minister Scott Morrison's interview with Ray Hadley, 2GB

RAY HADLEY: Prime Minister, good morning to you.   PRIME MINISTER: G’day, Ray.   HADLEY: Gee, you’ve had a week.   PRIME MINISTER: Well, there's been a lot of weeks like this. This time last...

Scott Morrison - avatar Scott Morrison

Ray Hadley's interview with Scott Morrison

RAY HADLEY: I'm going to go straight to the Prime Minister, Scott Morrison is on the line right now. Prime Minister, good morning to you.    PRIME MINISTER: Good morning, Ray.   HADLEY: Just d...

Ray Hadley - avatar Ray Hadley

Defence and Veterans suicide Royal Commission

Today the Government has formally established a Royal Commission into Defence and Veteran Suicide following approval by the Governor-General.   Prime Minister Scott Morrison said the Royal Commi...

Scott Morrison - avatar Scott Morrison

Business News

Record year of growth for Tweed based business The Electrical Co

While many businesses struggled to stay afloat during the COVID-19 affected 2021 financial year, Tweed Heads based The Electrical Co. completed more than 50,000 smart meter installations across Aust...

a contributor - avatar a contributor

The Most Common Reasons why Employees End Up Leaving a Company

It is important for businesses to make sure they find the right people for their open positions. That is why a lot of companies are relying on professional outplacement services. A lot of companie...

NewsServices.com - avatar NewsServices.com

The little Aussie face sock startup is riding the personalized gift game

In a world where everybody has different desires, interests, and goals, what can be better than giving them things that meet their individual requirements. Personalized gifts have taken on the mar...

NewsServices.com - avatar NewsServices.com