The Ocean Engine That Regulates Earth's Climate

Every year, the ocean removes billions of tons of carbon dioxide from the atmosphere.

Most people assume that this happens because of whales, mangroves, or seagrass.

But the biggest carbon capture system on Earth is microscopic.

It is powered by microbes.

Invisible organisms drifting in the water column quietly regulate the Earth's climate.

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All right, let's just talk about it for a second.

Ocean microbes help regulate the global climate by capturing carbon and

transporting it into the deep ocean. This process is known as the biological carbon pump.

Without this system, scientists estimate atmospheric CO2

concentrations would be roughly 50% higher than they are today.

Let's think about that. 50% higher than they are today.

The ocean does not simply absorb carbon like a sponge.

Life in the ocean actively moves carbon from the atmosphere to the deep sea.

And microbes drive that system.

So the key question here is how do organisms smaller than a grain of sand help

regulate the entire planet's climate?

Here's the problem. Let's be honest, climate change is accelerating.

Human activities have dramatically increased atmospheric carbon dioxide.

Anybody who tells you differently is absolutely wrong.

Today, CO2 concentrations have exceeded 420 parts per million.

The highest levels seen in the last 3 million years.

The ocean helps buffer the planet from this rapid increase.

Scientists estimate that the ocean absorbs about 25% to 30% of the CO2 humans emit each year.

This buffer effects slows climate change.

Without the ocean absorbing carbon,

Earth's climate would be warming significantly faster than it is already.

But the ocean doesn't simply absorb carbon passively.

It's not just sitting there as carbon dioxide floats above the water and just kind of absorbs it.

A large portion of the carbon is moved into deeper waters through biological processes driven by microbes.

To hear some of the science of people research on the biological carbon pump.

It's one of the most important processes regularly in the Earth's climate,

so there's a lot of research on it.

Step 1 begins with phytoplankton.

This microscopic algae lived near the ocean's surface,

where sunlight penetrates the water.

Like plants on land, phytoplankton use photosynthesis to convert carbon dioxide

into organic carbon.

Scientists estimate that marine phytoplankton produce roughly half of the oxygen of the Earth

and fix about 50 gigatons of carbon annually,

comparable to all terrestrial plants combined.

Once phytoplankton converts carbon into biomass,

the carbon begins moving through the food web.

Zoo plankton grays on phytoplankton.

Fish consume zoo plankton.

But the key step in the carbon pump happens when organic matter begins sinking.

This happens through several pathways.

One we call marine snow.

Particles of dead phytoplankton,

fecal pellets from zoo plankton,

and fragments of organic material clump together into drifting aggregates known as marine snow.

These particles slowly sink through the water column.

Some sink hundreds of thousands of meters into the deep.

Microbes colonize these particles as they sink.

They break down the organic material, transforming it chemically.

Some carbon is recycled back into the surface waters,

but a fraction continues sinking deeper.

When carbon reaches waters below a thousand meters,

it can remain isolated from the atmosphere for hundreds of thousands of years.

Globally, scientists estimate the biological carbon pump transfers about 10 gigatons of carbon per year

from the surface waters towards the deep of the ocean.

That is a massive climate regulating process driven largely by microscopic organisms.

Let's talk about cyanobacteria.

Amongst the most important carbon capturing microbes in the ocean are cyanobacteria.

These organisms are photosynthetic bacteria that evolved more than 2.5 billion years ago,

and were responsible for producing much of the oxygen that transformed the Earth's early atmosphere.

Two of the most abundant species in the ocean are plora clorococcus and cyanocorococcus.

Sorry about the pronunciation.

I have trouble reading these.

Plora clorococcus is especially remarkable.

It is believed to be the most abundant photosynthetic organism on Earth.

Scientists estimate there may be around three octillion cells globally,

meaning a three followed by 27 zeros.

In some tropical ocean regions, a single millimeter of sea water may contain 100,000 or more

plorococcus cells.

These organisms capture carbon dioxide using sunlight and convert it into organic carbon.

Although each cell is tiny, their collective activity is enormous.

Together, plorocococcus and cyanocococcus contribute a significant portion of photosynthesis.

They form a foundation of many marine food webs supporting everything from zooplankton to large fish.

In many parts of the open ocean, nutrients are scarce.

These microbes dominate primary production.

Their activity is a major component of the biological carbon pump.

Climate change has the potential to disrupt the microbial systems that regulate carbon in the ocean.

One major risk is ocean warming.

Warm water tends to increase stratification, meaning the ocean becomes more layered.

Surface waters warm and become less dense, reducing mixing with colder nutrient rich water.

Phytoplankton rely on nutrients such as nitrogen, phosphorus, and iron that often come from deeper waters.

When mixing weekends, fewer nutrients reach the surface.

This can reduce phytoplankton productivity.

Another risk is change in plankton community composition.

Climate-driven warming often favors smaller phytoplankton species, including tiny peakoplankton.

Smaller cells tend to sink more slowly than larger plankton like diatoms.

Diatoms have silica cells that make them heavier, and they sink a lot quicker when they die.

If the ocean shifts towards smaller plankton communities, less carbon may be exported to deeper waters.

This could weaken the biological carbon pump.

The logical analysis found that warming oceans may reduce the efficiency of carbon export in some regions,

which means that more carbon will remain near the surface and eventually return to the atmosphere.

So what does success look like when we're talking about protecting the biological carbon pump?

Well, this will require protecting the conditions that allow microbial ecosystems to function.

One major factor is nutrient balance.

So excess nutrient pollution from agriculture can trigger harmful algal blooms that disrupt marine

ecosystems. So think about everything that's happening in Florida.

When Florida, the state of Florida moved to best practices in terms of regulating nutrients that come

out of big sugar, and it went into Lake Okeechibi. I think that's how you pronounce it.

I always forget how you pronounce it. And they go into those two rivers. One goes to the Atlantic,

one goes to the Gulf. A lot of times when you have excess nutrients in those rivers and the heat

kind of heats it up at the right time, all those nutrients and phytoplankton go into the ocean

in a heavy, heavy concentration. You get cyanobacteria, you get all this other algal blooms,

and then you get these red tides that we discussed in yesterday's episode where you have this mixing of,

you know, the right amount of nutrients, the right amount of wind, the right amount of currents

driven in the right way, and the right amount of dinoflagellates, which cause red tide,

and can kill a lot of other species and cause a nasty smell, and just the smothering of reefs,

as well as seagrasses that can help feed the entire food web. And so not having being able to

balance these nutrients and being able to monitor these nutrients is really important. So when

governments and policy makers try to go to best practices, these companies are not using best

practices. They're just using whatever they want to use. It's a ploy. That's how they get it.

So at the same time, some open ocean regions are nutrient limited. Understanding this balance

is critical for managing coastal ecosystems. So another key strategy is long-term plankton

monitoring, which can be really easy to do. Programs like the Continuous Plankton Recorder Survey,

which has been operating since the 1930s, help scientists track changes in plankton communities

across the entire ocean basins. These long-term data sets allow researchers to detect climate-driven

shifts in ocean ecosystems. Finally, scientists are increasingly working to incorporate microbial

processes into global climate models. For decades, many climate models simplified ocean biology.

But new research is improving how models represent microbial food webs and carbon export processes.

Understanding microbes is essential if we want to predict how the ocean will regulate climate

in the future. If you love the way this show breaks down science information and you're learning

from this, please consider following the podcast by hitting that follow button and of course

share it to someone that you think will benefit from this. So let's look into the final thoughts.

When we imagine climate solutions, we often picture forests, renewable energy and carbon capture

technology. But the ocean is already running one of the most powerful carbon capture systems on

earth. It's been doing so for millions of years and it is powered by organisms too small to see.

Tomorrow, we're going to look at another microbial ability. How microbes can help clean pollution

from the ocean? That's it for today's episode. If you have any questions or comments, please let me

know by going to SpeakUpForBlood.com, forward slash feedback. That's SpeakUpForBlood.com,

forward slash feedback. You can leave a voicemail or you can just type some stuff out,

questions, comments, whatever you want to do, feedback. I would love to hear it. Like I always say,

this is a podcast where I start the conversation, but I'd love for you to continue that conversation

and let's talk oceans. I want to thank you for joining me on today's episode of the How to

Protect the Ocean podcast. Have a great day. We'll talk to you next time and happy conservation.