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The Argo Evolution

Updated: May 31, 2019

Floating robots are changing our understanding of the ocean's role in climate

by Grace Greenwald and Shannon Switzer Swanson

Every second, humanity pumps an average of two and a half million pounds of carbon dioxide into the atmosphere, according to scientists’ best estimates. But where does all that carbon end up once it’s set free?

Climate scientists say that the world’s oceans are one major destination, as a global ‘carbon sink’. Day by day, oceans have been thought to sop up 50 percent of the carbon dioxide emissions we release by burning fossil-fuels, manufacturing cement, and converting forest into farmland, among many other activities.

While oceans absorb a large amount of carbon, they don’t soak it up at the same pace or volume across the planet. In fact, there’s one ocean that scientists have identified as the grand carbon ‘hoover’. It happens to be one few have heard of and even fewer have visited due to its remoteness and treacherous conditions. For years, it was widely estimated that 90 percent of CO2 absorbed by our seas is consumed by the ring of water that surrounds Antarctica: the ‘Southern Ocean’.

But what if that’s wrong? What if, in fact, the southern ocean is actually emitting carbon dioxide? And how did a crucial part of the carbon cycle get flipped on its head? This new theory about the Southern Ocean comes from data collected by an army of ocean-going robots, a floating armada of sensor buoys that have been launched into the seas of Antarctica. These buoys are the first to collect robust data in previously untraceable waters, and the people who developed them and tend to their care are dedicated to leveraging what they find to uncover the reality of ocean health and function. Their army of robotic buoys has put the remote Southern ocean, and its contributions to the carbon cycle, back in sight, and mind, with their discoveries.

‘People would often ask me: “You’re an oceanographer, how’s the ocean doing?” And my answer was always: “We don’t look”,’ Dr. Ken Johnson says as he stares from his desk out over a grey and choppy Pacific Ocean.

Johnson, a senior scientist in biogeochemical oceanography at the Monterey Bay Aquarium Research Institute (MBARI), has spent his life trying to change that. He is one of hundreds of scientists around the globe who tend to the buoys as part of the Argo Project, an international collaboration to explore large swaths of the ocean in minute detail.

The Argo program launched in 1999, and in its first decade, released 3,200 buoys into our oceans to collect a baseline of oceanic data – namely temperature and salinity. Around 2008, Johnson, who specializes in developing biogeochemical sensors, teamed up with other oceanographers to test the limits of sensor technology. Together they ushered in this new chapter in the Argo program, in which scientists and government agencies across the globe are now using sensors to study the chemistry, biology, and physical patterns of our oceans.

‘Our contribution has been inventing and adding chemical sensors that don’t need to be calibrated every second. You calibrate it once and then throw it in the ocean for five years,’ explains Johnson. These small steps in improving sensor technology leave researchers with more hours (and sanity) to focus on the real work.

After tinkering with his lab’s calibration methods and troubleshooting the sensor hardware, Johnson and his team at MBARI – which includes chemists, engineers, and machinists who develop and test all of the technology in-house – have turned their sensors on the Southern Ocean.  His lab’s latest efforts are part of the Southern Ocean Carbon and Climate Observations and Modeling project (SOCCOM). Housed at Princeton University, SOCCOM has been working with sensor specialists like Johnson to deploy buoys outfitted with biogeochemical sensors in order to more accurately measure the amount of CO2 the Southern Ocean absorbs and releases as part of our global carbon cycle.

In the Antarctic summer of 2018, a team of scientists, including Johnson, departed from the southernmost tip of South America – Ushuaia, Argentina – and sailed for two weeks dead south to reach the Southern Ocean and deploy 100 buoys fitted with the biogeochemical sensors developed by Johnson’s team. The data has been rolling in since, and it wasn’t what anyone was expecting: Instead of absorbing carbon dioxide from the atmosphere, in winter the Southern Ocean appears to be releasing it.

‘If one thinks land temperatures or rainfall events are [becoming] more extreme, or sea level higher and flooding more frequent, then one should care about what the Southern Ocean is doing. If it is emitting extra CO2, and this is a recent change, then we should be quite concerned. Climate will be shifting even faster,’ Johnson explains.

If a switch has flipped, and the Southern Ocean has shifted from being a sink that shackles carbon to a source that sets it free, then all of the negative effects of CO2 in the atmosphere will be further amplified by this newly-sovereign carbon – more droughts, more deadly storms, and more communities displaced by rising seas.

‘If it’s been emitting carbon all along, and we just didn’t have good enough data to realize this, it points to how little we understand about the carbon cycle, which exerts such a fundamental control on climate,’ Johnson continues, ‘Bottom line is that there’s going to have to be revision of our models of the global carbon cycle, particularly in the Southern Hemisphere.’

Understanding how carbon moves across the globe is essential for understanding how to manage a warming world. ‘Figuring out how the oceans participate in the global carbon cycle – understanding where gases are absorbed and where they are being burped back up – is the holy grail [of climate science],’ explains Dr. Lynne Talley, a physical oceanographer at Scripps Institute for Oceanography at the University of California San Diego.

Buoys don't get cold

How could scientists have gotten it so wrong? Until now, very little data was collected in the Southern Ocean during the winter, because it was dangerous and unproductive to send manned missions down there. On the Southern Ocean, ‘If summer is miserable, winter is miserable squared,’ says Johnson, who has been on tens of trips to study the near-polar climate. Their attempts to collect in the winter has never gone as planned, ‘The ship would be battened down with no one allowed to go out, which doesn’t exactly make for good conditions to collect data. We ended up with a fraction of the data we get in the summer.’

An excerpt of one of Johnson’s logs from a recent summer Argo-deployment illustrates the trials of such an expedition:

January 2nd, 2018

A constant 40 kn wind managed to make the ocean wild and furious. The roll was almost with no control. At midnight, staying in bed became a challenge. At 3AM, completely impossible.Things were dangerously flying in the cabin.

We had a maximum tilt of 40 degrees. At 50 degrees, the ship does not come back up. I have to admit that Zoe and I were planning what to bring with us to the lifeboat! It was so intense that nothing was secured to the deck anymore. All went crashing into each other, rolling back and forth, like a dense and unstoppable wave.

Thus, until now, scientists have built models of the Southern Ocean climate without data from the harsher winter months. But the autonomous Argo buoys have changed all that. They have allowed scientific measurements in the region to progress past the limits of human tolerance – withstanding the Antarctic winter and tempestuous waters to beam back data every ten days.

The Argo evolution: sensing the vital signs of the ocean

Collecting systematic data on ocean health was nearly impossible until recent technological developments like the Argo buoys. Dr. Steve Riser, a professor at the University of Washington who is in charge of designing, building, testing, and deploying the buoys to which Johnson attaches his sensors, says ‘as a community we just didn’t have the resources to look.’ Riser was one of the first to understand that new sensor technology could drastically reduce the resources they needed to answer their curiosities.

Before Argo, scientists would lower cables off the back of boats down to a depth of 2,000 meters – 1.2 miles down – to collect samples to measure ocean chemistry. The whole endeavor of lowering the cable and waiting on its slow, crawling ascent back to the surface, took more than 10 hours.

It cost $15,000 to fund the boat and manpower to collect that single sample. Now, Argo buoys take several samples a day at a small fraction of the cost, and send the data back to data centers across the globe, where it can be amassed and analyzed.

The early prototypes of these autonomous buoys were basic: measuring only temperature and salinity. Still, these measurements helped build more accurate depictions of currents and circulation.

‘I’m sure you’ve seen a globe with little arrows for all the current directions? In the past that was all false – a best guess. No one knew what the real ocean circulation was like. But we’ve taken our 12 years of Argo float data and been able to make a precise, real life map of global ocean circulation' says Riser.

As the sensor technology progressed, so did the breadth of measurements possible. Argo buoys now collect levels of oxygen, nitrogen, phosphorous, dissolved organic particulate matter, chlorophyll, and fluorescence. These are all critical to calculating an accurate carbon budget. ‘You can measure the vital signs of the ocean,’ says Johnson.

Riser, the world-renowned sensor guru, also emphasizes that while the buoy and sensor technology are neat, they are merely a vehicle for better understanding our oceans. ‘I didn’t get into this so I could employ buoys. I wanted the data. That was always my motivation: to get the data and do something good with it,’ says Riser.

Yet another unique element of Argo – in a world where competing perspectives, egos, and agendas often stall projects, those involved in Argo seem to agree that the global collaboration is one of the smoothest they’ve experienced.

‘There’s no committees or subcommittees. It’s a bunch of dedicated people around the world who get along together and agree to do the right thing,’ says Riser. From those interviewed, Argo seems to be a project that creates a space for scientists, who often work on isolated and disjointed projects, to stay connected as they aim for a common goal.

‘Working on Argo keeps scientist from becoming monkish. We have this brand new data no one’s ever seen before. It’s compelling to take a step back and be enthusiastic about it, rather than focusing in on our own little specialty,’ says Johnson.

The initial project mission envisioned in 1988 was to have a measurement every 300 kilometers across all the world’s oceans. This effort would need 3,000 floats and unprecedented effort from scientists and politicians globally. Numerous countries had an interest in monitoring the health of the oceans surrounding their borders with the US, France, and India as the three largest contributors. Being the country with the original vision, the US deployed buoys in the ocean space not claimed by a particular country or sponsor.

‘We tend to put our buoys in places where no one else has gone,’ explains Riser.

The Argo buoys can last for up to ten years and will continue to send information to Monterey via satellite for their entire lifetime, allowing for  studies over many years that can reveal changes in the ocean’s health. With all of this data streaming in, in their first eight years of deployment Argo buoys have surpassed the total global data on ocean chemical levels gathered during the past 100 years. In 2018, the buoys have doubled that amount again: filling gaps in knowledge about how our oceans work, including and especially how carbon cycles in the Southern Ocean.

Demystifying the high seas

Besides collecting data, connecting people to the daily rhythms and workings of the ocean (especially in the lonelier parts of the ocean often referred to as the ‘high seas’) has been a motivating driver of the Argo Project. Most people experience the ocean, if at all, via a coastline. But these buoys are showing us what goes on in the deeper waters, where few people are able to visit. Riser and his colleagues want people to know there’s a whole world of action going on in the furthest reaches of our seas.

‘The ocean looks all the same out there,’ explains Riser, ‘All the great information is below the surface, but there’s nothing to physically see: it’s all in the chemicals and nutrients. For geeky scientists like us it’s great, but for average Joes on the street it’s not very interesting.’

One way scientists are attempting to connect people to this wealth of activity is through outreach with coastal schools, engaging students in a program that allows classrooms to adopt, name, and track a float of their choosing on its voyages. ‘The kids get to name the floats. Some of the names are cool, but some are just bizarre. The most clever – Lil Sinker,’ Johnson laughs. Kids track their adopted buoy in real time as it drifts thousands of miles past the coast they know as home. The buoys are a point of grounding for the students to help makes the vastness of the ocean easier for them to visualize.

Knowledge is power, and that can be good or bad

Building and deploying buoys across the world’s oceans is a major feat of persistence and international coordination.

‘Sometimes I feel like I should’ve been trained in diplomacy in addition to chemistry,’ Johnson jokes.

Through such extensive work with hundreds of multinational stakeholders, the Argo project has amassed a critical amount of data in its 18-year tenure, and will likely continue to measure and explore our oceans for decades to come, presumably with more metrics, as Johnson and his team continue building upon their knowledge of sensor technology.

But with this data comes added responsibility. While the main purpose of Argo has been to advance our understanding of climate science, countries have found supplementary ways to use the data, raising ethical uncertainties about who has the power to use these global findings, and to what end.

For example, the Argo base in Hyderabad, India, has been producing what Johnson refers to as enhanced fishing zone maps. These provide guesses as to prime fishing locations based on the locations of nitrate concentrations measured by the Argo buoys. Nitrates are the fertilizer of the ocean: Plants and algae rely on it for food, and as the plants and algae thrive, aquatic life flocks to the area. These gatherings are spontaneous and fleeting and being able to spot them remotely from data-streaming to a computer can give fishing vessels an edge.

Johnson noticed that in maps produced by the website Global Fishing Watch, which tracks fishing vessels on the high seas using GPS data, the fishing vessels were clustered around the very same pockets of ocean that the Argo buoys identified as having high nitrate density. ‘I’m not sure how sustainable or not it is, but they are optimizing the data to catch fish,’ says Johnson.

And word is spreading

‘Fisheries agencies across the globe are wanting in. Korea wants to get 40 buoys into the Southern Ocean,’ Talley says.

But when asked how she feels about this, she responds, ‘I feel great about it. We just can’t sustain Argo by ourselves. It’s a different user.’ But she also goes on to emphasize that everyone must work together to make sure that the data is not being abused. ‘We don’t want to endanger Argo under any circumstance,’ she says.

When there are so many stakeholders needed to execute a project like Argo, something founded on a mission of making data available to the public, does any one country have the right to police what comes of their science? What if countries begin joining the effort only to exploit ocean life for financial gain? In an open-source era, Argo presents new ethical concerns over globally collaborative science

Regardless of participants’ intentions, it’s easy to see the benefits of the data Argo is amassing.

‘We’re creating the weather service for ocean health to really see what’s going on out there,’ Johnson explains. Not only can scientists now see what’s happening in the ocean on a given day, but moving forward scientists can identify trends and see how carbon levels are changing. Argo indeed seems to be leading us into a new era of proficiency on ocean health and climate wellness.

As our interview winds down, Johnson reminds us that nowhere is that data more important than in the Southern Ocean. He reminds us that the Argo buoys have flipped things upside down.

‘It’s not that we were off by 15 or 20 percent,’ he says as he stares out at the Pacific Ocean from his office, ‘We got the sign of the trend backwards, which has profound impacts for our understanding of the flow of carbon dioxide around the planet.’

Johnson, Riser, Talley and all of the scientists involved in Argo care about data. But they also adore the ocean, and it’s apparent that this work is a labor of love. Whether a carbon source or a sink, and as menacing as the Southern Ocean can be, those who have had the opportunity to travel to this icy pole are beguiled by it.

Buoys don’t sense cold, but they also can’t appreciate intrepid expeditions quite the way in-the-flesh scientists can. This is evidenced by Johnson’s closing line in his January 2018 MBARI blog following a successful data retrieval from a float:

The energy that I feel here, from the power of the waves, and the whips from the wind, makes me feel alive. I LOVE THE SOUTHERN OCEAN!!


Grace Greenwald is an undergraduate at Stanford University studying biology and creative writing. She is a terrible swimmer for someone who loves the ocean.

Shannon Switzer Swanson is completing a PhD in Environment and Resources at Stanford University. She studies human-ocean connections.


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