Darkness falls and I stand at the top of the research vessel Maria S Merian, on the bridge. This is the control center, with large windows providing an uninterrupted view of the stormy sea in all directions, and long rows of screens and maps displaying data coming from within, around, above and below the ship. Out here in the open ocean, it is essential to keep a close eye on what nature is up to. The lights are off so dark-adapted eyes can scan the waves, and the first officer uses the speakers to fill the room with smooth jazz and tranquility.
I hold on to the rail under the window with both hands, one leg against the desk behind me, as the ship rides into a wave about eight meters high and then crashes down the other side. It’s like a big roller coaster; you feel yourself floating just after the peak of the wave and then, as the ship hits the trough, you strain to resist the extra force of the floor.
Although the views are dramatic, we are here in the Labrador Sea because of something no human can directly see. In this northwestern corner of the Atlantic Ocean, between the southern tip of Greenland and Newfoundland, we can live for weeks in winter – in the cold and constantly stormy weather – in a certain scientific phenomenon. We’re here to learn more about a process that is fundamental to the way our planetary engine ticks. All around us the ocean is taking a deep breath – literally. The cooling between late November and February causes deep mixing between surface water and water at depth, facilitating essential transport of gases. I’m part of the British contingent of an international team of scientists here to study how that happens.
Our seas are doing us a huge favor by removing extra carbon from the atmosphere
Our society tends to see the great blue expanses on maps as just a liquid filler with fish in it. Nothing could be further from the truth. The connected global ocean is an engine, a dynamic 3D system with an internal anatomy that is constantly changing doing things that shape the world that we take for granted. It is a huge reservoir for heat and gases: carbon dioxide (CO2), oxygen, nitrogen and more. And where the vast surface of the sea touches the atmosphere, these gases can be transferred in both directions, changing their concentrations in the water and air.
Near the equator, for example, CO2 comes out of the water to rejoin the atmosphere, while here in the high latitudes it goes the other way. These processes are currently not in equilibrium: the ocean absorbs extra CO2 because we have increased the concentration in the atmosphere by burning fossil fuels and changing the land surface. Our seas are doing us a huge favor by removing extra carbon from the atmosphere, but we don’t understand all the details of this process on the surface, or how it might change in the future.
The ocean breathing that takes place here in the Labrador Sea is particularly important because this is one of the few areas where the surface is sometimes directly connected to the depth. Over most of the ocean, the upper layer of water (usually several tens of meters thick) floats on the colder, denser water below, remaining quite separated. But in this corner of the North Atlantic, surface water cools so much in winter that persistent storms can mix the top layer far down. It’s like an open drain in the deep ocean – anything that enters the sea here can just keep flowing down – and this is a crucial part of what’s called the ‘reversing circulation’, the slow global transport of seawater between the surface and the depth. One consequence is that animals that live about two-thirds of a mile below the surface and never see the sun’s light, from the little lanternfish to the giant squid, can still breathe oxygen.
Major winter storms at this location add oxygen to the surface water, which sinks downward and then sideways and further into the rest of the Atlantic Ocean, oxygenating the entire middle layer of the ocean. But our best computer models for how much oxygen flows this way don’t match what we actually measure. This matters because the entire world ocean is slowly losing oxygen – there is about 2% less now than in the 1960s. To predict what will happen in the future and its implications, we need to understand the conveyor belt that gets it there.
The Maria S Merian is a German research ship and there are 22 scientists and 24 crew members on board. Each team within this collaboration of researchers from Germany, Canada, the US and Great Britain studies a different aspect of the complex breathing process. The only way to make progress is to keep an eye on the physics and chemistry of the ocean, and what the surface and atmosphere are doing, and then put the data together – putting the puzzle together once we get back to the be dry. There have been relatively few experiments that could directly measure gases moving between the atmosphere and stormy open waters, and the last one (which I was also involved in) was 10 years ago.
Ten years later, we have new and more accurate measuring instruments and we know that we need to study a wider range of interconnected processes. This is a huge opportunity, and we are all aware that (for logistical and resource reasons) it will not happen again for some time. None of this is simple: these are new experiments in a violent environment; there is no guarantee that whatever you put over the side of the ship will come back intact, or that the wind and waves will allow us to carry out our plans. Every piece of data we get is precious.
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There are two methods of measuring ocean respiration, one from a tall mast on the bow of the ship that tracks the smallest details of wind direction and CO.2 concentration, and one that depends on measuring inert tracer gases that we injected into the water ten days ago (I’m writing this in late December), now at concentrations of about one in a million billion. Some on board are continuously taking water samples, both from the surface as the ship weaves around, and from a range of depths, mapping the 3D structures (masses of water distinguished by temperature or salinity) below us. Others have small underwater or surface vehicles, which are towed behind the ship or ‘fly’ short missions in the water.
I measure the bubbles of breaking waves at the surface – and how their size changes over time – because these are thought to speed up the transfer of some gases to the water. The difficulty is that all the interesting bubble processes occur in the top 2 to 3 meters, but the surface itself often moves up and down between 5 and 10 meters. To give me access to that uncomfortable upper layer, the mechanical engineering workshop at University College London, where I am based, made me a buoy that is basically a large hollow yellow stick with a heavy base that floats upright and is mostly submerged .
Nature is rich and beautiful, but rarely neat or easy, and we must take that into account
This provides a platform for my eyes and ears just below the waterline: with specialized bubble cameras, acoustic devices and dissolved gas sensors. It can drift freely for several days in heavy seas, following everything around it. We only have seven hours of daylight, so the buoy is always deployed at night. It takes a large crane and seven people to get it safely over the edge into the sea, and then you can only see the top 2 meters and the white flashing light above the waves.
There is almost always complete cloud cover, so the sky is black and the sea is black and you can’t see where they touch. The little blinking light drifts away into the darkness as years of work and preparation drift away and all that remains is faith in the technology. The beacon at the top emails me every half hour to tell me where it is, chatting away in the background of my day while I try not to think about some 50mph winds and wave heights of up to 30ft with the can do buoy. The relief when we find him a few days later is enormous.
Although we live in an age of technological surprises and constant information, data seems cheap. But our global ocean is huge, and there’s no easy way to scale up research into its innards. Marine science is still incredibly lacking in data – especially considering that the sea is at the heart of any climate model. Computer models are extremely powerful, but their job is to match the measurements we make in the real world. That is why we only know how well the models work when we have these critical figures. That’s why it’s important to make difficult measurements here, in the messy real world, and try to challenge our understanding of what’s happening around us. Nature is rich and beautiful, but rarely neat or easy, and we must take that into account.
Related: Why we must respect Earth’s last great wilderness – the ocean
I hope that the outcome of this project will be a much better understanding of the mechanisms that cause gases to move across the surface in stormy seas, and that this will mean that we can calculate much more robust carbon and oxygen budgets for the ocean. This won’t add to the strong arguments against burning fossil fuels – we already have more than enough science to know what we need to do to prevent the worst climate outcomes, and enough technology to help us achieve most of that.
But what this will do is help us understand and predict a changed ocean, and make better decisions about how to manage the consequences of our past actions. We live on a water planet, and any honest assessment of our own identity must reflect that. Ignoring the sea is not an option, which is why increasing our understanding of it is an essential step towards a better future.
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Blue Machine: How the Ocean Shapes Our World by Helen Czerski is published by Transworld (£20). In support of the Guardian And Observer Order your copy at Guardianbookshop.com. Delivery charges may apply