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Dr Helen Czerski from 麻豆传媒视频网站 Mechanical Engineering shares her experience in gathering data and understanding the carbon cycle of the ocean.

Using a 鈥榖ubble camera鈥� in stormy seas to understand the carbon cycle of the ocean

Scientists have understood for some time that the ocean has a huge store of carbon. The ocean actually absorbs a third of the extra carbon dioxide humans are adding to the atmosphere through burning fossil fuels. This matters, because we urgently need to track how carbon flows between the land, ocean and atmosphere, and governments and policy-makers need better tools to monitor and evaluate carbon reduction strategies.

Yet we still don鈥檛 completely understand the physical mechanisms by which carbon dioxide is taken in by the ocean, or how other gases like oxygen are transferred across the surface聽鈥� essentially the breathing process of the ocean. This knowledge is crucial for the carbon budget of the Earth, especially because of the need to predict how these processes will change in the future as the Earth system adapts to the changes that humans have caused.

In response to this, Dr Helen Czerski from 麻豆传媒视频网站 Mechanical Engineering has been working with scientists across the world to gather data and understand the process better. One important pillar of this was a research trip to the North Atlantic, supported by funding from the , the and the .

Research ships in stormy seas

鈥淭here are three big reservoirs of carbon on planet Earth,鈥� Dr Czerski explains. 鈥淭he atmosphere, the ocean and the land. The ocean is massive, but we tend to ignore it because we can鈥檛 see it. The atmosphere is less massive, but we pay a lot of attention to it because we walk around in it.鈥� It鈥檚 hard to study the details of invisible dissolved gases moving around in the ocean, but it鈥檚 now a priority.

Dr Czerski explains how different parts of the ocean are essentially breathing in and breathing out.

鈥淭he ocean is this big engine that's overturning,鈥� she explains. 鈥淚t's breathing out at the equator, and it's breathing in at the high latitudes, like the North Atlantic.鈥� Although scientists understand this process is happening, we don鈥檛 fully understand the mechanisms that control how much gas is coming and going, and how they might be affected as the planet warms up, if storms become more intense, or if other environmental factors change.

Research so far indicates that bubbles in the ocean may speed up the process of ocean breathing, but few people have tried to measure the bubbles themselves. Dr Czerski helped to design a novel high-resolution underwater optical instrument for imaging oceanic bubbles at the sea. This 鈥榖ubble camera鈥� 鈥� the only one of its kind currently in use 鈥� was designed specifically to count the number of bubbles just below the ocean鈥檚 surface, in very rough conditions. She has taken the camera on research ships, working alongside other scientists looking at different aspects of the ocean鈥檚 breathing system.

鈥淭o answer the questions we have, you absolutely have to have data from the ocean itself,鈥� Dr Czerski says. 鈥淎nd the only way to get that is to go to sea in a ship. We鈥檙e not at a stage where we can send robots, because we don鈥檛 know what the robots should be looking at.鈥�

The research ship to the North Atlantic carried scientists across career stages, who measured the waves, the weather, the movement of the gases, physical oceanography聽and much more. Dr Czerski measured the bubbles with the bubble camera. 鈥淚t takes photos in quite a specific way,鈥� she explains. 鈥淪eafarers have seen stormy seas for centuries, but the interesting bit is just a metre聽or two below the surface. The surface can be going up and down by 10 metres, so you need to get into that bit where you definitely don't want to go as a person. It's really complicated and difficult to measure, so that's what the camera is for.鈥�

An urgency to understand how the ocean breathes

During the six-week North Atlantic expedition, the team experienced three big storms and a number of smaller ones. Waiting for the storms was important to the project, as there was no existing data in violent conditions. The team needed to understand the difference that varying conditions make to the ocean鈥檚 breathing process. Dr Czerski was able to collect 鈥渢he only direct bubble population data for the highest wind speeds that anyone鈥檚 ever taken.鈥� She found that the top metre of the ocean is where the most important action is in terms of the breathing process and the role bubbles play.

However, there is a lot more work to be done to understand all the processes at play. 鈥淲hen you go out into these environments, it's not just about data collection, it's about seeing yourself as part of it,鈥� says Dr Czerski. 鈥淚t's messy, it's hard, it's dirty and it's physically exhausting. But we need to go into extreme environments to understand our own home.鈥�

Dr Czerski explains that the ocean is the Earth鈥檚 buffer for a number of gases, with the atmosphere sitting on top. 鈥淭he atmosphere is actually a relatively small reservoir of carbon and sitting right underneath it is this great big reservoir of carbon in the ocean,鈥� she says. 鈥淭hen you get the people trying to come up with ways to push carbon downwards.鈥� One of these ideas includes biological methods such as seagrass, to increase the amount of carbon the ocean can take in. Another is carbon sequestration, where carbon is collected, turned into rocks and placed into the ocean.聽But there are currently no robust methods to monitor and evaluate whether these methods will work in the long term, and thus there鈥檚 no certainty about the long-term consequences.

Dr Czerski says the risk with this is that scientists don鈥檛 know enough about the carbon cycle of the ocean yet to know if the carbon will stay there. 鈥淧eople are in a hurry to solve a problem,鈥� she says. 鈥淏ut it鈥檚 better to understand where carbon comes from and goes to, to have any chance of predicting what's going to happen in the future ocean.鈥�