The scientist and author of ‘AnthropOcean’ explains why protecting the ocean is fundamental to protecting human health.

Cristina Romera, oceanographer: “Scientists of the future will identify our era as the Plasticene”.

By Elisenda Pallarés

Cristina Romera Castillo (Jaén, 1982) is a chemist and oceanographer who studies the main component of the Earth’s hydrosphere, and observes the damage caused by human action. During her expeditions, she can spend weeks at sea studying the composition of the water. She claims that plastic has found its way into every corner of the ocean. She laments that the current generation will be the last to be able to marvel at the coral reefs that are dying because of warming seawater.

Romera is also the author of the book AntropOcéano (Espasa), in which she stresses that there are solutions to many of the problems that plague the ocean. She currently works at the Institute of Marine Sciences-CSIC in Barcelona and has received several international awards for her research on the ocean carbon cycle and the impact of microplastics on marine ecosystems. She is attending this interview in the midst of bureaucratic procedures to be able to continue her scientific work. Her message is clear: protecting the ocean is fundamental to protecting

She states in an article she recently published in the CCCB that the sea gives us back everything we give it. What are we giving it?

We are giving it more bad things than good, and I call this oceanic karma: everything we give it returns to us. If we give it protection and conservation it returns food and protection to our shores. And it is able to sequester more carbon, to remove it from the greenhouse gas emissions we have launched into the atmosphere. Conversely, if we give it litter, it is going to give us back litter like plastics in our fish. The same with other kinds of chemical pollution that we are dumping into the ocean and then eating in our food.

“The ocean absorbs 90% of the heat that greenhouse gases cause”.

– In relation to carbon sequestration, meteorologist Isabel Moreno explains that the ocean acts as a “lifeline in the face of climate change” What role does the ocean play in this crisis?

This has an impact on our lives that we are not aware of. The ocean absorbs a third of greenhouse gas emissions, the excess that we launch through anthropogenic activity. It also absorbs 90 per cent of the heat from those gases, so without the ocean temperatures would be much higher. But this does not come for free. Some consequences are the acidification of the water – which affects organisms with a calcareous structure or skeleton; the modification of ocean currents, which affects the climate; it also affects the fauna: some animals that cannot move die and others migrate to another area with cooler temperatures, which has an impact on fishing. There are many side effects.

– You study the impact of microplastics on marine systems and for it you go on expeditions. What is your field work like?

When we go on expeditions on a boat, they can last from a few days to months. We sleep on the ship, we campaign on the high seas, where we go to collect samples. In my case, I analyse water chemistry. Other colleagues analyse the microbiology of the water or the fish populations. Then all this work is put together to have a global picture of what is happening in the ocean. I think it’s really nice because you don’t just focus on your field, but you interact with other people and understand your data better.

What I do is throw an instrument called a rosette, which has sensors attached to it that measure temperature, salinity, oxygen, chlorophyll… With the temperature and salinity, for example, we can know the mass of water we have. The device is lowered to the bottom, down to 5,000 metres, and a computer displays the data and with that we can find out where the water we are seeing comes from. The water that comes from the Mediterranean is saltier than the water that comes from the Atlantic, so we can identify it. As the water does not mix, or mixes very slowly, it is in blocks and we can identify the origin of each water. There are also bottles that allow us to take water from where we are interested, and on deck we analyse the water from each mass.

– When you were analysing the water one day, you found a higher carbon signal than usual.

Analysing data from many oceanographic campaigns I saw that there was an accumulation of carbon in an area of the North Atlantic and I couldn’t find the explanation. While I was in Miami working at a university, a physicist who studied drifting plastic came to give a talk and explained the areas where it was accumulating. One of them was exactly where I saw this sign. Then it occurred to me that the plastic might be releasing carbon compounds and so I started to study it.

– Is it safe to say that microplastics have already reached every corner of the ocean?

Yes, microplastics are all those smaller than 5 mm and have been observed throughout the water column, on the seabed, on the surface, inside animals… They are getting everywhere.

– Apart from ecosystems, do microplastics have an impact on human health?

Yes, we still do not know very well what effects they have on our health. Many of the animals that we eat, the plastic that has been observed has been found in their stomachs and normally the guts are removed and we don’t eat them. But because the plastic is so small, we do not know if it can be translocated into tissues. It has been seen in some cases that the plastic can reach other organs or tissues.

And what I find most preoccupying are the chemical compounds in plastic. Because plastic is not the pure polymer, but a lot of additives are added to it to make it last longer. These additives are easily released into seawater. Also if we heat a plastic taper in a microwave, for example. Many of these chemicals are endocrine disruptors, others are carcinogenic, and they have been found to have an effect on the health of marine organisms. Doctor Nicolás Olea studies the effect of additives on human health and explains that they have also been linked to women’s health, with cases of endiometrosis. Urine tests have been carried out and all the people had these additives. They are small amounts but in constant exposure, so they can be a problem.

– Can the ocean be cleaned up?

No. There is so much plastic and so little of it! There is some initiative to remove large plastics from the surface, but only 1% of the plastic that reaches the sea has been found on the surface. The other 99% is presumed to be in the water column or on the seabed. It is very difficult to clean up, and the technology that has been proposed will also remove the micro-organisms that are critical to the marine ecosystem. I think over time that plastic will settle to the bottom?

– Will it finally degrade?

We think it will be buried at the bottom for hundreds of years and scientists in the future who study the sediment will find a layer of plastic and identify our era as the Plasticene. The main factor in the degradation of plastic is sunlight; on the seabed, you don’t have sunlight, the water is cold and there is not as much oxygen as on the surface. So, on the seabed, you don’t even know how long it can last.

“The Mediterranean has all the problems that the ocean has, but raised to the nth degree”.

– Marine heatwaves are becoming more frequent. Is the Mediterranean a sea particularly vulnerable to global warming?

Yes, the Mediterranean has all the problems that the ocean has, but raised to the nth degree. If there is overfishing in general, it is even more so in the Mediterranean. In the global ocean overfishing of fish species is 35%, in the Mediterranean it is 75%. The accumulation of plastics in the Mediterranean is equivalent in many areas to that of the subtropical gyres, which is where most plastic accumulates. It is a sea with a lot of anthropogenic pressure because many people are living on its shores and there is a lot of chemical pollution. As it is poorly connected to the global ocean – it is only connected through the Strait of Gibraltar – there is less water exchange and more rubbish is concentrated. It is warming up a lot, last year in June we had September temperatures, the highest of the year.

– Perhaps when people talk about the climate crisis and biodiversity, they think more about forests.

Terrestrial ecosystems are visible and marine ecosystems are suffering at least as much. But we are not aware of the problems the ocean is suffering. When there is coral bleaching due to marine heat waves, you don’t see it in the media, you do not know unless you work on it. But when there is a fire in a forest, everybody sees it. I think we need to give more visibility to the problems that the ocean has because if you do not know, you do not protect it. We think a lot about trees, but there are ocean ecosystems that have vegetation and store up to ten times more carbon per hectare than terrestrial ecosystems. These are mangroves, seagrass meadows or salt marshes. It is not known that removing them also removes the ocean’s carbon sequestration function.

– The UN has reached an agreement to approve the Global Oceans Treaty with the aim of protecting 30% of international waters.

It is a very positive and unprecedented decision. If the open ocean is protected, this allows the UN target of protecting 30% of the ocean to be met. Let’s hope it really happens.

– Your book is called AntropÓceano and it makes it very clear that human action damages the seas, but it also highlights positive actions that are being carried out.

Marine protected areas are very important because they protect biodiversity. In aquaculture, more sustainable methods will be proposed. In Southeast Asia, many mangrove areas have been eliminated, which we have already mentioned that they capture a lot of carbon, and now they are being restored because they have seen that it was economically better to have the mangroves than the activity that replaced them. Seagrasses can also be restored, although it is more difficult. Just as there are green carbon credits and companies pay for trees to be planted, blue carbon credits are now being introduced to restore marine ecosystems.

– The most important thing would be to curb carbon emissions?

Yes, that is the main thing. We need to continue restoring ecosystems but it is essential to reduce emissions. There is no point in planting trees or conserving ecosystems if we launch so many emissions that ecosystems can’t cope. And we are already late in reducing emissions.

– This is what the new IPCC report says. It’s time for political action, isn’t it?

Politicians have the greatest capacity to solve all these problems. So do multinational companies. Sometimes there is a lot of ignorance, it is important that people are aware. And on an individual level, what we can do is to choose well who we vote for and where we buy our products. It is also essential to reduce consumption because we have an exaggerated consumption that generates a very high carbon footprint. We have to try to make things last as long as possible instead of buying and throwing them away all the time.

— Source: Published in Climática on 22 March 2023 and reproduced on Servindi under their terms and conditions.