Exploring the hidden depths with Carlos Duarte

It sounds unbelievable to hear but it is often said we know more about the surface of our own Moon than we do about the depths of the oceans and seas, and the life that might reside in them.

If you ever need someone to point you in the right direction and give you even the slightest bit more clarity about the oceans and seas, that would be Carlos M. Duarte, a marine ecologist who has studied everything from the frosty polar oceans to the warmer climes of the tropical ones. He’s researched the ecosystems at the deepest depths as well as those closer to shore.

Born in Lisbon, Portugal in 1960, Carlos Duarte has an impressive record when it comes to understanding how life can exist in our oceans or even any body of water in general. He has a bachelor’s degree in Biology, combined with a Ph.D. in limnology (the study of inland aquatic ecosystems), and is a prolific publisher, having published more than 900 scientific papers so far.

His expertise in the field of marine ecology led to him to explore ways in which conserving and restoring marine ecosystems can help mitigate, and adapt to, climate change, which led to Carlos being called the 12th most influential climate scientist in the world, according to Reuters, who published a special Reuters Hot List of scientific movers and shakers in 2021. Knowing what makes our oceans tick gives Carlos Duarte an insight into how we might be having an impact on our oceans, and so we sat down to speak with him to see how deep it all truly goes.

A drop in the ocean

When we think climate change, it’s very easy to bring it back to the close confines of our own lived experience. Sea levels are rising but we tend to only think about what happens up here on dry land, and not about the churn happening out in the ocean. At least 70 per cent of the Earth’s surface is water, and yet 15 per cent of life on earth is classified as marine life. Going even deeper, up to 91 per cent of the species living in the oceans are yet to be classified at all.

Once I was asked, what was the biggest risk to the oceans, and I replied, the biggest threat to the oceans is that we give up on the vision of a healthy ocean.

Our oceans do more than sustain life in their hidden depths, but also help maintain a healthy biome across the planet itself. As Carlos tells us, “The ocean is a big thermal regulator of the planet, as water has such a huge capacity in terms of thermal capacity to store heat…Without the ocean, we would be experiencing extremes in temperature, as we see in areas far inland.”

Carlos gives us a fascinating example of what happens in the real world, when you live in a landlocked region, cut off from any bodies of water which might help keep temperatures in check. He tells us about countries such as Kazakhstan, one of the world’s largest landlocked countries, which experiences highly volatile temperature swings. He claims: “They experience temperatures ranging from 40 degrees Celsius maximum down to minus 50 degrees minimum, and that’s because they’re far away from the ocean.”

By contrast, the UK is an entirely coastal country, and temperatures stick to a narrower corridor between zero to 20 degrees Celsius on average, with the odd extreme either way, but hardly anything like the swings seen in Kazakhstan. Other than being a thermal regulator, the oceans are a key food source for many organisms besides humans. Carlos adds that the omega-3 oils found almost exclusively in seafood have a vital role to play in human history. He adds, “Without the ocean, we would probably still be primates jumping around somewhere on the savanna, because the exponential rise in the size of our brains, from which our intelligence comes from, was derived from the time we connected to the ocean food web.”  This is not just a legacy of the past, as Carlos is adamant that our mental health and intelligence continues to depend heavily on healthy “blue” foods.

In case the role of the oceans hasn’t quite sunk in, it effectively helped steer the path of human evolution itself. To our ancestors, the oceans have helped keep land temperatures within a survivable range, while also offering up a source of brainfood in the form of seafood.

Shockwaves in the deep

For all that the oceans have given us, humans give things back in return but not all of them are pleasant or helpful in the slightest. Many marine organisms have evolved to have ways of communicating and hearing which make them far more sensitive to a host of noises compared to humans, whose ears are the product of millions of years of evolution on dry land. Since the days of Aristotle and Da Vinci, we have known that sound travels easily and far through water, though in a different way to travelling through air.

Human activity in the oceans has grown significantly, especially with the advent of globalisation and the mass import and export of goods all over the planet. Conveying goods by air can prove costly and face constraints in terms of weight, while conveyance by water is a far easier, time-tested solution.

As Carlos explains, “Now, about 90 per cent of the goods exchanged in global markets are transported across the ocean.”

All of this churn in the water creates a cacophony of sound which is dubbed anthropogenic noise, or noise derived exclusively from the activities of humans which has an impact on the environment. Carlos led a highly influential paper on the subject, which concluded that anthropogenic noise is a major stressor for marine life. Examples of this type of noise stem from simple things like the noise introduced by cavity of propellors and the roar of ship engines to sonar equipment transmitting beeps across the oceans. While there is a lack of conclusive evidence that anthropogenic noise actively increases the mortality risk for marine life or lessens the settlement of their larvae, there is evidence to suggest it changes their behaviour and leads to missed opportunities to feed and occupy habitats within their range.

“Sound travels very far in the ocean”, Carlos reveals. “The only area of the planet that might be pristine in terms of sound might be Antarctica, because shipping activity is quite restricted there. There’s no trade, there are only research vessels and a few other vessels that can be found there. Therefore, Antarctica might be the only acoustically unpolluted area left in the ocean.”

In effect, anthropogenic noise has contaminated the oceans to such an extent that only the furthermost reaches of the ocean are free from this hubbub, and only because they appear to serve no use for our own ends at present. Carlos tells us about how scientists monitor the soundscapes of the oceans using specialised microphones designed to work underwater called hydrophones. These special forms of recording equipment can pick up on sounds which may have emanated thousands of kilometres away. What Carlos tells us next serves as a reminder that nowhere is immune to the impact of the changing climate.

Rather than mobilising young people into action, it is mobilising people into fear and apathy… because they feel that the problem is too large, too difficult to think about, and too large for them to have a positive impact.

“When we were working on a paper, some of my colleagues were sitting in southern Australia, and they were processing hydrophone data. On that week, the dominant sound on their hydrophones was actually the sound of collapsing ice sheets in the ocean. The closest place where this could have been happening, because this was in Perth, where the hydrophone was placed, was about 4,000 km away in Antarctica.” If anyone doubts the impacts of climate change, Carlos and his colleagues have conclusive evidence of what’s happening, because beneath the ocean surface, it’s producing sounds for all to hear, and now they have it on tape. Warming temperatures make the ice sheets more brittle, increasing the likelihood of them breaking apart, and once they do so, they melt, raising the likelihood for more breakages and melting to occur. In the meantime, all that marine organisms can do is hear the carnage being wreaked from below the surface, seemingly powerless to stop it.

Waves of apathy

At present, the generation coming of age and starting to dominate debates globally, especially in all things environmental is the Millennial generation, or those born between the 1980s and the 1990s. These people grew up as the new millennium was dawning and are now grappling with a world which has started changing from beyond recognition. Baby boomers who lived out their coming of age during the latter parts of the 20th century faced the threat of mutually-assured destruction during the Cold War, but now Millennials are facing up to a host of existential problems related to the very planet we live on.

Many will have heard of the likes of the Great Pacific Garbage Patch, a so-called floating island of plastic which conjures up images of a nightmarish dense mound of plastic swallowing up all in its path, choking the life out of our oceans. In actual fact, this garbage patch exists at a low density, so low that not even satellites can spot it from Earth-orbit.

Rather than existing as massive mounds of insurmountable plastic, much of this patch consists of fingernail-sized or smaller-sized pieces of microplastic suspended in the water which only get smaller over time. It is estimated that some of the common pollutants which comprise much of these garbage patches globally include 50-year-old pieces of old plastic plus fibres derived from discarded toilet paper.

While still incredibly damaging to the environment, the Great Pacific Garbage Patch has been misrepresented and struck fear about the state of the world in the heart of many Millennials. Carlos believes such fears have been blown out of proportion and refers to a phenomenon known as ‘eco-anxiety’, which he believes is actually more of a hindrance than a help. “Rather than mobilising young people into action, it is mobilising people into fear and apathy”, according to Carlos, “because they feel that the problem is too large, too difficult to think about, and too large for them to have a positive impact.”

By trying to get young people engaged and shocked out of their comfort zone, specific issues such as the Great Pacific Garbage Patch may have been over-egged. This may have been done to such an extent that Millennials, the generation which will ultimately bear a great burden in tackling climate change in the years to come, might feel too shell-shocked about the state of the planet to act. Carlos brings home the reality of the situation, and how much agency we have to maintain the health of our oceans, recounting a poignant question he was once asked on the subject.

“Once I was asked, what was the biggest risk to the oceans, and I replied, the biggest threat to the oceans is that we give up on the vision of a healthy ocean.”

Electrification of boats and ships goes some of the way towards potentially minimising the impact of anthropogenic noise. Cleaner engines and more efficient propellors mean less sound, and better energy efficiency, and less sound means fewer stressors to upset marine organisms moving forward. Not only that, but reducing reliance on hydrocarbon-powered vessels on the high seas minimises the risk of fuel leaking into the water and poisoning it in the process. When we visited Extreme E’s floating hub, the St Helena, with which Carlos is most familiar with due to his work with Extreme E as a Scientific Committee member, the phrase emblazoned on its side struck a chord.

It bore the phrase: “Not Electric…Yet!”, as if to say electrification of the waves is a challenge, but one which could soon be overcome. Until then, anthropogenic sound continues to serve as an invisible form of pollution, which we should bear in mind every bit as much as microplastics, CFCs, dioxins and furans or any other kind of pollutant you care to mention. As with so many things when it comes to the environment, especially according to Carlos, human beings are the catalysts for much of the changes happening to our planet, and we are instrumental in shaping its future. The real question for the future is this: will we step up to cancel out the anthropogenic noise and tidy up our act, or will we hide away in our own silos, and just prove to be a drop in the ocean? We’ll have to make a decision sooner or later, because the oceans are all around us, a reminder that oceans don’t just divide but keep us connected, whether we like it or not.

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