Over a career spanning seven decades, David Attenborough has brought the strangeness, beauty and wonder of the natural world to British television, in programmes such as Life on Earth and Blue Planet, and campaigned for environmental conservation. In Ocean, published on 8 May to coincide with Attenborough’s 99th birthday, he and his long-time collaborator Colin Butfield turn their attentions to this last great wilderness, still the most unexplored habitat on Earth. In a series of emails, Attenborough and the New Statesman corresponded about the damage mankind has done to the ocean, as well as its incredible resilience and how it could be restored.
You have filmed in deserts and jungles, mountainsides and grasslands. What is it about life under the waves that draws you back to the ocean?
Over the decades I have made documentaries about many different habitats and regions across the world. The oceans cover such a large proportion of the globe that they inevitably include many fascinating habitats and creatures. However, the underwater world has always been harder to access, let alone film. Now scientists are constantly discovering new things. In less than a century, technological developments have progressed so far that scientists are able penetrate much deeper into the ocean. We are also able to get better images than ever before, and together that makes it an exciting time to film in the oceans.
It is also an important time. We are beginning to realise just how much we rely on a healthy ocean and the amount of damage we are doing to it. In Ocean, we also try to tell that story and reveal the benefits to all of us of allowing life under the waves to recover.
The impact of human society on the warming seas is well documented, but there remains a sense that in the deep, life goes on as it has for millennia. Is that true, or does what we do on the surface have consequences thousands of metres down?
The deep ocean is certainly not the featureless abyss we once thought, but has many remarkably different features and habitats. We still know relatively little about the deep compared to almost every other part of the ocean. As far as we know, life progresses at a slower pace in the deep. There is less oxygen and fewer nutrients, and we think cellular processes happen more slowly. As a result, many species live a long time and reproduce late in life.
We certainly do already influence the deep in a number of ways. Many deep-sea species appear to rely on nutrients falling from nearer the surface, so the reduction in marine life from these parts of the ocean will probably affect the deep too. Furthermore, many species migrate between the deep and surface water, so catching those species in more accessible waters alters the deeper ecosystem. We are all too aware these days of the damaging presence of plastics across the globe, but especially in the oceans, where it has been found even in the deep. But that is not all. Indiscriminate fishing practices and accidental interference on and near the surface probably also affect the deeper areas of the oceans.
There has been an incredible recovery in whale populations in the past 40 years. Do you believe similar revivals are possible for other species threatened by humans?
The story of the recovery of the great whales is indeed one of great hope, though the job is not done yet. International agreements have allowed whale populations to increase in numbers at a surprisingly rapid rate, especially for such vast, slow-growing creatures.
There is no reason why this should not be possible for many species. We now understand so much more about how the ocean works. We need to fish with more care for the environment, avoiding indiscriminate damage. We have seen that when we protect areas properly, even migratory species that only pass through them can benefit.
More than that, it is becoming increasingly clear that setting up properly protected areas in the ocean can allow such a regeneration of fish populations that, in a remarkably short time, stocks beyond the protected areas also increase, allowing fishing communities to catch more fish, rather than less.
Does the ocean have the ability to regenerate in the same way the ozone layer does? Will life always find a way?
We have certainly seen, in most ocean habitats, that if given time and space, life can recover surprisingly fast – often much faster than the equivalent area on land. The exception is probably deep-water habitats, where things are much slower growing and live longer, and as a result, recovery is also slower.
Viewed over geological time, life will almost certainly find a way. Our planet has experienced mass extinctions before and new life has always evolved to replace that which went extinct. However, this process takes hundreds of thousands of years, so if we were looking at it from the perspective of what we need, as humanity, to thrive, then a stable ocean with abundant marine life is vital.
If we protect parts of the ocean, there is every reason to believe that the recovery in marine life within those areas will be so substantial it will spill out into the surrounding ocean. It’s win-win-win. We would have more fish to eat, incredible marine reserves full of wonderful life, and the process of restoration would draw down more carbon from the atmosphere, helping us stabilise the climate in a way that is cost-effective and unintrusive to our daily lives.
Around 250 million years ago, the “Great Dying” killed 96 per cent of marine species, possibly as a result of global warming depriving oceans of oxygen. How might today’s warming affect deep-sea species?
Changes in oxygen levels in the ocean are indeed causing profound problems. In the upper levels of the ocean, we see what are known as “dead zones”, where oxygen levels are so low they create near-anoxic environments where little life can live. Many of these are not small patches but enormous swathes of coastal sea. It is important to note that climate change is not the only contributing factor to these dead zones: agricultural run-off, in particular fertiliser, creates algal blooms that very quickly change the oxygen levels in an area.
As for the impact of oxygen levels on deep-sea life, it’s hard to say for sure. One of the particular challenges of the deep is how difficult it is to study and how small a percentage of that area we have adequately explored. What we can say for sure is that there are many traces of human activity affecting the deep. We are catching fish at ever-deeper levels and studies have also shown pollution from human activities is finding its way to the deep sea. The deep-sea environment is of vital importance to stability on our planet, yet we’re still quite a long way off understanding how it works and how our actions affect it.
Global coral bleaching has affected 84 per cent of the ocean’s reefs this year, primarily due to rising temperature levels. Is the damage now irreparable?
Prolonged ocean heat waves, which are one of the major causes of coral bleaching, are getting so regular and extreme that many predictions for the future of coral reefs are dire. However, there is some hope.
As far as we know, coral bleaching has always happened from time to time. Under normal circumstances, heat waves are short enough that the coral quickly recovers. However, if a heat wave continues for too long, the reef gets swamped with algae and the coral dies. What we have discovered is that where there are healthy fish populations, algae growth is kept in check by grazing fish, which gives the coral more time to recover.
This will not work indefinitely. If we continue to warm the planet, then in time most coral reefs will indeed disappear. However, keeping fish populations healthy will buy the coral more time and give us a fighting chance of still having coral reefs in the future.
“Ocean: Earth’s Last Wilderness” by Sir David Attenborough and Colin Butfield is published by John Murray. “Ocean with David Attenborough” is in cinemas now
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This article appears in the 07 May 2025 issue of the New Statesman, The Peace Delusion