sea-change required to restore our Oceans

By Michael H. Depledge


Andrea Vercetti

Will the human race continue its reckless abuse and damage of the oceans and marine ecosystems, or will human endeavours become gloriously and deeply interwoven with the restoration of their health in a new era of sustainable prosperity. Professor Michael Depledge is optimistic, despite the huge task ahead.

Imagine aliens arriving in our solar system to have a look around. The beautiful, blue, third planet from the Sun would undoubtedly attract their attention. Looking down from their spaceship the visitors might well be astonished to see Earth’s endlessly undulating surface formed by our indomitable, restless oceans. Beneath the rolling waves that cover 70 per cent of the planet, a bewildering array of exquisite and extraordinary life forms await discovery, from the smallest microbes to the largest marine mammals, with every size of organism in between. These vast and ancient oceans formed around 3.8 billion years ago, and have been home to myriad species, most of which have come and gone. As only 20 per cent of the ocean floor has been explored so far, the surviving 226,000 species currently identified probably represent only 10-15 per cent of all those that populate the sea. The ocean fauna and flora will inevitably evolve further over future centuries as environmental conditions change.

What of Earth’s human inhabitants, almost a third of whom live within 100 km of the seacoast? Throughout most of our history less than 1 billion of us have inhabited the planet at any one time, inflicting relatively modest, local impacts on the marine environment, mainly in estuarine and coastal areas where we have gathered to fish and trade goods. But over the last 250 years, the human population has increased enormously, reaching around 8 billion, leading to dire consequences. Examples are legion: over-fishing, chemical and microbial pollution, coastal zone destruction, habitat loss, invasive species, damage associated with oil and gas extraction, commercial shipping activities, tourism, and more recently, new threats from deep sea mining.

The rapid loss of biodiversity and the progressive collapse of many marine ecosystems, notably coral reefs, sea grass communities and mangroves, have ensued. Superimposed on this devastation has been the more insidious threat of climate change which is causing the redistribution of many species as the oceans heat up and currents alter course. Even the resilient Gulf Stream, which carries warm water from the Gulf of Mexico northeast across the Atlantic Ocean, is showing early signs of breakdown. More than 90 per cent of the warming that has taken place on Earth over the last 50 years has occurred in the oceans, pushing some invertebrates towards their thermal limits, potentially resulting in mass mortalities in equatorial, near-shore seas. Melting polar ice is raising sea-levels at unprecedented rates. Over time, the coastal flooding generated will severely damage the infrastructure of harbours and ports worldwide. When combined with ocean acidification as atmospheric carbon dioxide dissolves in our seas, these changes not only put life in the sea in jeopardy, but our own lives too.

We can choose to respond. Educating ourselves, policymakers and politicians about the oceans is key. Greater ocean literacy is the first step in ensuring the transition to sustainable lifestyles. Some view Earth as having a single global ocean but adopting a more nuanced approach will better facilitate implementing practical, restorative measures. The National Geographic Society has identified five interconnected oceans: The Arctic, Atlantic, Indian, Pacific and Southern oceans. These water bodies are very different; some surrounding the frozen Poles, others occupying predominantly subtropical and tropical regions; some with heavily populated coastlines, while others are remote from civilisation. These, and many other differences, require diverse strategies and policies to secure improvements.

Despite the immense task ahead, reasons for optimism remain. With the advent of the UN Decade of the Oceans several countries have shown renewed interest in restoring the oceans and regenerating coastal communities. Destructive oil and gas exploration is dwindling as the offshore renewable energy revolution proceeds. More stringent environmental regulations have the power to ameliorate ecological damage caused by shipping; curbing the release of antifouling chemicals, stopping the transference of invasive species via contaminated bilge water and, of course, limiting greenhouse gas emissions.

Crucially, exploitation of fisheries can be mitigated by turning instead to the development of sustainable aquaculture, both onshore, using recirculating, seawater purification systems and vegetable feedstocks, as well as offshore, employing open ocean aquaculture. Most chemical and microbial pollution of the sea is from land-based sources—especially agriculture, manufacturing industries, diffuse domestic usage and discharges of sewage (both treated and untreated). Policies will undoubtedly be needed to create step changes in waste detoxification and intensification of recycling. The longer we wait, the more costly it will be in terms of environmental damage, economic decline, and pollutant-induced human diseases.

Few appreciate the enormous potential of the oceans to fuel the future economic life of our societies. The ocean economy will be worth US$3 trillion by 2030: 95 per cent of trade is already seaborne. Thrilling new industries involving autonomous ships, renewable wind and wave energy generation, novel marine pharmaceuticals, and new building materials derived from marine resources, plus many other ocean-based innovations, have the potential to drive economic growth and create future employment.

“Few appreciate the enormous potential of the oceans to fuel the future economic life of our societies”

Michael H. Depledge

A particularly exciting development over the last decade has been renewed interest in the oceans as a means of fostering health and wellbeing. Many of us are inspired by sensational coastal vistas, glorious beaches and fascinating cliff walks, but now scientists have provided robust evidence that time spent by the sea really does improve physical and mental health. Policymakers have learnt from programmes such as the ‘Blue Gym’ and ‘Blue Health’ that facilitating access to the sea can reduce health inequalities and regenerate coastal communities, at the same time lowering the burden on healthcare systems.

As our imagined aliens leave our solar system on their journey home, they will have much to contemplate. They will have seen humans recklessly abusing and damaging the oceans, but paradoxically, also enjoying seaside holidays, aspiring to coastal lifestyles, relishing seafood and loving a dip in the sea! They will be left pondering whether or not human indifference and inaction will seal the fate of marine ecosystems, or if future human endeavours will become gloriously and deeply interwoven with the restoration of the health of the oceans, in a new era of sustainable prosperity.