On 21 December 1872, HMS Challenger set sail from Portsmouth on a voyage that would transform our knowledge of our planet. Sailing with state-of-the-art equipment and a complement of 243 scientists and crew, the former British warship zigzagged for 70,000 nautical miles (130,000km) across the globe, taking thousands of physical, biological and chemical measurements of the sea and seabed.
Huge underwater mountain ranges, deep abyssal trenches and strange entities such as Venus’s flower basket – whose delicate tissue resembled spun glass – were discovered during the three-and-a-half-year expedition. Once thought to be a uniform watery expanse containing little of interest, the oceans were revealed to be deep, vibrant and filled with wonderful life forms.
That was 150 years ago. Today, the fecundity and majesty of the high seas revealed by Challenger are being destroyed before scientists have had a proper chance to explore their wonders, marine biologists warn. “Our vast, deep ocean is incredibly fragile and its greatest threat is us,” the science journalist Olive Heffernan states in this comprehensive and disturbing investigation of the avarice and lawlessness that now afflict our ungoverned oceans.
The speed and scale of the destruction is staggering. Consider deep-sea trawling: huge nets and chains weighing several tonnes are now routinely dragged across the seafloor to sweep up cod, haddock and shrimp. Coral beds are smashed, species left homeless and entire ecosystems wrecked. “It is unclear whether these environments can ever fully recover,” says Heffernan.
Then there is deep-sea mining. Corporations are planning to hoover up mineral nodules that litter the seabed. Vast plumes of sediments would be released, along with viruses, microbes and other pollutants. Abyssal ecosystems as yet unstudied by science would be wrecked and species wiped out before we became aware of their existence.
In addition, there is the indiscriminate dumping of waste and the discarding of plastics that choke fish and seabirds. There are pirate fishers who use enslaved crews to catch endangered species and tankers that sink and spill their oil. And then there are the entrepreneurs who want to sprinkle the seas with iron compounds to boost phytoplankton growth and increase their absorption of carbon dioxide, thus helping in the fight against global heating. The fact such interventions would also trigger the widespread growth of poisonous algal blooms is ignored.
As to the cause of this oceanic crisis, Heffernan is clear. At every turn, politicians have allowed economic gain to be prioritised over sustainability and have created a free-for-all that allows lax enforcement and apathy to remain the status quo. The high seas are the planet’s last great commons and weak, poorly enforced international agreements are now permitting their exploitation and destruction by a small group of opportunists.
One in every five fish we now eat is caught illegally, while a mere 20 companies are responsible for more than half the plastic waste that is choking our seas and the creatures that dwell in them. It is a stark, grim story, succinctly told by Heffernan, who struggles hard to find notes of optimism. “This narrative was intended to reassure myself and others that despite our fraught relationship with the ocean, everything will work out fine. But as I sat down to write, I realised my view of the future isn’t quite so rosy,” she states.
It is hard to disagree. It took men and women a long time to comprehend the wonders of the deep but only a very brief period to begin their destruction. From that perspective, there is little to engender optimism for our short-term future on this planet.
• The High Seas: Ambition, Power and Greed on the Unclaimed Oceans by Olive Heffernan is published by Profile (£22). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply
