Ocean Infrastructure Has Basically Created Cities at Sea

Ocean Infrastructure Has Basically Created Cities at Sea
Offshore oil rigs off the coast of Scotland. (Photo: Jeff J. Mitchell, Getty Images)

The oceans may seem vast and indomitable, and yet humanity has found a way to spread its influence over them. New findings show that the world’s oceans are cluttered with all other sorts of human infrastructure.

The coverage area of human activity is so wide, our ocean infrastructure footprint is equivalent to the footprint of cities on land — and it’s poised to grow in the coming decade, creating a bizarro real-life Waterworld. Human seaward expansion provides some benefits to natural ecosystems, but the message in the findings published on Monday in Nature Sustainability is clear: The world has to be deliberate or risk further screwing over the seas.

These findings are the first of their kind to map humanity’s watery footprint. The researchers mapped a range of human activities happening both nearshore and far offshore, including oil rigs, pipelines, cables, fish farms, ports, and offshore wind farms. The findings show that 32,000 square kilometres of seafloor, an area about the size of Maryland, have been directly colonised by human activities and infrastructure. But that physical footprint only tells part of the story; all told, up to 3.4 million square kilometres of seascapes have been impacted by human activities. That includes noise from ports and other knock-on effects.

The overall footprint of human infrastructure in the ocean accounts for 1.5 per cent of all economic exclusive zones or areas that are generally within 370 kilometres of countries’ coastlines. That footprint is on par with the amount of land on Earth turned over to cities. It’s also likely an underestimate because researchers didn’t look at coastal defences like sea walls.

While China has seen the most construction, including a huge area of aquculture and fish farming, other countries also get a few superlatives. The UK has the biggest offshore wind footprint as a pioneer in the industry. The U.S., meanwhile, can lay claim to the ignominious title of offshore drilling leader: Nearly half of offshore drilling’s footprint can be found in the Gulf of Mexico alone.

By 2028, ocean construction could grow out by up to 70 per cent from its current range, driven by aquaculture and wind and tidal energy farms, the researchers predict. Though again, that could be an underestimate since we’re going to need a lot more coastal protections to deal with rising seas as a result of climate change.

The extended footprint of infrastructure only tells part of the story of humans’ impact on the seas. Overfishing, marine heat waves driven by climate change, sea-level rise, and catastrophes like oil spills are all putting pressure on marine life and the ecosystems they depend on. Developments on land can also impact the high seas, including building hard defences against the sea that can strangle out ecosystems like mangroves or agriculture runoff that has led to toxic dead zones. Scientists warned in a landmark report last year that oceans will “transition to unprecedented conditions” this century as the planet warms at a rate ecosystems will struggle to adapt to.

As the fate of the oceans go, so goes our fate. We rely on them for sustenance, to suck up carbon dioxide, and a host of other benefits. The results of the new study point to the need to think about how and where we develop at sea more carefully given the stress we already put on marine life. Some developments like protecting and restoring coastal wetlands as opposed to building new defences can be a win-win solution that keeps ecosystems intact and provides flood control. There are also signs that offshore wind farms can be ecologically beneficial by creating artificial reefs, though it’s still an area of active research to figure long-term consequences and if they may invite non-native species or have other unintended impacts.

Much like cities on land, though, it’s clear we need to make decisions that allow us to live in better harmony with nature. The alternative is having oceans that may look blue and watery on the surface, but seem more like the Sahara under the waves.