Ocean Infrastructure Has Basically Created Cities at Sea

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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 12,355 square miles

(32,000 square kilometers) of seafloor, an area about the size of Maryland, have been directly colonized by human activities and infrastructure. But

that physical footprint only tells part of the story; all told, up to 1.3 million square miles (3.4 million square kilometers) 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% of all economic exclusive zones or areas that are generally within 230

miles (370 kilometers) 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 defenses 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% 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 defenses 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 defenses 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.

 

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Humans' construction 'footprint' on ocean quantified for first time

Aquaculture farms in the coast of China's northeast province of Liaonin. Credit: NASA Earth Observatory.

 

In a world-first, the extent of human development in oceans has been mapped. An area totalling approximately 30,000 square kilometres—the

 

equivalent of 0.008 percent of the ocean—has been modified by human construction, a study led by Dr. Ana Bugnot from the University of Sydney

 

School of Life and Environmental Sciences and the Sydney Institute of Marine Science has found.

 

The extent of ocean modified by human construction is, proportion-wise, comparable to the extent of urbanised land, and greater than the global

 

area of some natural marine habitats, such as mangrove forests and seagrass beds.

 

When calculated as the area modified inclusive of flow-on effects to surrounding areas, for example, due to changes in water flow and pollution, the

 

footprint is actually two million square kilometres, or over 0.5 percent of the ocean.

 

The oceanic modification includes areas affected by tunnels and bridges; infrastructure for energy extraction (for example, oil and gas rigs, wind

 

farms); shipping (ports and marinas); aquaculture infrastructure; and artificial reefs.

 

Dr. Bugnot said that ocean development is nothing new, yet, in recent times, it has rapidly changed. "It has been ongoing since before 2000 BC," she

 

said. "Then, it supported maritime traffic through the construction of commercial ports and protected low-lying coasts with the creation of structures

 

similar to breakwaters.

 

"Since the mid-20th century, however, ocean development has ramped up, and produced both positive and negative results.

 

"For example, while artificial reefs have been used as 'sacrificial habitat' to drive tourism and deter fishing, this infrastructure can also impact

 

sensitive natural habitats like seagrasses, mudflats and saltmarshes, consequently affecting water quality.

 

"Marine development mostly occurs in coastal areas—the most biodiverse and biologically productive ocean environments."

 

A map showing the physical footprint of marine construction globally, in square kilometres. Credit: Bugnot et al., 'Current and projected global extent of marine built structures', Nature Sustainability.

 

Dr. Bugnot, joined by co-researchers from multiple local and international universities, also projected the rate of future ocean footprint expansion.

 

"The numbers are alarming," Dr. Bugnot said. "For example, infrastructure for power and aquaculture, including cables and tunnels, is projected to

 

increase by 50 to 70 percent by 2028.

 

"Yet this is an underestimate: there is a dearth of information on ocean development, due to poor regulation of this in many parts of the world.

 

"There is an urgent need for improved management of marine environments. We hope our study spurs national and international initiatives, such as

 

the EU Marine Strategy Framework Directive, to greater action."

 

The researchers attributed the projected expansion on people's increasing need for defences against coastal erosion and inundation due to sea level

 

rise and climate change, as well as their transportation, energy extraction, and recreation needs.

 

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