Humans have degraded 84% of the world’s coastlines, new study reveals

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According to our first global research published recently, only about 16% of the world’s coastal regions are in relatively good condition, and many are so degraded that they cannot be restored to their original state.

The places where the land meets the sea are crucial to the functioning of our planet. They support biodiversity and the livelihoods of billions of people. But to date, understanding of the general state of the Earth’s coastal regions is poor.

Our research, involving an international team of experts, revealed an alarming story. Humanity exerts strong pressure on nearly half of the world’s coastal regions, including a large proportion of protected areas. All nations must step up their efforts to preserve and restore their coastal regions – and now is the time to start.

The ribs are vital

Coastal regions encompass some of the most diverse and unique ecosystems on Earth. They include coral reefs, kelp forests, seagrass beds, mudflats, mangroves, estuaries, salt marshes, wetlands, and coastal woodland habitat.

Many animal species, including those that migrate, depend on coasts for reproduction, food and protection. Coastal sites are also where rivers drain, mangrove forests exchange nutrients with the ocean, and tidal currents are maintained.

Humans also need ribs. Among other functions, they support our fisheries, protect us from storms and, most importantly, store carbon to help mitigate climate change.

As many as 74% of the world’s population lives within 50 kilometers of the coast, and humans exert pressure on coastal environments in multiple ways.

In marine environments, these pressures include:

  • Fishing at different intensities
  • Earth nutrients, organic chemicals and light pollution
  • Direct human impacts such as through recreation
  • Maritime transport
  • Climate change (and associated ocean acidification, sea level rise and increased sea surface temperatures).

On land, human pressures on our coasts include:

  • Built environments, such as coastal developments
  • Disturbance
  • Electrical and transport infrastructure
  • Croplands and pastures, which cleanse ecosystems and cause the runoff of chemicals and nutrients into waterways.

To date, assessments of the world’s coastal regions have largely focused only on land or ocean, rather than considering the two domains together. Our research attempted to address this.

disturbing picture

We have integrated existing human impact maps for land and ocean areas. This allowed us to assess the spectrum of human pressure on the Earth’s coastal regions to identify which are heavily degraded and which are intact.

Both maps use data up to the year 2013 – the most recent year for which consistent data is available.

No coastal region was immune to human influence. However, 15.5% of Earth’s coastal regions remained untouched – in other words, humans had exerted little pressure. Many of the intact coastal regions were in Canada, followed by Russia and Greenland.

Large stretches of untouched coastline have also been found elsewhere, including in Australia, Indonesia, Papua New Guinea, Chile, Brazil and the United States.

Disturbingly, 47.9% of coastal regions were exposed to very high levels of human pressure. And for 84% of countries, more than half of their coastal regions were degraded.

In addition, human pressures were high in about 43% of the protected coastal regions – these regions would have been successful in conserving nature.

Coastal regions containing seagrass, savanna and coral reefs had the highest levels of human pressure compared to other coastal ecosystems. Some coastal regions may be so degraded that they cannot be restored. Coastal ecosystems are very complex and once lost it is probably impossible to restore them to their original state.

What destination now?

It is safe to say that untouched coastal regions are now rare. We urge governments to urgently conserve coastal regions that remain in good condition, while restoring those that are degraded but can still be repaired.

To help you with this global task, we have made our dataset publicly available and free here.

Of course, good conservation and restoration actions will vary from place to place. Actions may include, but are not limited to:

  • Improving environmental governance and laws related to encroaching development
  • Increase well-resourced protected areas
  • Mitigate land use change to prevent increased pollution runoff
  • Better community and local engagement
  • Strengthening indigenous participation in the management of coastal regions
  • Effective management of fisheries resources
  • Coping with climate change
  • Address the geopolitical and socio-economic drivers of damage to coastal environments.

Additionally, there is an urgent need for national and global policies and programs to effectively manage the areas where land and ocean converge.

Humanity’s impact on the Earth’s coastal regions is already severe and widespread. Without urgent change, the implications for coastal biodiversity and society will become even more profound.

Brooke Williams is a postdoctoral researcher, Amelia Wenger is a researcher and James Watson is a professor at The University of Queensland.

This article first appeared on The Conversation.

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