The Many Facets Of How Much

How much of the world's land is covered by forests? How much of the ocean is unexplored? How much of the universe do we know about? These are all questions that can be answered with a simple search, but the answers may surprise you.

How much of the ocean has been explored?

The ocean makes up about 71% of the Earth's surface, and it is the biggest ecosystem of the planet, holding 99% of all habitable space in the world. Despite this, it is estimated that only 5% of the ocean has been explored and charted by humans. This figure depends on what is meant by 'explored' – while the ocean surface has been surveyed, the ocean floor has not been extensively explored. The Seabed 2030 initiative is working to map the ocean floor and, in June 2024, it reported that it had charted just over 26% of the world's underwater terrain. However, habitats are not two-dimensional and the average depth of our oceans is 3,600m. Ocean exploration technology is relatively new, and it is only in the last few decades that we have been able to start discovering the ocean's depths and floors.

How much of the ocean is designated as marine protected areas?

Marine protected areas (MPAs) refer to any part of the ocean that receives some level of protection under international, federal, state, local, or tribal law. There are more than 5,000 MPAs worldwide, but this only protects about one percent of the global ocean. The United Nations (UN) has set a goal for 10% of the world's oceans to be protected by 2020. However, reports show that only about 2-5.7% of the world's oceans are protected areas.

The UN's World Database on Protected Areas, which records MPAs submitted by countries, suggests that more than 15,000 MPAs protect more than 27 million square kilometres (almost 10.6 million square miles) of ocean. The IUCN World Commission on Protected Areas (WCPA) and UNEP World Conservation Monitoring Centre (WCMC) have created what they call 'The Official MPA Map', which suggests that 2.8% of the total ocean is protected. This includes about 10% of territorial seas (0-12 nautical miles), 5% of Exclusive Economic Zones (EEZ) (12-200 nautical miles), and 0.14% of the High Seas (beyond 200 nautical miles) within marine protected areas.

When considering only the known no-take marine reserves and no-take zones within zoned multiple-use marine protected areas, only 0.6% of the ocean is under the strongest form of marine protection. The majority of no-take protection is comprised of only a handful of very large and remote marine protected areas, with the Chagos Marine Protected Area being the largest at 640,000 km2.

How much of the ocean's seafloor has been mapped?

As of June 2024, 26.1% of the global seafloor had been mapped with modern high-resolution technology. This is a significant increase from 2017, when only 6% of the world's oceans floor had been adequately mapped, and 2021, when the figure was 20%.

The ocean floor has been mapped using altimeter data collected by satellites, but these maps are low-resolution, with a resolution of 1.5 kilometres, or about one mile. This means that if any dimension of a seafloor feature is a mile or bigger, we can see it in this map. However, these maps offer limited detail and can omit things such as volcanic craters or shipwrecks.

Only about 5% of the global ocean has been mapped by modern multibeam sonar systems, which are usually mounted to ships and can reveal the seafloor in greater detail. Mapping the seafloor with multibeam sonar is time-consuming, as a ship must move slowly and systematically to ensure there are no gaps. It has been calculated that it would take one ship nearly 1,000 years to map the entire ocean at all water depths.

In the United States, there is an entire organisation, NOAA Ocean Exploration, dedicated to exploring the deep ocean and filling the gaps in our understanding of the world's deep waters and the seafloor. Using the NOAA Ship Okeanos Explorer, NOAA Ocean Exploration has mapped over 2 million square kilometres (772,204 square miles) of seafloor. While almost 52% of the seafloor beneath US waters had been mapped to modern standards, the nation's seafloor is larger than the land area of all 50 states, the District of Columbia, and the five territories combined. Thus, there is still a significant amount of seafloor left to be mapped at high resolution.

To combat this lack of information, two nonprofit organisations came together in 2018 to found the Nippon Foundation-GEBCO Seabed 2030 Project, an international effort aimed at mapping 100% of the ocean floor by 2030.

How much of the ocean's species have been discovered?

The ocean covers 71% of the Earth's surface, making it the largest ecosystem on the planet. Scientists estimate that there are between 700,000 and 1 million species in the ocean, mostly animals, and excluding most microorganisms, of which there are millions.

It is believed that around two-thirds of ocean species are yet to be discovered or officially described. To date, approximately 240,000 marine species have been discovered and named.

The Ocean Census, the largest programme in history to discover life in the ocean, has set an ambitious target of finding at least 100,000 new marine species in the first decade. Recent technological advances in high-resolution imaging, DNA sequencing, and machine learning mean scientists can now accelerate the process of species discovery.

On average, around 2,000 new species are discovered each year, a figure that hasn't changed significantly since the 1800s. However, the ocean will never be fully explored, and we have a great deal more to learn about what resides within it.

How much of the ocean is unexplored?

It is estimated that only 5% of the ocean has been explored by humans, meaning that over 80% of the ocean remains uncharted and unseen. This is because ocean exploration technology is relatively new, and the depths of the ocean pose many challenges to human exploration, such as increased pressure, decompression sickness risk, and orientation difficulties.

The ocean covers most of the Earth's surface, yet it remains one of the most vulnerable and least understood places on the planet. With satellites, we can chart the ocean's surface temperatures, waters, and colour (an indicator of plant life), but we need much more advanced technology to map its deeper parts.

Despite humanity's quest for knowledge and discovery, the vastness of the ocean remains a mystery, an invitation to explore and learn. As we peer into the abyss, we are confronted with a frontier that holds the keys to untold stories of our planet's past, present, and future, hidden within its depths.

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