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One fifth of the ocean floor now mapped

Current mapping coverage of the ocean floor. Black is used to depict areas where there are no direct measurements (including some areas where the data source is not well defined); blues correspond to water depth (darker blue is deeper) Current mapping coverage of the ocean floor. Black is used to depict areas where there are no direct measurements (including some areas where the data source is not well defined); blues correspond to water depth (darker blue is deeper) The Nippon Foundation-GEBCO Seabed 2030
23 Jun
2020
A fifth of the ocean floor has now been mapped, taking researchers a step closer to the goal of a complete seabed map by 2030

It seems incredible, but humans know far more about the surface of Mars than about the surface of our own planet. While 90 per cent of Mars’ surface has been mapped by high resolution cameras, only a fifth of the world’s ocean floor has been likewise mapped.

Nevertheless, this is still a huge leap forward.

Launched in 2017, the Nippon Foundation-GEBCO Seabed 2030 Project aims to facilitate the complete mapping of the global ocean floor by 2030. On Monday, it announced the inclusion of 14.5 million square kilometres of new bathymetric data (an area twice the size of Australia), extending coverage to 19 per cent of the ocean floor. When the project – a collaboration between the Nippon Foundation of Japan and the General Bathymetric Chart of the Oceans (GEBCO) – was launched in 2017 at the United Nations Ocean Conference, only six per cent of the oceans had been mapped to modern standards.

The difference between our interstellar record and that closer to home reveals how difficult it is to accurately penetrate water and map the surface below. The first attempts to do so centred on a desire to safely navigate the oceans. In the early 1800s sailors measured depths using ‘sounding poles’ and later with ‘lead lines’ – ropes with lead weights at the bottom and marked with numbers. The rope would be lowered into the water and marked when it hit the bottom. Repeating this movement allowed researchers to build a picture of the ocean floor’s topography (though not an accurate one).

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The early 20th century saw the use of ‘wire drag surveys’ in which a wire attached to two vessels was dragged between two points. Where the wire hit an obstruction it would become taut, revealing the position of rocks or other obstructions. The rest of the 20th century saw the development of sonar techniques, beginning with single-beam sonars and progressing to the multi-beam sonars used today.

Today’s sonar instruments can emit 1,500 sound waves per second, painting the seafloor in a fanlike pattern. This creates a detailed ‘sound map’ that shows ocean depth, bottom type, and topographic features. Increasingly, remotely operated vehicles are also being deployed to record supplementary video at different sites.

ChangesVer3 to 4 Ryder nolabels 1A sonar map of the seafloor at the top of Greenland [Image: GEBCO Seabed 2030]

The pictures created today are a far cry from the limited ones produced by early navigators. The reasons for creating such pictures are also different, or at least wider. While safe navigation remains one good reason to map the seafloor, it is only part of the picture. Bathymetric data can alert scientists to environmental changes and allow researchers to better analyse sea level rise, land erosion and subsidence. It’s also a crucial tool for understanding life in the ocean.

‘The shape of the seabed is fundamental to a whole bunch of ocean processes,’ says Jamie McMichael-Phillips, Seabed 2030 project director. ‘So that might be ocean current circulation, it might be geohazards. Why is that important? Well, if you can predict the flow of ocean currents then you can look at the movement of bodies of water and you can use that to help you model sea level rise.

‘It also affects sea temperature which affects migratory species. Traditional fishing grounds may change as the sea temperature rises and areas of marine stewardship and Sites of Special Scientific Interest may also change if some of the flora and fauna change accordingly. It also allows the prediction of the strength and path of tsunamis, so a better seabed model allows you to model those events better. And, if you look at that 81 per cent that is yet to be surveyed, there will undoubtedly be areas that we need to protect, but we don’t know where they are and how to protect them because we haven’t mapped the seabed.’

Of course, there is another reason why humans might find the seafloor interesting. Some parts of the deep sea floor are home to minerals commonly used in modern technology. It could harbour hitherto unknown deposits of oil and gas. Would a more complete picture of the ocean floor open the way for greater exploitation of its resources? McMichael-Phillips thinks not.

‘I would suggest that the organisations that want to look at deep sea mining, that want to go and look at the exploration of mineral resources, have got huge research and development budgets and can actually go out and gather this data for themselves. If they do so, that information becomes proprietary, it’s not available to anybody else. With the Gebco Seabed 2030 initiative, we’re gathering that data and making it available for absolutely everybody. So that means whichever side of the debate you are on, you have full access to the data and you have not had to pay to go and collect it. It levels the playing field.’

(In respone to this, a spokesperson from Lockheed Martin – the compay that has a wholly owned UK subsidiary called UK Seabed Resources who are one of the licence holders in partnership with UK Government to explore for polymetallic nodules on the deep sea floor – got in touch to say that bathymetric data collected by UK Seabed Resources during exploration for deep seabed minerals is publicly available and is included in the GEBCO project.)

shutterstock 1298021569The project team hope to make use of advances in autonomous and remotely operated vehicles. This autonomous surface vehicle could be used to deploy an autonomous underwater vehicle (AUV)

To reach its goal, the Seabed 2030 project will rely on a number of different data collection methods, from linking up with existing scientific expeditions and placing a sonar operative on-board, to citizen science – in which private or merchant vessels are encouraged to collect data using a simple data logger. For more inaccessible areas, the team is looking to advances in autonomous vehicles.

It will take a combination of all these data collection methods to hit the goal. ‘We can’t do this all ourselves,’ says McMichael-Phillips. ‘We need to motivate governments, academics, commercial organisations, and the general public in helping us achieve this mission vision. We’ve got 81 per cent of the ocean floor still to map – that broadly equates to twice the size of Mars. We’ve been to Mars many times, let’s focus on our own ocean and get that fully mapped by the year 2030.’

This article was updated to include the response from Lockheed Martin

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