Nº 7 2012 > Submarine cables for climate monitoring

Green undersea cables

Telecommunications embrace science in the deep ocean

Submarine cables for climate monitoring and disaster warningBuoy for early tsunami warningsGreen undersea cables
Submarine cables for climate monitoring and disaster warning
Buoy for early tsunami warnings

Submarine telecommunication cables equipped with sensors could monitor the climate and reduce the risk of tsunami disasters. To achieve this vision would require incorporating scientific sensor equipment in submarine repeaters, which amplify optical data as they travel across oceans. A new report entitled “A Strategy and Roadmap: Enabling the Availability of Submarine Repeaters Equipped with Scientific Sensors for Climate Monitoring and Disaster Risk Reduction” sets out the actions that ITU, the World Meteorological Organization (WMO) and the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization (UNESCO/IOC) need to take to make this vision a reality.

Today, the submarine telecommunication cables criss-crossing the Pacific, Atlantic and Indian Ocean floors simply transmit huge data — notably global Internet traffic — between continents. But they could do much more. As global communications continue to expand and develop, older submarine cable systems are systematically retired after a lifetime of about 25 years and replaced with more modern and robust equipment. This offers an opportunity over time to add ocean observation devices to the submarine cable repeaters, progressively creating an extensive network of sensors for environmental monitoring and disaster warning.

“These sensory data are fundamental to ocean and climate monitoring for global change and for tsunami and earthquake disaster-risk reduction. The vision is for today’s broad telecommunication networks to morph over time into broader telecommunication networks that also sense their ocean environment,” says the report’s author Rhett Butler.

Such a monitoring network would provide better early warning signals than current systems. More generally, it would also improve scientific intelligence on oceans and the climate. Science, society and the telecommunication sector would all be winners. Data from submarine monitoring equipment would help governments manage risks more effectively.

Responding to Rome’s call for action

Delegates at a workshop organized jointly by ITU, WMO and UNESCO/IOC in Rome in September 2011 considered the opportunity of using submarine cables for ocean and climate monitoring and disaster warning. The outcome was a call for action, and the report “A Strategy and Roadmap: Enabling the Availability of Submarine Repeaters Equipped with Scientific Sensors for Climate Monitoring and Disaster Risk Reduction” was published by the three organizations as a response to a specific request by the workshop.

The report outlines the main technical, commercial, financial and legal matters that need to be resolved to develop a cable infrastructure capable of performing the dual tasks of telecommunication and monitoring. Rhett Butler explains that “Compared with the extensive scientific monitoring coverage of the upper ocean by satellites, ships, and buoys, there are few resources available for monitoring the deep ocean and seafloor.”

The report is intended for governments, climate and weather agencies, tsunami warning centres and agencies, earthquake information and response agencies, disaster risk reduction agencies, submarine cable telecommunication companies, and scientific organizations, among other stakeholders.

Design constraints: pros and cons of different sensors

With regard to the type of equipment to be fitted into repeaters, there are a number of options to choose from: absolute pressure gauges, which sense pressure; thermistors, which sense temperature; seismic sensors; micro-electromechanical system accelerometers, which sense acceleration; salinity (or conductivity) sensors; acoustic modems; and hydrophones.

There is already some experience of using undersea sensors for climate monitoring purposes, for instance tsunami gauges fitted to buoys (although buoys have often been damaged or vandalized) or absolute pressure gauges used for earthquake monitoring in the United States.

Bearing in mind engineering constraints, it is preferable to start with the simplest options. These would probably be the thermistors, absolute pressure gauges and micro-electromechanical systems, because these operate passively and autonomously, at low data rates.

While acoustic modems, hydrophones and salinity sensors might be attractive options in the longer term, they currently present some disadvantages. Salinity sensors need to become more robust, because they require contact with seawater. The use of hydrophones might call for significant adjustments to the repeater. Acoustic modems suffer from similar drawbacks to those of hydrophones, and could be sensitive to submarines, creating security concerns unless their range of operation is restricted.

Commercial and legal aspects

It is crucial that the primary function of the cables — to transmit large amounts of information between continents — is not compromised by a secondary scientific role. Companies that operate and own the cable communication infrastructure need to be able to guarantee its effectiveness, so should be responsible for managing and engineering the development of the cables for research purposes. Dialogue between commercial cable companies, maintenance authorities and governments has already been successfully established, and it makes sense to continue operating within this framework.

Alongside the commercial considerations, some legal knots need to be untied. The rules for laying cables are not fully compatible with those for scientific research, potentially limiting the use of cables for monitoring purposes.

Under the United Nations Convention on the Law of the Sea (UNCLOS, 1982), environmental monitoring using submarine cable repeater equipment would probably be officially classed as “marine scientific research”, which in turn is subject to different rules depending on which part of the ocean is concerned.

The principal difference in legal status lies between two basic zones. The first covers the exclusive economic zone (EEZ), continental shelf and territorial sea of coastal States. In practice, the continental shelf includes both the exclusive economic zone and territorial waters. The second includes the high seas and the seabed (known as the Area), which lie beyond the first zone, 350 nautical miles (648 kilometres) from the coastal baseline. States can regulate and require consent for marine scientific research as far as the boundary of the continental shelf but not beyond it. However, States and companies are permitted to lay cables and pipelines both on the continental shelf, and on the high seas and seabed.

It follows that environmental monitoring and sensor use should be limited to the high seas and seabed. Given that cables within the continental shelf are usually buried, this may not be a severe constraint. However, States need to be persuaded to agree to environmental monitoring within the continental shelf. The creation of a safety zone of 500 metres around a scientific research installation, which may be accorded for the purposes of marine scientific research, is a possible option.

The report’s author points out that “Currently the global environmental monitoring systems for ocean, weather, climate, tsunami, and earthquakes are developed, installed, and operated by governments. However, monitoring the environment of the seafloor with submarine telecommunication cables relies exclusively on infrastructure developed, installed, and operated by the private sector.”

The 2nd workshop on “Submarine Communications Networks For Climate Monitoring and Disaster Warning” jointly organized by ITU, WMO and UNESCO/ IOC will be held on 20–21 September 2012 in Paris, France.

This 2nd workshop will provide an opportunity to start developing a strategic plan for the deployment of dual-purpose submarine telecommunication cables in the high seas. It will explore scientific and societal needs, consider new engineering technologies, business opportunities, legal challenges, and begin to propose bases of standards that may be applied for the development of projects for submarine telecommunication cables with sensors.

Steps that ITU, WMO and UNESCO/IOC should take

The report shows how the United Nations—through its specialized agencies ITU, WMO, and UNESCO/IOC — can work with telecommunication companies to take the first steps towards realizing the vision of incorporating sensors into submarine cables.

ITU, WMO, and UNESCO/IOC should take every opportunity to publicize the outcome of the Rome workshop since linking submarine cables with green benefits would create public goodwill, which would in turn encourage cable owners, manufacturers and operators to participate, in the hope of benefiting from a public relations bonanza.

ITU, WMO, and UNESCO/IOC should organize an engineering workshop to bring cable repeater manufacturers together with sensor manufacturers in order to reach an understanding of the specific engineering challenges. Cable manufacturers should be able to work directly with sensor manufacturers in designing prototype repeaters that incorporate sensors. It would be helpful to invite the International Cable Protection Committee (ICPC) to co-sponsor the event and provide a neutral forum for the discussions.

ITU, WMO, and UNESCO/IOC should invite governments, cable companies and philanthropists to fund non-recurring engineering costs for prototype development because, as the report concludes, developing a “prototype environmental monitoring repeater is the crucial step for eventual success.”

The expertise of scientific institutes and agencies should inform the debate on environmental monitoring objectives. To this end, ITU, WMO, and UNESCO/IOC should, in particular, ask agencies operating deep ocean instrumentation to participate — for example, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Canada’s North East Pacific Time-Series Undersea Networked Experiments (NEPTUNE), European Sea Floor Observatory Network (ESONET), and the United States National Science Foundation (NSF) and National Oceanic and Atmospheric Administration (NOAA).

ITU, WMO, and UNESCO/IOC should sustain their positive engagement with telecommunication companies that develop, own and operate the submarine cable systems. They should also encourage cable manufacturers to recommend and engineer reliable, low risk and cost-effective ways for transmitting sensor data from the submarine cable repeaters.

It will be up to ITU, WMO, and UNESCO/IOC to vet the specifications of ocean observation sensors to be incorporated into the repeaters, with ITU taking the lead in developing a standard for an environmental monitoring repeater.

The lack of an internationally agreed definition of “marine scientific research” worries submarine cable owners and telecommunication companies, because environmental monitoring activities may face scrutiny even if limited to the high seas. It would be helpful if ITU, WMO and UNESCO/IOC were to seek a ruling on this matter from the UNCLOS International Tribunal, in order to have a clear path forward.


This article is based on the report A Strategy and Roadmap: Enabling the Availability of Submarine Repeaters Equipped with Scientific Sensors for Climate Monitoring and Disaster Risk Reduction researched and written by Rhett Butler. The report also draws on prior research conducted from December 2011 to March 2012. The author thanks Andres Figoli (Telefónica), Amir Delju (WMO), David Meldrum (UNESCO/IOC), John You (University of Sydney), Cristina Bueti and Erica Campilongo (ITU) for their helpful review of a prior draft. Additional information and materials on this report can be found at: www.itu.int/itu-t/climatechange.

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