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Extended Continental Shelf


Fact Sheet
Bureau of Oceans and International Environmental and Scientific Affairs
Washington, DC
March 9, 2009

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Extended Continental Shelf Frequently Asked Questions

  1. What is the continental shelf? What is the extended continental shelf (ECS)?

Under the Convention on the Law of the Sea, every coastal State (i.e. country) has a continental shelf out to 200 nautical miles from its coastal baselines (or out to a maritime boundary with another coastal State), and beyond that distance if certain criteria are met. Article 76 of the Convention sets forth the criteria upon which a coastal State may establish continental shelf that extends beyond 200 nautical miles. The extended continental shelf (ECS) is that portion of the continental shelf that lies beyond this 200 nautical mile limit. Note the juridical (legal) continental shelf is not necessarily the same as what a scientist would call a continental shelf.


  1. What sovereign rights do coastal States have over the continental shelf?
  • Exploration, exploitation, conservation, and management of non-living resources of the seabed and subsoil of the continental shelf, such as ferromanganese crusts, ferromanganese nodules, gas hydrate deposits, and petroleum;
  • Exploration, exploitation, conservation, and management of living, “sedentary” resources, such as clams, crabs, corals, scallops, sponges, and mollusks.
  • Exclusive control over marine scientific research on the shelf;
  • Control over the construction, operation and use of artificial islands, installations and structures;
  • Control over the delineation of the course for laying pipelines;
  • Regulation of drilling and mining; and
  • Control and prevention of marine pollution in connection with some activities on the ECS.

While a continental shelf is coincident with the exclusive economic zone (EEZ) out to 200 nautical miles, the ECS is not an extension of the EEZ. Sovereign rights that apply to the EEZ, especially rights to the resources of the water column (e.g., pelagic fisheries) do not necessarily apply to the ECS.


  1. How are the outer limits of the ECS determined?

The process to determine the outer limits of a State’s ECS involves the collection and analysis of data that describe the depth, shape, and geophysical characteristics of the seabed and sub-sea floor, as well as the thickness of the underlying sediments. The specific types of data that may need to be collected include: bathymetric data, seismic reflection and refraction data, and other geophysical data such as magnetic and gravity data, and physical samples and cores from the seafloor.

A coastal State may use any combination of two formulas provided under Article 76 so as to maximize the extent of its ECS. One formula is based on morphology alone, while the other uses a combination of morphology and sediment thickness. Article 76, however, mandates two cutoff lines that, like the two formulas, can be implemented in any combination when determining the limits of an ECS, whichever is more beneficial to the coastal State. The first is based on bathymetry and limits an ECS to 100 nautical miles from the 2,500 meter isobath. The second is based on distance, and limits an ECS to 350 nautical miles from a State’s coastal baselines, with certain exceptions.


  1. Do all coastal States have an ECS? How many other States have an ECS?

Coastal States that meet the criteria in Article 76 may establish a continental shelf beyond 200 nautical miles. An estimated 60 coastal States have a continental shelf that extends beyond 200 nautical miles. Fifteen have made a submission in whole or in part to the Commission on the Limits of the Continental Shelf (CLCS).


  1. What is the Commission on the Limits of the Continental Shelf (CLCS)?
The CLCS is an expert body established by the Convention on the Law of the Sea. A coastal State that is party to the Convention may submit the coordinates of its identified ECS, along with supporting data and analyses, to the CLCS. The CLCS consists of 21 members, elected by those States that are party to the Convention. Experts in geology, geophysics, or hydrography, members of the CLCS serve in a personal capacity. They examine coastal States’ ECS submissions and make recommendations to the submitting States. If the coastal State establishes its ECS limits “on the basis of” CLCS recommendations, those limits are “final and binding.”

  1. Can the actions of the CLCS impact areas where maritime boundaries have yet to be determined?

No. The CLCS has no mandate to settle boundary disputes, nor can it make any decisions that will bias future resolution to such disputes. Any boundary disagreements must be resolved between the States themselves.

The United States Extended Continental Shelf

  1. Do the rights of the United States over its continental shelf depend upon accession to the Convention and making a submission to the CLCS?

No. Customary international law, as reflected in the Convention, confers such rights on a coastal State. At the same time, joining the Convention would allow the United States to gain access to the procedure that maximizes international recognition and legal certainty regarding the outer limits of its continental shelf.



  1. Where is the United States’ ECS and how large is it?

The extent of the U.S ECS has not been determined. However, a 2002 study by the Joint Hydrographic Center at the University of New Hampshire identified several areas where the United States may have extended continental shelf: the Atlantic East Coast, the Gulf of Mexico, the Gulf of Alaska, the Bering Sea, the Arctic Ocean, Kingman Reef/Palmyra Atoll, and the Mariana Islands/Guam. The prospective ECS identified in that study amounts to about one million square kilometers or approximately twice the size of California. Roughly half of that area is off Alaska. Additional analyses and data collection suggest an even larger ECS, in these and other areas.

There are no official maps yet that show the extent of the U.S. ECS. As additional data are collected and existing data analyzed, we will begin to come to a more definitive conclusion as to the extent of the U.S. ECS.

  1. How much will collecting this data cost? How long will it take?

Estimating total cost for data collection depends on a number of variables including vessel time, logistics, data to be collected, and ultimately the total area where the U.S. will substantiate an ECS. The U.S. ECS Task Force is currently conducting a study that will estimate more definitively the remaining work and ultimately the remaining costs. Likewise, once this study is complete, we will have a better idea of how long this effort may take.

In FY08, the U.S. Government spent $5.8 million on ECS efforts. This budget came from three separate funding streams. Most of it is derived from money newly directed to the ECS Project by the Office of Management and Budget, while $1.3 million is from a grant through NOAA to the University of New Hampshire, and $0.3 million is programmatic funds from the USGS.

Since 2002 the Joint Hydrographic Center at the University of New Hampshire has received funding through NOAA (approximately $10 million) as directed by Congress for the initial data study and bathymetric data collection.

  1. What agencies are involved in the United States’ program? What are their respective roles?

The work to define the U.S. continental shelf is coordinated by the U.S. Extended Continental Shelf Task Force, an interagency body headed by the U.S. Department of State, and established in early 2007. Participants in this Task Force include: U.S. Geological Survey, National Oceanic and Atmospheric Administration, Executive Office of the President, Joint Chiefs of Staff, U.S. Navy, U.S. Coast Guard, Department of Energy, National Science Foundation, Environmental Protection Agency, Minerals Management Service, and Arctic Research Commission.

Each agency and institution involved has its own respective role in the Project. For example, NOAA has taken the lead in collecting bathymetric data, USGS has taken the lead in collecting seismic data, Coast Guard operates the United States Coast Guard Cutter Healy, an icebreaker, NSF has made Healy available through its scheduling process, Navy has provided survey ships for collecting bathymetric data off the U.S. East Coast, while State Department chairs the Task Force and handles the Project’s legal and diplomatic aspects.

  1. Why is determining the limits of the U.S. continental shelf important now?
  • The United States has an inherent national interest in knowing, and declaring to others with specificity and certainty, the extent of our sovereign rights with regard to our continental shelf beyond 200 nautical miles.
  • Establishing ECS limits will define the ECS area in concrete geographical terms, thus enabling the United States to exercise its continental shelf rights with significantly greater certainty in the future.
  • The collection and analysis of the data necessary to support the establishment of the U.S. ECS will, in itself, provide a better scientific understanding of formation and transformation processes of our continental margins. The United States will gain specific insights related to such areas as climate variability, marine ecosystems, undiscovered or unconventional energy and mineral resources, and hazards resulting from extreme events, such as earthquakes and tsunamis.
  • Because most countries are working under a submission deadline (e.g., Canada has a 2013 deadline), it is an opportunity for the U.S. to take advantage of cooperative efforts now which will save time and money.

  1. Why now, given the United States has yet to accede to the Convention? Is this a race for resources or a modern-day land grab? Is it because of climate change?

Establishing the extended continental shelf is not a race for resources or a land grab, nor is it driven by climate change. Parties to the Convention are proceeding according to the process set out in Article 76, Annex II, and decisions of the States Parties, to make timely submissions. ECS boundary issues between adjacent or opposite States must be decided between the States involved. It’s not a question of first-come, first-served.

If the Senate acts favorably on accession to the Convention, the United States will have ten years to make a submission to the CLCS. The U.S. is trying to get a head start in collecting and analyzing data for an ECS that is likely to be among the largest in the world and that occurs in multiple, non-contiguous areas across the globe, including a portion of the Arctic that presents significant challenges for data collection.

  1. How much are the resources in the United States’ extended continental shelf worth?

The ECS is a very large area; only limited data have been collected to make any determinations on the potential value of resources. Given the likelihood of ferromanganese crusts, ferromanganese nodules, gas hydrate deposits, and petroleum reservoirs on or beneath the ECS, it is likely the resources are worth many billions of dollars.

  1. Are there additional exploration and development plans once the ECS is established? Will the U.S. issue lease blocks, for instance?

Decisions about exploration or development of ECS resources (with the exception of a relatively small area in the Gulf of Mexico) will not be made for a number of years.

Other Countries

  1. What other countries have ECS in the Arctic? Will any of these countries have overlapping ECS with the United States?

We believe each of the five Arctic States (Canada, Denmark, Norway, Russia, and the U.S) has an ECS in the Arctic Ocean. Two (Russia and Norway) have made a submission to the CLCS; the Russian submission honors the provisional boundary agreed between the U.S. and the Soviet Union in 1990. Canada and the United States have yet to agree to a maritime boundary that would divide the continental shelf.

  1. Is the United States cooperating with other countries in collecting ECS data?

The United States is currently working only with Canada in regard to collecting ECS data, although we have met with experts from other countries to learn more about their ECS work.

Beyond data collection, however, there is wider cooperation across all five Arctic States (Canada, Denmark, Norway, Russia, and the U.S). High-level officials from each met in Ilulissat, Greenland at the end of May 2008 and agreed that the law of the sea provides a foundation for responsible management of the Arctic Ocean. They also pledged their commitment to freedom of navigation in Arctic waters, preservation and protection of the fragile marine environment of the Arctic Ocean, cooperative marine scientific research, and orderly settlement of any possible overlapping ECS claims.

  1. Does the fact that the United States and Canada have yet to define a maritime boundary in the Beaufort Sea/Arctic Ocean affect the delimitation of ECS areas for both countries?

No. The United States and Canada are cooperating to collect the data necessary to define the continental shelf. While the United States and Canada have yet to agree on a maritime boundary in the Beaufort Sea/Arctic Ocean, they will work out the maritime boundary on a bilateral basis at an appropriate time.



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