By Hannah Hoag
Under UNCLOS, a coastal state is entitled to the continental shelf area (and its buried resources) that lies within 200 nautical miles of its coastline, called the Exclusive Economic Zone (EEZ). But it can also extend that claim, if it has the data.
Of the five nations with coastlines on the Arctic Ocean, four – Canada, Denmark, Norway and Russia – have ratified the agreement; the U.S. has not. Once ratified, a nation has 10 years to gather the necessary data, analyze it and submit it to the Commission on the Limits of the Continental Shelf.
Countries can go about finding that outer limit in one of two ways, said Richard Haworth, a member of the commission.
The first approach scrutinizes the slope of the seabed. As it extends away from the coast, the steepness of its slope changes. The point where it makes its most abrupt change – from very steep to much less so – marks the foot of the slope; 60 nautical miles seaward of that point is one way to define the continental limit, said Haworth.
The second method is more complicated, but gives nations the opportunity to extend their claims even further, relying on the geology of the seabed. A layer of sedimentary rock extends from dry land into the sea, its thickness tapering as it moves seaward. Scientists measure the thickness of the sediment – using acoustic and seismic mapping devices – as it extends further out to sea. When its thickness is 1 percent of the distance back to the foot of the slope, “that is where you put the iron spike in the sea floor,” Haworth said.
Picture: Christopher Michel [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons