With Shell receiving conditional approval to drill in the Chukchi Sea in offshore Alaska, the phrase “continental shelf” has come up a lot lately. The term also appears whenever territorial disputes in the Arctic make the news. But maps such as this one published by the Economist don’t exactly clarify what the continental shelf is, nor how its geography and terrain are literally at the bottom of so many disputes in the Arctic and indeed worldwide. So how can we better depict this underwater terrain, especially up north?
The International Bathymetric Chart of the Arctic Ocean (IBCAO) is the gold standard when it comes to cartographically displaying the texture of the continental shelf in the Arctic. The map has a resolution of 500 meters and much of the data comes from state-of-the-art multibeam surveys. You can read more about how the map was made in a paper published in Geophysical Research Letters in 2012.
However, what the map doesn’t display is geopolitical data. It’s interesting, for instance, to overlay the outlines of countries’ exclusive economic zones (EEZs) onto the bathymetric data. But before we do that, let’s look a bit more at the shelf’s topography.
Using the ETOPO1 1 Arc-Minute Global Relief Model available from the National Oceanic and Atmospheric Administration, I made a simple map in ArcGIS displayed at the top of this post of the continental shelves in the Arctic.* While the continental shelf exists in reality as an underwater extension of a continent, it’s important to remember that even the idea of a continent is a social construct. If we were to redraw the world’s continents from an underwater, continental-shelf based perspective, we likely wouldn’t divide North America and Asia.
With this in mind, it becomes clear why it will be so hard to divvy up the continental shelf. Due to the presence of countries on top of the continental shelves, they will ultimately not be so much geologically as politically defined. Is the much-disputed Lomonosov Ridge, for instance, an extension of the Canadian, Russian, or Danish continental shelf? The fact that each country could claim it based on supposedly objective bathymetric evidence demonstrates the malleability of geology to political aims.
Picture: Petty Officer 3rd Class Patrick Kelley [Public domain], via Wikimedia Commons