Read full article (PDF file, 1.5 MB)
Jabal al-Tair is an island lying halfway between Yemen and Eritrea, northwest of the Bab al-Mandeb passage at the mouth of the Red Sea. On December 17, 1999, an arbitral tribunal concluded that the island belonged to Yemen, entitling the country to claim the surrounding maritime zones. On that basis, the tribunal delimited the maritime boundary with Eritrea. Eight years later, on September 30, 2007, the volcano that created Jabal al-Tair exploded after having lain dormant since the late nineteenth century and collapsed the western portion of the island. What would have happened to the Yemeni-Eritrean boundary if the island had disappeared entirely?
Under the United Nations Convention on the Law of the Sea (UNCLOS or the Convention), a coastal state may claim a twelve-mile territorial sea, a twenty-four-mile contiguous zone, a two hundred-mile exclusive economic zone, and a two hundred-mile continental shelf. These four zones are measured from “baselines”—lines generally following the contours of the coast. However, coastlines are constantly changing: the explosion of Jabal al-Tair, although dramatic, is hardly a unique example of coastline shift. In addition to the destruction or formation of islands, coastlines continually move through the processes of accretion, avulsion, erosion, the melting of glaciers, seismic movements, and mining. The pace of those activities is likely to increase. Scientists predict that climate change and the associated rise in sea level may cause significant and unpredictable coastline shift. Already over half of the Mississippi and Texas shorelines have eroded “at average rates of 3.1 to 2.6 [meters per year] since the 1970s, while 90% of the Louisiana shoreline [has] eroded at a rate of 12.0 [meters per year].” A one-meter rise would flood seventeen percent of Bangladesh. Even a thirty-centimeter rise could cause the coastline to retreat forty-five meters in some areas.
Yet UNCLOS is silent on whether baselines, and therefore maritime zones, shift with the coastline—whether they are “ambulatory.” That gap creates potentially significant uncertainty in the law of the sea. Billions of dollars are at stake: maritime zones are sources of great wealth for coastal states, containing “[a]ll exploitable offshore hydrocarbons, all commercially usable minerals in unconsolidated sediments, . . . over 90 per cent of the commercially exploitable living resources of the sea, nearly all marine plants, and all known sites suitable to the production of energy . . . .” Those zones also provide states with important navigational, scientific, and jurisdictional rights.
To address this uncertainty, several scholars have proposed that baselines should be fixed to specific geographic coordinates such that maritime limits and boundaries would be permanent, akin to most land boundaries. Two chief concerns motivate this proposal. One group of scholars has argued that, without fixed baselines, island states submerged by rising sea levels will lose their maritime entitlements. Fixing baselines would permit the stateless populations to permanently retain rights to their historic maritime zones. This first issue is not the concern of this Note. A second group of scholars has focused on a broader concern: stability. They argue that baselines should be permanently fixed, since constant flux in limits and boundaries will almost certainly give rise to resource conflicts. This Note focuses on this second concern and questions whether it is overstated. Stability is indeed central to the international boundaries regime, but the analysis underlying the proposal to fix baselines has not considered an independent source of stability: treaty law.
Although UNCLOS is a formidable attempt to provide a comprehensive regime for management of the oceans, encompassing issues as diverse as maritime delimitation, pollution, and piracy, the Convention is not the sole relevant governing law for maritime entitlements. It interacts with the larger body of international law, including the Vienna Convention on the Law of Treaties (Vienna Convention). Those arguing for permanently fixed baselines have conflated maritime limits and maritime boundaries in their analysis, thus overlooking the relevance of the Vienna Convention and treaty law to boundaries. The fundamental differences between limits and boundaries must therefore be considered when assessing the stability, or instability, of maritime zones with ambulatory baselines.
Where a state’s claimed territorial sea or exclusive economic zone does not overlap with any other state’s claim, the area may be unilaterally claimed, barring protest from other states. The outmost extent of such territorial sea and exclusive economic zones are called “limits” or “outer limit lines,” respectively. Where, however, two or more states have overlapping claims, the states must reach agreement on the delimitation of the contested area, and establish “lines of delimitation.” For the sake of clarity, this Note will refer to such lines of delimitation as maritime boundaries. Treaty law, in particular the Vienna Convention, plays an important role in the establishment, interpretation, and termination of these boundary agreements.
This Note argues that under the Vienna Convention, boundary agreements are highly stable despite coastline shift. The states parties to a maritime boundary treaty may not use geographic change as grounds for unilateral termination. Hence, regardless of whether baselines are ambulatory or fixed, the international maritime boundary regime is largely secure. However, in a limited number of scenarios, coastline shift may generate new rights for third states. Fixed baselines may substantially impinge on those rights, suggesting that the proposal does not satisfactorily resolve the problem of unstable maritime entitlements.
Part II begins by describing coastline shift and establishes that, although climate change may have an unprecedented impact on the scale of changes, the problem of unstable coastal geography is not novel. Despite this, UNCLOS contains no provisions indicating whether baselines are ambulatory. Further, state practice only tentatively suggests a general understanding of baselines as ambulatory. The Part concludes that the status of baselines remains an open question.
Part III reviews the underlying principles at stake when considering whether to fix baselines. Fixed baselines address two main concerns: instability and inefficiency. However, the proposal would undermine two underlying principles of UNCLOS. The first is the historic premise that the land dominates the sea: all maritime entitlements derive from the land. A state therefore may claim only maritime zones adjacent to its coastline. The second is equity: each claim on the ocean reduces the collective common heritage of the high seas and seabed resources. As coastlines retreat, if outer limits remain fixed, coastal states would control an increasingly large area of the oceans. Although the total area of the high seas would not shrink, the question remains as to who should “benefit” from retreating coastlines: the coastal state or the global community?
The four concerns identified in Part III—instability, inefficiency, historical land tie, and equity—often conflict. The extent to which they are in opposition, however, depends on the geographic scenario. Part IV lays out five possible scenarios of coastal geographic change. The first two scenarios address limits, a detailed consideration of which is beyond the scope of this Note. Rather, this Note focuses on the third, fourth, and fifth scenarios, which address the impact of coastline shift on boundaries. Most maritime boundaries fall within scenario three. In such cases, coastline shift will only affect the areas of the delimited maritime zones, but not the type of zones between two states, and thus will not create new rights for third states. Those agreements are internally stable, as discussed in Part V. The fourth and fifth boundary scenarios address a subset of maritime boundaries: the rare cases in which shifting coastlines may generate new maritime zones, and therefore new rights for third states. Although Part V establishes that, as in scenario three, those agreements are internally stable, Part VI outlines how boundaries in the fourth and fifth scenarios may not be externally stable.
Part V addresses the internal stability of all maritime boundary agreements, as between states parties. Some authors have suggested that coastline shift from climate change may constitute a fundamental change in circumstances (rebus sic stantibus or “things standing thus”), justifying unilateral termination under Article 62 of the Vienna Convention. According to that argument, if baselines are ambulatory, countries can unilaterally terminate maritime boundary agreements. The Part reviews the drafting history of the Vienna Convention to conclude that Article 62 does not permit unilateral termination under such circumstances. Further, even if a state could invoke Article 62 to terminate a boundary agreement, it should reasonably have anticipated changes in coastal geography. Thus, the state would be unable to demonstrate that unchanging coastal geography was an essential basis for its consent—necessary for invoking Article 62. Part V therefore concludes that regardless of whether baselines are ambulatory or fixed, coastline shift will not affect the internal stability of maritime boundary agreements as between the states parties.
Part VI turns to consider a small subset of maritime boundaries: cases potentially creating new rights for third states. While most boundary agreements will likely be unaffected by ambulatory baselines, for a small category of highly important boundary agreements, the issue of whether baselines are ambulatory or fixed has significant effects on the rights of third states. Those agreements are internally stable, as discussed in Part V, but face external uncertainty under the doctrine of pacta tertiis. The doctrine under Article 34 of the Vienna Convention provides that an agreement between states may not infringe upon the rights of third states without their consent. As such, tribunal decisions have focused on third-state rights at the time an agreement is concluded, maintaining that states may not conclude agreements where third states have overlapping claims. But what happens if shifting coastlines generate rights for third states, such as widening an international strait beyond twenty-four miles? Part VI analyzes the potential for states to invoke such newly generated rights and concludes that, even in rare cases where such rights may be created, the existing boundary agreements will likely remain in effect.
In sum, while this Note recognizes that fixed baselines would provide increased stability in the case of maritime limits, it concludes that ambulatory baselines will have a less destabilizing impact than some scholars predict. Moreover, in some rare instances, fixed baselines might even significantly impinge on third-state rights.
