Sea Level Rise and Shifting Maritime Jurisdictional Limits

Clive Schofield

Australian National Centre for Ocean Resources and Security (ANCORS)

Sea Level Rise

• IPCC’s estimated range of sea level rise: 0.38-0.59m by the end of the century?

• Growing consensus that this estimate is overly conservative

• Great uncertainty over the critical questions of how much and how quickly?

Maritime Jurisdictions Zones

The Area

200 M

Sea Level

12 MContiguous

zone

Territorialsea

12 M

Exclusive Economic Zone (EEZ)

Water Column, Sea-bed, Subsoil

Rise Deep Ocean

Inte

rna

l w

ate

rs

Te

rrit

ori

al

Se

a B

as

eli

ne

(Extended Continental Shelf)

Continental ShelfSea-bed, Subsoil, Sedentary Species

High Sea

Shelf

LowerSlopemadeandi@ugm.ac.id © 2008

UpperSlope Plateu

orTerrace

Migrating Baselines = Shifting Limits

• Maritime jurisdictional limits measured from baselines: Predominantly normal baselines, low-water line baselines

• Traditional interpretation: ambulatory baselines and consequently shifting limits Coastlines dynamic – low water line susceptible to change As normal baselines move, the limits drawn from them also

shift

• Not a new phenomenon• As sea level rises so the low-water line migrates inland • Dramatic horizontal shifts to normal baselines possible

from slight changes to sea level vertically

Impacts on Islands

• Sea level rise/shifting baselines will also impact on the classification of insular features

• Most common normal baseline used, Lowest Astronomical Tide (LAT) – a very low low water line

• Critical basepoints may be unstable or ephemeral insular features Vulnerable to sea level rise leading to downgrading of

islands to mere rocks or low-tide elevations Impact on capacity to generate claims to maritime

jurisdiction

Implications

• Implications for: Extent and limits of maritime claims Enforcement issues Delimitation of maritime boundaries

• Loss of jurisdiction over vital marine resources• Jurisdictional uncertainty• Potential for conflict

Potential Responses

• Fix normal baselines physically Can key basepoints be preserved through sea

defences, ‘building-up’ and/or reclamation? Long tradition and an option for critical basepoints but

unrealistic for long coastlines?

• Fix normal baselines legally• Fix the limits of maritime zones

Okinotorishima: Maritime Claims

Okinotorishima

Okinotorishima

Physical defences unrealistic for long coastlines?

Fix Normal Baselines Legally

• Choice of chart depicting normal baseline left up to the coastal State (LOSC, Article 5)

• Chart the legal document• Can a coastal State therefore choose a chart that is

advantageous to it? What if there is a difference between the low water line shown

on the chart and reality?

• The drafters of the Convention did not anticipate sea level rise

• BUT: Ambulatory baselines may be fixed with straight baselines on unstable coasts Connection to the low water line still required

Fixing Limits and Boundaries

• Once agreed maritime boundaries remain fixed even though the baselines used to construct them may regress What if the territory in question disappears entirely?

• The outer limits of the continental shelf may also be fixed as “final and binding”

• Fix (declare) maritime limits Provides the advantage of certainty and the

preservation of existing maritime claims BUT: Increasing tension between fixed limit and

receding or disappearing normal baseline it is measured from