Sea Level Rise and Impacts on Maritime Zones and Limits

As the oceans warm and ice melts, the Intergovernmental Panel on Climate Change (ipcc) in its Fifth Assessment Report (AR5) now predicts a global average sea level rise of up to one meter by 2100. AR5 also emphasizes that sea level rise will have “a strong regional pattern, with some places experiencing significant deviations of local and regional sea level change from the global mean change.” These predictions pose serious and possibly existential threats to the inhabitants of low-lying islands and coastal areas, and pose challenges for the international legal system to respond in an orderly and humane way to these novel situations. In 2012, the International Law Association (ila) established a new Committee to look specifically at these issues. This article looks at the work undertaken by the Committee to date regarding the law of the sea aspects of its mandate and identifies some considerations for its future work.

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Reconciling global mean and regional sea level change in projections and observations

Nature Communications ◽

10.1038/s41467-021-21265-6 ◽

2021 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Jinping Wang ◽

John A. Church ◽

Xuebin Zhang ◽

Xianyao Chen

Keyword(s):

Sea Level ◽

Climate Models ◽

Tide Gauge ◽

Sea Level Change ◽

Global Network ◽

Weighted Mean ◽

Level Change ◽

Regional Sea Level ◽

Global Mean ◽

Regional Sea Level Change

AbstractThe ability of climate models to simulate 20th century global mean sea level (GMSL) and regional sea-level change has been demonstrated. However, the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) and Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) sea-level projections have not been rigorously evaluated with observed GMSL and coastal sea level from a global network of tide gauges as the short overlapping period (2007–2018) and natural variability make the detection of trends and accelerations challenging. Here, we critically evaluate these projections with satellite and tide-gauge observations. The observed trends from GMSL and the regional weighted mean at tide-gauge stations confirm the projections under three Representative Concentration Pathway (RCP) scenarios within 90% confidence level during 2007–2018. The central values of the observed GMSL (1993–2018) and regional weighted mean (1970–2018) accelerations are larger than projections for RCP2.6 and lie between (or even above) those for RCP4.5 and RCP8.5 over 2007–2032, but are not yet statistically different from any scenario. While the confirmation of the projection trends gives us confidence in current understanding of near future sea-level change, it leaves open questions concerning late 21st century non-linear accelerations from ice-sheet contributions.

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A scaling approach to project regional sea level rise and its uncertainties

Earth System Dynamics ◽

10.5194/esd-4-11-2013 ◽

2013 ◽

Vol 4 (1) ◽

pp. 11-29 ◽

Cited By ~ 77

Author(s):

M. Perrette ◽

F. Landerer ◽

R. Riva ◽

K. Frieler ◽

M. Meinshausen

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

General Circulation ◽

Ice Sheets ◽

General Circulation Models ◽

Ice Melt ◽

Probabilistic Forecasts ◽

Regional Sea Level ◽

Global Mean

Abstract. Climate change causes global mean sea level to rise due to thermal expansion of seawater and loss of land ice from mountain glaciers, ice caps and ice sheets. Locally, sea level can strongly deviate from the global mean rise due to changes in wind and ocean currents. In addition, gravitational adjustments redistribute seawater away from shrinking ice masses. However, the land ice contribution to sea level rise (SLR) remains very challenging to model, and comprehensive regional sea level projections, which include appropriate gravitational adjustments, are still a nascent field (Katsman et al., 2011; Slangen et al., 2011). Here, we present an alternative approach to derive regional sea level changes for a range of emission and land ice melt scenarios, combining probabilistic forecasts of a simple climate model (MAGICC6) with the new CMIP5 general circulation models. The contribution from ice sheets varies considerably depending on the assumptions for the ice sheet projections, and thus represents sizeable uncertainties for future sea level rise. However, several consistent and robust patterns emerge from our analysis: at low latitudes, especially in the Indian Ocean and Western Pacific, sea level will likely rise more than the global mean (mostly by 10–20%). Around the northeastern Atlantic and the northeastern Pacific coasts, sea level will rise less than the global average or, in some rare cases, even fall. In the northwestern Atlantic, along the American coast, a strong dynamic sea level rise is counteracted by gravitational depression due to Greenland ice melt; whether sea level will be above- or below-average will depend on the relative contribution of these two factors. Our regional sea level projections and the diagnosed uncertainties provide an improved basis for coastal impact analysis and infrastructure planning for adaptation to climate change.

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The transient sensitivity of sea level rise

Ocean Science ◽

10.5194/os-17-181-2021 ◽

2021 ◽

Vol 17 (1) ◽

pp. 181-186

Author(s):

Aslak Grinsted ◽

Jens Hesselbjerg Christensen

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Carbon Dioxide Emissions ◽

Radiative Forcing ◽

Climate Models ◽

Climate Model ◽

Greenhouse Gas Emission ◽

Rate Of Change ◽

Intergovernmental Panel ◽

Global Mean

Abstract. Recent assessments from the Intergovernmental Panel on Climate Change (IPCC) imply that global mean sea level is unlikely to rise more than about 1.1 m within this century but will increase further beyond 2100. Even within the most intensive future anthropogenic greenhouse gas emission scenarios, higher levels are assessed to be unlikely. However, some studies conclude that considerably greater sea level rise could be realized, and a number of experts assign a substantially higher likelihood of such a future. To understand this discrepancy, it would be useful to have scenario-independent metrics that can be compared between different approaches. The concept of a transient climate sensitivity has proven to be useful to compare the global mean temperature response of climate models to specific radiative forcing scenarios. Here, we introduce a similar metric for sea level response. By analyzing the mean rate of change in sea level (not sea level itself), we identify a nearly linear relationship with global mean surface temperature (and therefore accumulated carbon dioxide emissions) both in model projections and in observations on a century scale. This motivates us to define the “transient sea level sensitivity” as the increase in the sea level rate associated with a given warming in units of meters per century per kelvin. We find that future projections estimated on climate model responses fall below extrapolation based on recent observational records. This comparison suggests that the likely upper level of sea level projections in recent IPCC reports would be too low.

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The transient sensitivity of sea level rise

10.5194/os-2020-68 ◽

2020 ◽

Author(s):

Aslak Grinsted ◽

Jens Hesselbjerg Christensen

Keyword(s):

Carbon Dioxide ◽

Sea Level Rise ◽

Sea Level ◽

Carbon Dioxide Emissions ◽

Climate Models ◽

Carbon Dioxide Emission ◽

Rate Of Change ◽

Intergovernmental Panel ◽

Transient Climate Response ◽

Global Mean

Abstract. Recent assessments from the Intergovernmental Panel on Climate Change implies that global mean sea level is unlikely to rise more than about 1.1 m within this century, but with further increase beyond 2100, even within the most intensive future anthropogenic carbon dioxide emission scenarios. However, some studies conclude that considerably greater sea level rise could be realized, and experts assign a substantially higher likelihood of such a future. To understand this discrepancy, it would be useful to have scenario independent metrics that can be compared between different approaches. The concept of a transient climate response has proven to be useful to compare the response of climate models. Here, we introduce a similar metric for sea level science. By analyzing mean rate of change in sea level (not sea level itself), we identify a near linear relationship with global mean surface temperature (and therefore accumulated carbon dioxide emissions) in both model projections, and in observations on a century time scale. This motivates us to define the Transient Sea Level Sensitivity as the increase in the sea level rate associated with a given warming in units of m/century/K. We find that model projections fall below extrapolation based on recent observational records. This comparison indicates that the likely upper level of sea level projections in recent IPCC reports would be too low.

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Islands Awash Amidst Rising Seas: Sea Level Rise and Insular Status under the Law of the Sea

The International Journal of Marine and Coastal Law ◽

10.1163/15718085-13431098 ◽

2019 ◽

Vol 34 (3) ◽

pp. 391-414 ◽

Cited By ~ 2

Author(s):

Clive Schofield ◽

David Freestone

Keyword(s):

Climate Change ◽

South China Sea ◽

International Law ◽

Sea Level Rise ◽

Sea Level ◽

Legal Framework ◽

Law Of The Sea ◽

Intergovernmental Panel ◽

State Practice ◽

The Face

Abstract This article considers the potential impacts of sea level rise on maritime zones with particular reference to impacts on islands. It considers the sea level rise predictions of the Intergovernmental Panel on Climate Change; it outlines the existing legal framework for coastal baselines and insular features established by the 1982 Law of the Sea Convention. It highlights the work of the International Law Association Committee on International Law and Sea Level Rise, which in its 2018 report had identified the development of a body of State practice among the States and Territories of the South Pacific regarding the maintenance of existing maritime zone claims in the face of sea level rise. That practice is considered, together with the implications of the 2016 Tribunal Award on the South China Sea case on maritime zone claims based on islands.

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Ice sheet contributions to future sea-level rise from structured expert judgment

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1817205116 ◽

2019 ◽

Vol 116 (23) ◽

pp. 11195-11200 ◽

Cited By ~ 104

Author(s):

Jonathan L. Bamber ◽

Michael Oppenheimer ◽

Robert E. Kopp ◽

Willy P. Aspinall ◽

Roger M. Cooke

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Predictive Capability ◽

Intergovernmental Panel ◽

Process Understanding ◽

Temperature Scenario ◽

Global Mean Sea Level ◽

Observational Record ◽

Global Mean

Despite considerable advances in process understanding, numerical modeling, and the observational record of ice sheet contributions to global mean sea-level rise (SLR) since the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change, severe limitations remain in the predictive capability of ice sheet models. As a consequence, the potential contributions of ice sheets remain the largest source of uncertainty in projecting future SLR. Here, we report the findings of a structured expert judgement study, using unique techniques for modeling correlations between inter- and intra-ice sheet processes and their tail dependences. We find that since the AR5, expert uncertainty has grown, in particular because of uncertain ice dynamic effects. For a +2 °C temperature scenario consistent with the Paris Agreement, we obtain a median estimate of a 26 cm SLR contribution by 2100, with a 95th percentile value of 81 cm. For a +5 °C temperature scenario more consistent with unchecked emissions growth, the corresponding values are 51 and 178 cm, respectively. Inclusion of thermal expansion and glacier contributions results in a global total SLR estimate that exceeds 2 m at the 95th percentile. Our findings support the use of scenarios of 21st century global total SLR exceeding 2 m for planning purposes. Beyond 2100, uncertainty and projected SLR increase rapidly. The 95th percentile ice sheet contribution by 2200, for the +5 °C scenario, is 7.5 m as a result of instabilities coming into play in both West and East Antarctica. Introducing process correlations and tail dependences increases estimates by roughly 15%.

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International Law and Sea Level Rise

Brill Research Perspectives in the Law of the Sea ◽

10.1163/24519359-12340006 ◽

2019 ◽

Vol 2 (3) ◽

pp. 1-86

Author(s):

Davor Vidas ◽

David Freestone ◽

Jane McAdam

Keyword(s):

International Law ◽

Sea Level Rise ◽

Sea Level ◽

Human Mobility ◽

Forced Migration ◽

Intergovernmental Panel ◽

Biennial Conference ◽

State Practice ◽

Relevant Context ◽

And Sea Level

AbstractThis issue contains the final version of the 2018 Report of the International Law Association (ILA) Committee on International Law and Sea Level Rise, as well as the related ILA Resolutions 5/2018 and 6/2018, both as adopted by the ILA at its 78th Biennial Conference, held in Sydney, Australia, 19–24 August 2018.In Part I of the Report, key information about the establishment of the Committee, its mandate and its work so far is presented. Also, the background for the establishment of the Committee is explained, drawing on: (a) conclusions of the ILA Committee on Baselines and the related ILA Resolution 1/2012; (b) scientific assessments, such as by the Intergovernmental Panel on Climate Change (IPCC), regarding on-going sea level change and projections of future rise; and (c) more broadly, scientific findings regarding the profound changes taking place in the Earth system since the mid-20th century and predictions for their acceleration in the course of the 21st century. All of this has prompted the need, and provided the Committee with the relevant context, for the study of the options and elaboration of proposals for the development of international law.Part II of the Report addresses key law of the sea issues through a study of possible impacts of sea level rise and their implications under international law regarding maritime limits lawfully determined by the coastal States, and the agreed or adjudicated maritime boundaries. This includes the study of the effects of sea level rise on the limits of maritime zones, and the analysis of the subsequently emerging State practice regarding the maintenance of their existing lawful maritime entitlements. The guiding consideration in developing the proposals and recommendations by the Committee for the interpretation and development of international law regarding the maritime limits and boundaries impacted by sea level rise has been the need to avoid uncertainty and, ultimately, facilitate orderly relations between States and contribute to the maintenance of international peace and security. A related ILA Resolution 5/2018 addresses maritime limits and boundaries impacted by sea level rise.Part III of the Report addresses international law provisions, principles and frameworks for the protection of persons displaced in the context of sea level rise. The notion of ‘human mobility’ is used as an umbrella term that refers to all relevant forms of the movement of persons and, in the context of this report, covers displacement (which is forced), migration (which is predominantly voluntary), planned relocation and evacuations (which both may be forced or voluntary). This part of the report takes the form of principles entitled the ‘Sydney Declaration of Principles on the Protection of Persons Displaced in the Context of Sea Level Rise’ with commentaries. Accordingly, ILA Resolution 6/2018, which also contains the Sydney Declaration of Principles, addresses the protection of persons displaced in the context of sea level rise and contains recommendations by the Committee to this effect.

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Evolution or Revolution? Evaluating the Territorial State-Based Regime of International Law in the Context of the Physical Disappearance of Territory Due to Climate Change and Sea-Level Rise

Canadian Yearbook of international Law/Annuaire canadien de droit international ◽

10.1017/cyl.2016.4 ◽

2016 ◽

Vol 53 ◽

pp. 66-118

Author(s):

CATHERINE BLANCHARD

Keyword(s):

Climate Change ◽

International Law ◽

Sea Level Rise ◽

Sea Level ◽

Small Island ◽

Legal Scholarship ◽

Territorial State ◽

Legal Literature ◽

One Step ◽

International Legal System

AbstractThe threat of the permanent physical disappearance of the territory of states no longer belongs to the mythical realm, and the situation is particularly imminent for small island developing states. While most international legal scholarship has so far focused on issues stemming from territorial disappearance, this article goes one step further. It questions the appropriateness of the classical notion of the territorial state — a socio-cultural and politico-legal entity evolving on a defined territorial area — as the basis for an international legal system faced with new realities created by climate change, sea-level rise, and globalization. After examining the current rules on statehood within the context of the physical disappearance of states’ territories and looking into the solutions suggested in the legal literature to address territorial loss, this article assesses a new way of understanding statehood by exploring theoretical lenses through which a new model of statehood could be contemplated.

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Climate-change–driven accelerated sea-level rise detected in the altimeter era

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1717312115 ◽

2018 ◽

Vol 115 (9) ◽

pp. 2022-2025 ◽

Cited By ~ 261

Author(s):

R. S. Nerem ◽

B. D. Beckley ◽

J. T. Fasullo ◽

B. D. Hamlington ◽

D. Masters ◽

...

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Altimeter Data ◽

Intergovernmental Panel ◽

Mean Sea Level ◽

Simple Extrapolation ◽

Global Mean Sea Level ◽

Satellite Altimeter Data ◽

Global Mean

Using a 25-y time series of precision satellite altimeter data from TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3, we estimate the climate-change–driven acceleration of global mean sea level over the last 25 y to be 0.084 ± 0.025 mm/y2. Coupled with the average climate-change–driven rate of sea level rise over these same 25 y of 2.9 mm/y, simple extrapolation of the quadratic implies global mean sea level could rise 65 ± 12 cm by 2100 compared with 2005, roughly in agreement with the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5) model projections.

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Contribution of Land Water Storage Change to Regional Sea-Level Rise Over the Twenty-First Century

Frontiers in Earth Science ◽

10.3389/feart.2021.627648 ◽

2021 ◽

Vol 9 ◽

Author(s):

Sitar Karabil ◽

Edwin H. Sutanudjaja ◽

Erwin Lambert ◽

Marc F. P. Bierkens ◽

Roderik S. W. Van de Wal

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Climate Models ◽

Sea Level Change ◽

First Century ◽

Level Change ◽

Regional Sea Level ◽

Twenty First Century ◽

Land Water ◽

Global Mean

Change in Land Water Storage (LWS) is one of the main components driving sea-level rise over the twenty-first century. LWS alteration results from both human activities and climate change. Up to now, all components to sea-level change are usually quantified upon a certain climate change scenario except land water changes. Here, we propose to improve this by analyzing the contribution of LWS to regional sea-level change by considering five Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models forced by three different Representative Concentration Pathway (RCP) greenhouse gas emission scenarios. For this analysis, we used LWS output of the global hydrological and water resources model, PCR-GLOBWB 2, in order to project regional sea-level patterns. Projections of ensemble means indicate a range of LWS-driven sea-level rise with larger differences in projections among climate models than between scenarios. Our results suggest that LWS change will contribute around 10% to the projected global mean sea-level rise by the end of twenty-first century. Contribution of LWS to regional sea-level rise is projected to be considerably larger than the global mean over several regions, up to 60% higher than global average of LWS-driven sea-level rise, including the Pacific islands, the south coast of Africa and the west coast of Australia.

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