GCRI · Oceans and Coasts
Island resilience
Small islands face sea-level rise, cyclones and droughts with limited land, freshwater, infrastructure and economies that depend on imports, tourism and fisheries. Some low-lying atolls face questions about long-term habitability. This page sets out how risks combine on islands, how island resilience is measured with scarce data, and what evidence serves island governments, communities and their partners.
Island resilience on the record.
Island resilience: how the risk develops.
Island connectivity and energy, water, food systems. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Limited freshwater
Islands rely on thin freshwater lenses, rainwater and desalination. Sea-level rise, overwash and drought salinise and deplete these supplies.
Single events, national impacts
One cyclone can damage a large share of an island state’s housing and infrastructure and set its economy back years.
Dependence on imports and links
Fuel, food and medicines arrive by sea and air through one or two ports and airports. Disruption isolates islands quickly.
Debt and costs constrain recovery
High costs of infrastructure and frequent disasters add to public debt, limiting investment in adaptation and recovery.
Ocean state in Pacific Island states.
Marine heat, chlorophyll and sea temperature over Pacific Island states, from NASA GIBS. Each layer carries its own date.
The interactive map needs JavaScript; the layer list and sources are below.
Layers 3
Ocean state, for this page
About this layer
- Evidence
- Observed
- Source
- GHRSST MUR25 (NASA JPL PO.DAAC)
- Provider
- NASA JPL PO.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite analysis
- Newest at build
- 2026-10-12
- Resolution
- about 2 km grid
- Uncertainty
- Satellite analysis of how far sea temperature departs from its usual value for the date shown; a marine heat indicator, not a coral bleaching alert.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (clouds and sun glint leave gaps)
- Source
- MODIS Aqua ocean colour (NASA OB.DAAC)
- Provider
- NASA OB.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite retrieval; clouds and sun glint leave gaps
- Newest at build
- 2026-10-13
- Resolution
- about 1 km grid
- Uncertainty
- Satellite estimate of chlorophyll-a near the sea surface on the day shown, an indicator of plankton and ocean productivity; not a measure of fish stocks or harmful blooms.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- GHRSST MUR (NASA JPL PO.DAAC)
- Provider
- NASA JPL PO.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite analysis
- Newest at build
- 2026-10-12
- Resolution
- about 1 km grid
- Uncertainty
- Gap-filled satellite analysis of sea surface temperature for the date shown; not a reef or species condition report.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS Black Marble (VNP46A2) (NASA LAADS DAAC)
- Provider
- NASA LAADS DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite radiance, corrected for moonlight and atmosphere
- Newest at build
- 2026-10-12
- Resolution
- about 500 m grid
- Uncertainty
- Satellite night-time radiance for the date shown; lights are a proxy for electricity use and outages, not a measurement of supply or access.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS NOAA-20 corrected reflectance (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- daily; Satellite image
- Newest at build
- 2026-10-14
- Resolution
- about 250 m grid
- Uncertainty
- Satellite image. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Estimated
- Source
- Gridded Population of the World v4.11 (NASA SEDAC (CIESIN, Columbia University))
- Provider
- NASA SEDAC (CIESIN, Columbia University)
- Licence
- CC BY 4.0
- Vintage
- null; Census-based estimate, static (2020)
- Resolution
- about 1 km grid
- Uncertainty
- Census-based estimate of people per square kilometre in 2020, shown as exposure context; not a count of people affected by any hazard.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
Keyboard, with the map focused
Hold Ctrl or ⌘ and scroll to zoom
Latest available
NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth
Loading the latest NASA imagery.
Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.
Ocean state, framed on Pacific Island states.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.
Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONET · NASA PACE OCI · NASA JPL OPERA DIST-ALERTSources and licences
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- GHRSST Level 4 MUR analyses, NASA Jet Propulsion Laboratory; distributed by the NASA Physical Oceanography DAAC (PO.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- MODIS Aqua ocean colour, NASA Ocean Biology Processing Group; distributed by the NASA Ocean Biology DAAC (OB.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- VIIRS Black Marble night-time lights, NASA Goddard Space Flight Center; distributed by the NASA Level-1 and Atmosphere Archive and Distribution System (LAADS DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Center for International Earth Science Information Network (CIESIN), Columbia University. 2018. Gridded Population of the World, Version 4 (GPWv4): Population Density, Revision 11. NASA Socioeconomic Data and Applications Center (SEDAC). Licensed under CC BY 4.0. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). doi:10.7927/H49C6VHW. CC BY 4.0
- ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
- Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
- © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). ODbL
- Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
- Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
- Live: NASA EONET Events are indicative, not authority warnings.
- Observed (EO): NASA PACE OCI. We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- Observed (EO): NASA JPL OPERA DIST-ALERT (contains modified Copernicus Sentinel data 2026). We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- NASA GIBS: We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
- Optional layers (10 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.
Layers and dates
- Sea surface temperature anomaly: GHRSST MUR25, NASA JPL PO.DAAC · 12 Oct 2026
- Ocean chlorophyll-a concentration: MODIS Aqua ocean colour, NASA OB.DAAC · 12 Oct 2026
- Sea surface temperature: GHRSST MUR, NASA JPL PO.DAAC · 12 Oct 2026
- Night-time lights, daily: VIIRS Black Marble (VNP46A2), NASA LAADS DAAC · 12 Oct 2026
- True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
- Population density, 2020: Population: CIESIN, Columbia University, Gridded Population of the World v4.11 (2018), NASA SEDAC, CC BY 4.0 · static
Small islands experience every domain’s risk in concentrated form.
Island analyses are designed for the Regional Systems series. The Antigua and Barbuda Agenda for Small Island Developing States (2024) sets the decade’s priorities; island governments decide.
- Island-scale data on water, power and food.
- Lessons from recovery after cyclones.
Coastal adaptation pathways.
The screen a team would use to follow this subject: its measures, states and decisions. Names are examples and values are illustrative.
Coastal adaptation pathways
Island resilience · Coastal zone A · Sea level scenario set
Flood extent by scenario
illustrative coastline
Relative sea level
Adaptation pathways
| Dune nourishment | 0.3 | 3 | Raise seawall | Overtopping twice in 5 yr |
| Raise seawall | 0.7 | 6 | Managed realignment | Seawall at design limit |
| Managed realignment | 1.5 | 20 | Relocate assets | Community decision |
What is measured, and how well.
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Land below a stated elevation | percent of land area | per assessment | Elevation data | ESTIMATED |
| Freshwater lens thickness | metres | per survey | Groundwater surveys | OBSERVED |
| Disaster losses relative to economy | percent of GDP | per event | Post-disaster assessments | ESTIMATED |
| Food import dependence | percent of food supply imported | annual | Food balance data | ESTIMATED |
| Public debt | percent of GDP | annual | Public finance statistics | Published statistics |
| International connectivity | count of shipping and air services | annual | Transport data | REPORTED |
Stocks, flows, delays and a tipping threshold.
Two stocks, pressure and adaptive capacity, joined by a reinforcing growth loop, a delayed balancing response and damage when pressure outruns capacity; past the threshold the system can tip. Teaching model with stated illustrative values, not a prediction. The map on this page shows Pacific Island states; the model itself is not tied to a place.
Controls
- Growth of pressure
- 6.0% a year
- Efficacy of capacity in reducing pressure
- 4.0% a year
- Investment response to perceived pressure
- 20%
- Perception delay
- 4.0 years
- Tipping threshold of pressure
- 60 index
- Amplification past the threshold
- 2.0 times
- Years simulated
- 50 years
Readouts
- Peak pressure
- 113 index
- Capacity at the end
- 186 index
- Years over the threshold
- 15.8 years
Numbers, methods and sources
| Year | Pressure | Capacity | Perceived |
|---|---|---|---|
| 0 | 20.0 | 50.0 | 20.0 |
| 4 | 23.3 | 44.9 | 21.2 |
| 8 | 27.2 | 42.2 | 24.0 |
| 12 | 31.7 | 42.3 | 27.7 |
| 16 | 36.8 | 45.5 | 32.2 |
| 20 | 42.3 | 51.5 | 37.2 |
| 24 | 47.9 | 60.3 | 42.6 |
| 28 | 53.2 | 71.3 | 48.0 |
| 32 | 57.8 | 84.3 | 53.1 |
| 36 | 66.4 | 98.4 | 58.4 |
| 40 | 82.7 | 115.9 | 69.7 |
| 44 | 97.8 | 139.7 | 83.8 |
| 48 | 109.1 | 169.4 | 97.3 |
Methods
- System dynamics Forrester (1961), Industrial Dynamics, MIT Press; Sterman (2000), Business Dynamics
- Critical transitions and tipping points Scheffer and others (2009), Early-warning signals for critical transitions, Nature 461
- Causal loop diagram Sterman (2000), Business Dynamics, McGraw-Hill
- Uncertainty fan (parameter Monte Carlo) Spiegelhalter, Pearson and Short (2011), Visualising uncertainty about the future, Science 333
- One-at-a-time sensitivity (tornado) Saltelli and others (2008), Global Sensitivity Analysis: The Primer, Wiley
Data
No observed data enters this model: it runs on the teaching values set by the controls, to be replaced with a programme’s own evidence.
Across the six pillars, led by Nexus Consortium
- Experiments Labs
- Built in Oceans and Coasts in Foundry
- Tested at Oceans and Coasts in Universe
- Codified in Climate and Earth Systems in Standards
- Published in Oceans and Coasts in Reports
- Taught in Faculty of Earth and Environmental Sciences in Academy
Where the evidence comes from.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| Antigua and Barbuda Agenda for SIDS and UN-OHRLLS data | SIDS priorities and development statistics | Public, UN terms of use |
| Pacific Data Hub (Pacific Community) | Statistics and geospatial data for Pacific island countries | Open, licence per dataset |
| Post-Disaster Needs Assessments for island states | Damage and loss after major events | Public, terms per publisher |
| Copernicus DEM and lidar where available | Island elevation | Licence per product (to check) |
| IMF and World Bank debt sustainability analyses | Public debt and fiscal risk | Public, terms per institution |
Model Island resilience as a system. Run the cascade.
Assembled from the Nexus Standards area profile Oceans and coasts risk standards: the hazards it names, the systems and sectors that carry the loss, the controls that dampen it and the data that observe it. Choose the components, pick an initiating hazard and step through the cascade. The Map view places the run on an example geography with open data. Every coupling weight is a stated assumption you can change. A teaching model, not a forecast, an assessment or a certification. To model a place of your own choosing, open the full System Builder.
Hazards
- Sea-level rise
- Storm surge
- Coastal erosion
- Heatwave
- Ocean acidification
- Harmful algal bloom
- Extreme fire weather (set off downstream)
- Wildfire (set off downstream)
- Heat-driven grid stress (set off downstream)
- Agricultural drought (set off downstream)
- Flash drought (set off downstream)
- Snow drought (set off downstream)
- Ground-level ozone episode (set off downstream)
- Meteorological drought (set off downstream)
- River flood (set off downstream)
- Coastal flood (set off downstream)
- Estuary flood (set off downstream)
- Mass displacement (set off downstream)
Systems and couplings
- Oceans and coasts risk standards
- Supply chain and trade risk Cascade
- Food and agriculture risk standards Cascade
- Climate risk standards Common driver and feedback
- Cities and urban systems risk standards Exposure
Controls
NS-0Constitution and principlesNS-1The UNI and the artefact catalogue (grammar v0.2: domain, sector, region and environment segments)NS-3Risk record UNIs (grammar, legacy crosswalk, allocation authority)NS-3bDataset and product metadata profile (STAC, DCAT, PROV-O)NS-5Figure, map and visualisation standard (with the UI/UX kit)NS-9Contextual UNIs (deployments, instances, programme instances)NS-11Verification and monitoring (evidence, attestations, zero-trust conformance observation)NRS-X3Oceans and coasts riskNRS-H11Hazard family: Coastal and sea-level hazards (NHS-1 water.coastal)NRS-H79Hazard family: Mental health crises (NHS-1 health.mental)NRS-H12Hazard family: Ocean-state extremes (NHS-1 water.ocean-state)NRS-H67Hazard family: Ocean circulation and marine tipping (NHS-1 planet.ocean-tipping)NRS-K18Domain pack profile: Oceans coastal (DOMAIN-018)
Observation
- Copernicus Marine Service ocean products (listed for reference)
- Coral Reef Watch daily 5 km heat stress products (listed for reference)
- PSMSL tide gauge mean sea level records (listed for reference)
- GEBCO global bathymetric grid (listed for reference)
- Argo float profiles (listed for reference)
- Average marine acidity (pH) measured at agreed suite of representative sampling stations
- Index of coastal eutrophication and floating plastic debris density
- Direct economic loss attributed to disasters in relation to GDP, including damage to critical infrastructure
Example geography
- Pacific Island states: 150 hexagonal cells
- Night lights tonight, outages (VIIRS Day/Night Band), NASA GIBS
- Surface water through cloud, 30 m (OPERA DSWx-S1 radar), NASA GIBS
- Rain rate, last half hour (IMERG), NASA GIBS
- Surface air temperature, daytime (AIRS), NASA GIBS
Who decides, and what the evidence serves.
Oceans and Coasts prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| Island governments | Which adaptation measures and relocations to plan | Exposure profiles; freshwater assessments |
| Regional organisations | How to share capacity and data across islands | Connectivity and data inventories |
| Development partners and lenders | How to support adaptation without adding unsustainable debt | Fiscal and loss evidence |
Outputs this topic produces
- Island exposure profiles combining sea level, cyclone and drought
- Freshwater security assessments
- Connectivity and import dependence analyses
- Evidence notes for island adaptation and finance planning
How Island resilience is modelled, measured and tested.
The model, its assumptions, its data and its uncertainty, in the form a scientist or engineer would check. Structures follow published methods. The values drawn are illustrative, not findings.
Earth observation chain
How a satellite or sensor record becomes evidence on island resilience, and where each step adds uncertainty.
- 01 · Acquireorbit, sensor and revisitUncertainty: gaps from cloud and orbit
- 02 · Calibrateradiometric and geometricUncertainty: sensor drift
- 03 · Correctatmosphere and terrainUncertainty: aerosol and slope assumptions
- 04 · Retrieve or classifythe variable or the classUncertainty: model and training error
- 05 · Validateagainst ground truthUncertainty: sample design and size
- 06 · Publishwith error bars and lineageUncertainty: stated, never hidden
The questions experts ask.
- Which island lifelines depend on a single asset, such as one port, airport, power station or desalination plant?
- How long can an island sustain fuel, food and medicine supply when shipping stops?
- How will sea-level rise, saltwater intrusion and coral loss change habitability?
- How do remittances, tourism and import dependence shape recovery after a disaster?
- Which local and traditional knowledge improves preparedness?
Concentrated, compound exposure.
Island systems are tightly coupled. Diesel imported by sea runs power stations; power runs desalination and water pumping; water and power run hospitals, cold chains and communications. A port closure or fuel shortage can therefore cascade quickly through every service. Freshwater lenses on low islands float on seawater and are vulnerable to over-pumping, drought and saltwater intrusion from storm overwash and sea-level rise.
Coral reefs and mangroves protect many islands from waves and supply fisheries and tourism. Their decline from heat and local pressure reduces protection and income together. Recovery is shaped by economic structure: small markets, high import costs, distance from suppliers and fiscal constraints slow reconstruction, while diaspora remittances and community networks often sustain households.
Energy transition is a resilience question on islands. Replacing imported diesel with local renewables and storage can reduce dependence on shipping, but it introduces new dependencies on equipment, maintenance skills and spare parts that must also withstand storms.
Methods and their limits.
Lifeline mapping
Mapping dependencies between energy, water, transport and communications to find single points of failure.
Freshwater lens studies
Groundwater models and monitoring of salinity on low islands; data are often limited.
Participatory assessment
Local and traditional knowledge of hazards, resources and recovery, recorded with consent.
Limits: national statistics often average across islands with very different exposure, and high-resolution elevation and bathymetry data are missing for many islands, which limits flood and wave modelling.
How it is studied, and what the methods cannot say.
- 01Ocean and coastal scienceRegional sea-level budgets · Marine heatwave analysis · Wave climate assessmentApplied here
- 02Geospatial information systemsCoastal exposure mapping · Marine spatial planning layers · Fishing effort mappingApplied here
- 03Extreme value theory and tail riskExtreme sea level return levels · Amplification factors · Extreme wave heightsApplied here
- 04Water and environmental engineeringCoastal defence options · Coastal wastewater planning · Adaptation pathwaysApplied here
- 05Earth and geophysical scienceDelta subsidence · Sediment budgets · Tsunami source characterisationApplied here
Where this page’s references lead.
The bodies and documents this page is read against. Status and editions change; each link goes to the issuing body.
Questions and answers.
Why are small islands highly exposed?
What is a freshwater lens?
Will atolls become uninhabitable?
Why do islands need a dedicated topic?
Does the platform work with island communities?
Is relocation part of the analysis?
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