G-P19 · TOPIC · optimization-under-uncertainGCRI dossier · service level R0
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Topic dossier · Systems Science and Modelling

Optimization under uncertainty

Plans for infrastructure, reserves and portfolios must work across futures that cannot be predicted. Optimization under uncertainty chooses decisions that perform well on average, hold up in bad cases or stay acceptable across many scenarios. This page sets out the main approaches, from stochastic to robust optimization and decision-making under deep uncertainty, how their results are tested, and what evidence serves the planners who rely on them.

01In brief

The short answer.

Optimization under uncertainty is the choice of decisions that perform well across many possible futures instead of one forecast. Stochastic methods optimise expected performance with probabilities, robust methods guard against bad cases, and adaptive plans with triggers keep options open as uncertainty resolves.

02Geography

Hazards and exposure in North America.

For optimization under uncertainty, in GCRI's spatial-intelligence reading, the map opens on true-colour imagery, land cover and rain with relief in 3D and true colour from NASA GIBS, framed on North America; every other NASA layer, live feed and forecast waits in the layer list.

The interactive map needs JavaScript; the layer list and sources are below.

Layers 3

Hazards and exposure, for this page

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.

For optimization under uncertainty, in GCRI's spatial-intelligence reading, the map opens on true-colour imagery, land cover and rain with relief in 3D and true colour from NASA GIBS, framed on North America; every other NASA layer, live feed and forecast waits in the layer list.Satellite and model products as NASA publishes them, each with its own date; indicators, not assessments of any place; claim ceiling INTEGRATED.

Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · Copernicus Sentinel-2 L2A · NASA HLS S30Sources 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 H3 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 H3 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 H3 cells where shown (modified). NASA open data
  • MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • GPM IMERG precipitation, NASA Precipitation Processing System; distributed by the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 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 H3 cells where shown (modified). NASA open data
  • 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 H3 cells where shown (modified). 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 H3 cells where shown (modified). ODbL
  • Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 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.
  • Globe: MapLibre GL JS 6.9.1, BSD-3-Clause, © MapLibre contributors.
  • Observed (EO): Copernicus Sentinel-2 L2A (contains modified Copernicus Sentinel data 2026), Microsoft Planetary Computer
  • Observed (EO): NASA HLS S30 (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).
  • Optional layers (35 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

  • True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
  • Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
  • Precipitation rate, daily mean: GPM IMERG, NASA GES DISC · 12 Oct 2026
  • Flood water, 3-day composite: VIIRS Global Flood Product, NASA LANCE · 14 Oct 2026
  • Sea surface temperature anomaly: GHRSST MUR25, NASA JPL PO.DAAC · 12 Oct 2026
  • Land surface temperature, day, 8-day composite: VIIRS NOAA-20 Level 3, 8-day, NASA LANCE · 14 Sep 2026

03Console

Coupled model runner, in outline.

The working screen behind this subject: its structure, terms and states. Names are placeholders and values illustrative.

Coupled model runner

Optimization under uncertainty · Coupled model A · Scenario set 3

Ensemble runningGCRI · Systems Science and Modelling

Model coupling graph

nodes: models · edges: exchanged variables

Coupled components

Hydrology1 dayrunoffYes
Power system1 hdemand, outagesYes
Economy1 quarteroutput, pricesPartial
Population1 yearexposureYes

Ensemble output

Coupled model runner: the screen's structure, terms and states for Optimization under uncertainty.Placeholder names and illustrative values; a design, not a record or a live system.
04The question

Optimization under uncertainty: how the risk develops.

Robust and adaptive decisions when futures are deeply uncertain. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.

Mechanism

Optimal for one future is fragile

A plan optimised for a single forecast can perform badly if the future differs. Representing uncertainty explicitly avoids this trap.

Mechanism

Stochastic methods use probabilities

Stochastic programming optimises expected performance across scenarios with assigned probabilities, which needs those probabilities to be credible.

Mechanism

Robust methods guard the worst case

Robust optimization chooses decisions that perform acceptably for all scenarios within a set, trading average performance for protection.

Mechanism

Adaptive plans keep options open

Plans with decision points and triggers adapt as uncertainty resolves, avoiding commitments that lock in poor outcomes.

05Key terms

Terms used on this page.

Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.

TermDefinition
Stochastic programmingOptimization that represents uncertain parameters with a set of scenarios and their probabilities.
RegretThe difference between a chosen plan's outcome and the best possible outcome in a given scenario.
SatisficingSeeking a solution that meets acceptable thresholds instead of the single best.
06Indicators

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.

IndicatorUnitCadenceSource typeLabel
Scenarios evaluatedcountper analysisAnalysis documentationDECLARED
Regret of chosen plandifference from best plan in each scenarioper analysisRobustness analysisMODELLED
Value of the stochastic solutiondifference between stochastic and deterministic plansper analysisOptimization outputsMODELLED
Satisficing sharepercent of scenarios meeting objectivesper analysisRobustness analysisMODELLED
Adaptation triggers definedcountper planPlan documentationDECLARED
Out-of-sample performanceobjective value on held-out scenariosper analysisTestingMODELLED
07Canvas

From sources to decisions.

The topic as a computational graph: named sources feed the methods, an evidence review gates the outputs, and the decisions stay with the authorities that hold them.

Pipeline canvas · Optimization under uncertainty as a run graphDesign, not a record
Optimization under uncertainty: from horizon scanning to wind-tunnelled policySignals from horizon scanning are clustered into drivers; the most uncertain and impactful define scenario axes; narratives are written; policies are wind-tunnelled against each scenario and signposts monitored. Design of the process, not a record of a run.

Fig. 02Nodes carry their type, two metric rows and a state; connectors show what feeds what; dashed frames name the owners; the timeline is the cadence. Design of the pipeline, not a record of a run.

08Sources

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.

SourceWhat it givesLicence class
Society for Decision Making under Deep Uncertainty resourcesMethods and case studies for robust and adaptive planningPublic, terms to check
Open-source optimization tools such as Pyomo and JuMPModelling languages for stochastic and robust optimizationOpen source, BSD and MPL licences
EMA WorkbenchExploratory modelling and analysis toolkitOpen source, BSD licence
Operations research literature on stochastic programmingMethods and applicationsLicence per publication
Published adaptive pathway plans, such as delta programmesApplied adaptive planningPublic records, licence per government
09Decisions

Who decides, and what the evidence serves.

Systems Science and Modelling prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.

Who decidesThe questionEvidence this page serves
Infrastructure and resource plannersWhich plans hold up across plausible futuresRobustness analyses; pathway designs
Analysts across Nexus platformsWhich optimization approach suits their questionMethod selection guides
Finance and audit bodiesWhether planning analyses considered uncertainty adequatelyAnalysis documentation

Outputs this topic produces

  • Method selection guides for planning under uncertainty
  • Robustness and regret analyses
  • Adaptive pathway designs with triggers
  • Teaching material on optimization under uncertainty
10Core questions

What experts ask about decisions under uncertainty.

  • Is the aim to perform best on average, to avoid the worst outcomes, or to perform acceptably across many futures?
  • Which uncertainties can be described with probabilities, and which cannot?
  • Which decisions can be delayed, adapted or reversed as information arrives?
  • How do trade-offs between objectives change across scenarios?
  • What signals would indicate that a strategy needs to change?
11Mechanisms and drivers

Why optimal can be fragile.

Classical optimization assumes a known model and known inputs. A strategy optimised for a single forecast can be finely tuned to that forecast and fragile if the future differs. In infrastructure planning, for example, a design optimised for one climate projection may fail under another.

Stochastic optimization handles uncertainty described by probability distributions, seeking the best expected performance or managing risk measures. Robust optimization seeks solutions that perform well across a set of possible conditions without probabilities.

Under deep uncertainty, when experts cannot agree on models or probabilities, methods such as robust decision making and adaptive pathways explore many futures, identify where strategies fail, and design plans that can change course when signposts are observed.

12Methods and data

Methods and their limits.

  1. 01

    Stochastic programming

    Optimising expected outcomes over scenarios, using optimization and operations research. Requires credible probabilities.

  2. 02

    Robust optimisation

    Optimising worst-case or regret across uncertainty sets. Can be conservative.

  3. 03

    Exploratory modelling

    Running models across many futures to find vulnerabilities, using decision analysis. Computationally demanding.

  4. 04

    Adaptive pathways

    Sequencing actions with triggers for change. Requires monitoring and institutional capacity.

These methods support judgement, they do not replace it. The choice of objectives and acceptable risks is a value choice for decision-makers.

14Questions

Questions and answers.

What is robust optimization?
An approach that finds solutions that remain feasible and perform acceptably for all values of uncertain parameters within a defined set.
What is deep uncertainty?
A situation where parties cannot agree on models, probabilities or how to value outcomes, so planning seeks robust and adaptive strategies.
What is an adaptive pathway?
A sequence of actions with decision points that lets a plan change course as conditions evolve, keeping future options open.
Is a robust strategy always more expensive?
Often it costs more upfront but reduces the risk of costly failure. The trade-off is made explicit.
Does the platform choose strategies?
No. It develops methods. Choices remain with decision-makers.
Systems Science and Modelling

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