Introduction

The Committee on Earth Observation Satellites (CEOS) Earth Observation (EO) Handbook has a long and proud history highlighting the role of satellite EO in support of society’s greatest challenges and opportunities. This 2026 edition focuses on the central role of satellite EO in helping society address adaptation and resilience at all scales in the face of varied and increasing hazards and risk conditions.

The role of satellite EO in adaptation and resilience can be understood through the hazards, environmental changes, and risk drivers which need to be measured, monitored, and addressed. Hazards encompass a wide range of processes, singular and chronic phenomena, and human activities that may cause loss of life, injury or other health impacts, property damage, social and economic disruption or environmental degradation. These include biological, climatic, environmental, geophysical, hydrometeorological, and technological hazards, many of which are increasing in frequency, intensity, or complexity. Risk emerges through the interaction of hazards, exposure, and vulnerability, each of which is shaped by environmental, social, economic, and institutional conditions. Multi-hazard events may involve compounding or cascading impacts, such as a landslide which then results in a toxic waste spill or increased fuel loads for wildfires. Many contemporary risks emerge not from isolated hazards alone, but from the interaction of pressures across interconnected systems.

EO allows for long-term measurement and monitoring of hazards and their drivers. For example, observational records indicate that global mean near surface temperature has increased by approximately 1.26°C above pre-industrial levels (1850–1900 baseline). This magnitude of warming is associated with measurable changes in climate-related hazards, including more frequent and intense heat events, shifts in precipitation patterns, increased likelihood of heavy rainfall episodes in many regions, and accelerating sea-level rise driven primarily by thermal expansion and cryospheric melt. These changes interact with existing social, environmental, and economic vulnerabilities, reinforcing the need for EO-informed adaptation and resilience planning.

Other examples of hazards and their drivers that can be measured by EO include: development and urbanisation patterns that may alter land use and cause heat island effects; water stress and drought leading to salinisation, subsidence, and resource conflicts; economic changes such as inflation eroding community resilience; biodiversity loss disrupting ecosystem services; and constraints on mobility that reduce adaptive capacity, particularly during geohazards. Every hazard that becomes a disaster highlights the need for informed adaptation, resilience planning and risk management in our society.

Adaptation is the process of adjustment to actual or expected hazards, including evolving climatic conditions and associated impacts, in order to moderate harm or exploit beneficial opportunities. Adaptation involves a wide range of reactive and proactive actions aimed at lowering risk by reducing exposure and vulnerability to hazards and increasing adaptive capacity. The transboundary and cascading nature of risks increasingly demands effective adaptation at multiple scales, including the global level.

Resilience refers to the capacity of systems – natural, built, economic, and social – to withstand disturbances, maintain essential functions, and recover efficiently under conditions of stress, uncertainty, and environmental and climatic change. In the context of rising hazard risk, resilience encompasses absorptive capacity (withstanding shocks), adaptive capacity (adjusting to evolving conditions), and, where necessary, transformative capacity (reconfiguring systems to remain viable over the long term). While adaptation often targets specific hazards or sectors, resilience strengthens the underlying robustness and flexibility of interconnected systems across local, national, and global scales.

The 2026 EO Handbook seeks to provide a broad understanding of the importance of satellite EO for all stakeholders in these processes. EO is uniquely suited to support adaptation and resilience because risk is inherently spatial and dynamic. Satellite EO data provide consistent, repeatable, and globally comparable measurements of key environmental variables across local to planetary scales, including surface temperature, atmospheric and soil moisture, vegetation condition, land deformation, surface water extent, sea level, smoke, volcanic ash, land use and land use change including urban expansion. This synoptic perspective enables objective risk assessment, early warning, long-term trend analysis, and performance monitoring of adaptation interventions. Crucially, EO data transcend administrative boundaries, supporting coordinated responses to transboundary and cascading risks, while its continuity and standardisation allow decision-makers to track change over time and evaluate whether resilience-building measures are delivering measurable outcomes.