The Safe Landing Climates Lighthouse Activity is an exploration of the routes to “safe landing” spaces for human and natural systems. It will explore future pathways that avoid dangerous climate change while at the same time contributing to the United Nations Sustainable Development Goals (SDGs), including those of climate action, zero hunger, clean water and sanitation, good health and well-being, affordable and clean energy, and healthy ecosystems above and below water. The relevant time scale is multi-decadal to millennial.

The Lighthouse Activity will focus on five main scientific themes (click on each heading to expand the link) with a Working Group on each theme:

Scope: We aim to identify risks from low-probability, high-impact possibilities with global-scale ramifications. What is known about their occurrence probabilities and consequences, and what significant scientific gaps exist? This theme will seek to identify any unexpected risks (cf. ozone hole resulting from heterogeneous chemistry) and to better incorporate known risks into projection ensembles. Risks that we will consider will include large natural carbon release, ice shelf/sheet collapse, regime shift of ocean/atmosphere circulation, extreme cloud feedbacks and climate sensitivity, the multiplicative effect of compound hazards, biome (e.g., Amazon) collapse, “Fireball Earth,” and large-scale extremes that challenge adaptation such as large-scale desertification, land, and marine heatwaves or storm sequences that exceed physiological limits or otherwise render large regions effectively uninhabitable.

We will identify adaptation limits for human, land, and ocean ecosystems and resources, worst case (extreme/existential) scenarios, and global-scale tipping elements and points. We will also examine how (or if) tail risks could be avoided – or caused – by general or specific climate mitigation efforts, including negative emissions (Carbon Dioxide Removal (CDR)) or geoengineering / Solar Radiation Management (SRM). This activity will be informed by the results from the carbon cycle, water, and sea level themes.


  • Sufficient understanding of the physical processes underlying tipping points and high-impact events to reliably quantify risks
  • Earth System Models that can credibly incorporate tail risks, compound extremes, uncertain shocks, and tipping elements including those arising from feedbacks between multiple components of the Earth system
  • Strategies to accurately and transparently incorporate low probability/high impact possibilities into projections, risk analysis, and adaptation planning. We anticipate collaboration with the Analysis, Integration, and Modeling of the Earth System (AIMES) project and others for expertise on scenarios and planning.

Scope: We will explore the acceptability and climate implications of carbon dioxide removal (CDR) systems (including bioenergy with carbon capture and storage (BECCS)) while maintaining food and water supply, preserving biodiversity, and limiting ocean acidification. A further goal is to assess the risk of surprises or a rapid change in Greenhouse Gases (GHGs), including large or rapid carbon release (e.g., from permafrost melt, large scale fires, or the Southern Ocean), the reversibility of the anthropogenic perturbation, and climate and carbon cycle feedbacks in the context of negative emissions. We will also explore metrics for controlling short- vs. long-lived forcing in the context of negative emissions, and implications for allowable GHG emissions in the context of the Paris Agreement. We will build an understanding of the coupled carbon-energy-water cycle, impact on food, water supply, and biodiversity.


  • Improved observation and modelling of terrestrial biogeochemistry (in particular permafrost) and possible future sources of GHGs, as well as the ocean carbon cycle, especially in the Southern Oceans.
  • Improved integration of ocean and land biogeochemistry models within Earth System Models to better constrain the future evolution of natural GHGs sources and sinks in a world with negative emissions
  • Improved understanding of the risk of land/ocean CO2 release when atmospheric CO2 decreases
  • Assessment of CDR strategies (efficacy, side effects, etc.).

Scope: We will address uncertainties in the long-term redistribution of water in land-based natural systems or reservoirs, their resilience and vulnerabilities, and impacts of changes to these systems. Key systems include glaciers (crucial for water supply in mountain regions) and tropical rainforests (which play an important role in the local water cycle and deliver other important ecosystem services). We consider impacts on these systems from climate change and also from direct human impacts (e.g., deforestation, agriculture, aerosol darkening of glaciers), seek to determine thresholds of tolerance beyond which substantial change or collapse occurs, and better characterize the possible consequences for society and ecosystems if this were to occur. We aim to integrate research across physical/climate and social sciences and local and indigenous knowledge to assess and communicate the value of these systems and assess the implications of different mitigation and adaptation scenarios including SRM/geoengineering. This will also be used to prioritize science needs, among which are water recycling and transport, atmospheric chemistry in the canopy area, and feedback mechanisms between these water systems and regional and global climate.


  • Address gaps in understanding and modeling of coupling between the land biosphere, cryosphere, and atmosphere, including via chemical processes and aerosols
  • Address gaps in knowledge of forest and glacier dynamics and resilience
  • Connect physical sciences with human systems (e.g., water management, adaptation) in order to ensure water resource changes and responses are reflected in safe landing
  • pathways.

This Theme will draw on and extend the International Geosphere-Biosphere Programme (IGBP) Large Scale Biosphere-Atmosphere Experiment (LBA-ECO), and work with Future Earth, Global Energy and Water Exchanges (GEWEX) (including ANDEX), Past Global Change (PAGES), and the Climate and Cryosphere (CliC) Core Project.

Scope: We aim to quantify an “acceptable” rate of sea-level rise and its irreversibility from multiple decades to millennia. We will estimate the impact of storm surges and cyclones on coastal communities and assess the potential for adaptation. The aim will be to improve projections by facilitating better coordination between global climate, cryosphere, and coastal modeling. This requires a regional/local perspective and interaction with coastal planners because anthropogenically induced sea-level hazards are already affecting coastal habitats and threatening livelihoods in some regions. Depending on the local setting, safe landing in terms of sea level means that the rate of sea-level rise must be limited, slowed, or reversed to allow adaptation measures to keep pace and be effective.


  • More accurate understanding and prediction of poorly understood processes including ice sheet melting and future ice loss in Antarctica and Greenland, storm surges, and other global and regional sea-level drivers (including land subsidence)
  • A fuller range of ice sheet models of different levels of complexity and resolution with evaluation to better constrain uncertainties
  • New research on frameworks of coastal planning, adaptation, coastal protection, and the limits of adaptation
  • Interaction of modelling efforts across spatial scales from global to coastal

This topic will draw on the WCRP Grand Challenge on Regional Sea-Level Change and Coastal Impacts and the Climate and Cryosphere (CliC) Core Project.

Scope: This activity determines what climate trajectories and destinations are actually safe, and for whom? Which ones are unsafe and why? We will bring together interdisciplinary communities to determine pathways and “landings” that preserve habitability and food security, and identify societal adaptation limits and changes that must be avoided. This may involve finding a common footing for measuring and comparing impacts as seen from the SDG point of view. Addressing this goal requires a framework for defining and measuring safety, giving attention to how various communities are individually affected and should consider interactions between SDGs, adaptation, and mitigation measures, including geoengineering.


  • Understanding and constraining individual risks, and assigning overall levels of risk to different potential future pathways
  • Consideration of adaptation and resilience strategies across communities and ecosystems, and the impact of these and mitigation actions on SDGs, both regionally and globally.

This effort will draw on results from the other four themes. The construction of burning embers (e.g. Zommers et. al, 2020) in IPCC WGII and the underlying science ask similar questions. The lighthouse team is interacting with the teams from the Sixth Assessment Report (AR6), consulting on how to go beyond AR6 and on how to make a step-change in our understanding of these risks associated with climate change rather than refining existing embers.

Safe Landing Climates

For more information, please see the draft Safe Landing Climates Science Plan (2021).

Contact This email address is being protected from spambots. You need JavaScript enabled to view it. (WCRP Secretariat) for further information.