Early warning signals for monitoring supplies
Published 19 August 2026
This is not a statement of government policy.
Rapid projects support government departments to understand the scientific evidence underpinning a policy issue or area by convening academic, industry and government experts at a single roundtable. These summary meeting notes seek to provide accessible science advice for policymakers. They represent the combined views of roundtable participants at the time of the discussion and are not statements of government policy.
This publication considers the following question, taken from a meeting note of a roundtable chaired by Anjali Goswami (Department for Environment, Food and Rural Affairs (Defra) Chief Scientific Adviser) facilitated by the Government Office for Science on 2 March 2026.
How should the United Kingdom (UK) use early warning signals toÌýmonitorÌýthreats to its supplies of food,ÌýwaterÌýand timber?
Summary of roundtable findings
Single indicators of risk to ecosystems often miss cascading disruptions across food,ÌýwaterÌýand timber supplies.
Complex ecosystems, such as boreal forests, are especially difficult toÌýmonitorÌýusing existing indicators.
Monitoring sudden changes to ecosystems posesÌýa different setÌýof challenges toÌýmonitoringÌýlong‑termÌýecosystem degradation. Future approaches should, however,ÌýseekÌýto combine tracking of both kinds of risk to provide a more holistic judgement of an ecosystem’s stability.
Indicators add most value when theyÌýhave clear owners andÌýpre‑agreedÌýthresholds for response, so thatÌýsubsequentÌýactions can be proportionate andÌýtimely.
The UK has rich monitoring of its own ecosystems, but siloed datasets with limited access undermine integrated, national early warning practices. Other countries have shown that operationally relevant monitoring isÌýfeasible.
There are promising monitoring methods that use continuously updated modelling: these blend satellite,ÌýhydrologyÌýand field observations to deliver rolling shortÌýandÌýmedium‑termÌýforecasts of ecosystem stress, akin to weather forecasting.
Reliability of available indicators for signalling disruption
1. There is no single, dependable approach to monitoring changes across food, water and timber ecosystems combined.Ìý
2. Traditional early-warning systems (such as those tracking changes in ecological populations) cannotÌýanticipateÌýcascading disruptions – past behaviour and trends in ecosystems are not a good predictor forÌýtheÌýfuture.
3. There has been promising use of using natural-capital indicators (for example changes to soil quality, species, vegetation; Lenton and others, 2022) to judge whether ecosystems can still deliver services we rely on. This approach links ecosystemÌýmonitoringÌýdirectly to service delivery risk and highlights where degradation is likely to affect policy goals.
a. In the forest estate, a composite Forest Biodiversity Index (Forest Research, no date given) is already used as a biodiversity condition metric, illustrating howÌýnatural‑capitalÌýindicators can be assembled from available datasets.
4. Complex ecosystems, such as those prioritised in Defra’s current assessment, are especially difficult toÌýmonitorÌýusing existing indicators.
a. Available monitoring tools have been designed for detecting changes to more simple forest ecosystems, for example, where satellite and field indicators align well, and anomalies are easier to interpret (for example, NOAA Climate Resilience Toolkit, no date given).
b. By contrast, boreal forests are complex ecosystems ofÌýdifferent typesÌýof trees interspersed with peatlands/lakes. They span multiple owners, withÌýlong periodsÌýof darkness and frequent cloud/snow. Both ground data and satellite sensing are inconsistent in such an ecosystem, leading to missed changes or false alarms.
Tipping points versus gradual ecosystem changes
5. Different indicators areÌýrequiredÌýto detect abrupt tipping points versus evidence of long-term degradation (Global Tipping Points, 2025a). These 2 challenges also require different monitoring strategies and policy responses.
6. Abrupt tipping points are sudden shifts where an ecosystem flips to a new state and does not, or cannot, easily recover (Global Tipping Points, 2025b), such as rapid forest die-off (Rotbarth and others, 2024) or outbreak-driven food supply chain disruption.
a. Indicators for this look for loss of resilience (for example, slower recovery after minor drought, De Keersmaecker and others, 2015) which are typically easier to study. There is a higher chance of irreversible outcomes under these circumstances, which lowers the threshold for evidence needed to escalate actions from early warning signals (EWS).
b. The AtlanticÌýMeridionalÌýOverturning Circulation (AMOC1) is a good example of a well-understood EWS; warning signs can be risk assessed effectively to inform decision making (Van Westen and others, 2024; Richie and others, 2019;ÌýCarnicerÌýand others, 2019).
7. Indicators for gradual degradation are typically slow, cumulative declines in the condition and functioning of ecosystems, such as biodiversity loss, declining amounts of ground water in rivers, or forest health decline.
a. These changes do not require a formal tipping point to have major impacts onÌýsupply, butÌýare harder to measure and can have less influence over decision makers.
b. Standard forestry production models handle gradual trends but are poor at capturing sudden disruptions (such as due to drought (Meyer and others, 2025), storms, pest outbreaks (Mohr and others, 2025)), which have the potential to erase decades worth of supply.
c. Standardised precipitation/streamflow indices are also effective at providing situational awareness for drought and water availability (UKCEH, 2025; UKCEH drought inventory, no date given).
d. Some ecosystemÌýmonitoringÌýsystems in the UK are on a multi-annual repeat cycle, such as the rolling 5-year National Forest Inventory. Such repeat cycles may not be enough to detect change early.
8. Future monitoring approaches should combine tracking of tipping point risks (sudden, often non-linear, and potentially irreversible; Seddon andÌýMilkoreit, 2025) as well as tracking of degradation (smoother, more gradual changes) to provide a more holistic judgment of an ecosystem’s stability.
Data integration and systemic barriers
9. In the UK, data and modelsÌýlargely remainÌýsiloed across climate, biodiversity, hydrology,ÌýagricultureÌýand forestry, which prevents consideration of routine, integratedÌýearly‑warningÌýindicators at national scale.
a. Many universities, businesses,Ìýnon-governmental organisations (NGOs)Ìýand citizen science groups alreadyÌýmonitorÌýenvironmental data. An effective early warning system should draw on and compile theseÌýsources, andÌýnot rely solely on government datasets.
10. Government‑collectedÌýenvironmental datasets are often notÌýopen access. They can lack consistency and be fragmented across different projects and ecosystems. Data usability is a major barrier, with many datasets difficult to access or interpret without specialist training. This reduces their value for researchers and policymakers and hindersÌýevidence‑basedÌýdecisions.
a. For example, satellite remote sensing can already detect droughts, heatwaves,ÌýfloodsÌýand peatland water loss, but access to government data (for example,ÌýNational Forest Inventory) is constrained, which hinders calibration and measurement of uncertainty.
11. International examples show that integrated, rapid monitoring is feasible, but the UK lacks equivalent systems and infrastructure to manage growing data volume, data diversity (the different types of data required to fully support modern ecosystem monitoring) and complexity (including novel ecosystem and microbial data).
a. Improving domestic recycling and processing capability would reduce reliance on imported raw materials and overseas processing.
Improving indicator quality
12. Moving from static analysis to dynamic modelling can help to deliver more rolling hindcasts/forecasts and allows better measurement of uncertainty (Chan and others,Ìý2026),Ìýsimilar toÌýweather forecasting. Iterative ensemble prediction (that is running a model multiple times to get a range ofÌýpossible scenarios) and data assimilation (regularly pulling in new observational data) offer major advances, enabling improved assessment of biodiversity and ecosystem risks.
13. Deep Artificial Intelligence (AI) learning and advanced analytics can integrate multiple data streams (satellite, climate, hydrology, field data) to generate nearÌýreal‑timeÌýindicators of ecosystem stress. These approaches are in use internationally, but are not yet routine or fully operational:
a. Brazil conducts deforestation monitoring, where satellite data are processed rapidly to detect forest loss and trigger enforcement action (Planet Labs PBC, 2025).
b. Czechia conductsÌýbark‑beetleÌýdetection, usingÌýhigh‑frequencyÌýremote sensing to guide forest management decisions (Planet Labs PBC, 2019).
How indicators can be used to guide government decisions
15. Indicators should be designed to trigger decisions rather than just describe risk. There are ways, for example, of usingÌýdifferent levelsÌýof indicator outputs to set thresholds for action (for example watch/alert/action), with each level having clear ownership and pre-agreed responses (for exampleÌýescalate inspections, activate drought measures).
16. Action should be taken whilst risks are stillÌýemerging, not only once the evidence is beyond doubt. While some technical indicators still need development, especially for abrupt ecological change, policy officials already have sufficient warning to act on the drivers of risk, particularly in food and timber supply chains and in preparing for water-related risks (such as drought and scarcity).
a. When the consequences of inaction could be irreversible, scientific evidence needs to be framed in terms that clearly show what is at stake for food supplies, water availability, economicÌýstabilityÌýand national security so that decision makers can act in time.
Meeting participants
The following participants attended the meeting:
- Anjali Goswami (Chair; Defra CSA)
- Alex Pigot (UCL)
- Chris Clements (University of Bristol)
- Emily Lines (University of Cambridge)
- James Morison (ForestÌýResearch)
- John Dearing (University of Southampton)
- Katie Facer-Childs (UKCEH)
- Michael Rice (Client Earth)
- Pete Langdon (University of Southampton)
- Ruth Waters (Natural England)
- Tim Lenton (Exeter University)
- Yannick Wurm (ARIA)
References
Carnicer J, Domingo-Marimon C,ÌýNinyerola M, Camarero JJ, Bastos A, López-Parages J,ÌýBlanquer L, RodrÃguez-Fonseca B, Lenton TM, Dakos V, Ribas M, Gutiérrez E,ÌýPeñuelas J and Pons X (2019)ÌýÌý
Chan W,ÌýFacerChilds KA, Tanguy M, Magee E, Bulut B, Stringer N, KnightÌýJÌýandÌýHannaford J (2026)ÌýÌý
Forest Research (no date given)ÌýÌý
Global Tipping Points (2025a)ÌýÌý
Global Tipping Points (2025b)ÌýÌý
Lenton TM, Buxton JE, Armstrong McKay DI, Abrams JF, Boulton CA, Lees K, PowellÌýTWR, Boers N, Cunliffe AM and Dakos V (2022)ÌýÌý
Meyer BF, Darela-Filho JP, Gregor K, Buras A, Gu Q-L, Krause A, Liu D,ÌýPapastefanouÌýP,ÌýAsuk S, Grams TEE, Zang CS andÌýRammig A (2025)ÌýÌý
Mohr JS,ÌýBastit F,ÌýGrünig M, Knoke T, Rammer W, Senf C, Thom D and Seidl R (2025)ÌýÌý
NOAA Climate Resilience Toolkit (no date given)ÌýÌý
Planet Labs PBC (2019)ÌýÌý
Planet Labs PBC (2025)ÌýÌý
Rotbarth R, van Nes EH, Scheffer M and Holmgren M (2024)ÌýÌý
Seddon J andÌýMilkoreit M (2025)ÌýÌý
Ritchie PDL, Smith GS, Davis KJ,ÌýFezz C,ÌýHalleck-Vega S, Harper AB, Boulton CA,ÌýBinner AR, Day BH,ÌýGallego-Sala AV,ÌýMecking JV, Sitch S, Lenton TM andÌýBateman IJ (2019)ÌýÌý
UK Centre for Ecology and Hydrology (no date given)ÌýÌý
van Westen RM,ÌýKliphuis M and Dijkstra HA (2024)ÌýÌý
UKCEH (2025)Ìý