Identifying potential tipping points in the benefits derived from the UK's land ecosystems

Our research aims to identify whether the benefits flowing to us from the UK's land ecosystems - including the provision of food, recreational value, water quality, natural flood protection, and greenhouse gas storage - could pass 'tipping points' this century as a result of climate change, land-use change, policy change and their interaction.

Here we take a 'tipping point' to mean a large and persistent change in the benefits flowing from an ecosystem. As such it could be due to a tipping point in the drivers of an ecosystem - here climate change, land-use change, or policy change - or it could be due to a tipping point within the ecosystem itself such that even a small change in its drivers triggers a large change in the flow of benefits. Our aim is to understand which of these kinds of tipping points could occur and predict when they might occur and where they might arise geographically.

To assess this we will use a set of three state-of-the-art models combined with mathematical methods of tipping point detection. The three models will capture (at unprecedented spatial resolution) the functioning of the UK's land ecosystems, the benefits flowing from them, and how they are affected by climate change, land-use change and policy change. Two of these models - called 'JULES' and 'LPX' - capture the cycling of water and carbon through ecosystems, including changes in vegetation. We will use them to explore potential tipping points in carbon storage, greenhouse gas fluxes, and freshwater services, including natural flood protection - which is provided by water storage in upland peatlands and lowland flood plains. We will also examine the prediction that blanket bogs, and the large stores of carbon they hold, are threatened to disappear due to climate change.

The resulting understanding will be used to update the third model - called 'TIM' (the integrated model) - which brings together our natural science knowledge of ecosystem processes with economic understanding of how farmers and foresters change their use of the land when climate or policy changes. As 75% of the UK is some form of managed agricultural land, this understanding of the influences upon human land-use is crucial. We will improve the representation of carbon stocks and greenhouse gas fluxes in TIM, based on the other models, and include a representation of natural flood protection. We will also drive the model with new, high resolution climate change projections and use TIM to examine how land users will respond to climate change across different areas of the country.

Our methods for detecting tipping point will be applied to the output of the three models to examine where and what type of tipping points occur under different scenarios for the future of the UK climate. As TIM is used in the UK National Ecosystem Assessment and its follow-on this will provide a direct feed-through to policy advice, especially via the UK government's 'Natural Capital Committee'. The 'tipping point enabled' version of TIM will be used to revisit existing climate change and policy scenarios to see how the results and corresponding advice are altered.

The main outcomes of the project will be the first integrated analysis of potential tipping points in the benefits flowing from UK land ecosystem services, together with important improvements to the established framework (TIM) used for quantifying and evaluating UK ecosystem stocks and benefit flows, and assessing policy options.

We anticipate that the main beneficiaries of the proposed research will be: (i) relevant parts of the UK government and corresponding advisors and policymakers; (ii) organisations that manage land/ecosystems, and; (iii) members of the general public.

(i) UK Government and advisors, policymakers. UK government bodies including Defra, DECC, the Natural Capital Committee (NCC; independent advisors), the Environment Agency, Forestry Commission, Natural England, Scottish Natural Heritage, Natural Resources Wales, and the Joint Nature Conservation Committee will be primary beneficiaries of our project. Across these government bodies there is considerable policy interest in the valuation of ecosystem services and a need to understand the potential for tipping points to cause abrupt and damaging changes to the delivery of those services. There is a need to consider how this could affect policy assessments - as reflected, for example, in the third state of natural capital report of the NCC. Co-I Bateman is a member of the NCC and his previous analyses using TIM of the specific policy target of increasing woodland area are featured as best practice in the Government's 25 Year Environment Plan (Defra, 2016). DECC will also be interested in the project's contribution to the long-term goal of developing capacity to estimate annual country-level GHG emission estimates, and especially the potential for abrupt changes in those emissions.

(ii) Non-governmental ecosystem management organisations. The results of our project will be useful to the wide range of private, public and third organisations that own and manage the UK's land and freshwater ecosystem services, which amongst others include private landowners, the Crown Estate, farmers, wildlife trusts, rivers trusts, the National Trust, water companies, national park authorities, AONBs and the RSPB. They need easily-accessible information to understand the value of the ecosystem services they manage, and to support them in managing ecosystems to maximise their multi-dimensional benefits and avoid reaching tipping points that might affect their ability to provide these benefits.

(iii) The general public. The public derive multiple benefits, enjoyment and interest from the UK's natural capital. It is important to raise awareness of the threats that face these natural environments and what we need to do to avoid damaging them to the point that they no longer provide the services that they are valued for.

There are also clear economic benefits of managing land ecosystems to avoid tipping points - e.g. for the tourist industry, agricultural production, and healthcare savings from people spending time in the natural environment.