Land Use Transformations

This story map presents analysis of how land use in Scotland would need to change if the net-zero GHG emission, climate adaptation and other environmental objectives are to be achieved.  The analysis is being conducted as part of the  Land use Transformations  project (JHI-C3-1) in the Scottish Government funded Strategic Research Programme 2022-27.  The story map is a "living” document that will continue to be updated and expanded over the course of the research programme.

The story map is structured with a vertical “spine” of Chapters that step through the framing and assumptions underpinning the analysis, the input datasets, the ways in which the land use changes are generated and how the consequences of the land use change can be interpreted. This structure reflects the Quantitative Story Telling process adopted across the research for science-stakeholder engagement (Table 1). 

The story map also uses horizontal arrows to present further details on the theory, data, processes, examples and interpretation that underpin the outputs. Diagrams can be clicked on for full size display.

The SSP used in this analysis is SSP1: Sustainable Development.  SSP1 is considered to have the lowest combination of challenges for achieving mitigation and adaptation. In this scenario there is a slow move towards a sustainable path with inclusive development that respects perceived environmental boundaries. Management of the global commons slowly improves, educational and health investments accelerate the demographic transition, and the emphasis on economic growth shifts toward a broader emphasis on human well-being. Driven by an increasing commitment to achieving development goals, inequality is reduced both across and within countries. Consumption is oriented toward low material growth and lower resource and energy intensity (van Vuuren et al., 2017).

The land-use change components of all the SSP baseline scenarios cover a broad range of possible futures. For example, the scenarios show that in the future total cultivated land can expand or contract by hundreds of millions of hectares over this century. The SSP1 scenario features a sustainable land transformation with comparatively little pressure on land resources due to low population projections, healthy diets with limited food waste, and high agricultural productivity. Consistent with the SSP1 narrative, this scenario depicts a reversal of historical trends, including a gradual, global-scale and pervasive expansion of forests and other natural lands (Riahi et al., 2017;  UK-SSP1-ScenarioFactSheet.pdf(ukclimateresilience.org) ).

The scenario aligns well with the policy positions of Scottish Government policy and to much of civil society in Scotland.  The objectives of SSP1 are demanding and imply significant degree of change from current status quo and trajectories. The lower GHG emissions associated with SSP1 do though lead to the lowest levels of projected climate warming across the set of alternative SSPs. This is the pathway that has the greatest potential to avoid tipping into catastrophic climate change and aligns with the Sustainable Development Goals ( Sustainable Development Goals | National Performance Framework ).

Land use change for any given scenario could theoretically happen anywhere, however, for SSP1 low emission scenario, the bias towards sustainable development would lead to expect multi-benefits for land use change to be considered. This is done here through the concept of ecosystem services. Further restrictions on the location of new woodlands are also included to consider bio-physical restrictions, respect current policies (e.g. peat protection), and conservation status. Both subjects are further detailed below.

For achieving a low-emission scenario simulated land use change targeted woodland expansion (including silvo-arable and silvo-pastoral) and decreased grazing intensity to benefit four aspects of ecosystem services: carbon storage, carbon emissions, biodiversity, and pollination. The scenario realisation will be first illustrated with an example of one run of the model using a Sankey diagram (change of Hectares from one land use to another) and a comparison of baseline and scenario land cover/use maps (slider map), then statistics across 50 runs of the model will be presented.

Total woodland area (new woodlands, broadleaves, and coniferous) rises from 17.64% to 23.89% of Scotland’s land area (note these percentages are conditioned by the use of our baseline map – LCM19). The new woodlands are assumed to be Broadleaves to support biodiversity and multi-functionality but in future work some could be native pinewoods when these are close to existing pinewood stands. 

“Silvo-arable and silvo-pastoral reaches 0.77% and 3.28% of Scotland’s land area respectively. De-intensification of grazed grasslands equates to 3.04% of Scotland’s land area. 2.32% of the land area sees intensive grasslands become new woodlands while 1.81% of the land area becomes silvo-pastoral.

Each run of the land use change model provides one realisation meeting all the scenario parameters. However, it does not provide a single optimised land use change map that would be the unique best answer. By running the model multiple times (runs), the space and degree of freedom in realising the scenario is explored.

Thus, in a first instance, the above scenario set up was run 50 times, and two main statistics are reported here. How often a land use change happened at any location (Count) and a quick estimate on the relative impact on the four aspects of Ecosystem Services considered in this analysis.

This story map illustrates a process of downscaling Shared Socio-Economic Pathways (SSP) from a planetary scale storyline to land use targets at Scotland level and their translation into maps of land use change. The chosen land use targets and their spatial interpretation for the Scottish landscapes (bio-physical and socio-economic) is only one potential representation of the SSP1 storyline, so further translation options or refinements could be explored.

As implemented to date, the patterns of land use change highlight the risk that, while overall the low emission scenario (towards net zero) objectives may be achievable, there is a risk of un-even burden sharing, i.e. the potential for land use change to be concentrated in particular areas within Scotland. This is highlighted by the high levels of afforestation (new woodlands and silvo-pastoral) simulated in Clyde Valley and Ayrshire, and the higher level of silvo-arable in the North-East. This raises the question of the need for explicit benefits and burden-sharing between regions (and sectors), that reflects both their capacity for change (e.g. capacity for C sequestration through tree planting) and the overall need for their land use to change (e.g. lowering grazing intensity) to support the scenario objectives.

For this analysis, land use targets for lowering emissions were set up at national scale, and the modelling allocated them to satisfy delivery of four aspects of ecosystem services. Different spatial patterns would emerge if other or further targets were also included, with the potential that eventually not all targets might be feasible to achieve (the simulation would thus fail). There is also the need to consider whether targets or priorities ought to be set up at regional or catchment levels, and if the simulated land use changes ought to be quantified at those levels. These cross-scale issues remain challenging.

Over 30 spatial datasets were integrated to shape the land use changes towards benefiting multiple ecosystem services, including biodiversity, and lowering Carbon emissions.  The analysis has highlighted where there may be inconsistencies (for example between land cover and land use mapping) or definitional issues (for the extent of peatland and carbon rich soils).  Further development of the modelling process will identify where such issues occur, resolve issues where possible, and otherwise quantify the levels of remaining uncertainty and their implications.

The land use scenario mapping is part of a longer-term research effort in the 2022-27 Land Use Transitions project, which will see further analysis (adding new elements into the process), improved analysis (refining the data and methods used) and more scenarios (to allow comparison between desirable and undesirable trajectories).

One of the key priorities for new elements will be to include farm structure (which land is owned/used by which decision makers) in the land use change modelling. Types and/or sizes of business and their location within Scotland can be used to shape the degree and types of land use change that may occur. By representing these constraints in the analysis, it is likely more difficult to achieve the objectives of the Sustainable Development SSP but by doing so highlights where there may need to be changes in policy (including the basis of future financial support for agriculture), the operation of markets or societal demands.

Evaluation of the net change in GHG emissions per instance of land use change needs to be implemented to test outcomes rather than relying on assumptions within the scenario specification.  This is particularly true since where the land use occurs will have profound influence on the degree of net change in GHG emissions (e.g., contrasting afforestation on higher or lower carbon soils).  The implications for livestock numbers of the lower grazing intensity limits also need to be quantified, including what the assumption should be made on substitution for such grazing by imported feeds, livestock products (meaning net zero might be achieved by offshoring), or decreased consumption.  Changes in arable cropping will also be influenced by climate change impacts on land capability so integration of the Future LCA will be undertaken to guide where such changes may occur.

Another key challenge is in visualising and otherwise interacting the sets (n=50) of alternative land use maps, each achieving the stated objectives but doing so in different ways and with different implications.  A key aspect in this regard will be seeking to identify alternative land use maps that make the most extreme trade-off between the various objectives (the pareto-optimal solutions).  By identifying more of such alternatives (through thousands of simulations), it may be possible to start to define the shape of any trade-offs or synergies between objectives.

The priority for the moment (in late 2022) is on the Further and Improved analyses, set out above, since the focus is on how the Net Zero and other environmental and social objectives might be achieved.  Other scenarios, such as SSP3 Regional Rivalry, which has greater risks of severe climate impact, may be analysed in subsequent years (2023+) where the focus will be on how to increase climate resilience or adaptive capacity.