Societal breakdown as an emergent property of large-scale behavioural models of land use change

Abstract

Abstract. Human land use has placed enormous pressure on natural resources and ecosystems worldwide and may even prompt socio-ecological collapses under some circumstances. Efforts to avoid such collapses are hampered by a lack of knowledge about when they may occur and how they may be prevented. Computational models that illuminate potential future developments in the land system are invaluable tools in this context. While such models are widely used to project biophysical changes, they are currently less able to explore the social dynamics that will be key aspects of future global change. As a result, strategies for navigating a hazardous future may suffer from “blind spots” at which individual, social and political behaviours divert the land system away from predicted pathways. We apply CRAFTY-EU, an agent-based model of the European land system, in order to investigate the effects of human behavioural aspects of land management at the continental scale. We explore a range of potential futures using climatic and socio-economic scenarios and present a coherent set of cross-sectoral projections without imposed equilibria or optimisation. These projections include various behavioural responses to scenarios including non-economic motivations, aversion to change and heterogeneity in decision-making. We find that social factors and behavioural responses have dramatic impacts on simulated dynamics and can contribute to a breakdown of the land system's essential functions in which shortfalls in food production of up to 56 % emerge. These impacts are largely distinct from, and at least as large as, those of projected climatic change. We conclude that the socio-economic aspects of future scenarios require far more detailed and varied treatment. In particular, deviation from simple economic rationality at individual and aggregate scales may profoundly alter the nature of land system development and the achievability of policy goals.

How model paradigms affect our representation of future land-use change

“…This paper uses two contrasting models of the European land system: CRAFTY-EU (Brown et al 2019b) and the IMPRESSIONS Integrated Assessment Platform (IAP) (Harrison et al 2015(Harrison et al , 2019. Both models cover all European Union Member States except Croatia, as well as the UK, Norway and Switzerland.…”

“…A full model description and the online model itself are available at http://www.impressions-project.eu/show/IAP2_14855. CRAFTY-EU is an application of the CRAFTY framework for agent-based modelling of land use change (Murray-Rust et al 2014;Brown et al 2019b) that covers the same extent as the IAP at the same (10 arcminute) resolution. CRAFTY uses the concept of Agent Functional Types (AFTs) (Arneth et al 2014) to simulate land use change over large geographical extents while capturing key behaviours of decision-making entities (agents) that include individual land managers, groups of land managers and institutions or policy bodies (Holzhauer et al 2019).…”

“…Importantly for this study, CRAFTY-EU is parameterised on the basis of the IAP, taking IAP outputs as exogenous conditions and replacing only the land allocation component to provide alternative land use projections under identical driving conditions. CRAFTY-EU is initialised on the IAP's baseline map, and only diverges from that stable baseline 'solution' as scenario conditions change (Brown et al 2019b). Land use productivities are also calculated from IAP outputs dependent on land use allocation, with the result that productivities are set to zero where the IAP determines production to be economically infeasible.…”

“…For this study, RCPs were simulated in the IAP using outputs from two global-regional climate models (EC_Earth/RCA4 for RCP2.6, and HADGEM2-ES/RCA4 for RCPs 4.5 and 8.5 (Harrison et al 2019)). Scenario outcomes are described for CRAFTY-EU in Brown et al (2019b) and for the IAP in Harrison et al (2019) and Papadimitriou et al (2019). In addition to these established scenarios, one scenario combination (RCP4.5 -SSP3) was simulated with additional variations in model parameterisations.…”

“…In this study, both models are run until the mid-2080s (defined as a 30-year timeslice in the IAP, and the year 2086 in CRAFTY-EU). Both use a spatial grid of resolution 10 arcmin x 10 arcmin (approximately 16km x 16km in Europe), but simulated land classes differ between the two models (as described in Brown et al 2019b) and are standardised here as described in Table 1, to focus on major, comparable forms of agricultural and forestry management. Other forms of land use and management (e.g.…”