Centre for the Study of Existential Risk, University of Cambridge, Cambridge, United Kingdom.
LIUC - Carlo Cattaneo University, Castellanza, Lombardia, Italy.
PLoS One. 2023 Nov 16;18(11):e0293391. doi: 10.1371/journal.pone.0293391. eCollection 2023.
In this study, we propose a simplified model of a socio-environmental system that accounts for population, resources, and wealth, with a quadratic population contribution in the resource extraction term. Given its structure, an analytical treatment of attractors and bifurcations is possible. In particular, a Hopf bifurcation from a stable fixed point to a limit cycle emerges above a critical value of the extraction rate parameter. The stable fixed-point attractor can be interpreted as a sustainable regime, and a large-amplitude limit cycle as an unsustainable regime. The model is generalized to multiple interacting systems, with chaotic dynamics emerging for small non-uniformities in the interaction matrix. In contrast to systems where a specific parameter choice or high dimensionality is necessary for chaos to emerge, chaotic dynamics here appears as a generic feature of the system. In addition, we show that diffusion can stabilize networks of sustainable and unsustainable societies, and thus, interconnection could be a way of increasing resilience in global networked systems. Overall, the multi-systems model provides a timescale of predictability (300-1000 years) for societal dynamics comparable to results from other studies, while indicating that the emergent dynamics of networks of interacting societies over longer time spans is likely chaotic and hence unpredictable.
在本研究中,我们提出了一个简化的社会-环境系统模型,其中考虑了人口、资源和财富,资源开采项中的人口贡献呈二次关系。鉴于其结构,对吸引子和分叉进行分析处理是可能的。特别是,在开采率参数超过临界值时,会从稳定的平衡点出现到极限环的 Hopf 分叉。稳定的平衡点吸引子可以解释为可持续的状态,而大振幅的极限环则表示不可持续的状态。该模型被推广到多个相互作用的系统中,在相互作用矩阵中出现小的非均匀性时会出现混沌动力学。与需要特定参数选择或高维度才能出现混沌的系统相比,这里的混沌动力学是系统的一种通用特征。此外,我们还表明,扩散可以稳定可持续和不可持续社会的网络,因此,互联可能是增加全球网络系统弹性的一种方式。总的来说,多系统模型为社会动态提供了可预测的时间尺度(300-1000 年),与其他研究的结果相当,同时表明,在更长的时间跨度内,相互作用的社会网络的涌现动态很可能是混沌的,因此是不可预测的。