A comprehensive study of UK climate change policies based on complex systems modeling: Evidence from 2001 to 2020

The United Kingdom is a highly industrialized and economically developed country, with greenhouse gas (GHGs) emissions historically well above the global average, thereby significantly contributing to global climate change. Over the past two decades, the UK government has introduced a range of measures to mitigate emissions, such as enacting legislation and employing market-based mechanisms. Between 2001 and 2020, the number of climate policies issued by the government and think tanks increased by 73 and 171 times, respectively, accompanied by a 43% reduction in GHGs and a 44% reduction in CO₂ emissions. Although prior research has identified a negative correlation between policy quantity and emissions, the relative importance of specific policy themes remains unclear. In this study, we employed the Latent Dirichlet Allocation (LDA) model to identify key thematic topics within UK climate policies published from 2001 to 2020. Subsequently, Partial Least Squares (PLS) regression was applied to quantify the contribution of each policy theme to reductions in GHGs emissions. Our quantitative results show that policies emphasizing themes such as “climate”, “carbon”, “greenhouse”, “gas”, and “low” accounted for 73.3% of the total emission reduction. Furthermore, we modeled the policy system as a complex network to assess structural interactions. These findings provide actionable insights for policymakers seeking to design more effective climate strategies.