This study investigates whether refugee inflows and general population growth exert distinct effects on environmental outcomes in the United Kingdom, specifically examining whether forced migration creates unique ecological pressures compared to structural demographic changes. Utilising annual data from 1965 to 2024, the study applies a Multivariate Wavelet–Quantile Regression (MWQR) framework, complemented by Wavelet Quantile Regression (WQR) for robustness, to capture nonlinear, distribution-dependent, and time-horizon-specific relationships between demographic dynamics and \(CO_{2}\) emissions. The results reveal a significant divergence in environmental transmission mechanisms. Refugee inflows are associated with transitory, short-run effects concentrated at lower and middle emission quantiles, with impacts dissipating over longer horizons as refugees integrate into the host's infrastructure. In contrast, general population growth exerts a persistent, structural "scale effect," particularly at high-emission regimes and long-term horizons. Fossil fuel consumption consistently amplifies emissions, whereas renewable energy penetration acts as a critical buffer, mitigating demographic-driven environmental pressure. Based on these findings, we suggest that environmental policy should prioritise decarbonising the refugee integration phase by upgrading the energy efficiency of temporary housing and asylum-reception infrastructure. Furthermore, as demographic impacts are regime-dependent, the UK should focus on accelerating grid decarbonisation to decouple structural population growth from emissions, rather than pursuing restrictive migration policies for environmental purposes. Coordinating humanitarian settlement with low-carbon urban planning is essential for achieving long-term sustainability.
