The convergence in ecological footprint intensity across ECOWAS countries: evidence from a novel approach

Ecological footprint intensity (EFI) reflects the amount of ecological footprint utilized to generate one dollar of GDP per capita. Analyzing EFI convergence among countries unveils the efficiency of ecological footprint usage while considering GDP per capita differences. This study investigates the convergence process of EFI across 12 Economic Community of West African States (ECOWAS) countries from 1961 to 2018. Unlike previous studies focusing on convergence across the entire period, this research employs a novel approach using the discrete wavelet transform (DWT) to decompose the EFI series into different frequency scales (short, medium, and long-run). This methodology enables us to assess convergence patterns across various time frames, providing a more comprehensive understanding of the convergence process. We then apply the Fourier Augmented Dickey-Fuller unit root test to examine convergence across each frequency. Our findings reveal that while short-term convergence is evident for all 12 countries, medium and long-term convergence patterns vary. These results highlight the importance of considering time periods when developing environmental policies.