Quantifying anthropogenic impacts on CO₂ and CH₄ emissions: statistical insights and hotspot detection in East Africa

Abstract

East Africa (EA) faces significant challenges related to greenhouse gas (GHG) emissions, particularly carbon dioxide (CO₂) and methane (CH₄), largely driven by biomass burning (BB) from agricultural fires and wildfires. Despite their importance, the spatiotemporal variability of these emissions remains poorly understood. This study quantifies CO₂ and CH₄ emissions across EA (2001-2022), revealing significant CO₂ emission peaks in 2005 (32.5 million tonnes), 2016 (29.8 million tonnes), and 2020 (31.2 million tonnes), alongside an 18% increase in CH₄ emissions between 2015 and 2020. BB accounted for approximately 54% of total CO₂ emissions (~17 million tonnes) and 74% of CH₄ emissions (~16 million tonnes), with regional hotspots including Northern Uganda (NUG), Tanzania (TZ), and South Sudan (SS) exhibiting the highest intensities, especially during dry seasons where emissions surged by up to 40%. Analysis of regional trends reveals a significant decline in CO₂ emissions in the Western Transition (WTZ) (slope = -13.02, p = 0.0004), likely reflecting effective mitigation such as forest restoration and REDD+ programs, supported by satellite-observed greening. In contrast, SS, NUG, and the Southeastern Tanzania (SETZ) showed negative but statistically insignificant CO₂ trends, indicative of fluctuating land-use pressures rather than sustained mitigation. CH₄ emissions rose significantly in the WTZ (slope = 15.67, p = 0.0001), driven by agricultural intensification, with a marginal increase in NUG, while remaining stable in SS and the SETZ. Non-stationarity in emissions (ADF p > 0.05) across regions highlights the influence of dynamic socio-environmental factors such as land-use changes, policy shifts, and climate variability. These findings emphasize the urgent need for improved fire management, sustainable land practices, and integrated mitigation strategies to address EA's growing environmental threats and contribute to global climate goals under the Paris Agreement.

Keywords: Air quality; Biomass burning; Climate change; Emissions; GHG.