How armed conflict shapes environmental trends in Yemen?

Abstract

The ongoing conflict in Yemen has resulted in widespread socio-economic disruption and environmental degradation, with more than half of the population requiring humanitarian aid. In such conflict-affected contexts, direct field assessments are often unfeasible, making remote sensing an essential tool for environmental monitoring. This study integrates multi-temporal satellite observations, including the Moderate Resolution Imaging Spectroradiometer (MODIS), the Global Precipitation Measurement Version 6 (GPM v6), and the Tropical Rainfall Measuring Mission (TRMM). It also uses station-based and gauge-corrected climate products, such as the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) and TerraClimate, along with atmospheric reanalysis data from the fifth-generation European Centre for Medium-Range Weather Forecasts Reanalysis (ERA5). These datasets were integrated to evaluate the impacts of prolonged armed conflict on vegetation dynamics, water stress, and climate variability across Yemen from 2001 to 2024. We examined national-scale spatiotemporal patterns using annual trends, breakpoints, and spatial comparisons between pre-conflict and conflict periods. The escalation of the civil war during 2011-2015 coincides with a marked decline in the aridity index and the Normalized Difference Vegetation Index (NDVI), accompanied by an increase in potential evapotranspiration (PET). These changes suggest conflict-driven impacts on vegetation and water balance, likely resulting from agricultural disruption. From 2016 onward, a partial recovery in NDVI and the aridity index, alongside reduced PET, indicates the onset of environmental stabilization following the initial conflict shock. Although precipitation shows no persistent long-term trend, it displays pronounced interannual variability. Surprisingly, agricultural areas in Yemen have increased between 2010 and 2020 over some regions despite the ongoing conflict, which may have forced populations to settle in new areas, converting previously unused or marginal land into farmland. Overall, the findings reveal the complex interactions between conflict, climate variability, and ecosystem resilience, underscoring the value of satellite monitoring in politically inaccessible regions.