Abstract

Arid and semi-arid ecosystems face severe threats from climate extremes, yet the underlying physiological mechanisms driving long-term vegetation collapse remain under-researched in Western Iraq. This study quantifies the impact of climate change on vegetation dynamics in Ramadi over a 44-year period (1980–2024). Using a hybrid approach, long-term climate time-series data were evaluated via the non-parametric Mann-Kendall test and Sen’s slope estimator, while Landsat satellite imagery (1993 and 2024) was processed using NDVI to track phenological changes during the peak growing season (January) and dry season (July). Statistical analysis revealed a significant progressive warming trend (Z=+4.82,p<0.0001), with mean annual maximum temperatures increasing at a rate of 〖0.044〗^∘ "C/year" , amounting to a cumulative rise of 〖1.9〗^∘ "C" . This thermal shift was compounded by a statistically significant rainfall decline of -1.82" mm/year" (Z=-2.15,p=0.031) and an unprecedented surge in annual evaporation of +14.5" mm/year" (Z=+3.95,p=0.0001). Satellite observations showed a dramatic breakdown in ecological resilience: dense winter vegetation cover plummeted from 49.7% in 1993 to just 6.3% in 2024, while summer desertification expanded barren land to dominate 69.4% of the area. Strong statistical correlations confirmed these trends, showing NDVI positively linked to precipitation (r=0.82) and inversely tied to temperature (r=-0.78). The study indicates that this structural degradation is driven by synergistic heat-drought stress; elevated vapor pressure deficits (VPD) force prolonged stomatal closure, triggering carbon starvation and hydraulic failure. These findings demonstrate that the ecosystem has breached a critical resilience threshold, requiring immediate, targeted conservation interventions.

interventions.