Climate–Vegetation Dynamics and Sensitivity across Iraq Using Long-Term Earth Observation Data

Abstract

Climate change is intensifying temperature and water stress across dryland regions, increasing the need for spatially consistent, long-term monitoring of vegetation responses. Iraq is especially exposed because strong climatic gradients, recurrent drought and limited water availability coincide with extensive rain-fed and irrigated land. This study assessed climate–vegetation dynamics across Iraq from 2001 to 2025 using MODIS normalized difference vegetation index (NDVI), CHIRPS precipitation and ERA5-Land 2-m air temperature. Mean October–May precipitation, January–May NDVI trends and detrended climate–NDVI correlations were analysed on a common 0.1° grid. Vegetated pixels were subsequently classified as rainfall-sensitive, heat-sensitive, sensitive to both, without a strong expected relationship, or displaying another strong relationship direction. Wet-season precipitation showed a pronounced gradient from very high totals in northern and northeastern Iraq to low and very low totals across the west, southwest and south. Significant greening was considerably more widespread than browning, with the strongest positive NDVI trends concentrated in northern, northeastern and central agricultural areas. After removal of linear trends, precipitation–NDVI correlations were predominantly positive and spatially extensive, whereas significant temperature–NDVI correlations were mainly negative and concentrated in northern, eastern and southeastern Iraq. The integrated classification was dominated by rainfall sensitivity, while combined rainfall and heat sensitivity formed distinct north-central and southeastern clusters. These results provide a national spatial baseline for identifying vegetation regions associated with interannual water and heat variability. The sensitivity classes represent statistical associations rather than causal attribution.