A two-decade remote sensing assessment of sea surface temperature trends in Pakistan's exclusive economic zone
Abstract
Climate-induced changes in sea surface temperature (SST) have become an important indicator for assessing marine environmental variability and its ecological consequences. This study investigated seasonal and interannual SST variability within Pakistan’s exclusive economic zone (EEZ) using moderate resolution imaging spectroradi-ometer (MODIS) satellite observations acquired between 2002 and 2022. The analysis focused on five representative months (January, March, May, August, and October) to characterize seasonal thermal variability, compare decadal changes, and evaluate temporal patterns using linear regression and the non-parametric Mann–Kendall trend test. The results revealed distinct seasonal differences in SST variability across the study period. The highest SST values were consistently observed during May and August, while January represented the coldest conditions. Over the 20-year observation period, SST changes reached 1.00 °C in January, 0.90 °C in March, 1.53 °C in May, 1.50 °C in August, and 1.32 °C in October, with an overall average change of 0.52 °C. Decadal comparison indicated enhanced thermal variability during 2012–2022, particularly in January. Statistical analyses showed that significant temporal changes were limited to specific thermal indicators: March exhibited significant decreases in annual maximum SST and temperature difference, whereas August showed a significant increase in annual minimum SST. Most remaining variables displayed substantial interannual variability without statistically significant monotonic trends. The findings indicate that SST variability within Pakistan’s EEZ is season-dependent and cannot be adequately described by a uniform warming pattern. By combining long-term satellite observations with statistical trend assessment, this study provides one of the first comprehensive evaluations of seasonal and decadal SST variability for Pakistan’s EEZ, helping to address the limited availability of long-term regional assessments. Although the analysis was based on representative seasonal observations rather than continuous monthly records, it establishes a valuable baseline for future investigations of thermal variability and contributes scientific evidence to support marine environmental monitoring, climate-change assessment, and sustainable management of Paki-stan’s coastal and marine ecosystems.