A warm-season drought reconstruction in central-northern Pakistan inferred from tree rings since 1670 CE and its possible climatic mechanism

Abstract

Understanding past warm-season drought variability and its underlying climatic mechanisms is crucial for effective drought management and climate adaptation strategies. In this study, we develop a regional chronology (RC) spanning from 1620 to 2017 CE by utilizing dendrochronological techniques and tree-ring data from two stands of Abies pindrow. The RC reveals a significant positive correlation (p < 0.05) with self-calibrated Palmer drought severity index (scPDSI) and precipitation and a significant negative correlation with temperature. We use a simple linear regression model between RC and climate data to reconstruct a 348-year-long (1670–2017 CE) warm-season (April-July) drought variability from central-northern Pakistan. The reconstructed scPDSI reveals a 44% variance of the scPDSI during the common calibrated period 1950–2017 CE. Spatial correlation shows a positive field correlation with central-northern Pakistan, extending predominantly to neighboring regions. MTM (multi-taper method) spectral analysis reveals inter-annual cycles (6.8, 3.2, 2.7, 2.5, and 2.3 years) and multi-decadal cycles (11.7, 15.2, 16.2, 17.9, and 128 years). The internal-annual cycles demonstrate a possible linkage between reconstructed scPDSI and El Niño–Southern Oscillation (ENSO). The reconstructed scPDSI agrees well with the moisture-sensitive tree-ring records from northern Pakistan and neighboring regions. Our reconstruction shows a significant correlation with the South Asia Summer Monsoon Index (SASMI), Atlantic Multi-decadal Oscillation (AMO), ENSO, Pacific Decadal Oscillation (PDO), and solar activity, emphasizing that all these factors have some influence on the drought variability in central-northern Pakistan. This study has important implications for disaster management and proactive measures for mitigating the impact of drought on both natural ecosystems and human populations in central-northern Pakistan and associated regions.