RETRACTED: Summer temperature variability in the Hindu Kush region of northern Pakistan: Insights from tree rings of Pinus wallichiana A. B. Jacks since 1790 C.E.

Abstract

The Hindu Kush high-altitude regions of Pakistan are currently experiencing severe consequences as a result of global warming. In this sense, increasing soil erosion and the quick melting of glaciers are two particularly evident effects. In such a scenario, understanding long-term temperature changes is crucial for making accurate forecasts about how the Hindu Kush region may experience regional temperature changes in the future. In this study, the climate tree-ring width (TRW) analysis designated a positive and significant correlation (r = 62.2, p < 0.001) between the TRW chronology and the June to September (summer) mean maximum temperature (MMT). Using the tree-ring width of Pinus wallichiana A. B. Jacks, we reconstructed summer temperatures in the Hindu Kush region from C.E. 1790. Statistical analysis showed that the reconstruction model has explained 38.7% of the climate variance during the instrumental period of C.E. 1967 to 2018. Five extremely warm summer periods (≥ 4 years; before the instrumental period C.E. 1967–2018) of C.E. 1804–1830, 1839–1862, 1876–1879, 1905–1910, 1923–1935, and six cold summer periods, i.e., 1790–1803, 1832–1838, 1863–1875, 1880–1904, 1911–1922, and 1936–1945, have been observed during the past 229 years. Individually, the year C.E. 1856 (31.85°C) had severe warmth, whereas C.E. 1794 (29.60°C) was observed with extreme cold. The spectral multi-taper method (MTM) shows significant (p < 0.05) cycles, which take place about every 9.3, 5.7, 4.2, and 3.6 years. In particular, the 9.3-year cycle, which closely aligns with the 11-year solar activity cycle, suggests a potential correlation between solar activity and local temperature fluctuations. Moreover, our reconstruction demonstrates a significant degree of consistency when compared to actual data and regional temperature reconstruction series, instilling a strong logic of trust in the reliability and accuracy of our findings. This evidence reaffirms that our reconstruction shows significant and dependable regional temperature signals, notably for the Hindu Kush region.