A reconstruction of June–July temperature since AD 1383 for Western Sichuan Plateau, China using tree‐ring width

Abstract

Global warming has a significant impact on the ecosystem of the high‐altitude areas of the Tibetan Plateau, such as land degradation and the rapid retreat of glaciers. It is important to understand the effects of global warming occurring over hundreds or thousands of years. However, the long‐term reconstruction of temperature is still lacking for the region of Western Sichuan Plateau (WSP). In this study, we reconstructed summer (June–July) temperatures back to 1383 for the WSP region based on a significant positive correlation between the standard chronology and summer temperature. The reconstruction passed statistical tests and explained 55.4% of the climatic variance in the period for which data are available (1962–2005). There have been five periods with warm summers and five with cold summers during the past 623 years. Warm periods occurred in 1383–1445, 1525–1590, 1700–1724, 1825–1870, and 1930–1960, while relatively cold periods occurred in 1446–1524, 1591–1675, 1725–1824, 1900–1929, and 1961–1990. A comparison with observed data and regional temperature reconstruction series shows that the reconstruction has a high degree of consistency and is indicative and reliability. The spatial correlation was analysed with Climatic Research Unit gridded data to detect the spatial representativeness of the reconstruction, confirming that the reconstruction has a strong regional temperature signal for the WSP. Furthermore, ensemble empirical mode decomposition indicates quasi‐oscillations of 2.8–3.3, 6.4–8.3, 11.1–14.2, 25–38.4, 89, and 138 years in the reconstructed temperature time series during the past 623 years. El Niño Southern Oscillation cycles, solar activity, and Atlantic multi‐decadal oscillation may be the primary forcing factors. Meanwhile, the coordinated action of temperature‐induced drought stress with a late growing season related to delayed snowmelt can potentially be attributed to the divergence problem (observed around 2005).

Hydrological Extremes in the Upper Yangtze River Over the Past 700 yr Inferred From a Tree Ring δ18O Record

“…Peak streamflow in the UYR occurs during the summer season (Figure S1 in Supporting Information ). Previous study has shown that this region is dominantly influenced by ISM in boreal summer (Y. Zhang, Fang, et al., 2021; Y. Zhang, Li, et al., 2021). We also used the monthly gridded (2.5° × 2.5°) pressure, wind, and specific humidity (300500 hPa isobar data) data from the NCEP/NCAR reanalysis data set (Kalnay et al., 1996) to analyze the direction and distribution total water vapor flux over the study region and the surroundings.…”

“…Therefore, we decided to apply isotope analyses to the trees cross‐dated by Y. Zhang, Li, et al. (2021), to investigate regional hydrological changes over the past centuries.…”

“…The mean annual total precipitation is ∼597 mm (over the period 1961-2017) and is concentrated during the summer season (June-August; Y. Zhang, Li, et al, 2021).…”

“…This site is located on the southeastern Tibetan Plateau and is influenced mainly by the ISM as indicated by synchronized peaks of precipitation and temperature during boreal summer (Figure 1b; Y. Zhang, Li, et al, 2021). The sampled spruce is a shallow-rooted and shade-tolerant tree species, which occurs mainly at altitudes of 3,800-4,500 m in the alpine zone of the southeastern Tibetan Plateau.…”

“…The final tree-ring width chronologies were developed using ARSTAN software (Cook & Holmes, 1986) and are analyzed and discussed in detail in Y. Zhang, Li, et al (2021), who identified a significant summer temperature signal in the tree ring width index. Previous studies have found that the stable oxygen composition of tree rings can record a regional moisture or hydrological signal in southeastern Tibetan Plateau (An et al, 2014;Grießinger et al, 2011Grießinger et al, , 2017Wernicke et al, 2015Wernicke et al, , 2017a.…”