August‐September Temperature Variability on the Tibetan Plateau: Past, Present, and Future

Abstract

To assess the recent warming on the Tibetan Plateau (TP), some tree‐ring‐based temperature reconstructions have been performed. However, most of the previous studies focused on the local or regional scale. In this study, we analyzed the recent variability of August‐September temperature using observations from 79 TP meteorological stations, and the observed records were extended back to 1,572 based on a tree‐ring maximum density network comprising 17 sites. Moreover, the future August‐September temperature scenarios on the TP are also presented using the ensemble mean of five regional climate models. The tree‐ring maximum late‐wood density network shows good capacity to reconstruct the August‐September temperature variability at the spatial scale of the whole TP (i.e., 79‐station average; r1951–2014 = 0.80, P < 0.01). The reconstruction suggests that the instrumental epoch is the warmest interval of August‐September over the past four and a half centuries on the TP, and the decadal‐scale August‐September warming since the 1960s is unprecedented. The ensemble simulation of five regional climate models indicates that persistent August‐September warming will occur on the TP in the future. The magnitude of August‐September warming is approximately 1.56 ± 0.30°C and 3.02 ± 0.29°C over the period 2006–2049 under the Representative Concentration Pathways (RCPs) 4.5 and P8.5 scenarios, respectively. These results imply a further ecological and environmental change on the TP linked to the persistent warming in the future.

Reconciling the Discrepancy of Post-Volcanic Cooling Estimated from Tree-Ring Reconstructions and Model Simulations over the Tibetan Plateau

“…Two August-September mean temperature reconstructions (Duan2018 and Duan2019) [17,20] were used in this study to be compared with the climate model simulations. Both reconstructions were based on a regional tree-ring maximum latewood density (MXD) network comprising 739 MXD measurement series from 17 sites on the TP.…”

“…Both reconstructions were based on a regional tree-ring maximum latewood density (MXD) network comprising 739 MXD measurement series from 17 sites on the TP. The series, Duan2019 [20], was reconstructed using observed August-September mean temperature anomalies (with respect to 1986-2005) and thus the long-term trend remained. The series, Duan2018 [17], was reconstructed as the August-September mean temperature deviation for each year relative to the preceding 5-year mean and thus the long-term trend was removed to capture the abrupt change of the late summer temperature following a volcanic eruption.…”

Unprecedented recent late-summer warm extremes recorded in tree-ring density on the Tibetan Plateau

“…Both reconstructions show a good spatial representativeness for August-September temperature variability over the TP (i.e. 79-station average) (Duan et al , 2019.…”

“…Two up-to-date reconstruction series of August-September mean temperature based on tree-ring maximum latewood density (MXD) on the TP (Duan et al , 2019 are used to identify the late summer temperature extremes over the past four centuries. One of the August-September temperature series covering the period of 1572-2014 was reconstructed based on the actual August-September mean temperature anomalies with respect to 1986-2005 (hereafter T Aug-Sep -ano), and thus it remains the long-term trend (Duan et al 2019). The other reconstruction covers the interval of 1620-2014 , but this reconstruction was performed based on the instrumental August-September temperature deviations in each year relative to the preceding 5 year mean (hereafter T Aug-Sep -dev).…”

“…Shi et al (2015) reconstructed the June-August temperature variability in the east TP over the past 212 years using a tree-ring width network, and found that extreme events of summer temperature occurred frequently since 1950. Based on the decadal evaluation, the other studies also suggested that summer/late summer temperature in the last decade (Liang et al 2009 or since the 1960s (Duan et al 2019) was unprecedented warm in the southeastern TP over their reconstruction periods. These previous tree-ring reconstructions found the recent summer/late summer warm or warm extremes over a time scale of the past several centuries.…”