A tree ring-based winter temperature reconstruction for the southeastern Tibetan Plateau since 1340 CE

Shekhar²,

et al. 2021

The Cryosphere

Abstract. Tree-ring δ18O values are a sensitive proxy for regional physical climate, while their δ13C values are a strong predictor of local ecohydrology. Utilizing available ice-core and tree-ring δ18O records from the central Himalaya (CH), we found an increase in east–west climate heterogeneity since the 1960s. Further, δ13C records from transitional western glaciated valleys provide a robust basis for reconstructing about 3 centuries of glacier mass balance (GMB) dynamics. We reconstructed annually resolved GMB since 1743 CE based on regionally dominant tree species of diverse plant functional types. Three major phases became apparent: positive GMB up to the mid-19th century, the middle phase (1870–1960) of slightly negative but stable GMB, and an exponential ice mass loss since the 1960s. Reasons for accelerated mass loss are largely attributed to anthropogenic climate change, including concurrent alterations in atmospheric circulations (weakening of the westerlies and the Arabian Sea branch of the Indian summer monsoon). Multi-decadal isotopic and climate coherency analyses specify an eastward declining influence of the westerlies in the monsoon-dominated CH region. Besides, our study provides a long-term context for recent GMB variability, which is essential for its reliable projection and attribution.

Section: Three Major Phases In the Mass Balance Dynamicssupporting

confidence: 84%

Section: Three Major Phases In the Mass Balance Dynamicsmentioning

confidence: 73%

Central Himalayan tree-ring isotopes reveal increasing regional heterogeneity and enhancement in ice mass loss since the 1960s

Shekhar²,

et al. 2021

The Cryosphere

“…In the southeastern Tibetan Plateau, it was reported that winter temperature is the major growth factor of the pine sp. trees (Liang et al 2016;Huang et al 2019;Li et al 2020) In this study, the current year temperature during August was the most important factor related to the ring width index of Pinus latteri. On the other hand, other climatic factors, for example, total monthly rainfall in January and August and average monthly relative humidity in August, had a positive relationship with the growth of Pinus latteri.…”

Section: Discussionmentioning

confidence: 55%

A 324-years temperature reconstruction from Pinus latteri Mason at highland in Chiang Mai Province, Thailand

et al. 2020

Abstract. Lumyai P, Palakit K, Suangsathaporn K, Wanthongchai K. 2020. A 324-years temperature reconstruction from Pinus latteri Mason at highland in Chiang Mai Province, Thailand. Biodiversitas 21: 3938-3945. The objective of this study was to investigate the relationship between the growth of Pinus latteri and climate data in Chiang Mai Province, Thailand. Dendrochronological techniques were used to analyze 35 sample cores. The cross dated ring width data could be extended back for up to 324 years (1692-2015). The relationship between ring-width index and climate data indicated a significant correlation (p < 0.01) with the monthly rainfall in January, monthly temperature in August and September, extreme maximum temperature in August and mean maximum temperature in March and August. The reconstructed average monthly temperature in August was estimated at around 27.35 °C, a warming period could have occurred in 1694-1702, 1834-1844, 1848-1866, 1873-1876, 1884-1890, 1896-1902, 1911-1927, 1942-1958, and 1986-1990, with cooling periods occurring in 1703-1722, 1739-1752, 1865-1872, 1877-1883, 1891-1895, 1903-1910, 1928-1941, 1959-1961, and 1968-1970, which could explain the high fluctuations in temperature. Periods in the range 2.1-2.5, 10.1 , and 13.5 years were found to be common with the variations in El Niño-Southern Oscillation. In conclusion, the pine growth information can be used to monitor the variations in climate in Thailand.

“…Similarly, some glacier‐fluctuation episodes from the Gawalong glacier (1768, 1918) (Zhu et al, 2013), Lhamkoka glacier (1777, 1918), Gyalaperi glacier (1763) (Bräuning, 2006), Xinpu glacier (1746, 1927), Gongpu glacier (1910), Zepu glacier (1785), and Baitong glacier (1757) (Hochreuther et al, 2015) in the southestern Tibetan Plateau were closely synchronized with our moraine dating in the Manang valley in the central Himalayas. Furthermore, the periods with advancing glacier corresponded with cold intervals (1796–1874 and 1900–1936), as shown by tree ring‐based spring temperature reconstruction from the lower part of the Manang valley (Aryal et al, 2020), and from the southestern Tibetan Plateau (1892–1927 and 1958–1981) (Huang et al, 2019). The synchronization between ages of the dated moraines and higher snow accumulation epochs (Figure 6) implied that higher snow accumulation period may link with formation of moraines.…”

Section: Discussionmentioning

confidence: 93%

Retreating Glacier and Advancing Forest Over the Past 200 Years in the Central Himalayas

et al. 2020

Self Cite

The Himalayan glaciers, as unique reservoirs of freshwater for densely populated Asian countries, have been receiving considerable attention in public and scientific research. However, little is known about their long-term fluctuations as related to climate variability. Herein, we reconstructed glacier fluctuation events by tree ring-based moraine dating and repeated photographs. We assessed these fluctuations over the past 200 years in the Gangapurna and Annapurna III glaciers, located in the central Himalayas. We detected five major glacier fluctuation events in the 1790s, 1920s, 1930s, 1960s, and 1970s. A higher rate of glacier recession was observed from the 1980s onward, coinciding with climate warming. As shown by repeated photographs, the retreating rate of the Gangapurna glacier from 1979 to 2016 (up to 24.4 m yr −1) is much higher than the Annapurna III glacier (7.54 m yr −1) from 1950 to 2016. Their different frontal retreat rates were likely related to microtopography and glacier sizes. Older moraines developed during and after the Little Ice Age (LIA) were already covered by dense forest, presenting the evidence for retreating glaciers and advancing forests in the central Himalayas. Ongoing warming tends to speed up such ecological processes by resetting biophysical environment of the deglaciated forefields. In general, glaciers have shown retreating trends over the last 200 years, presenting a risk for preserving water resources in the Himalayas and nearby regions. Alternatively, advancing forest tends to amplify warming rate by reducing albedo, which is a new issue for investigating ecohydrological feedbacks between mountain forests, climate, and water resources. Plain Language Summary The Himalayan glaciers, as unique reservoirs of freshwater, have been receiving considerable attention in public and scientific research. However, there is a huge knowledge gap on long-term glacier fluctuations. For example, Intergovernmental Panel on Climate Change (IPCC) in its Fourth Assessment Report asserted that glaciers in the Himalayas will likely disappear by the year 2035 under the present rate of glacier recession. This statement raised scientific criticisms and presented the necessity to have a better understanding on past glacier fluctuations. However, little is known about long-term glacier fluctuations and ecological processes on the deglaciated forefields. Herein, we reconstructed glacier fluctuation events by tree ring-based moraine dating and repeated photographs for the Gangapurna and Annapurna III glaciers over the past 200 years in the central Himalayas. This study presents the first detailed evidence for the fluctuation history of Himalayan glaciers over the past 200 years. According to the minimum age of the moraines, the glacier retreat occurred during the 1790s with successive recessions during the 1920s, 1930s, 1960s, and 1980s. The central Himalayas are characterized by retreating glaciers and advancing forest during the past 200 years, presenting a challenge for ecological assessment and re...