Climatic variations over the past millennium revealed by tree ring from the Tibetan Plateau

AbstractThe ecological environment of the headwater area of the Yellow River, west China, is seriously deteriorating because of the harsh natural environment, weakened ecological systems and intensified human activities as well as regional climate changes. Forests and glaciers coexist in this area. Glaciers in the area have retreated over the last decade because of climate change. Most glaciers on the Tibetan Plateau (TP) tend to retreat during warm intervals and advance during cold intervals. Tree-ring records provide an important index for examining past climate changes. A total of 139 core samples from 97 living cypresses (Juniperus przewalskii) in the central region of the Yellow River headwater area, the Animaqin mountains, northeastern TP, were sampled from three sites that are close to each other. The chronologies were developed using the ARSTAN program. Analyses indicate that these tree-ring width records reflect the summer maximum temperature of the study area over the past 700 years. The tree-ring records and the glacier advances recorded by terminal moraines are compared. Inferred summer maximum temperatures suggest three cold periods during the Little Ice Age, around AD1500, 1700 and 1850. These cold intervals are consistent with the glacier moraine record from the region.

Download Full-text

Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ<sup>18</sup>O of tree-ring cellulose

Climate of the Past ◽

10.5194/cp-11-327-2015 ◽

2015 ◽

Vol 11 (2) ◽

pp. 327-337 ◽

Cited By ~ 42

Author(s):

J. Wernicke ◽

J. Grießinger ◽

P. Hochreuther ◽

A. Bräuning

Keyword(s):

Relative Humidity ◽

Tibetan Plateau ◽

Tree Ring ◽

Summer Season ◽

Ice Age ◽

Transfer Model ◽

The Tibetan Plateau ◽

The Past ◽

Dry Conditions ◽

Hydroclimatic Variables

Abstract. We present an 800-year δ18O chronology from the eastern part of the Tibetan Plateau (TP). The chronology dates back to AD 1193 and was sampled in AD 1996 from living Juniperus tibetica trees. This first long-term tree-ring-based δ18O chronology for eastern Tibet provides a reliable archive for hydroclimatic reconstructions. Highly significant correlations were obtained with hydroclimatic variables (relative humidity, vapour pressure, and precipitation) during the summer season. We applied a linear transfer model to reconstruct summer season relative humidity variations over the past 800 years. More moist conditions prevailed during the termination of the Medieval Warm Period while a systematic shift during the Little Ice Age is not detectable. A distinct trend towards more dry conditions since the 1870s is apparent. The moisture decline weakened around the 1950s but still shows a negative trend. The mid-19th century humidity decrease is in good accordance with several multiproxy hydroclimate reconstructions for south Tibet. However, the pronounced summer relative humidity decline is stronger on the central and eastern TP. Furthermore, the relative humidity at our study site is significantly linked to the relative humidity at large parts of the TP. Therefore, we deduce that the reconstructed relative humidity is mostly controlled by local and mesoscale climatic drivers, although significant connections to the higher troposphere of west-central Asia were observed.

Download Full-text

A Millennial Summer Temperature Reconstruction for the Eastern Tibetan Plateau from Tree-Ring Width*

Journal of Climate ◽

10.1175/jcli-d-14-00738.1 ◽

2015 ◽

Vol 28 (13) ◽

pp. 5289-5304 ◽

Cited By ~ 32

Author(s):

Jianglin Wang ◽

Bao Yang ◽

Fredrik Charpentier Ljungqvist

Keyword(s):

Tibetan Plateau ◽

Tree Ring ◽

Ring Width ◽

Summer Temperature ◽

Temperature Variability ◽

Tree Ring Width ◽

Eastern Tibetan Plateau ◽

The Past ◽

Temperature Reconstructions ◽

Past Millennium

Abstract Although tree-ring-width-based temperature reconstructions of centennial-to-millennial length have previously been published for many parts of the eastern Tibetan Plateau (ETP), a millennium-long regional-scale composite reconstruction with annual resolution has so far been lacking. Here, the authors present a reconstruction of June–August (JJA) temperature variability over the ETP for the period AD 1000–2005 using a nested composite-plus-scale (CPS) approach to 12 temperature-sensitive tree-ring width chronologies, including 946 individual tree-ring width series. The composite reconstruction reveals warm episodes occurring during much of the sixteenth, nineteenth, and twentieth centuries and cold episodes during much of the eleventh, seventeenth, and eighteenth centuries. The period AD 1996–2005 is likely the warmest decade in the context of the past millennium. The authors explore the influence of possible forcings, finding only a weak direct relationship of temperature changes over the ETP with solar forcing at multidecadal time scales but a robust in-phase relationship with the Atlantic multidecadal oscillation (AMO) during the past millennium. This suggests that the AMO may play an important role in controlling summer temperature variability over the ETP at multidecadal time scales. A comparison with temperature reconstructions from the higher latitudes of East Asia, central-eastern China, and the whole of the Northern Hemisphere shows that the cold eleventh century and the warm nineteenth century prevailing over ETP are somewhat unique, suggesting regional specific characteristics of the temperature variability in this region. This result highlights the need to further increase the number of millennium-long, high-resolution temperature records from East Asia.

Download Full-text

Supporting Restoration Decisions through Integration of Tree-Ring and Modeling Data: Reconstructing Flow and Salinity in the San Francisco Estuary over the Past Millennium

Water ◽

10.3390/w13152139 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2139

Author(s):

Paul H. Hutton ◽

David M. Meko ◽

Sujoy B. Roy

Keyword(s):

San Francisco ◽

Tree Ring ◽

San Francisco Estuary ◽

Salinity Intrusion ◽

Estuarine Ecosystem ◽

Freshwater Flow ◽

The Past ◽

Decadal Scale ◽

Tree Ring Data ◽

Past Millennium

This work presents updated reconstructions of watershed runoff to San Francisco Estuary from tree-ring data to AD 903, coupled with models relating runoff to freshwater flow to the estuary and salinity intrusion. We characterize pre-development freshwater flow and salinity conditions in the estuary over the past millennium and compare this characterization with contemporary conditions to better understand the magnitude and seasonality of changes over this time. This work shows that the instrumented flow record spans the range of runoff patterns over the past millennium (averaged over 5, 10, 20 and 100 years), and thus serves as a reasonable basis for planning-level evaluations of historical hydrologic conditions in the estuary. Over annual timescales we show that, although median freshwater flow to the estuary has not changed significantly, it has been more variable over the past century compared to pre-development flow conditions. We further show that the contemporary period is generally associated with greater spring salinity intrusion and lesser summer–fall salinity intrusion relative to the pre-development period. Thus, salinity intrusion in summer and fall months was a common occurrence under pre-development conditions and has been moderated in the contemporary period due to the operations of upstream reservoirs, which were designed to hold winter and spring runoff for release in summer and fall. This work also confirms a dramatic decadal-scale hydrologic shift in the watershed from very wet to very dry conditions during the late 19th and early 20th centuries; while not unprecedented, these shifts have been seen only a few times in the past millennium. This shift resulted in an increase in salinity intrusion in the first three decades of the 20th century, as documented through early records. Population growth and extensive watershed modification during this period exacerbated this underlying hydrologic shift. Putting this shift in the context of other anthropogenic drivers is important in understanding the historical response of the estuary and in setting salinity targets for estuarine restoration. By characterizing the long-term behavior of San Francisco Estuary, this work supports decision-making in the State of California related to flow and salinity management for restoration of the estuarine ecosystem.

Download Full-text

Modulation of the relationship between summer temperatures in the Qinghai–Tibetan Plateau and Arctic over the past millennium by external forcings

Quaternary Research ◽

10.1017/qua.2021.3 ◽

2021 ◽

pp. 1-9

Author(s):

Feng Shi ◽

Anmin Duan ◽

Qiuzhen Yin ◽

John T Bruun ◽

Cunde Xiao ◽

...

Keyword(s):

Tibetan Plateau ◽

Global Climate ◽

Volcanic Eruptions ◽

Warm Period ◽

Temperature Correlation ◽

The Past ◽

External Forcings ◽

Centennial Variation ◽

Summer Temperatures ◽

Past Millennium

Abstract The Qinghai–Tibetan Plateau and Arctic both have an important influence on global climate, but the correlation between climate variations in these two regions remains unclear. Here we reconstructed and compared the summer temperature anomalies over the past 1,120 yr (900–2019 CE) in the Qinghai–Tibetan Plateau and Arctic. The temperature correlation during the past millennium in these two regions has a distinct centennial variation caused by volcanic eruptions. Furthermore, the abrupt weak-to-strong transition in the temperature correlation during the sixteenth century could be analogous to this type of transition during the Modern Warm Period. The former was forced by volcanic eruptions, while the latter was controlled by changes in greenhouse gases. This implies that anthropogenic, as opposed to natural, forcing has acted to amplify the teleconnection between the Qinghai–Tibetan Plateau and Arctic during the Modern Warm Period.

Download Full-text

Process-based modeling of tree-ring formation and its relationships with climate on the Tibetan Plateau

Dendrochronologia ◽

10.1016/j.dendro.2017.01.002 ◽

2017 ◽

Vol 42 ◽

pp. 31-41 ◽

Cited By ~ 11

Author(s):

Minhui He ◽

Vladimir Shishov ◽

Nazgul Kaparova ◽

Bao Yang ◽

Achim Bräuning ◽

...

Keyword(s):

Tibetan Plateau ◽

Tree Ring ◽

Ring Formation ◽

The Tibetan Plateau

Download Full-text

Spatial‐temporal characteristics of drought and flood disasters in Yunnan Province on the margin of the Tibetan Plateau over the past 620 years

International Journal of Climatology ◽

10.1002/joc.7309 ◽

2021 ◽

Author(s):

Jie Niu ◽

Liming Wang ◽

Kunwu Yang ◽

Shengzhi Liu ◽

Jiqing Yin ◽

...

Keyword(s):

Tibetan Plateau ◽

Yunnan Province ◽

The Tibetan Plateau ◽

Temporal Characteristics ◽

The Past ◽

Drought And Flood ◽

Flood Disasters

Download Full-text

Extremes in the magnitude of annual temperature cycle on the Tibetan Plateau over the past three centuries

Climate Dynamics ◽

10.1007/s00382-018-4346-5 ◽

2018 ◽

Vol 52 (5-6) ◽

pp. 3599-3608 ◽

Cited By ~ 2

Author(s):

Jianping Duan ◽

Zhuguo Ma ◽

Naiming Yuan ◽

Lun Li ◽

Liang Chen

Keyword(s):

Tibetan Plateau ◽

Temperature Cycle ◽

The Tibetan Plateau ◽

The Past ◽

Annual Temperature Cycle

Download Full-text

Melting Ice Rivers

Dirty, Sacred Rivers ◽

10.1093/oso/9780199845019.003.0011 ◽

2012 ◽

Author(s):

Cheryl Colopy

Keyword(s):

Global Warming ◽

Tibetan Plateau ◽

The Netherlands ◽

Sea Level ◽

The Tibetan Plateau ◽

Mount Everest ◽

The Past ◽

The North ◽

The World ◽

The Government

From a remote outpost of global warming, a summons crackles over a two-way radio several times a week: . . . Kathmandu, Tsho Rolpa! Babar Mahal, Tsho Rolpa! Kathmandu, Tsho Rolpa! Babar Mahal, Tsho Rolpa! . . . In a little brick building on the lip of a frigid gray lake fifteen thousand feet above sea level, Ram Bahadur Khadka tries to rouse someone at Nepal’s Department of Hydrology and Meteorology in the Babar Mahal district of Kathmandu far below. When he finally succeeds and a voice crackles back to him, he reads off a series of measurements: lake levels, amounts of precipitation. A father and a farmer, Ram Bahadur is up here at this frigid outpost because the world is getting warmer. He and two colleagues rotate duty; usually two of them live here at any given time, in unkempt bachelor quarters near the roof of the world. Mount Everest is three valleys to the east, only about twenty miles as the crow flies. The Tibetan plateau is just over the mountains to the north. The men stay for four months at a stretch before walking down several days to reach a road and board a bus to go home and visit their families. For the past six years each has received five thousand rupees per month from the government—about $70—for his labors. The cold, murky lake some fifty yards away from the post used to be solid ice. Called Tsho Rolpa, it’s at the bottom of the Trakarding Glacier on the border between Tibet and Nepal. The Trakarding has been receding since at least 1960, leaving the lake at its foot. It’s retreating about 200 feet each year. Tsho Rolpa was once just a pond atop the glacier. Now it’s half a kilometer wide and three and a half kilometers long; upward of a hundred million cubic meters of icy water are trapped behind a heap of rock the glacier deposited as it flowed down and then retreated. The Netherlands helped Nepal carve out a trench through that heap of rock to allow some of the lake’s water to drain into the Rolwaling River.

Download Full-text