Response of Inland Lakes to Climate Change across the Tibetan Plateau Investigated Using Landsat and ICESat Data

The Tibetan Plateau experienced tremendous climate change during the past four decades. Due to the large size, widely distribution of cryosphere, and diverse landforms, different parts of the plateau may experience different climate and cryosphere changing patterns. The changes of inland lakes within the plateau are important indicators of climate change as these lakes are fed by precipitation, permafrost degradation, and glacier melting that are all sensitive to climate change. To examine the spatial and temporal differences of lake variations across the Tibetan Plateau, Landsat images and ICESat/GLAS altimetry data were used to extract the changes in surface areas of 26 lakes selected from six different sub-regions during the 1970s-2010 and the changes in lake elevations of these lakes during 2003-2009. An automated model to extract lake surface area and elevation from Landsat and ICESat data is developed to improve the efficiency of processing the large amount of satellite data. By applying this model, the spatial and temporal changing patterns of selected 26 inland lakes across the Tibetan Plateau during the past four decades are revealed. The lakes from different parts of the Tibetan Plateau show different changing patterns. The lake expansion firstly started from the Central Tibetan Plateau in the 1980s, then moving northward and northwestward; the Northeastern and Northwestern Tibetan Plateau experienced obvious expansion after the late 1990s, and this expansion is still continuing in the northern part, whereas the rapid lake expansion either slowed down or stopped in the central and southern parts of the plateau. The differences in lake changing pattern are caused by diverse climatic regimes and the pattern of the cryospheric distribution in the Tibetan Plateau. For the southern part of the plateau, the change in precipitation and evaporation seems to be the dominating factor to control the lake changes; however, the cryospheric change caused by temperature increase is the most important factor influencing the lake fluctuations in the northern part. These patterns can provide insight into the mechanism of lakes dynamics in response to climate and cryospheric changes; and be applied to assess the potential impacts of climate change on water resources in the Tibetan Plateau

Impacts of climate change on Tibetan lakes: patterns and processes

High-altitude inland-drainage lakes on the Tibetan Plateau (TP), the earth’s third pole, are very sensitive to climate change. Tibetan lakes are important natural resources with important religious, historical, and cultural significance. However, the spatial patterns and processes controlling the impacts of climate and associated changes on Tibetan lakes are largely unknown. This study used long time series and multi-temporal Landsat imagery to map the patterns of Tibetan lakes and glaciers in 1977, 1990, 2000, and 2014, and further to assess the spatiotemporal changes of lakes and glaciers in 17 TP watersheds between 1977 and 2014. Spatially variable changes in lake and glacier area as well as climatic factors were analyzed. We identified four modes of lake change in response to climate and associated changes. Lake expansion was predominantly attributed to increased precipitation and glacier melting, whereas lake shrinkage was a main consequence of a drier climate or permafrost degradation. These findings shed new light on the impacts of recent environmental changes on Tibetan lakes. They suggest that protecting these high-altitude lakes in the face of further environmental change will require spatially variable policies and management measures

Lake area changes and their influence on factors in arid and semi-arid regions along the Silk Road

In the context of global warming, the changes in major lakes and their responses to the influence factors in arid and semi-arid regions along the Silk Road are especially important for the sustainable development of local water resources. In this study, the areas of 24 lakes were extracted using MODIS NDVI data, and their spatial-temporal characteristics were analyzed. In addition, the relationship between lake areas and the influence factors, including air temperature, precipitation, evapotranspiration, land use and land cover change (LULCC) and population density in the watersheds, were investigated. The results indicated that the areas of most lakes shrank, and the total area decreased by 22,189.7 km2 from 2001 to 2016, except for those of the lakes located on the Qinghai-Tibetan Plateau. The air temperature was the most important factor for all the lakes and increased at a rate of 0.113 °C/a during the past 16 years. LULCC and the increasing population density markedly influenced the lakes located in the middle to western parts of this study area. Therefore, our results connecting lake area changes in the study region highlight the great challenge of water resources and the urgency of implementation of the green policy in the One Belt and One Road Initiative through international collaboration

Geomorphological Evolution and Palaeoenvironmental Change in the Western Alashan Plateau, China

Although neotectonic activity is considered to be the main factor of theterrain evolution of the Qinghai Tibet Plateau and its surrounding high-altitude areas, further geomorphological analysis and literature analysis areneeded for the understanding of the geomorphic evolution and the Quaternary environment change of the western area of the Alxa Plateau nearthe northern Tibet Plateau. The purpose of this study is to investigate thedistribution of site-specific geomorphic units of the landforms developedin the vast topography of Ejina Basin (Western Alxa), in order to identifythe geostructural and climatic causes of the geomorphic landscape and itsimpact on the change of paleoenvironment. At present, the climate andhydrological conditions in Ejina are relatively monotonous and stable. Inaddition to tectonic dynamic factors, the most widely distributed landform in the basin is climate landform. There are both geomorphologicaland sedimentological anomalies of Aeolian landforms occurred in thewhole basin, indicating that the underlying surface effect (retention effect) of river (Ejina River) and its related uneven ground and weak winderosion (deflation) process in the nearby area may be the important factors controlling the formation of Ejina dunes, rather than the arid climate.It is believed that the extensive interaction between the aeolian and fluvialprocesses is the main mechanism of the regional geomorphic difference inEjina Basin. According to the comparability of regional geomorphologyand sedimentology, the period of the formation of relic geomorphologyin the edge of Ejina Basin can be reasonably attributed to the local glacialmaximum of the last glacial. The geomorphic transformation from quasiplain and desert valley to desert plain, the appearance of widely movingsand dunes and the presence of large ancient lake geomorphology allindicate that the drought index of Ejina Basin is increasing on the scaleof geomorphic formation. Paleogeomorphological and chronological evidences show that the climatic and hydrological conditions of the basin inthe last glacial period and the early Holocene are much better than thoseat present. For example, the average annual precipitation in the area before 39-23ka BP is between 60-350 mm (about 36 mm today), but thereare large waves in the Holocene. The coexistence of various climates andlandforms in Ejina Basin and the resulting geomorphic diversity shouldbe the composite result of various geomorphic processes and surface processes besides glaciation. The low aridity (relative humidity) in the EjinaRegion in the late Pleistocene may be the result of the enhancement of thewesterly rain belt and the weakening of the Asian Winter Monsoon in thearid region of Central Asia

Energy and Water Cycles in the Third Pole

As the most prominent and complicated terrain on the globe, the Tibetan Plateau (TP) is often called the “Roof of the World”, “Third Pole” or “Asian Water Tower”. The energy and water cycles in the Third Pole have great impacts on the atmospheric circulation, Asian monsoon system and global climate change. On the other hand, the TP and the surrounding higher elevation area are also experiencing evident and rapid environmental changes under the background of global warming. As the headwater area of major rivers in Asia, the TP’s environmental changes—such as glacial retreat, snow melting, lake expanding and permafrost degradation—pose potential long-term threats to water resources of the local and surrounding regions. To promote quantitative understanding of energy and water cycles of the TP, several field campaigns, including GAME/Tibet, CAMP/Tibet and TORP, have been carried out. A large amount of data have been collected to gain a better understanding of the atmospheric boundary layer structure, turbulent heat fluxes and their coupling with atmospheric circulation and hydrological processes. The focus of this reprint is to present recent advances in quantifying land–atmosphere interactions, the water cycle and its components, energy balance components, climate change and hydrological feedbacks by in situ measurements, remote sensing or numerical modelling approaches in the “Third Pole” region

6th Third Pole Environment Workshop

This report contains abstracts from the 6th Third Pole Environment Workshop, held at the Byrd Polar and Climate Research Center, on May 15-18, 2016.Institute of Tibetan Plateau Research, Chinese Academy of SciencesU.S. Third Pole Environment Office, Byrd Polar and Climate Research CenterOffice of Research and Office of Academic Affairs, The Ohio State Universit

Remote sensing of glacier change in the Central Qinghai-Tibet Plateau and the relationship with changing climate

2016-2017 > Academic research: refereed > Publication in refereed journal201804_a bcmaVersion of RecordPublishe