Search

Glaciers are susceptible indicators of climate change and crucial parts of the world's water cycle. In the context of global warming, we took the Urumqi Glacier No.1 (UG1) as an example, which is situated at the source of the Urumqi River on the northern slope of the Tianshan Mountains, Xinjiang, combined with the climate data of Daxigou Meteorological Station from 1980 to 2020, and the change of glacier mass balance and its response to extreme climate are discussed. The results suggest that the glacier mass balance of UG1 showed a downward trend over the studied 41-year period, and the mass loss increased. The cumulative glacier mass balance value was −19,776 mm w.e., and the average annual value was −482 mm w.e.a−1. The Mann-Kendall trend test showed that the change point occurred around 1994, and the mass balance of UG1 became more negative after 1994. In the same period, the changing mass balance trend of UG1 was not the same in different seasons. The inter-annual variation of summer mass balance was drastic, showing a marked downward trend; the inter-annual change of winter mass balance was small, showing a slight uptrend. The changing of extreme climate indices where UG1 is located showed that only TX90p and TX10p changed observably from 1980 to 2020, and the extreme precipitation indices changed evidently and had been on the rise. The changing trend of extreme climate indices indicated that the temperature was rising, the warming was significant, and the precipitation was increasing. During 1980–2020, the glacier mass balance was substantially correlated with the extreme temperature indices (TX90p, TXx) but not with the extreme precipitation indices. Analyzing on a seasonal scale, the summer mass balance was memorably correlated with the extreme temperature indices (TX90p, TX10p, TXx), and the correlation coefficient between winter mass balance and the extreme precipitation index R95p and winter precipitation was in the range 0.36~0.40 (p < 0.05). According to the correlation between glacier mass balance and extreme climate indices, the summer mass balance was mainly affected by temperature, and the winter mass balance was affected primarily by precipitation. [ABSTRACT FROM AUTHOR]

This study deploys RTK-GNSS in 2012, TLS in 2015 and UAV in 2018 to monitor the changes of Urumqi Glacier No. 1 (UG1), eastern Tien Shan, and analyzes the feasibility of three technologies in monitoring the mountain glaciers. DEM differencing shows that UG1 has experienced a pronounced thinning and mass loss for the period of 2012–18. The glacier surface elevation change of −0.83 ± 0.57 m w.e. a−1 has been recorded for 2012–15, whereas the changes of glacier tongue surface elevation in 2015–18 and 2012–18 were −2.03 ± 0.95 and −1.34 ± 0.88 m w.e. a−1, respectively. The glacier area shrunk by 0.07 ± 0.07 × 10−3 km2 and the terminus retreat rate was 6.28 ± 0.83 m a−1 during 2012–18. The good agreement between the glaciological and geodetic specific mass-balances is promising, showing the combination of the three technologies is suitable to monitor glacier mass change. We recommend application of the three technologies to assess each other in different locations of the glacier, e.g. RTK-GNSS base stations, ground control points, glacier tongue and terminus, in order to avoid the inherent limitations of each technology and to provide reliable data for the future studies of mountain glacier changes in western China. [ABSTRACT FROM AUTHOR]

• An improved ecological footprint model developed based on ecosystem service value. • Stable equivalence and highly varying yield factors were observed in Urumqi, China. • Per capita ecological footprint and carrying capacity rose and waned, respectively. • Energy land contribution to ecological deficit larger than other land categories. • Built-up area, population, and GDP/capita strongly influence footprint depth. Natural capital is essential for human survival, continuation of modern civilization, and realization of sustainable development goals. Therefore a scientific framework is required for evaluating regional natural capital consumption and its capacity for ensuring sustainable development. Regional sustainability assessment can be conducted by applying the ecological footprint theory and modeling methods. However, traditional models focus on the production function of land, while disregarding the versatility of ecosystems and therefore cannot demonstrate the supply–demand relationship and their balance for ecological footprint based on the flows of ecosystem services. In this study, an ecological footprint model based on ecosystem service values was developed and used to measure the ecological footprint and carrying capacity of Urumqi city in China during 1995–2018. Subsequently, the partial least squares method was used to identify the factors driving the changes in the ecological footprint depth of Urumqi. The results showed that: (1) the equivalence factors of Urumqi were relatively stable, in the following order: water area (7.81) > forest land (2.08) > grassland (0.67) > cultivated land (0.35). The yield factors varied highly, in the following order: cultivated land (1.08) > forest land (0.78) > water area (0.76) > grassland (0.72). (2) During 1995–2018, the per capita ecological footprint increased by 2.83 times, ecological carrying capacity decreased by 34.74%, and ecological deficits increased by 15.76 times. Moreover, the energy land-use contribution to the deficits was larger than that of other land categories owing to its high proportion and rapid growth. (3) Within 24 years, the ecological footprint of Urumqi increased in size and depth by 1.78 and 2.45 times, respectively. Therefore, Urumqi requires approximately quadruple the current land area to meet the residents' resource consumption demands under sustainable development. (4) The three extremely important factors influencing the change in ecological footprint depth in Urumqi were built-up area, permanent resident population, and per capita gross domestic product (GDP), with the values of variable importance in projection being 1.17, 1.15, and 1.15, respectively. Compared with the traditional model, the improved model proposed has the advantages of reducing accounting errors, reflecting product attributes, and considering land versatility. The results may facilitate the reasonable use and management of natural capital in Urumqi, thereby promoting the sustainable social, economic, and environmental development of the city. They also provide reference for the sustainable development of similar oasis cities and arid regions with high ecological security risk. [ABSTRACT FROM AUTHOR]