Most glaciers in China lie in high mountainous environments and have relatively large surface slopes. Common analyses consider glaciers’ projected areas (2D Area) in a two-dimensional plane, which are much smaller than glacier’s topographic surface extents (3D Area). The areal difference between 2D planar areas and 3D surface extents exceeds −5% when the glacier’s surface slope is larger than 18°. In this study, we establish a 3D model in the Muzart Glacier catchment using ASTER GDEM data. This model is used to quantify the areal difference between glaciers’ 2D planar areas and their 3D surface extents in various slope zones and elevation bands by using the second Chinese Glacier Inventory (CGI2). Finally, we analyze the 2D and 3D area shrinking rate between 2007 and 2013 in Central Tianshan using glaciers derived from Landsat images by an object-based classification approach. This approach shows an accuracy of 89% when it validates by comparison of glaciers derived from Landsat and high spatial resolution GeoEye images. The extracted glaciers in 2007 also have an agreement of 89% with CGI2 data in the Muzart Glacier catchment. The glaciers’ 3D area is 34.2% larger than their 2D area from CGI2 in the Muzart Glacier catchment and by 27.9% in the entire Central Tianshan. Most underestimation occurs in the elevation bands of 4000–5000 m above sea level (a.s.l.). The 3D glacier areas reduced by 30 and 115 km2 between 2007 and 2013 in the Muzart Glacier catchment and Central Tianshan, being 37.0% and 27.6% larger than their 2D areas reduction, respectively. The shrinking rates decrease with elevation increase.
Abstract Extreme dry and wet events can result in significant crop yield losses. However, the impact of consecutive occurrence of dry and wet extremes on crop yield remains unclear. Here, we investigate the hotspots of compound dry and wet (CDW) extremes across global rice croplands and their impacts on rice yield. We identify a significant increasing trend in the frequency of CDW extremes during 1981–2016. The risk of yield loss caused by CDW extremes can be twice as high as the risk from individual wet and dry extremes. Furthermore, we find that global rice croplands face a 43% higher risk of rice yield loss due to dry‐to‐wet extremes compared to wet‐to‐dry extremes. Our findings provide new insights into the sustainability of global rice production and food security in the face of compound hydrological extremes.
Abstract The simultaneous occurrence of droughts and floods in neighboring regions amplifies the threats posed by droughts and floods individually. Nonetheless, few studies have been conducted to investigate the simultaneous occurrence of drought and flood events. Here we explore the spatiotemporal characteristics and the shift pattern of droughts and pluvials over Eastern China from a three‐dimensional perspective, using the self‐calibrated Palmer Drought Severity Index and the Climate Research Unit data set as well as four regional climate model simulations. We find that Eastern China experienced droughts and pluvials simultaneously in different locations during boreal summer, and it is projected to simultaneously experience more frequent and more intense droughts and pluvials under a warming climate. Specifically, we investigate the pattern of more pluvials in Southeast China and more droughts in Northeast China for the historical period of 1975–2004. This pattern dynamically evolves under climate warming: the pluvial‐dominated regime shifts from Southeast to Northeast China, while the drought‐dominated regime shifts from Northeast to Southeast China. The weakening strength of the western Pacific subtropical high and a northward displacement of the monsoon rain belt may both contribute to the pattern of more pluvials in Northeast China and more droughts in Southeast China. These findings provide insights into the development of adaptation strategies and emergency response plans for enhancing society's resilience to the spatial co‐occurrence of dry and wet extremes.
Abstract The consecutive occurrence of meteorological dry and wet extremes has been receiving increasing attention due to potentially larger social and environmental impacts than single extremes. However, the changing characteristics of transitions between dry and wet periods remain poorly understood. Here we investigate the dynamic evolution of dry‐to‐wet transitions in response to climate warming, using the Standardized Precipitation Evapotranspiration Index as well as observations and general circulation models for the periods of 1954–2014 and 2040–2100. We find that approximately three‐fifths of global land area are projected to experience an accelerated dry‐to‐wet transition. Southern Asia has been experiencing the most severe dry‐to‐wet transitions and is projected to suffer more frequent, more intense, and accelerated dry‐to‐wet transitions. The increasing potential evapotranspiration (PET) variability plays an important role in accelerating the dry‐to‐wet transition in Southern Asia, while precipitation and PET variabilities contribute to the intensification of dry‐to‐wet transitions in Southern North America.
Abstract Exploring the dynamic evolution of the abrupt alternation between wet and dry spells in adjacent months plays a crucial role in water resources planning and agricultural development in a changing climate. The dry‐wet abrupt alternation (DWAA) has been studied based on hydrometeorological observations over the past several years. However, little effort has been made to explore DWAA from a climate projection standpoint. Furthermore, few studies have investigated potential interrelationships between DWAA and heavy rainfall. In this study, the interrelationships between DWAA events and heavy rainfall with various intensities as well as potential evapotranspiration are revealed explicitly through the convection‐permitting climate simulations for 10 climate divisions over Texas in the United States. Our findings disclose that the increasing heavy rainfall and potential evapotranspiration lead to more frequent occurrence of DWAA events over a larger spatial extent. Heavy rainfall with daily precipitation greater than 20 mm contributes most to the occurrence of DWAA. In addition, a severe phenomenon of dry‐wet‐dry alternation is projected to appear due to the increasing number of heavy rainfall and drought events as well as the deteriorated soil water holding capacity under global warming.
Abstract The dry‐wet abrupt alternation (DWAA) event, which is defined as the phenomenon of dry (or wet) spells abruptly following wet (or dry) spells, magnifies the influence of individual wet and dry events. The dynamic evolution of DWAA events has not been studied for different climate zones of China that is particularly susceptible to dry and wet extremes. This study explores the future changes in the abrupt alternations between dry and wet extremes across 10 climate divisions of China, with a thorough assessment of dry and wet conditions using the Standardized Precipitation Evapotranspiration Index (SPEI). We take advantage of an ensemble of regional climate model simulations including the Providing Regional Climate Impacts for Studies (PRECIS) experiment and five CORDEX East Asia experiments to produce high‐resolution climate information for a baseline period of 1975–2004 and a future period of 2069–2098. Our findings disclose that a total of 70% of China's land area suffered from the DWAA events at least once during 1975–2004. The wet‐dry alternation event is projected to become more frequent in summer, and a prominent increase in the number of dry‐wet alternation events is expected to occur in spring over most parts of China. Moreover, an increasing number of DWAA events with intensified magnitude is projected to strike the North China Plain dominated by warm temperature and humid zone, which is the most densely populated region of the country and is also the largest agriculture production area. Our findings also reveal a strong positive correlation between DWAA and heavy rainfall. The 95th percentile rainfall event contributes most to the wet‐dry alternation event for most climate divisions of China.
Malignant growth and metastasis of gastrointestinal stromal tumors (GIST) occur in some patients even during the course of treatment, but their mechanisms remains poorly understand at the molecular level so far. Profiles of protein expression in gastric GIST tissues were explored using protein microarray analysis, down-regulation of SPARCL1 (secreted protein acidic and rich in cysteine-like protein 1) was validated by RT-qPCR, western blot and immunohistochemistry. The effect of specific shRNA-induced SPARCL1 downregulation on the biological traits of GIST 882 cell was investigated. We then employed a mouse xenograft model to investigate whether the low-expression of SPARCL1 impact the metastasis ability of GIST cells in vivo. SPARCL1 was significantly downregulated in the gastric GIST with high-grade malignance as compared with low-grade malignance, its expression was closely correlated with tumor size, mitotic index, distant metastasis at the time of initial diagnosis and tumor progression of GIST (P < 0.05). Moreover, results of the Cox analysis showed that expression of SPARCL1 is an independent prognostic predictors for gastric GIST (P = 0.008; HR 0.157, 95% CI 0.040~ 0.612). Downregulation of SPARCL1 promoted cell migration and invasion, but did not affect proliferation, cell cycle and apoptosis of GIST 882 cells. In mouse xenograft model, GIST cells with the decreased expression of SPARCL1 presented an enhanced ability of liver metastasis (P < 0.05). Taken together, our present study demonstrated that SPARCL1 have a certain degree of malignancy-suppressing potential through inhibiting the metastasis of gastric GIST.
Abstract The reliable projection of future changes in hydrological drought characteristics plays a crucial role in providing meaningful insights into agricultural development and water resources planning under climate change. In this study, we develop probabilistic projections of hydrological drought characteristics through a convection‐permitting climate simulation and a multimodel hydrological prediction for two major river basins in South Texas of the United States. The probabilistic hydrological drought projection depicts the future evolution of spatiotemporal characteristics of droughts under best‐ and worst‐case scenarios. Our findings reveal that there is a considerable variation in hydrological drought regimes near the urban area in South Texas. And the prolonged severe drought events are expected to be punctuated by the increasing extreme precipitation in a changing climate. This could lead to an increasing number of the dry‐wet abrupt alternation events. Moreover, hydrological droughts are projected to occur more frequently for the fall season in the Guadalupe River Basin and for the winter season in the Blanco River Basin, advancing our understanding of future changes in seasonal characteristics of hydrological droughts at a river basin scale.
Gastric neuroendocrine neoplasms (G-NENs) are uncommon, and data on their management is limited. We here investigated the clinicopathological characteristics, surgical and survival outcomes in G-NENs among Chinese. Moreover, we will discuss their prognostic value. From existing databases of the West China Hospital, we retrospectively identified 135 consecutive patients who were surgically treated and pathologically diagnosed as G-NENs from January 2009 to August 2015. This entire cohort comprised 98 males and 37 females, with a median age of 60 years. Twenty-five patients underwent endoscopic resection, while 110 patients underwent open/laparoscopic surgery. Thirty-nine patients had neuroendocrine tumor G1 (NET G1), seven patients had neuroendocrine tumor G2 (NET G2), 69 patients had neuroendocrine carcinoma G3 (NEC G3) and 20 patients had mixed adenoneuroendocrine carcinoma (MANEC). The median survival was not achieved for both NET G1 and NET G2 versus 19 months (range 3–48) for NEC G3 and 10.5 months (range 3–45) for MANEC. The 3-year survival rates for stage I, II, III, and IV were 91.1 %, 78.6 %, 51.1 % and 11.8 %, respectively (P < 0.001). As for the prognostic analysis, both surgical margin and the newly updated World Health Organization (WHO) classification were independent predictors of overall survival (OS). G-NENs are a kind of rare tumors, and patients with NET G3 and MANEC have unfavorable prognosis even surgically treated. Moreover, surgical margin and the new 2010 WHO criteria are closely associated with OS for G-NENs.
Abstract The global crop ecosystem is critically dependent on snow availability, which has diminished in numerous snow-dependent regions due to increasing snow droughts associated with warmer winters. However, our understanding of crop yield sensitivity to snow droughts and how this sensitivity evolves remains limited. In this study, we find that from 1960 to 2020, approximately 51% of winter wheat croplands have experienced a significant increase (5.3−6.7% per year) in the frequency of snow droughts. To assess the sensitivity of winter wheat yield to snow droughts, we utilized explainable machine learning, gridded yield datasets, and the standardized snow water equivalent index (SWEI) from 1982 to 2016. Our findings reveal a positive association between yield anomalies and SWEI under snow drought conditions and a significant increase in the sensitivity of yield to SWEI over 24% of Northern Hemisphere winter wheat croplands. Additionally, enhanced accumulation of growing degree days, increased vapor pressure deficit (VPD), a slight decrease in total precipitation, and increased heavy rainfall are identified as dominant factors amplifying yield sensitivity to snow droughts. These findings highlight an increasing vulnerability of crop systems to snow droughts over the past three decades, which is crucial for informing risk management and adaptation of agriculture to a warming future with less snow.
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