Urban agglomeration is an advanced spatial form of integrating cities, resulting from the global urbanization of recent decades. Understanding spatiotemporal patterns and evolution is of great importance for improving urban agglomeration management. This study used continuous time-series NTL data from 2000 to 2018 combined with land-use images to investigate the spatiotemporal patterns of urbanization in the three most developed urban agglomerations in China over the past two decades: the Beijing–Tianjin–Hebei urban agglomeration (BTH), the Yangtze River Delta urban agglomeration (YRD), and the Guangdong–Hong Kong–Macao Greater Bay Area (GBA). The NTL intensity indexes, dynamic thresholds, extracted urban areas, and landscape metrics were synthetically used to facilitate the analysis. This study found that the urbanization process in the study areas could be divided into three stages: rapid urbanization in core cities from 2000 to 2010, a fluctuating urbanization process in both core cities and surrounding cities from 2010 to 2015, and stable urbanization, mainly in surrounding cities with a medium size after 2015. Meanwhile, the urbanization level of GBA was higher than that of YRD and BTH. However, with the acceleration of urban development in YRD, the gap in the urbanization level between GBA and YRD narrowed significantly in the third stage. In addition, this study confirmed that the scattered, medium-sized cities in YRD and GBA were more developed than those in BTH. This study showed that continuous NTL data could be effectively applied to monitor the urbanization patterns of urban agglomerations.

Deterioration of the urban thermal environment, especially in megacities with intensive populations and high densities of impervious surfaces, is a global issue resulting from rapid urbanization. The effects of landscape patterns on the urban thermal environment within a single area or single period have been well documented. Few studies, however, have explored whether the effects can be adapted to various cities at different urbanization stages. This paper investigated the variations of these effects in the five largest and highly urbanized megacities of China from 1990 to 2020 using various geospatial approaches, including concentric buffer analysis, correlation analysis, and hierarchical ridge regression models. The results indicated that the effects of landscape patterns on the urban thermal environment were greatly variable at different urbanization stages. Although landscape composition was more important than landscape configuration in determining the urban thermal environment, the standard coefficients of composition metrics continuously decreased from 1990 to 2020. However, configuration metrics, such as patch density, edge density, and shape complexity, could affect the land surface temperature (LST) to a larger extent at the highly urbanized stage. The urbanization process could also affect the cooling effect of urban green space. At the initial stage of rapid urban expansion in approximately 2000, urban green space explained the most variation in LST, with a value as high as 10%. To maximize the cooling effect, the spatial arrangement of urban green space should be highlighted in the region that was 10–15 km from the city center, where the mean LST experienced a significant decline. These results may provide deeper insights into improving the urban thermal environment by targeted strategies in optimizing landscape patterns for areas at different urbanization stages.

Grasslands cover over 50% of the Qinghai–Tibetan Plateau (QTP), playing a critical role in water conservation, soil retention, carbon sequestration, biodiversity, and supporting pastoral livelihoods. Due to the high-altitude and cold-climate conditions, the QTP is highly vulnerable to climate change. Understanding the relative importance of the drivers of grassland degradation is essential for developing adaptive management strategies. While numerous studies have explored these drivers, the impacts of large-scale ecological restoration efforts since 2000, particularly across different grassland types and degradation-recovery phases, remain underexplored. This study analyzes 40 years of grassland vegetation dynamics on the QTP, identifying key inflection points and classifying regions into four ‘degradation-restoration’ trajectory types. The effects of climatic and anthropogenic drivers across distinct temporal phases are quantified. The results indicate that 6.56% of grasslands are in continuous degradation, while 28.97% are at risk of potential degradation risk. Drought and grazing emerge as the primary drivers of vegetation change, while restoration and afforestation programs play a significant role in enhancing recovery. Our findings underscore the spatiotemporal variability of grassland responses and emphasize the need for targeted grazing management and integrated water resource planning to optimize restoration outcomes. This study provides a framework for differentiated grassland management in the face of climate change and human pressures on the QTP.

Glaciers continuously affected by climate change are of great concern; their supply and runoff variation tendency under the pressure of increasing populations, especially in dryland areas, should be studied. Due to the difficulty of observing glacier runoff, little attention has been given to establishing high-resolution and long-term series datasets established for glacial runoff. Using the latest dataset using digital elevation models (DEMs) to obtain regional individual glacier mass balance, simulating the spatiotemporal regime of glacier runoff in oases that support almost the entire income in the dryland areas of China (DAC) could be possible. The simulations quantitatively assess glacier runoff, including meltwater runoff and delayed runoff, in each basin of the DAC at a spatial resolution of 100 m from 1961 to 2015, classify glaciers according to the potential climatic risks based on the prediction results. The total glacier runoff in the DAC is (98.52 ± 67.37) × 10⁸ m³, in which the meltwater runoff is (63.43 ± 42.17) × 10⁸ m³, accounting for 64.38 %. Most basins had continuously increasing tendencies of different magnitudes from 1961 to 2015, except for the Shiyang River basin, which reached its peak in approximately 2000. Glacier runoff nurtured nearly 143,939.24 km² of oasis agricultural areas (OAA) until 2015, while 19 regions with a total population of 14 million were built alongside the oases, where glacier runoff occupies an important place in agricultural, industrial and municipal water consumption. Therefore, providing a long time series of glacier runoff for different river basins is of great significance to the sustainable development of the oasis economy in the arid zones.

The spatiotemporal regimes of glacier runoff (GR) under a warming climate are of great concern, especially in dryland areas in northwestern China (DAC). Due to the difficulty of observing GR, little attention has been given to the spatiotemporal change in GR at regional scales. This study uses the regional individual glacier mass balance (GMB) dataset developed by digital elevation models (DEMs) to simulate the spatiotemporal regime of GR using atmospheric parameters considering both ablation and accumulation processes on glaciers. In this study, GR, including glacier meltwater runoff (MR) and delayed water runoff (DR) of the DAC, was quantitatively assessed at a catchment scale from 1961 to 2015. The total annual GR in the DAC was (100.81 ± 68.71) × 10⁸ m³ in 1961–2015, where MR accounted for 68%. Most basins had continuously increasing tendencies of different magnitudes from 1961 to 2015. The least absolute shrinkage and selection operator (LASSO) and random forest techniques were used to explore the contributions of climate factors and glacier physical properties to GR, and the results indicated that climate factors could explain 56.64% of the variation. In comparison, the remaining 43.36% could be explained by the physical properties of glaciers themselves (i.e., degree-day factor on ice, degree-day factor on snow, glacier median height, aspect, and slope). This study not only improves our understanding of the spatiotemporal change in GR in the drylands of northwestern China at spatial and temporal resolutions but also highlights the role of physical properties in explaining the heterogeneous dynamics among GRs unlike previous studies that only emphasize rising temperatures.