Landscape ecological safety is of great significance in maintaining ecological balance, ecological protection, economic development, and promoting the sustainable use of regional land resources. This study collects three-phase remote sensing (RS) image data of 2000, 2010, and 2020 to elucidate the spatial and temporal changes in land use of the Guizhou Plateau Karst Watershed. We construct a landscape ecological security index using the ArcGIS and landscape pattern index method. With the spatial autocorrelation theory, we analyze the evolution of watershed landscape patterns and changes in characteristics of ecological security. The results show that the cultivated land is being converted to construction land in the watershed from 2000 to 2020. The percentage of the patch area of the constructed land is increasing. However, the patch cohesion of the cultivated land, grassland, and watershed is decreasing. The ecological safety of the Nanming River Basin landscape is in a positive trend, clustering in the central urban areas. The growth rate of the landscape ecological safety index increased by 5.80% from 2000 to 2020, and the aggregation of the ecological safety index was dominated by high–high aggregation and low–low aggregation, which was spatially positively correlated with the spatial aggregation effect. The findings provide a scientific reference for managing ecological balance and optimizing the land resource allocation in karst watersheds.

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In recent years, there has been rapid urbanization development in China. The rapid expansion of cities and the increase in the proportion of the area of impervious surfaces have caused urban flooding problems. The karst area in Southwest China is characterized by a sensitive ecosystem, poor self recovery ability and typical karst development. The problems of a fragile and imbalanced water ecology are particularly prominent in karst areas, making it necessary to explore the applicability of the concept of sponge cities in such environments. This study reviews the technical ideas, methods and concepts of sponge cities in China and abroad in recent years. Guiyang, a typical karst mountain city in China, was taken as an example in this study. This was because Guiyang has special hydrogeological characteristics as well as the current urbanization development processes that are affecting the water resources and the environment in the region. It is believed that the construction of mountain sponge cities in karst areas should be mainly through source reduction, process control and end management, combined with intelligent construction methods. Focus should be on strengthening the prevention and control of soil erosion in key areas and risk areas and on properly handling the relationship between urban construction and water resources and ecological environment protection.

The existence of global warming is common knowledge. However, it can be predicted that there may be cooling zones worldwide based on the mechanism of terrestrial biophysical processes. Here, the Theil–Sen median trend, the Mann–Kendall trend test method, continuous wavelet transformation, and the Hurst exponent were used to study the cooling trends, abrupt change times, periodicity, and future sustainability of temperature changes in different cooling zones since the 1900s based on the CRU dataset. We found an amazing result; 8,305,500 km2 of land surface had been cooling since the 1900s, covering five continents and 32 countries, accounting for 86% of land area in China, and distributed over 16 zones. The average cooling rate of the cooling zones was −0.24 °C/century. The maximum cooling rate was −1.40 °C/century, and it was 1.43 times the average rate of global land warming (0.98 °C/century). The cooling zones near the sea were greatly influenced by ocean currents and were mainly affected by a small time scale periodicity of less than 30 years, whereas the cold zones located relatively far from the sea and less affected by ocean currents were mainly affected by medium time scales of more than 30 years. Moreover, 32.33% of the cooling zones, involving 2,684,900 km2, will be continuously cooling in the future, and the rest will probably warm up in 2114, 2041, 2096, 2099, 2119, 2073, 2048, and 2101, respectively. The study will help us to further understand the essential characteristics of global climate change, and to find more theoretical bases for mitigating global warming and exploring surface cooling mechanisms.