Abstract
Abstract. Land cover is the physical material at the surface of the Earth. As the cause and result of global environmental change, land cover change (LCC) influences the global energy balance and biogeochemical cycles. Continuous and dynamic monitoring of global LC is urgently needed. Effective monitoring and comprehensive analysis of LCC at the global scale are rare. With the latest version of GLASS (Global Land Surface Satellite) CDRs (climate data records) from 1982 to 2015, we built the first record of 34-year-long annual dynamics of global land cover (GLASS-GLC) at 5 km resolution using the Google Earth Engine (GEE) platform. Compared to earlier global land cover (LC) products, GLASS-GLC is characterized by high consistency, more detail, and longer temporal coverage. The average overall accuracy for the 34 years each with seven classes, including cropland, forest, grassland, shrubland, tundra, barren land, and snow/ice, is 82.81 % based on 2431 test sample units. We implemented a systematic uncertainty analysis and carried out a comprehensive spatiotemporal pattern analysis. Significant changes at various scales were found, including barren land loss and cropland gain in the tropics, forest gain in the Northern Hemisphere, and grassland loss in Asia. A global quantitative analysis of human factors showed that the average human impact level in areas with significant LCC was about 25.49 %. The anthropogenic influence has a strong correlation with the noticeable vegetation gain, especially for forest. Based on GLASS-GLC, we can conduct long-term LCC analysis, improve our understanding of global environmental change, and mitigate its negative impact. GLASS-GLC will be further applied in Earth system modeling to facilitate research on global carbon and water cycling, vegetation dynamics, and climate change. The GLASS-GLC data set presented in this article is available at https://doi.org/10.1594/PANGAEA.913496 (Liu et al., 2020).
Highlights
Land cover (LC) is the physical material at the surface of the Earth
Based on the accuracy assessment and data intercomparison results, it can be seen that the global LC mapping products of 1982–2015, Global Land Surface Satellite (GLASS)-GLC, are reliable with high accuracies and that the global long-term mapping framework we designed is effective
Systematic uncertainty analysis was performed on a global scale based on the results of the accuracy assessment and its geographical distribution
Summary
Land cover (LC) is the physical material at the surface of the Earth. It is the result of both natural and human forces (Running, 2008; Sterling et al, 2013; Tucker et al, 1985; Gong et al, 2013; Yang et al, 2013). It is an important source of information to understand the complex interaction between human activities and global changes (Lambin et al, 2006). More frequent land cover information at the global scale is highly desirable
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