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Abstract:
The Randolph Glacier Inventory (RGI) is a globally complete collection of digital glacier outlines that plays a crucial role in global and regional glaciological research. We introduce the RGI version 7.0, which is our best estimate of global glacier outlines (excluding the two ice sheets) around the year 2000. Unlike previous versions which were compiled manually, RGI7 is generated from the Global Land Ice Measurements from Space (GLIMS) glacier database, ensuring full traceability of single outlines to their original authors. The dataset is generated with Python scripts selecting outlines according to community decisions during an open review process. About 73% of the outlines (42% of the total area) in RGI7 are obtained from new inventories. This led to considerable quality improvements especially in High Mountain Asia, parts of Alaska, northern Canada, northern Greenland, Caucasus and Middle East, the Tropics, South America, New Zealand, and the Antarctic Periphery. Strikingly, the number of outlines increased by 27%, from 215,547 to 274,589. Smaller glaciers are now better inventoried and snow fields are less likely to be mapped as glaciers. Since these two improvements compensated each other, the total area in RGI7 (706,735 km2) is only 0.1% more than in RGI6. Regionally, area changes can be considerably larger (e.g. -18% in Low Latitudes, +9% in South East Asia). The new RGI generation process is open-source, fully reproducible and easily adaptable, making future updates straightforward to generate.
