Impacts\nof Urban Expansion on Terrestrial Carbon Storage\nin China

Urban\nexpansion is one of the main factors driving terrestrial\ncarbon storage (TCS) changes. Accurate accounting of TCS and rigorous\nquantification of its changes caused by historical urban expansion\nmay help us to better predict its changes in the future. This study\nfocuses on the carbon impacts of urbanization in China where the share\nof the urban population has increased from 18% in 1978 to 59% in 2017\nand the growing will continue in the coming decades. Our results show\nthat China’s TCS decreased at an accelerating pace over the\npast three decades with an average reduction of 0.72TgC/y in 1980–1990\nand 8.72TgC/y in 2000–2010, mostly due to conversion from cropland\nand woodland to urban land. Through simulating urban expansion under\nfour scenarios from 2010 to 2050, we found a potential increasing\ntrend in land conversion from woodland to urban land. This conversion\ntrend would result in carbon storage loss at an average rate of 9.31TgC/y\n∼ 12.94TgC/y in 2010–2050. The increasing trend in both\nland conversion and carbon storage loss is especially visible in the\npopulation centers of the Yangtze River Delta and the Pearl River\nDelta. Considering that the indirect emission effects of urbanization,\nsuch as farmland displacement, population migration, and land degradation,\nmay be much larger, the overall emission impact of forthcoming urban\nexpansion in China would increase the uncertainty of the nation’s\ncarbon emissions and potentially undermine China’s targets\nas committed in the Paris Climate Agreement.