Land cover change dominates decadal trends of biogenic volatile organic compound (BVOC) emission in China

Abstract. Satellite observations reveal that China has been leading the global greening trend in the past two decades. We assessed the impact of land cover change on total BVOC emission in China during 2001–2016 and found a significant increasing trend of 1.09 % yr−1 with increases of 1.35, 1.25 and 1.43 % yr−1 for isoprene, monoterpenes and sesquiterpenes, respectively. Comparison of different scenarios showed that vegetation change is the main driver of BVOC emission change in China. Considerable heterogeneity was observed on regional scales, with the highest increasing trends of BVOC emission found in the Qinling Mountains and in the south of China. The BVOC emission for the year 2016 in these two regions was enhanced by 61.89 and 67.64 % compared to that of 2001, respectively. We compared the long-term HCHO vertical columns (VC) from the satellite-based Ozone Monitoring Instrument (OMI) with the estimation of isoprene emission in summer. The results showed statistically significant positive correlation coefficients over the regions with high vegetation cover fractions. In addition, the isoprene emission and HCHO VC both showed statistically significant increasing trends in the south of China where these two variables have high positive correlation coefficients. This result supports our estimation of the variability and trends of BVOC emission in China. Although anthropogenic sources comprise ∼63 % NMVOC emissions in China, the continued increase of BVOC will enhance the importance of considering BVOC when making policies for controlling ozone pollution in China along with ongoing efforts to reduce anthropogenic emissions.