Ecological restoration and rising CO2 enhance the carbon sink, counteracting climate change in northeastern China

The impact of climate change, rising CO2, land-use/land-cover change and land management on the carbon cycle in terrestrial ecosystems has been widely reported. However, only rarely have studies have been conducted to clarify the impact of climate change and rising CO2 on the carbon sink contributed by ecological restoration projects (ERPs). To better understand the impact of climate change and rising CO2 on ERPs, we took the Beijing-Tianjin Sand Source Control Project zone as an example to set up different scenarios to distinguish the confounding effects of these factors on the regional carbon budget based on a remote sensing data-driven model. Compared with business as usual, our results show that climate change caused a carbon loss of 78.97 Tg C. On the contrary, ERPs contributed a carbon sink of approximately 199.88 Tg C in forest and grassland. Furthermore, rising CO2 also contributed an additional carbon sink of 107.80 Tg C. This study distinguished the individual effects of different factors, and clarified the net carbon sink contributed by ERPs and rising CO2 and their significance for enhancing the regional carbon sink and reversing the adverse effects of climate change on the carbon sink. Furthermore, ERPs can sequester carbon more effectively and faster compared with rising atmospheric CO2 concentration.