Rapid climate changes responsible for increased net global cropland carbon sink during the last 40 years

Cropland ecosystem is an essential site for the terrestrial carbon cycle. However, the carbon sink potential has been severely underestimated or even considered nonexistent since the carbon sink capacity of the cropland ecosystem has been long neglected, which leads to a dearth of systematic comprehension regarding the carbon sink potential, evolutionary trends, and driving mechanisms of cropland ecosystem. We attempted to select GPP, NPP, and NEP as indicators to represent cropland carbon sink and designed six scenarios to reveal the spatiotemporal evolution characteristics and climate-driven mechanism of the global cropland ecosystem carbon sink. The results demonstrate that the global cropland ecosystem carbon sink has shown great potential during 1982–2018. Despite the consistent increase in global soil respiration, the three carbon sink indicators of gross primary productivity, net primary productivity, and net ecosystem productivity all exhibited significant upward trends driven by climate change, with average growth rates of 2.41, 2.38, and 0.34 g C m−2 yr−1, respectively. The increase in CO2 concentration is the most crucial climate factor influencing carbon sink growth in cropland ecosystem (29.89 %), controlling the rise of carbon sink across 32.58 % of global cropland areas. This study provides new theoretical guidance for consolidating and enhancing ecosystem carbon sink to promote the achievement of global carbon neutrality goals.