Temporal and Spatial Dynamics of Summer Crop Residue Burning Practices in North China: Exploring the Influence of Climate Change and Anthropogenic Factors

Better understanding the complex mechanisms underlying the variations in crop residue burning (CRB) intensity and patterns is crucial for evaluating control strategies and developing sustainable policies aimed at the efficient recycling of crop residues. However, the intricate interplay between the CRB practices, climate variability, and human activities poses a significant challenge in this endeavor. Here, we utilize the high spatiotemporal resolution of satellite observations to characterize and explore the dynamics of summer CRB in North China at multiple scales. Between 2003 and 2012, there was a significant intensification of summer CRB in North China, with the annual number of burning spots increasing by an average of 499 (95% confidence interval, 252-1426) spots/year. However, in 2013, China promulgated the stringent Air Pollution Prevention and Control Action Plan, which led to a rapid decrease in the intensity of summer CRB. Local farmers also adjusted their burning practices, shifting from concentrated and intense burning to a more dispersed and uniformly intense approach. Between 2003 and 2020, the onset of summer CRB shifted earlier in North China by 0.75 (0.5-1.1) days/year, which is attributed to the combined effects of climate change and anthropogenic controls. Specifically, the onset time is found to be significantly and negatively correlated with spring temperature anomalies and positively correlated with anomalies in the number of spring frost days. Climate change has led to a shortened crop growing season, resulting in an earlier start to summer CRB. Moreover, the enhanced anthropogenic controls on CRB expedited this process, making the trend of an earlier start time even more pronounced from 2013 to 2020. Contrary to the earlier onset of summer CRB, the termination of local wheat residue burning experienced a notable delay by 1.0 (0.8-1.4) days/year, transitioning from mid-June to early July.