Increasing Accumulated Temperature Pushed the Maize Planting Limit Northwards: Phenomenon Analysis and Coping Strategy

Climate warming is driving the northward movement of crop planting limits, especially for maize in Northeast China. While previous studies focused on dynamics of the potential northern limit of maize (PNLine), the movement of the actual northern limit of maize (ANLine) and its agricultural impacts remain underexplored. To bridge the gap, this study first developed a method to detect the ANLine using satellite‐derived crop data and kernel density estimation. To assess the driving factors behind the expansion of maize acreage, an empirical analysis was conducted in the maize‐soybean key competitive region (KCR). Finally, we calculated the climate‐warming driven maize acreage expansion over the past two decades and projected its changes for the next decade. Results showed that the PNLine and ANLine moved northwards by an average of 101.67 and 75.4 km from 2000 to 2020. The two lines showed a strong correlation ( r = 0.78, p < 0.05). The increasing accumulated temperature was the key driver behind these movements. A 10°C·d increase in AAT10 is associated with a 3.12% increase in maize acreage in the KCR. From 2001 to 2020, ∼49.5% (2.83 × 10 6 ha) of the maize acreage expansion could be attributable to climate warming. By 2030, climate warming is projected to expand the maize acreage by 2.43, 2.66, and 3.19 × 10 6 ha under the SSP1‐2.6, SSP2‐4.5, and SSP5‐8.5 scenarios. These findings highlight the need for strategies to narrow the profit gap between maize and soybean, offering insights for regional crop planting structure adjustments and agricultural sustainability under climate change.