Effects of climate change on paddy expansion and potential adaption strategies for sustainable agriculture development across Northeast China

Sustainably feeding an increasing population is a grand challenge in the context of climate change and rapid urbanization. Over the past decades, there has been a remarkable trend in paddy expansion into the mid-high latitude regions of Northeast Asia, especially in China. Yet, knowledge on paddy expansion patterns and corresponding responses to climate change and socioeconomic factors are limited. To bridge this gap, satellite-based land use data for 1990, 2000, 2010 and 2018 at 30-m resolution, as well as historical and projected climatic data (including ERA5 data for 1982-2019 and GCMs data of CMIP5 for 2006-2050) and diverse socioeconomic data, were utilized to investigate patterns and quality changes of paddy fields across Northeast China. Results showed that the 0 degrees C isotherm moved northward by 270 km during 1961-2000 and 190.5 km during 2000-2019. Net paddy area expanded by 2.6 x 104 km2 in Northeast China during 1990-2018; in Heilongjiang Province, paddy area dramatically expanded by about 4.0 x 104 km2 during 1958-2018, of which 1.8 x 104 km2 and 2.2 x 104 km2 increment in 1958-2000 and 2000-2018, respectively. Even though climate hiatus occurred around 2010, the expansion rate of paddy area in Northeast China was up to 1.76 x 103 km2/a during 2010-2018. In addition to warming climate, improved agricultural technologies and physical inputs, increasing market demands, and agricultural policy implement were largely responsible for the paddy expansion in Northeast China. However, continuously cultivated paddy fields had generally more suitable natural conditions and better infrastructure than newly cultivated paddy fields. This study provides some potential suggestions for the sustainable development of modern agriculture in Northeast China.