Increasing cropping intensity in response to climate warming in Tibetan Plateau, China

Effects of global warming on agriculture have attracted lots of attention; however, agricultural response to climate change has been hardly documented in alpine regions. The Tibetan Plateau (TP) has a low agricultural portion, but it is an increasing minority, which plays an important role in regional food security due to growing population. The region of Brahmaputra River and its two tributaries in Tibet Autonomous Region (BRTT) is the main alpine agricultural area in the TP. Rapid warming has substantially affected agro-climate resources there and altered cropland pattern as well as cropping intensity. In this study, we explored how climate warming affected cropping intensity in past decades in BRTT. The potentially spatial distributions of single and double cropping systems in different decades (1970s, 1980s, 1990s and 2000s) were simulated based on a cropping suitability model, considering climatic, terrain and water factors. The results showed a significant increase of cropping intensity in some regions, in response to climate warming. The area suitable for single cropping increased from 19 110 km2 in 1970s to 19 980 km2 in 2000s, expanding from the downstream valleys of Lhasa River and Nyang Qu River of the tributaries of Brahmaputra to upstream valleys. The area suitable for double cropping gradually increased from 9 km2 in 1970s to 2015 km2 in 2000s, expanding from the lower reaches of Brahmaputra River in Lhoka Prefecture to the upper ones, as well as the Lhasa River tributaries. The upper limit elevation suitable for single cropping rose vertically from 5001 m above sea level (ASL) to 5032 m ASL from 1970s to 2000s, meanwhile that of double cropping rose from 3608 m ASL to 3813 m ASL. Overall, increased cropland area and cropping intensity due to climatic warming could increase food production in BRTT to some extent. Further investigation about potential uncertain effects from warming is still needed for regional agricultural adaption to climate change.

► The response of alpine agriculture to climate change was explored in Tibet.
► Cropping intensity in central Tibet increased significantly due to climate warming.
► Agriculture could benefit from the cropping extension and intensification in Tibet.
► Cropping suitability assessment implied spatial pattern for future land exploitation.