Trends and Changes in Temperature, Precipitation, and Water Surplus and Deficit in China over the Last 30 Years

Dissecting the main features of climate change offers basic data for understanding how climate change affects ecosystem processes and provides scientific and technological support for climate change response. Over the last few decades, the rapid increase in temperature in the Chinese region has had a significant impact on ecosystems. However, few studies have hitherto focused on whether there are transitions in temperature and precipitation temporal trends and whether there are regional differences. Furthermore, the temperature and precipitation changes in the past decades have caused significant changes in moisture gain/loss levels, while the trends of moisture gain/loss in China have received poor attention. A sufficient understanding of the changes in moisture gain/loss levels in different regions can help us better understand the dry and wet changes in the region and improve the efficiency of water resource management and usage. Analyzing the temporal and spatial distribution of the turning points of temperature and precipitation changes will help understand the change trend of water profit and loss and spatial differences. Based on the observational data of 2479 meteorological stations in China, this study uses the segmented regression method to analyze the temporal change trends of annual average temperature, annual precipitation, and water surplus and loss from 1981 to 2015, and the temporal and spatial patterns of turning points. The main results are the following. (1) The national average temperature increased significantly from 1981 to 2015, which demonstrated obvious phase-change characteristics and regional differences: In Yunnan and in northern and northeastern regions, the temperature changed between 1991 and 1995, while the temperature in Yunnan began to increase significantly after 1991. The temperature transition period in most parts of southern Northeast and North China occurred between 1996 and 2000, and the temperature transition period in the southern coastal areas occurred between 2001 and 2005. The temperature increased significantly before the turning point, while it stagnated after the turning point. (2) The temporal precipitation trend in China from 1981 to 2015 significantly differs between different regions. In the arid areas of the western regions and the Shandong Peninsula, the annual precipitation increased significantly, while the precipitation in the southwestern region decreased significantly. In Shaanxi, Shanxi, and other places, the temporal trend of precipitation has turned. The precipitation decreased significantly before the turning point and increased significantly after the turning point. In most parts of the country, the number of precipitation days has decreased, the precipitation intensity has increased, and the frequency of extreme precipitation events has increased. (3) From 1981 to 2015, the water surplus and loss and the standardized precipitation evapotranspiration index in most areas of China dropped significantly, and China showed a trend of aridification. The temporal change trend of water surplus and loss occurred in Shanxi, Shaanxi, Yunnan, andYunnan. Shaanxi, Shanxi, and Yunnan decreased before the water surplus and loss turning point and increased after the turning point; Yunnan and other places increased before the water surplus and loss turning point and decreased after the turning point.