Yousay Hayashi

Future climate change, the agricultural water cycle, and agricultural production in China

Abstract Climate change would have a major impact on the hydrological cycle and consequently on available water resources, the potential for flood and drought, and agricultural productivity. In this study, the impacts of climate change on the agricultural water cycle and their implications for agricultural production in the 2020s were assessed by water-balance calculations for Chinese croplands. Temporal and spatial changes in potential evapotranspiration, actual evapotranspiration, soil-moisture, soil-moisture deficit, yield index, and cropland surface runoff under the baseline climate and a HADCM2 general circulation model (GCM) climate-change scenario were mapped on a grid of 0.5° latitude/longitude resolution. According to the analysis, agricultural water demand in south China is projected to decrease generally, and the cropland soil-moisture deficit would decrease due to climate change. However, in north China, agricultural water demand is expected to increase, and the soil-moisture deficit would increase generally. The changes in the water resources would have consequent impacts on the yield index. Cropland surface runoff during the growing period is expected to increase on some sloping croplands in the southwest mountain areas and in some areas along the south coast. These changes would have important implications for agricultural production. Particularly the rain-fed crops in the north China plain and northeast China would face water-related challenges in coming decades due to the expected increases in water demands and soil-moisture deficit, and decreases in precipitation.

Changes in agricultural water demands and soil moisture in China over the last half-century and their effects on agricultural production

It has become obvious in recent years that water is the most critical resource for Chinese agricultural ecosystems. Changes in agricultural water demands and soil moisture have significant implications for China’s water supply, the potential for drought and flood, and agricultural production. In the studies, we explored the changing trends in agricultural water demands, the changing trends and variability in soil moisture associated with both drought and increased surface runoff in Chinese croplands during the last half-century, and their impacts on agricultural production. We plotted temporal and spatial changes in agricultural water demands, soil moisture, soil-moisture variability, soil-moisture deficit, yield index, and surface runoff on a grid of 0.5 ◦ resolution. We found a trend toward agricultural water demands increasing, soil drying and significant changes in soil-moisture variability on the North China Plain and the Northeast China Plain. There was a significant decrease in agricultural water demands and a significant increase in soil-moisture levels in Southwest China, and a generally insignificant increase or decrease trend in agricultural water demands and soil-moisture levels in Southeast China. These changes in agricultural water demands and soil-moisture levels had corresponding impacts on soil-moisture deficit, and consequently on agricultural production. Increased surface runoff was found in the mountainous areas of the southwest and northeast, and in some areas along the South Coast.

Climate Change Impact on Rice Insurance Payouts in Japan

Abstract The authors constructed the framework for a preliminary assessment of climate change impact on the rice insurance payout in Japan. The framework consisted of various models ranging from climate projection downscaling, rice yield estimation, yield loss assessment, and rice insurance payout estimation. In this study, a simulation was conducted based on the dynamically downscaled regional climate projection with a lateral boundary condition given by the global climate projection of the Meteorological Research Institute Coupled General Circulation Model, version 2 (MRI CGCM2), under the A2 scenario of the Special Report on Emission Scenarios (SRES). Results indicated that rice yield in the 2070s will decrease slightly in central and western Japan and increase in northern Japan. The increase in yield was derived from a significant reduction in yield loss caused by cool-summer damage; on the other hand, the decrease in yield was caused by the increase in yield loss caused by heat stress and the shorten...

Terrestrial Water Cycle and the Impact of Climate Change

Abstract The terrestrial water cycle and the impact of climate change are critical for agricultural and natural ecosystems. In this paper, we assess both by running a macro-scale water balance model under a baseline condition and 2 General Circulation Model (GCM)-based climate change scenarios. The results show that in 2021–2030, water demand will increase worldwide due to climate change. Water shortage is expected to worsen in western Asia, the Arabian Peninsula, northern and southern Africa, northeastern Australia, southwestern North America, and central South America. A significant increase in surface runoff is expected in southern Asia and a significant decrease is expected in northern South America. These changes will have implications for regional environment and socioeconomics.

Changes in the Southwest Monsoon mean daily rainfall intensity in Sri Lanka: relationship to the El Niño–Southern Oscillation

Abstract Daily rainfall data for 187 stations in Sri Lanka spanning the period 1960–1996 were analyzed to investigate the spatial and temporal characteristics of the mean rainfall intensity (MRI) through this time interval with special focus on the Southwest Monsoon (May–September). Particular emphasis was laid on temporal changes in the MRI series. The mean and standard deviation (SD) of the MRI data showed considerable spatial variation. Regression analysis expressing precipitation as a function of time at the various stations revealed distinct spatial trends; the results point to high MRI in lowland areas and low MRI in mountain areas. Principal Components Analysis of the temporal relationships among a reduced set of stations located in an equal-sized grid showed that the three dominant principal components (PCs) are characterized by the maximum and minimum mean and SD of the MRI series together with the mean number of rainy days. The first, second and third PC modes show significant patterns of the MRI data series over the northern half, southern half and southwestern coastal belt of Sri Lanka, respectively. The time series pattern of the dominant PC modes revealed distinct changes in MRI over time. A noticeable higher value in MRI was found from 1977 to 1996; this tendency is most pronounced for the first PC mode. The time series of the Southern Oscillation Index was found to be closely related to changes in the MRI patterns associated with the first PC mode. In addition, El Nino years coincide with low values of the first PC mode. Some La Nina years show a positive response for the first and third PC modes, while there is no clear response for the MRI pattern identified by the second PC.

Erratum to “Future climate change, the agricultural water cycle, and agricultural production in China”

Erratum to “Future climate change, the agricultural water cycle, and agricultural production in China” [Agric. Ecosyst. Environ. 95 (2003) 203–215] Fulu Tao a,∗, Masayuki Yokozawa b, Yousay Hayashi b, Erda Lin a a Chinese Academy of Agricultural Sciences, Agrometeorology Institute, Beijing 100081, China b National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan

Erratum to “Future climate change, the agricultural water cycle, and agricultural production in China”: [Agric. Ecosyst. Environ. 95 (2003) 203–215]

Erratum to “Future climate change, the agricultural water cycle, and agricultural production in China” [Agric. Ecosyst. Environ. 95 (2003) 203–215] Fulu Tao a,∗, Masayuki Yokozawa b, Yousay Hayashi b, Erda Lin a a Chinese Academy of Agricultural Sciences, Agrometeorology Institute, Beijing 100081, China b National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan

Erratum: Future climate change, the agricultural water cycle, and agricultural production in China (Agriculture, Ecosystems and Environment (2003) 95 (203-215))

Erratum to “Future climate change, the agricultural water cycle, and agricultural production in China” [Agric. Ecosyst. Environ. 95 (2003) 203–215] Fulu Tao a,∗, Masayuki Yokozawa b, Yousay Hayashi b, Erda Lin a a Chinese Academy of Agricultural Sciences, Agrometeorology Institute, Beijing 100081, China b National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan