Correlation changes between rice yields in North and Northwest China and ENSO from 1960 to 2004

The correlations between ENSO (El Nino/Southern Oscillation) and crops in China have been recognized, but the research focusing on the causes behind the correlations still remains incomplete. in this study, we concentrate on the causal relationship between ENSO and rice yields in North and Northwest China. We found that there was an inconsistency in the observed correlation between rice yields and the occurrence of ENSO events during various periods from 1960 to 2004 in most provinces. Rice was vulnerable to El Nino events before 1980, while it seemed to benefit from the occurrence of such events following 1980. We established the reason for the change through a combination of mechanistic modeling and empirical statistical analysis. We concluded that much of this inconsistency in yield responses to ENSO can be attributed to the development of water supply systems throughout our study region. The meteorological impacts associated with ENSO events varied with water regime. This important finding provided a key explanation into the interaction processes between ENSO climate variability and the water supply in the rice production system, and further confirmed the importance of considering interactive effects between climate variability and human adaptation practices when assessing climate change impacts on agricultural variability. (C) 2008 Elsevier B.V. All rights reserved.