Climate Variability and Rice Production in Mainland Southeast Asia

Variations in crop yields and production over time are controlled by a combination of climate, genetics, management, socioeconomic variables, and government policies. By discerning the individual roles of these different influences, we can better understand the capacity of agricultural systems to adapt to change. Here we explore the impact of climate variability on rice yield in Mainland Southeast Asia (MSEA) from 1961-2017. We examine variations on three different spatial scales: MSEA region (all five countries: Cambodia, Laos, Myanmar, Thailand, and Vietnam), country-level yields, and province-level yields for Vietnam. Annual rice yields over this period have nearly tripled due to genetics and management, with Vietnam experiencing the largest increases. Spatial regression results between annual rice yield anomalies and climate data at the regional and country levels reveal clear influences of the El Niño-Southern Oscillation (ENSO) and the Pacific Meridional Mode (PMM). At the province level in Vietnam, many provinces show similar correlation patterns for winter-spring season rice (e.g., the co-occurring negative phase of ENSO (La Niña) and positive PMM lead to increased yields), however, summer rice shows much weaker patterns in the Pacific and Indian Ocean basins. Variations across provinces were also noted, particularly between the Red River and Mekong River Deltas. The history of this 56 year period, which included the Vietnam-American War and changes in land management policies in the Red River and Mekong Deltas, make it challenging to disentangle effects of ENSO/PMM and social factors on rice yields in these areas. However, these results highlight the importance of using a multidisciplinary approach and considering several spatial scales to help inform local decision making.