Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman Research article Evidence of climatic change in Vietnam: Some implications for agricultural production Kien Nguyen Duc a,b,∗ , Tiho Ancev b , Alan Randall b,c a Faculty of Economics and Development Studies, University of Economics, Hue University, 99 Ho Dac Di Street, Hue City, Viet Nam b School of Economics, The University of Sydney, Sydney, NSW, 2006, Australia c Environmental & Development Economics, The Ohio State University, Columbus, OH, OH 43210, USA ARTICLE INFO Keywords: Climate change Spatio-temporal pattern Statistical methods Geostatistical techniques Farming Vietnam ABSTRACT Systemic changes in environmental conditions, such as climate, can have a significant impact on both natural and human systems. This paper provides an improved understanding of the spatio-temporal variations in un- derlying climate processes, and the potential effects climate change may have on Vietnam's agricultural sector. Statistical methods were combined with geostatistical techniques to test the statistical significance of long-term trends in the climatic variables, graphically representing the distribution of climate patterns, identifying var- iations and trends of changes over time and their likely effects on agricultural production. By using records of monthly precipitation and temperature for a relatively long-term period (1975–2014) over a high density of 112 meteorological stations across the country, robust statistical and visual evidence of climatic change throughout Vietnam are provided. The Mann-Kendall trend test confirms the statistically significant long-term trends of rainfall and temperature in many regions across the country. The visual analysis shows remarkable changes in the spatio-temporal distribution patterns of those variables and most of the ‘hotspot’ areas identified by geos- tatistical mapping are in areas with confirmed long-term trends. The long-term significant trends are also concentrated in areas with very high proportion of agricultural land, particularly land used for rice production in the Red River and Mekong River deltas. The findings deliver a better understanding of underlying climate processes and impacts across regions of Vietnam and provide a basis to develop effective climate-related policies for agricultural production in response to changing climatic conditions. 1. Introduction Climatic conditions are changing across the globe but vary in di- rection, frequency, and intensity by location. The Intergovernmental Panel on Climate Change notes that globally averaged surface tem- perature showed an increasing linear trend of 0.85 °C between 1880 and 2012 (Stocker et al., 2014). It is also very likely that extreme weather events have increased in frequency and intensity on a global and local scale (Caesar et al., 2011; Pingale et al., 2014). In Vietnam, from the 1970s the recorded average temperature has increased by 0.26 ± 0.10 °C per decade, twice the rate of global warming for the same period (Nguyen et al., 2013). Total annual rainfall is dominated by a negative trend in five out of eight climatic zones of Vietnam (Nguyen et al., 2013). Changes in climate have also intensified the in- cidence and magnitude of extreme events such as floods, droughts, and typhoons. It has been estimated that climatic change may directly affect the livelihoods of about 10–12% of Vietnam's population and lead to the loss of approximately 10% of Gross Domestic Product (VNGP, 2011). Furthermore, the country's most climate-dependent activity – agricultural production – still dominates Vietnam's economy, ac- counting for 22% of GDP and 54% of the labor force (GSO, 2014). A better understanding of the pattern of climatic variability and change at various spatial and temporal scales is crucial to provide rig- orous evidence-based information to policy-makers at all levels in the decision-making process and to guide the development and im- plementation of appropriate adaptation responses (Conway et al., 2015; Nam et al., 2016). At the global and regional scales, a substantial number of studies have investigated and documented the changing patterns of climatic variables across space and time (Kundu et al., 2015; Nam et al., 2016; Portmann et al., 2009; Río et al., 2011; Stocker et al., 2014). However, most previous studies have concentrated either on testing the spatial and temporal trends in climate-related variables using statistical trend analysis methods such as the Mann-Kendall and Spearman rho tests (Jaiswal et al., 2015; Pingale et al., 2014; Xu et al., https://doi.org/10.1016/j.jenvman.2018.10.011 Received 10 April 2018; Received in revised form 3 October 2018; Accepted 4 October 2018 ∗ Corresponding author. Faculty of Economics and Development Studies, University of Economics, Hue University, 99 Ho Dac Di Street, Hue City, Viet Nam. E-mail address: ndkien@hce.edu.vn (K. Nguyen Duc). Journal of Environmental Management 231 (2019) 524–545 Available online 26 October 2018 0301-4797/ © 2018 Elsevier Ltd. All rights reserved. T