Abstract
Rice is a historically important crop in Portugal. This crop development and production strongly depend on atmospheric conditions in the growing season. Given the strong dependence of climatic conditions, climate change may pose a significant risk for future rice production. In the present study, a high spatial resolution bioclimatic characterization over the main rice producing region in Portugal was performed for the recent past (1950–2000) and for the future (2041–2060) under four different anthropogenic forcing scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5). This zoning is performed by using eight bioclimatic indices, based on temperature and precipitation, using a very high resolution gridded dataset (Worldclim). For the future period, an 11-member global climate model ensemble was used, also taking into account model/scenario uncertainties and bias. Additionally, a new index was developed to incorporate the main features of temperature and precipitation at each rice field level. Under recent past climates, a clear north–south gradient in temperature and precipitation is apparent, with the regions of Tejo and Sado presenting higher temperatures and lower precipitation than the Mondego and Vouga regions. Additionally, there is a coastal–inland effect due to the Atlantic Ocean influence. Under anthropogenic climate change, all indices point to annual higher temperatures and lower precipitations across all rice producing regions, accompanied by increased seasonality. Furthermore, the rise of summertime temperatures may substantially increase water demands, which, when unmitigated, may bring physiological problems in the crop development. We conclude that climate change may negatively impact the viability of rice production in Portugal, particularly taking into account the national grown varieties. Thus, adequate and timely planning of suitable adaptation measures are needed to ensure the sustainability of this historically important food sector.
Highlights
Rice (Oriza sativa L.) is the second most widely cultivated and consumed cereal in the world, behind maize
The present study aims at analyzing the impacts of climate change on rice bioclimatic growth conditions in Portugal
The objectives of the present study are five-fold—(1) to analyze recent-past bioclimatic indicators over the Portuguese rice growing areas using historical high-resolution gridded datasets, (2) to compute future changes of these bioclimatic indicators using a large ensemble of high-resolution climate models, (3) to analyze uncertainties found in these climate change projections, (4) to develop a metric that combines all bioclimatic indicators, allowing to establish the impact of climate change on future rice growing zones, and (5) to discuss potential adaptation measures
Summary
Rice (Oriza sativa L.) is the second most widely cultivated and consumed cereal in the world, behind maize. Rice is the staple food for nearly two-thirds of the world’s population [1]. World average productivity of rice has been gradually increasing from 3.89 t ha−1 in 2000 to 4.40 t ha−1 in 2011 [2]. India and China are the countries with the largest rice area in the world (44 × 106 ha and 30 × 106 ha, respectively). These two countries are responsible for an annual production of over 300 × 106 tons [2]
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