Climate Change in the Subtropics: The Impacts of Projected Averages and Variability on Banana Productivity

Abstract

The potential for bananas to produce year round is best expressed when water is abundant and daily temperatures are in the range of 20-30C. Zones with these conditions produce fruit for the global market. However, banana production, mainly for national markets, has developed in many subtropical areas under less than optimum conditions. Bananas are an important cash crop in southern Brazil, Paraguay and Argentina, in countries of North Africa, the Middle East and southern Africa, and in China and northern India. In these regions, bananas are subject to sub-optimum temperatures and short days. Highly favorable temperatures and long days in the summer may also include short periods of extreme temperatures above 35C, while rainfall is also highly variable. The effects of climate change on selected subtropical production areas were modeled in a two-step procedure using the EcoCrop model, under current growing conditions and for 2020 and 2050 using a set of 19 IPCC (Intergovernmental Panel on Climate Change) Global Climate Models (GCMs) under the SRES-A2 (business as usual) emission scenario. The modeling showed that current suitability for banana production in the subtropics is much lower than in the tropics with great variation in suitability within the subtropics. Of nine subtropical regions considered, two have improved conditions by 2020s, four are largely unaffected and three have a lower suitability. Our analysis also showed that, in terms of environmental conditions, certain sites are widely represented globally, offering options for technology transfer between sites. Other sites have few similar sites, which means that sites need to be carefully selected for approaches to technology development and transfer. The study leveraged site-specific information with widely available tools to understand potential effects of climate change in the subtropics. However, in order to fully understand the impacts of climate change on banana, the modeling tools used here need to be fully suited for semi-perennial crops to capture the effects of seasonal temperature and rainfall variability on crop cycle length and potential yields. INTRODUCTIONThe potential for bananas to produce year round is best expressed when water is abundant and daily temperatures are in the range of 20-30C (Simmonds, 1962). Numerous zones with

Climate change impacts on banana yields around the world

“…However, the optimum temperatures for regional models varied considerably, ranging from 20.1°C (95% CI = ± 0.1°C) for Brazil, to 30.4°C (95% CI = ± 0.1°C) for Africa (Fig 1; Supplementary table S2). Optimum total annual rainfall in our global model was estimated at 1673 mm (± 13 mm), which falls within the range previously reported 23 (900 mm -1700 mm). But again, regional models varied substantially (Fig 1;…”

“…In our global model, optimum mean annual temperature for banana productivity was estimated at 26.7°C (95% confidence interval = ± 0.04°C; Fig 1; Supplementary table S2), which is very similar to the commonly used optimum temperature of 27°C 10,22,23 . However, the optimum temperatures for regional models varied considerably, ranging from 20.1°C (95% CI = ± 0.1°C) for Brazil, to 30.4°C (95% CI = ± 0.1°C) for Africa (Fig 1; Supplementary table S2).…”

“…Hence, model fits are likely to be influenced by agro-economic factors in addition to banana plant physiology, and therefore, model interpretation requires caution (see Methods). Previous studies have largely assessed climate driven changes in the extent of land suitable for banana cultivation 10,22,23,28,29 , without considering the potential for competition with other staple crops and land-use types 30 . In contrast, analyses here focused on the more practical quantity of yield changes where bananas are already being grown.…”

Crop yield response to climate change varies with cropping intensity

“…Crop suitability was modelled using EcoCrop, which is a relatively simple suitability‐based model. It has been previously used to understand the geography of crop suitability and its responses to climate change for various crops, including banana (Ramirez et al ., ; Van Den Bergh et al ., ), cassava (Ceballos et al ., ; Jarvis et al ., ), sorghum (Ramirez‐Villegas et al ., ) and groundnut (Vermeulen et al ., ). EcoCrop has also been used to project future shifts in suitable areas for key staple foods across the globe (Lane & Jarvis, ).…”

Cyanobacteria From Brazilian Extreme Environments

“…Ecocrop has been used in banana (van den Bergh et al, 2012). Models such as Ecocrop use annual data for temperature and rainfall which limits their applicability for crops that have a 12-month cycle and that may use irrigation.…”