Will the banana get too hot?

Climate change could lead to lower yields in important crops

How does climate change affect banana crops? © skodonnell / istock
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Tropical fruits in trouble: Climate change could lead to significant crop losses in some banana-growing areas. As a forecast shows, it is just too hot and dry for the fruits of the world's largest producer India and in the important producer country of Brazil. But there is good news too: in some countries, the conditions for growing bananas may even get better in the future.

The banana is one of the most consumed fruits in our country. Their natural packaging, their pleasant sweetness and their satiating effect have made them a popular snack in the developed world. In many tropical and subtropical countries, banana is also an important staple food and represents an important economic factor as an export fruit.

"Given the importance of these fruits, it is surprising how little banana has been included in estimates of the impact of climate change on food and food security, " said Varun Varma and Daniel Bebber of the University of Exeter.

Do you risk crop losses?

Will global warming in banana harvesting possibly result in losses similar to those predicted by experts among others for wheat, corn or coffee? To find out, the scientists have now evaluated data on banana production in 27 countries. These nations account for 86 percent of global production and host 80 percent of the global acreage.

For their study, Varma and Bebber combined information on past years' returns with data on annual average temperatures and precipitation. Under what conditions could particularly many fruits be harvested in the respective regions? Based on these results, as well as information on the physiology of the banana, the research team finally developed models that depict the effect of climatic changes on the banana yield. display

Losses due to high temperatures

The results showed that annual harvests increased overall between 1961 and 2016 - an average of 1.37 tonnes per hectare. "This effect seems to have been driven mainly by rising temperatures, " explain Varma and Bebber. "Countries where warming has led to more ideal temperatures have seen productivity gains. Where the temperatures exceeded the regional optimum, crop yields were lost. "

According to the evaluations, the latter is true for four of the countries surveyed, but in the future, climate change in more banana-producing nations could have a negative impact, as the forecasts suggest.

India and Brazil as losers

For their glimpse into the future, the scientists used the climate scenario of unrestrained warming (RCP 8.5) as well as one in which climate protection at least provides for a mitigation of warming (RCP 4.5). The model simulations revealed that even with comparatively moderate warming, there will be significant crop reductions in ten countries over the next three decades.

Affected are therefore important banana exporters such as Colombia and Costa Rica. For India and Brazil - the largest and fourth largest producers - the model predicts significant losses. Other countries, on the other hand, could benefit from the progression of climate change. These include some African states and Ecuador, the export world champion in banana matters.

Weather extremes not yet taken into account

"Our predictions reveal that positive effects of climate change on global banana yields will continue in the future, but to a much lesser extent, " the researchers report. Overall, crop yields by 2050 could fall to 0.59 (RCP 4.5) or even 0.19 tonnes (RCP 8.5) per hectare.

However, as Varma and Bebber emphasize, these numbers only show part of the picture. Because they are based on average climate changes. "Other climate change-related threats, such as the increase in weather extremes, have not yet been taken into account, " they explain.

Mushroom as an additional threat

It seems clear that many important growers will have to adapt to noticeable changes in the future. "There will be winners and losers in the coming years, " says Bebber. The researchers hope that the countries now identified as vulnerable will respond by investing, for example, in irrigation technology and other measures.

"It is imperative that we prepare tropical agriculture for future climate changes, " concludes Bebber. However, heat and drought will probably not be the only challenge of the future. For even a dangerous fungus of the genus Fusarium from Southeast Asia threatens the banana. The pathogen has been spreading ever since the 1990s and is now also infecting fruits in East Africa and Central America. (Nature Climate Change, 2019; doi: 10.1038 / s41558-019-0559-9)

Source: Nature Press / University of Exeter

- Daniel Albat