Coffee production and prices have always been sensitive to climate change. For over a century now, whenever Brazilian producers are affected by a frost, prices rise, and supply becomes reduced. Even as recently as this year, key coffee-growing regions in Brazil were affected by frost, leading to a much-needed rise in prices for producers across the rest of the world. Also, the occurrence of extreme events is expected to be altered by climate change; some, such as excessive rainfall, may affect coffee flowering and drastically reduce yields .
Less known is coffee’s contribution to climate change with increasing intensification of production over recent decades, leading to higher use of fertilizer and irrigation, and a reduction in the use of shade trees. Nevertheless, over the past 10–15 years, producers and traders have become more aware of the impacts of climate change on the sustainability of supply. One of the first responses was from UK-based CaféDirect who launched a climate adaptation project in the mid-2000s, and have also been offsetting their emissions by purchasing verified carbon credits from reforestation undertaken by their producer suppliers .
More recently, last year, one of the world’s largest coffee processors, Nestlé, committed to achieving net zero carbon emissions by 2050, not just in its own operations, but along the whole of its supply chain, and more immediately halving greenhouse gas emissions by 2030. Within the coffee sector, they have committed to 100% sustainable sourcing and promoting coffee agroforestry where trees are planted to shade the coffee, which would also contribute to carbon sequestration. Once an interest only of smaller specialty coffee companies, this commitment has heightened interest amongst other companies, in achieving net zero carbon across the coffee sector, including major suppliers of Nestlé, with potential impacts from production through to trading. But how easy is it to achieve carbon neutrality through shaded coffee?
We know that shaded coffee plantations can hold significant stocks of carbon – about a third to a half of that of a forest, which is two or three times more than coffee plantations without shade trees. If you compare the carbon sequestered by shaded and unshaded coffee over a short timeframe, in a decade, the carbon sequestered by newly planted trees can even compensate the greenhouse gas emissions from the agronomic management of coffee – incorporating labour, fertilizer and other inputs for crop production – particularly from the use of nitrogen fertilizer . While the addition of shade trees to coffee plantations previously produced as monocultures can lead to an increase in carbon stocks, if coffee productivity declines, there is a danger that you would need a larger area under coffee production to meet global demand, potentially replacing forest. Our research in Central America where shade is traditional suggests that highly productive coffee can be combined with shade trees , but this requires experience to manage and may not be replicable in Brazil or Vietnam where much of the coffee is grown with irrigated or mechanized systems. Also, we have identified that some of the current coffee areas are expected to become marginal or unsuitable for coffee cultivation in the following decades, therefore being at risk of carbon loss due to changes to other less tree-intensive agricultural activities. Across Central America, 90% of the coffee area will experience a reduction in suitability, having a negative impact on the quantity and quality of the coffee produced, and therefore on income generation and economic sustainability of coffee farming for rural households .
Another challenge is that the carbon sequestering benefits of the trees are greatest when newly planted, but what about traditional coffee plantations that have been grown with shade trees for decades? While we know a lot about the carbon stocks of these systems, we know little about whether they are still actively sequestering carbon, or if they may have reached a stable state. Over past decades we have seen these traditional plantations removed or intensified due to their lower productivity , or establishment of new coffee plantations in forest areas under high coffee price years resulting in loss of carbon due to tree loss and/or land use change. Through its environmental payments scheme, Costa Rica has long provided support for new tree planting to convert coffee monocultures to shade agroforestry systems. However, this led to complaints that this provided funds to farmers who had previously removed shade, but those farmers who had maintained traditional shaded coffee systems were not eligible. In response to this, new incentive criteria have been developed, where shaded coffee that meets certain criteria of tree density and species diversity may receive payments. This is similar in principle to payments for forest conservation from REDD+ (the United Nations Collaborative Programme on Reducing Emissions from Deforestation and forest Degradation). Unfortunately, although the criteria are established, to date very little funding has been made available for this scheme.
To understand whether or to what degree established coffee agroforestry can contribute to the net zero carbon aims of the coffee sector, we need further research on these coffee systems. Long-term monitoring of the changes in carbon stocks and carbon emissions of established plantations is required, together with tools that represent the potential trade-off between farming practices for mitigation and adaptation to inform the coffee sector’s responses to climate change .
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