Crucial stock of genetic diversity could be lost to climate change
By Summit Voice
SUMMIT COUNTY — Coffee drinkers shouldn’t their favorite beverage for granted, according to researchers with London’s Kew Royal Botanic Gardens. Global warming could lead to the extinction of wild Arabica coffee plants well before the end of the century.
The study shows that climate change will cut Arabica habitat between 65 and 99 percent, even without factoring in the large-scale deforestation that has occurred in the highland forests of Ethiopia and South Sudan (the natural home of Arabica coffee).
The scientists also identified core habitat areas that could be used as preserves to try and maintain a population of Arabica coffee plants.
Wild Arabica is important to the entire coffee industry as a stock of genetic diversity. The plants are very sensitive to temperature and moisture in very localized microclimates, and coffee harvests have already suffered in recent years, with coffee prices soaring to their highest level in 30 years.
The Arabicas grown in the world’s coffee plantations are from very limited genetic stock and are unlikely to have the flexibility required to cope with climate change and other threats, such as pests and diseases.
“Coffee plays an important role in supporting livelihoods and generating income, and has become part of our modern society and culture,” said Aaron Davis, head of coffee research at the Royal Botanic Gardens. “The extinction of Arabica coffee is a startling and worrying prospect. However, the objective of the study was not to provide scaremonger predictions for the demise of Arabica in the wild. The scale of the predictions is certainly cause for concern, but should be seen more as a baseline, from which we can more fully assess what actions are required.”
“The worst case scenario, as drawn from our analyses, is that wild Arabica could be extinct by 2080. This should alert decision makers to the fragility of the species,” said Justin Moat, head of spatial information science at the Royal Botanic Gardens.
“Our aim is to develop and apply these analyses to other important and threatened plants, on a routine basis. There is an immense amount of information held in museum collections around the world, such as Kew, and we have only just started to unlock their potential for assessing some of society’s most pressing issues,” Moat added.
“As part of a future-proofing exercise for the long-term sustainability of Arabica production it is essential that the reserves established in Ethiopia to conserve Arabica genetic resources are appropriately funded and carefully managed,” said Tadesse Woldemariam Gole, of the environment and coffee forest forum in Ethiopia.
The research confirmed the climate sensitivity of Arabica, supporting the widely reported assumption that climate change will have a damaging impact on commercial coffee production worldwide. These are worrying prospects for the world’s favourite beverage – the second most traded commodity after oil, and one crucial to the economies of several countries.
First, the researchers used field studies and museum data, including herbarium specimens to estimate the distribution of the species. Then they used climate models to try and predict how climate conditions will change in that habitat, based several different emissions scenarios. The models showed a profoundly negative influence on the number and extent of wild Arabica populations.
A visit to the Boma Plateau in South Sudan provided an opportunity to test the modelling predictions via on-the-ground observation. On comparing these observations with a study on Arabica made on the Boma Plateau in 1941, it was clear that not all of the environmental stress evident could be attributed to deforestation or agriculture over the 70 year period.
The modelling predicted that Arabica could be extinct in these forests by the year 2020, due to climate change, and this appears to be realistic given the poor health (lack of seedlings, loss of mature Arabica specimens, low frequency of flowering and fruiting) of the remaining populations observed in 2012.
The outcome of climate change in Ethiopia for cultivated Arabica, the only coffee grown in the country, is assumed to be profoundly negative, as natural populations, forest coffee (semi-domesticated) and some plantations occur in the same general bioclimatic area as indigenous Arabica.
Optimum cultivation conditions are likely to become increasingly difficult to achieve in many pre-existing coffee growing areas, leading to a reduction in productivity, increased and intensified management, including the use of irrigation, and crop failure.
The researchers hope the study will form the basis for developing strategies for the survival of Arabica in the wild by identifying a number of core sites that might be able to sustain wild populations of Arabica throughout this century, serving as long-term in situ storehouses for coffee genetic resources.
In many areas of Ethiopia, loss of habitat due to deforestation might pose a more serious threat to the survival of Arabica, although it is now clear that even if a forest area is well protected, climate change alone could lead to extinction in certain locations. The study also identifies populations that require immediate conservation action, including collection and storage at more favorable sites (for example in seed banks and living collections).
The research was published in PLOS ONE on 7 November 2012.