Hugh Pickens writes writes: "Coffee is the world's favorite beverage and the second-most traded commodity after oil. Now Nick Collins reports that rising global temperatures and subtle changes in seasonal conditions could make 99.7 per cent of Arabica-growing areas unsuitable for the plant before the end of the century and in some areas as soon as 2020. Even if the beans do not disappear completely from the wild, climate change is highly likely to impact on yields and the taste of coffee, a beverage of choice among slashdot readers, will change in future decades. "The worst case scenario, as drawn from our analyses, is that wild Arabica could be extinct by 2080," says Justin Moat. "This should alert decision makers to the fragility of the species." Arabica is one of only two species of bean used to make coffee and is by far the most popular, accounting for 70 per cent of the global market including almost all fresh coffee sold in high street chains and supermarkets in the US and most of Europe. A different bean known as Robusta is used in freeze-dried coffee and is commonly drunk in Greece and Turkey, but Robusta's high caffeine content makes it much less pleasant to most palates. In some areas, such as the Boma Plateau in South Sudan, the demise could come as early as 2020, based on the low flowering rate and poor health of current crops. The researchers used field study and 'museum' data (including herbarium specimens) to run bioclimatic models for wild Arabica coffee, in order to deduce the actual (recorded) and predicted geographical distribution for the species. "Arabica can only exist in a very specific pace with a very specific number of other variables," says Aaron Davis, head of coffee research at the Royal Botanic Gardens. "It is mainly temperature but also the relationship between temperature and seasonality – the average temperature during the wet season for example.""