VOA常速英语2019--由于气候原因 咖啡品种不断减少（在线收听）

It’s a really long way to go for coffee, but the coffee these scientists are looking for you won’t find at your local cafe. This is a rare wild relative that grows in the jungles of Sierra Leone. Coffee has 124 of these cousins across tropical Africa and Asia, but 60% of the family is at risk of extinction, says Aaron Davis, head of coffee research at the Royal Botanic Gardens, Kew.

So the main threat to the world’s coffee species is deforestation, and that’s because most coffee species actually occur in forests. Those forest species may fight off disease better than domestic coffees, or they may do better in a drought where they may tolerate higher temperatures better. Davis says those traits are increasingly important as the planet heats up.

The species we grow occur in very narrow climate envelopes. That means that as the climate changes, as temperatures increase and rainfall decreases, the suitable area for growing this coffee diminishes. That means trouble for coffee-producing countries where the bean is a major source of income. An estimated 100 million small farmers worldwide grow coffee.

Climate change threatens wild coffee too. That’s why Davis and his colleagues are searching the jungles for them now. We don’t want to be in a situation where we find ourselves for acquiring some wild plant or some wild genes only to find actually it’s extinct in the world. Davis and colleagues say there’s no time to waste. Their new study found nearly half of all coffee species are absent from the world seed banks.

这条寻咖啡之旅是漫长之旅，但科学家寻找的咖啡并不是在当地咖啡馆能找到的寻常咖啡。这种咖啡是一种罕见的野生亲缘植物，长在塞拉利昂的丛林中。咖啡在非洲和亚洲有124类亲缘植物，但这个大家庭里有60%的部分要灭绝了，英国皇家植物园的戴维斯如是说道。

所以，全球咖啡品种面临的主要威胁是森林砍伐。这是因为，大多数咖啡品种都在森林中生长。这些依赖森林生长的品种比家庭种植的咖啡能够更好地抵御疾病，也能更好地应对干旱，可能可以更好地经受住高温。戴维斯表示，这样的性征是在全球变暖背景下愈发重要的品质。

我们种植的植物对生长的气候环境要求严苛。所以，随着气候变化的加剧，气温会升高，降雨量会减少，种植这种咖啡的适宜区域也会缩减。这对于盛产咖啡的国家来说是灾难，因为咖啡豆是他们的主要收入来源。预计全球有1亿名小农种植咖啡。

气候变化也威胁着野生咖啡的生存。因此，戴维斯及其同事现在正在丛林中搜索咖啡豆的踪影。我们不想走到这样一步：想要获取野生咖啡或者其基因，但最后却发现它已经从这世界上灭绝了。戴维斯及其同事表示，现在分秒必争。他们的最新研究发现，近半数咖啡品种在世界种子库里已经不存在了。