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As we sip our lattes and espressos and read the daily headlines, climate change can seem like a distant threat.  But travel a few thousand miles to the source of your caffeine fix, and the turbulence is all too real.

Consider the coffee farmers in Chiapas, Mexico, recently interviewed by researcher Elisa Frank from the University of California, Santa Barbara. Compared to the gentler showers they were used to, they are now seeing violent downpours that waterlog the plants in their care. “When we were growing up, the rains didn’t fall this much,” one interviewee told Frank. “The plants produce less. The leaves and fruit fall because of the wetness.”

Where farmers once enjoyed stable, mild conditions, the temperature now seesaws between cold that stunts growth, and heat that dries the berries before they can be harvested. Then there are the hurricanes and landslides; sometimes, the mud can swallow up plantations. As one farmer put it: “The weather is very strange. Strange things come that we didn’t see before.”

Peak coffee

These problems are by no means confined to Mexico. Farmers across South America, Asia and Africa are watching coffee plants dwindle as droughts, downpours, and plagues of pests attack their crops, as a result of global warming.

The world currently enjoys a two-billion-cup-a-day habit. How can we ensure that we get that caffeine fix in a turbulent climate?

The consequences of this unrest could soon work their way through the pipeline to your local coffee shop. The world currently enjoys a two-billion-cup-a-day habit. How can we ensure that the coffee still flows, when the crops are being ravaged by extreme weather? And if the farmers can’t meet that demand, will we soon reach “peak coffee”?

Some worry that our efforts to combat these challenges will only create further environmental devastation. Others suggest that the only solution is to change the beloved flavour of the drink itself. Whatever the answers, savour your espresso while you can: we may be facing the end of coffee as we know it.

Plagues of coffee rust devastated farms in Nicaragua last year - perhaps a foreboding sign of things to come (Credit: Getty Images)

The problem arises, in part, from the refinement of our palette. There are two main breeds of commercial coffee: the more aromatic Coffea Arabica, and the more bitter Coffea Robusta variety. Thanks to its complex flavours, Arabica is by far the world’s favourite, accounting for about 70% of the coffee we drink.

Those genteel qualities that we favour come at the price of the plant’s physical strength, however: it is far more sensitive to stress than its more robust cousin. As BBC Magazine recently explained, almost all the commercial Arabica plants have been bred from a very small stock taken from the mountains of Ethiopia – giving it very little genetic diversity and making it particularly vulnerable to climate change. The plant grows best between a very narrow range of relatively mild temperatures – 18 to 22C – and needs gentle, regular rainfall. “It needs a very particular climate that you can only find in a few locations around the globe,” says Christian Bunn at the Humboldt University in Berlin. That makes it very different from other crops, like corn – plants bred for thousands of years to adapt to many different environments.

Will our caffeine fix come at a heavy cost for the environment? (Credit: Getty Images)

The delicate Arabica plants just can’t cope with the new and unpredictable conditions that come with global warming. In Mexico, for instance, the rising temperature seems to have brought heavier rainfall, which is battering the plants before they have time to seed. “The coffee plant only flowers for 48 hours, so if something happens during flowering – if there’s a big storm – then the whole crop is destroyed,” explains Ainhoa Magrach at the Institute of Terrestrial Ecosystems, ETH Zurich.

Even when the plants did blossom, the berries were shrivelled and small

Other places have the exact opposite problem: drought. When Oxfam questioned coffee producers in the Rwenzori Mountains of Uganda, they complained that hotter, drier seasons were causing the plants to drop their flowers before they had turned to fruit. Even when the plants blossomed, the beans were shrivelled and small. Further stresses come from the fact that the coffee plant’s enemies can thrive in hotter weather – including pests such as leaf miners, coffee berry borers, mealy bugs and diseases like leaf rust, all of which ravage crops. During one of the most recent epidemics, Central America saw its harvests drop by 20% in 2013, after an onset of leaf rust  – and such events may be more common as the climate warms even more.

Calculating the long-term costs isn’t straightforward - it can be difficult to separate single, freak events from broader trends - but looking at coffee yields in Tanzania since the 1960s, one team has found that the crops fell from a high of 500kg per hectare to just over 300kg today. Importantly, the drop seems to closely follow a temperature rise of about 0.3C per decade, and an associated reduction in rainfall.

A whole year's coffee harvest can depend on just a few days of blossom, during which the plants are vulnerable to the extreme weather (Credit: Science Photo Library)

All of which paints a bleak picture for the future. Using the latest figures for climate change across the globe, Bunn’s calculations predict that the land suited to farming Arabica could drop by as much as 50% by 2050. Classic coffee-producing regions, such as Vietnam, India and most of Central America, will be hit particularly hard.

We can expect coffee to become more of a luxury, with prices shooting up by around 25% by 2050

The consequences will be serious for farmers and coffee lovers alike. For one thing, we can expect coffee to become more of a luxury, with prices shooting up by around 25% by 2050 according to Bunn’s calculations for his PhD thesis. It will be particularly noticeable, he says, considering that most other crops are set to become cheaper and cheaper as technology and productivity continues to improve. When that’s taken into account, coffee will in fact be 50% more expensive than it would have been without climate change, Bunn says.

It’s unlikely the farmers will see the profit. After years of turmoil, many may just choose to switch to more stable crops. “When we take our results and confront coffee producers, everyone tells us this is true – people in low-elevation Central America are already giving up on coffee production,” Bunn says. “Everyone is shifting to rubber plantations.”

The livelihood of 25 million people may depend on scientists finding a way to protect vulnerable coffee plants and their ripening berries (Credit: Getty Images)

The demand for coffee can only be met if we encroach on 2.2 million hectares of valuable rainforest

Given the money on offer, others will almost certainly move to fill our empty cups – and that could come at a huge cost to the environment. Magrach recently mapped out the areas suitable for Arabica farming and compared it to areas of natural interest. In the worst case scenario, she found that we will need to encroach on 2.2 million hectares of rainforest to meet the predicted demand – an area about the size of Wales. The result would be a significant loss of biodiversity.  

There may be better solutions. Given its hardiness, Robusta will be better able to weather the changes; Magrach’s models even suggest that its preferred habitat may grow as a result of the rising temperatures. If so, a simple change in taste may offset the coffee crash – provided we can grow to love its bitterness. “It would definitely be better for the forests,” says Magrach.  At the very least, she hopes that food labelling will make it clear in future whether the beans were farmed from vulnerable areas, so that consumers are aware of the environmental cost and can shop more ethically.

Others hope that improved farming techniques will instead keep the coffee flowing. Along these lines, the Coffee and Climate initiative is helping more than a dozen different coffee producers to join forces and share notes on the best ways to deal with the oncoming challenges. One option, for instance, is to graft Arabica strains to the roots of Robusta plants, making a hybrid that is more resistant to drought while retaining the preferred aromatic flavour.  Alternatively, selective breeding could help produce a variety that combines the best of both Robusta and Arabica. “It’s something people are working on, but we’re not sure when the new strains will be available,” adds Magrach.

The livelihoods of farmers and others in the coffee business – at least 25 million people according to one estimate – depend on us finding an answer, fast.  For the time being, the farmers face daily uncertainty, as Elisa Frank found during her interviews in Mexico. It can be hard to weather. Although many of the farmers listen to the TV forecasts, and try to prepare for the oncoming downpours, they can’t help but feel helpless, swept away by forces beyond their control.

Some of the farmers feel that the subject has almost become a taboo. “We talk very little about climate,” one told Frank. “We already know how it is here – and there is nothing we can do.”

David Robson is BBC Future’s feature writer. He is @d_a_robson on twitter.

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