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Coffee & Climate Change

Coffee is the seed of small cherry-like fruit and could be one of the major casualties of climate change. Recent research has found that climate change is already the delicate cycle of the coffee fruit's growth. If we continue on our present course coffee production will rapidly decrease in the countries that currently produce 75% of the world’s Arabica coffee.

This is not just bad news for coffee lovers. The entire livelihoods of millions of farmers, almost half of which live below the UN poverty line already rely on the coffee industry.

What is Arabica coffee?

Arabica coffee is one of the two main coffee plants that beans are harvested from, the other being Robusta. The genetic difference between Arabica and robusta is the same as the difference between apples and pears.

Arabica is the world’s most popular coffee variety and is the coffee found at specialty coffee shops. Arabica is also the the species of coffee used to create coffee leaf.

Where is Arabica coffee grown?

Although it originated in Ethiopia, Arabica is grown throughout Central America, Africa, and Asia. Producers farm coffee within a narrow region of the tropics known as the Coffee Belt. Brazil, Columbia, and Ethiopia are the world’s largest producers of Arabica, and millions of farmers in these countries’ entire livelihoods rely on the continued prosperity of the crop.

Arabica favours growing in areas where the average annual temperature stays between 18 to 23 degrees C. With such a narrow range of temperature Arabica is extremely sensitive to changes in climate. Heavy storms or temperature fluctuations often result in reduced yield. A key example was in 2021 when coffee production dropped by a third in Brazil following one of the worst droughts in recorded history, and prices skyrocketed as a result.

How is coffee impacted by climate change?

Impact of temperature of coffee yield

Research published in 2022 found that a global increase in temperature of 2 to 3 degrees C could result in a drastic decline in coffee production from the world’s leading producers.

Coffee plants are affected by temperature increases because hot, dry air means more moisture is removed from the plant, restricting its growth. The study, published in the Nature Food journal, examined the vapour pressure deficit (VPD) threshold in preference to temperature or rainfall figures as the former value gives a better indicator of how hot and dry the air is.

As temperatures increase, the vapour pressure deficit increases and the higher this value the more moisture is removed from coffee plants. The study found that there is a critical point in VPD after which the yield of Arabica coffee rapidly declines to the extent of 400 kilograms per hectare. A global increase in temperature of 2.9 degrees C could see the critical VPD reached in the countries that represent 90% of the global coffee production.

The study found that if the increase in global temperatures with climate change can be slowed to less than 2 degrees C in the coming century, then the coffee producers will have more time to adapt.

If we pass 2 degrees not only will production decrease, supply be interrupted, and coffee prices rise for the consumer soar, but the income and livelihoods of thousands of farmers across the globe will be devastated.

As temperatures change so does weather. Coffee relies on a cycle of a rainy season to give the plant moisture which induces it to grow flowers and then in turn the flowering will begin the fruit growing cycle. Erratic weather like strong rains during flowering will cause the flowers to be knocked off the tree and stop the fruit from ever growing.

Impact of disease on coffee yield

Coffee leaf rust roya
Called roya or rust this is a fungus on coffee leaves made more common by climate change

Not only are coffee plants affected by climate change due to an increase in global temperature, but also by an increase in another major threat to yield, disease. Climate change has been found to increase the likelihood of diseased crops, including ‘la roya’ or ‘stem rust’. This disease reduced coffee production by 15% in Central America between 2012 and 2013 and saw prices soar by 33%.

Impact of climate change on coffee farmers

Many Central American countries witnessed a mass reduction in coffee farm workers as the farmers choose the leave the coffee industry to live in more urban areas. In the 1970’s El Salvador was the 4th largest producer of Arabica Coffee in the world, remarkable for a country of its size. However, owing to disease, war, and political influence coffee production has rapidly declined and the country is now the 19th biggest supplier of Arabica globally. Other countries are expected to follow this trajectory if global warming cannot be slowed and producers cannot afford to employ workers.

What can be done to stop the impact of climate change on coffee?

It is clear that coffee production needs to adapt to the rise in global temperature, but also the reduction in precipitation and increase in extreme events like storms and heat waves that comes with this.

A recent study provided some hope, as Arabica coffee was previously thought to only grow at temperatures ranging from 18 to 23 degrees C, but a team from Brazil demonstrated that particular varieties of Arabica Coffee can be successfully grown at temperatures as high as 24 to 25 degrees C when under tightly controlled agricultural conditions.

However, the practicality of major changes to production, such as irrigating coffee crops has been called into question due to the high cost to farmers for the initial construction. Further research suggests that high levels of dry moist air can still cause significant damage to crops, even in highly irrigated soil.

A tactic to increase the income of farmers is through the diversification of their crop. Turning the typically pruned coffee leaves into a tea lets producers increase the value of their current crop. This gives producers an opportunity to invest in climate mitigation strategies like new cultivars or new farm infrastructure.

The suggestion that comes most highly recommended but possibly the hardest to achieve is to maintain global warming below 2 degrees C in the next century, in line with the Paris Agreement.

However, even major global cooperation could see us still fall short of this goal.


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