April 24, 2020

Merit 101: Terroir - Climate

By Jamie Isetts
Merit 101: Terroir - Climate

The goal of the Merit 101 series is to help educate all levels of coffee enthusiasts who want to learn more about who we are at Merit, as well as the many aspects of coffee.

Terroir: The Basics

Terroir is a French term that roughly means sense of the earth, originating from the French word “terre.” It encompasses all of the place-based flavor factors that influence the environment where a plant is cultivated, or where a culinary process (like fermentation) unfolds.

Coffee as nature intended, growing in its original habitat: the equatorial cloud forest of Kaffa, Ethiopia.

Terroir is the justification for the appellation d'origine contrôlée (AOC) system in France that recognizes wines, cheeses, and other products that come from specific regions. This is why, legally, only wines that come from France’s northeastern Champagne region can carry that name on the label, though similarly-styled sparkling white wines are produced throughout the world. Most of nature and humanity’s best collaborations (chocolate, honey, tea, spirits, meat) carry the effects of their provenance.

Coffee is no exception. Because terroir is a holistic concept, it can be difficult to break it down into components. This sense of place really does depend on the interaction of the entire system—people included. And it can change depending on what brackets you put around the term “place,” from country-wide generalizations (ex. “all Kenyan coffees are bright and acidic) to notes on specific parts of one farm (ex. “this lot from the rainy side of the mountain tastes fruitier than coffee grown on the dry side”).

Once you decide the scope of the place you’re talking about, you can start to identify the things that affect what you taste in your cup. In this three-part series, we’ll cover the effects of climate, ecology, and human cultivation on terroir.

Part I : Climate


Farms at high elevation (like Elvis Davila's, pictured here) have better starting conditions for specialty coffee. Jaén, Peru.

Frost is the limiting factor for Arabica coffee’s habitat. For this reason, it grows best in “the tropics,” a belt between the Tropics of Cancer and Capricorn, each about 23.5 degrees of latitude away from the equator. But high temperatures can cause problems too, like wilting and pests. Thus, Arabica is happiest in a goldilocks compromise of the two: equatorial mountains. These places (like coffee’s native habitat in western Ethiopia) are warm during the day and cool at night, an undulating but balanced climate that keeps the plant content.

As a quality-focused farmer, you want to plant as high on the mountain as possible without encountering frost. However, the cooler temperatures that keep fungi and insects away also cause the coffee trees (and their seeds, the coffee beans) to grow slowly and densely. This decreases the quantity of the coffee’s yield, but because the plant is putting more resources into less seeds, the quality increases. Denser beans, with the right roast, have a lot more nuance and flavor to give.

Most coffee companies (including Merit) list the coffee’s growing elevation in meters above sea level (masl). Generally, higher growing elevation equals better coffee. The idea here is that the whole equatorial Arabica “belt” experiences the same unchanging baseline temperature, and the only differing variable is how high up you are. Equatorial regions don’t experience seasons in the same way as, say, North America. Instead of cold winters and hot summers, they have milder annual shifts in temperature that are marked by rainy and dry seasons. This is the general paradigm for coffee production.


Latitude refers to the angle of a place to (and as a consequence, the distance from) the equator. The sun’s rays hit the earth straight on, year-round at the equator (0 degrees latitude), heating the ground more intensely and effectively making the sun “stronger.” This effect decreases the further you go from the equator and changes at different times of the year because of the way the earth rotates around its axis. Within the latitudes of the tropics, the angle of the sun’s rays hit the ground perpendicularly at least once throughout the year, causing that lack of seasons that allows us to generalize the climate in this zone.

Equating elevation to quality is a good rule of thumb, but it has some obvious limitations. The Tropics of Cancer and Capricorn are roughly 3200 miles apart. Even within this range, the angle of the sun varies more as you move away from 0 degrees latitude. A farm at 1500 masl in Ecuador will get more direct sun (and thus probably be warmer) than one at the same elevation in Mexico. The farm’s distance from the equator defines the range of ideal growing elevations, but within that spectrum the general trend of higher = better prevails.

Topography and Microclimates

A mountain pass on the way to a coffee farm. Such rugged topography captures wind and water in a way that creates microclimates. Oaxaca, Mexico. 

Elevation affects temperature, but the topography makes a big difference. A mountain plateau will have a much different climate than rolling hills or rugged peaks. The shape of the landscape traps wind and water in different ways, which also affects temperature since those elements carry heat. Whenever this creates a small pocket that’s different from the surrounding area, it’s called a microclimate.

Microclimates are especially common in mountain ranges because clouds often get trapped on one side of the peak, causing one side to receive most of the rainfall and the other to be disproportionately dry. Depending on what side of the mountain your farm is on, your coffee plants will experience a very different growing environment. 

Effect on open-air fermentation

Fermenting coffee (in this case, via the "washed" process) in open-air conditions. Chirinos, Peru.

Ripe coffee cherries contain lots of sugar. Having eaten many, I can attest to how tasty they are. Wild microorganisms (mostly yeast) also think they’re delicious, and will break down their sugar and spit out other stuff that affects the flavor we taste in the final cup, a process called fermentation. Yeast are sensitive, and the rate of this reaction has a big effect on what type of flavors compounds they’ll make, and how long it takes you to process one “batch” of coffee cherries. Fermentation slows down with less heat, and speeds up with more. Since most coffee farmers are processing their coffee in open-air environments, the starting temperature of fermentation is whatever the ambient air temperature is. A colder climate means your coffee will ferment more slowly. 

So in a nutshell, climate (elevation, latitude, topography) sets the stage for broad distinctions of coffee quality. In context, higher elevation means cooler temperatures, which makes the coffee denser and leads to more refined acidity and flavor. In our minds, these are very desirable qualities.

In Part Two, we’ll cover the effects of soil and above-ground ecology on coffee terroir.