WINTER EDITION/ ATTITUDE, ALTITUDE AND LATITUDE
Call us old fashioned but in winter coffee should be hot; but that doesn’t stop us from appreciating the Northern Hemisphere’s chilly months.
Now that we’re on topic what about climate change and the impact of colder temperatures on coffee bean growing?
STRIKING A BALANCE. Altitude and latitude are important. If grown roughly between 4,000 – 6,500 feet above sea level, coffee fruit has the opportunity to develop slowly, which means denser coffee beans and the potential for more complex flavors.
If coffee is grown too low in the tropics, the fruit matures rapidly resulting in a soft, insipid coffee (Hint: many Robusta beans.]
On the other hand, if grown too high, colder temperatures hinder development of coffee fruit resulting in low yields. It is believed that coffee grown at higher altitudes produces a better tasting. While this is true to a point, latitude also plays a role. The further a growing region is from the equator, the lower the coffee must be grown due to colder temperatures at comparable altitudes than those closer to the equator.
PICKY TEMPERATURE. The optimal temperature range of the Coffea arabica tree—source of 70% of the world's coffee—is 64°–70°F, which is most consistently found in upland elevations of tropical countries. Photosynthesis is slowed above these temperatures and frost damage can occur when temperatures hover around 0ºC.
MIND THE GAP. There is a direct relationship between extremes of day and nighttime temperatures and coffee quality. Experimental evidence has indicated that a large gap between day and nighttime temperatures is beneficial to the flavor of fruits. Since a coffee cherry is a fruit and the seed is in contact with the fruit, these benefits will be passed onto the seed and therefore into the cup.
GLOBAL WARMING WOES. If Earth’s climate continues to warm over the coming decades, obstacles to coffee cultivation will multiply. Consider Arabica coffee (Coffea arabica), the species grown for roughly 70 percent of worldwide coffee production. Arabica coffee’s optimal temperature range is 64°–70°. It can tolerate mean annual temperatures up to roughly 73°F.
NOT TOO HOT. Above those moderate temperatures, fruit development and ripening accelerate. (If you didn’t know, coffee “beans” are actually the pit, or seed, of the plant’s fruit.) Faster ripening might not sound bad, but it actually degrades coffee bean quality. Continuous exposure to temperatures up to and just over 86°F (30°C) can severely damage coffee plants, stunting growth, yellowing leaves, even spawning stem tumors.
SOURCE(S): National Oceanic and Atmospheric Administration and other coffee industry data.