Research finds global warming hurts production in Tanzania

Researchers from the University of Witwatersrand in South Africa have found that climate change has had a significant effect on Arabica yields in Tanzania. The team found that Tanzania’s minimum overnight temperature have risen 1.4 degrees Celsius from 1962 – 2010. Its research revealed that yields dropped 137 kilograms of coffee per hectare for every 1◦ C rise in minimum daily temperatures. Using the team’s current methodology, Arabica production in Tanzania would drop to 145 kilograms per hectare by 2060. However, the researchers found that current trends suggest a less optimistic future, predicting that yields would drop to below 100 kilograms per hectare by the year 2060. “Given that coffee production supports the livelihoods of more than 2.4 million individuals in Tanzania, and up to 25 million families worldwide, the forecast presented here has major livelihood implications,” the researchers reported. The researchers also found that Tanzania is experiencing below average rainfall more often.  Between 1962 and 1986, less than 45 per cent of crop years had below average rainfall, whereas between 1987 and 2010 more than 65 per cent of crop years had below average rainfall. The team compared its findings to studies conducted in countries with similar agro-climatic situations, including Brazil, Colombia, Costa Rica, Ethiopia and Kenya, and found similar trends concerning temperatures. According to the research, on the southeastern states of Brazil, the world’s largest coffee producer, minimum daily temperatures have increased 4.8◦C over the past 60 years. Similarly, substantial daily minimum increases have been recorded in Colombia and Venezuela, since 1960. Colombia is consistently the second largest producer of Arabica in the world and is one of several countries with an average yield decline of 30 per cent since 1990. Studies focusing on the African highlands have reported increasing minimum overnight temperatures in Ethiopia too. The genetic origin and largest African producer of Arabica has experienced increases in minimum temperature per decade of between 1 ◦C in the Asela region, to 1.4 ◦C in the Negele region. Negele is within the Yirgacheffe region where some of Ethiopia’s finest coffees originate. While there is a general warming trend for India, trends are varied and localised, particularly in the Western Ghats mountain range where the majority of Arabica is grown. The researchers said they hoped that their findings would encourage governments to take progressive measures to protect farmers and their crops.