UC Davis

Coffee is a perennial crop that plays an essential role in many emerging countries’ economies. It is estimated that the coffee value chain provides a livelihood for about 125 million people worldwide, including 25 million smallholder producers in developing countries (Krishnan, 2017). Coffee farmers, however, have experienced a number of threats in recent decades, including volatile coffee prices and rising production costs. Under the changing climate, additional challenges will be posed to small coffee producers, which may further threaten their economic viability. The most noted effect of climate change is rising temperature, which provides favorable environments for coffee pests and diseases, including coffee berry borer and coffee rust. Climate change also increases the likelihood of extreme weather events such as drought, frost, and flood, and the impact of such events on coffee plantations can be severe, including loss of trees. As such, understanding how this core industry will be impacted by climate change is critically important. This dissertation investigates the impacts of climate change on coffee production, a critical economic commodity in many developing countries. Through a panel fixed effects econometric modeling approach, this research analyzes how climatic variables such as temperature and precipitation influence coffee yields, particularly focusing on the differential effects during various growth stages of coffee plants. This study also utilizes projections from global climate models through the 21st Century to project the impacts of future climatic conditions on coffee yields.

The research estimates a weather-yield response model that captures the heterogeneous weather effects by including variables across critical coffee growth stages such as the blooming, fruit bearing and harvesting phase. The weather variables of interest include growing degree days (GDDs), harmful degree days (HDDs), freezing degree days (FDDs), precipitation, number of dry days, and coefficient of variation of precipitation.

In Brazil, the study reveals pronounced biennial variations in coffee yields, with GDDs positively affecting yields during the blooming stage, whereas HDDs exacerbate yield losses during the same period due to extreme heat. Additionally, my results indicate that prolonged dry periods before the blooming season benefit yields up to a threshold, beyond which yields may be adversely impacted by extended drought conditions. Conversely, in Colombia, coffee yields lack the pronounced biennial variation seen in Brazil. In terms of temperature effects, GDDs during the flowering and harvesting periods positively influence yields, and precipitation during the fruit-bearing stage negatively affects yields .

The dissertation also explores the role of elevation in moderating the impacts of weather variables on coffee production. It finds that in Brazil higher altitudes increase the susceptibility of coffee yields to negative climatic impacts due to the cultivation of different coffee varieties that vary in their response to temperature and moisture levels. In contrast, in Colombia, elevation does not significantly differentiate the impact of climatic variables on coffee yields.

Under IPCC’s middle of the road emission scenario, municipalities in most states are projected to see a drop in yield, ranging from 3% to 13% by the end of the century. On the contrary, Municipalities in Mato Grosso do Sul will benefit from the climate change, which would result in a 19% yield increase in the far future. The primary drivers include changes of GDDs and HDDs during blooming and harvesting periods, with mixed effects on future yields.

This dissertation examines the profound and varied impacts of climate change on coffee production in Brazil and Colombia, two of the world’s leading coffee producers. The findings underscore the necessity for adaptive strategies tailored to specific regional and varietal characteristics to mitigate the adverse effects of changing climatic conditions. Moreover, these results provide valuable insights that could be extended beyond Brazil and Colombia to understand the broader implications of climate change on coffee-producing regions worldwide.