Early flowering changes robusta coffee yield responses to climate stress and management

A bitter cup of coffee? Assessing the impact of climate change on Arabica coffee production in Brazil

Brazil, the world's largest producer and exporter of Arabica coffee, faces increasing challenges from climate changes. To maintain the sustainability of this commodity, innovative management techniques will be essential. This study aimed to assess the impact of climate projections, considering two CMIP6 emission scenarios (SSP2-4.5 and SSP5-8.5) on the phenology and yield of Arabica coffee in 36 representative locations across Brazil for the periods 2041-2060, 2061-2080, and 2081-2100. Observed meteorological data from the BR-DWGD (Brazilian Daily Weather Gridded Data) and projected data from CLIMBra (Climate Change Dataset for Brazil) were employed. An agrometeorological model, calibrated for Brazilian conditions, estimated yield and phenology. Results indicate significant impacts on coffee cultivation areas, mainly due to rising temperatures and increased water deficits. Projections also suggest changes in coffee phenology, with anthesis advancing in colder regions and delaying in warmer areas, while maturation timing occurring earlier in all climates. Yield increases from CO₂ fertilization were more pronounced in category C climates (Cfa, Cfb, Cwa, and Cwb), particularly in Cwb climates, reaching 2.9 bags ha-1 (3.7 bags ha-1 with irrigation) under the SSP2-4.5 scenario and 2.5 bags ha-1 (3.5 bags ha-1 with irrigation) under SSP5-8.5. However, higher temperatures and water deficits could cause severe yield losses, especially in Aw climates and under high-emission scenarios, where losses may reach 100 %. Irrigation will play an important role in mitigating yield losses, especially in northern regions such as northern Minas Gerais and Bahia, where yields could exceed 30 bags ha-1. While southern Minas Gerais, São Paulo, and northern Paraná are projected to have the highest yields, these regions also face greater uncertainty and variability. This study underscores the need for adaptive agricultural practices, the development of resilient coffee cultivars, and supportive research policies to ensure the sustainability of coffee farming in the face of climate change.

Assessing scale-dependency of climate risks in coffee-based agroforestry systems

Agroforestry is a management strategy for mitigating the negative impacts of climate and adapting to sustainable farming systems. The successful implementation of agroforestry strategies requires that climate risks are appropriately assessed. The spatial scale, a critical determinant influencing climate impact assessments and, subsequently, agroforestry strategies, has been an overlooked dimension in the literature. In this study, climate risk impacts on robusta coffee production were investigated at different spatial scales in coffee-based agroforestry systems across India. Data from 314 coffee farms distributed across the districts of Chikmagalur and Coorg (Karnataka state) and Wayanad (Kerala state) were collected during the 2015/2016 to 2017/2018 coffee seasons and were used to quantify the key climate drivers of coffee yield. Projected climate data for two scenarios of change in global climate corresponding to (1) current baseline conditions (1985-2015) and (2) global mean temperatures 2 °C above preindustrial levels were then used to assess impacts on robusta coffee yield. Results indicated that at the district scale rainfall variability predominantly constrained coffee productivity, while at a broader regional scale, maximum temperature was the most important factor. Under a 2 °C global warming scenario relative to the baseline (1985-2015) climatic conditions, the changes in coffee yield exhibited spatial-scale dependent disparities. Whilst modest increases in yield (up to 5%) were projected from district-scale models, at the regional scale, reductions in coffee yield by 10-20% on average were found. These divergent impacts of climate risks underscore the imperative for coffee-based agroforestry systems to develop strategies that operate effectively at various scales to ensure better resilience to the changing climate.