Our Project

We are an interdisciplinary team of scientists working together to addresses critical knowledge gaps related to climate effects on tea quality and their corresponding socio-economic responses. Tea is a fascinating study system as the most widely-consumed beverage in the world after water and as a quality-driven crop that has an extensive management history. Our primary study objective is to provide quantitative data on how and why tea quality is vulnerable to changing climate conditions, how farmer management decisions help them adapt to changes in climate and pests, and the resulting linkages to consumer purchasing decisions, markets, farmer livelihoods, and ecological knowledge.

This project is supported by the NSF Dynamics of Coupled Natural and Human Systems (CNH) Program. 

Project Outcomes


Co-PI Selena Ahmed Sampling Tea During the East Asian Monsoon

Co-PI Selena Ahmed sampling tea during the East Asian Monsoon

Quantify Climate Effects on Tea Quality and Yield:

The research showed that climate variables and herbivores have a dramatic and significant impact on tea quality and yields. Our work developed new tools to extract and quantify secondary metabolites that determine tea quality and identified key patterns with respect to variation of secondary metabolites. Specifically, we found that heavy precipitation and warmer temperatures (using elevation as a proxy for temperature) causes a shift in secondary metabolite profiles that contributes to reduction in tea quality. Our three-year analysis across study sites in China shows that tea secondary metabolite chemistry varies dramatically across sites, among seasons and years with some patterns linked to climate variables. While our study demonstrates that the climate poses challenges to farmers who try to maintain a high quality across seasons and years, we identified factors that can mitigate climate induced changes on tea quality. We found that herbivores and their cues induce changes that increase tea quality. Tea managed in different production systems also varied in tea quality with tea from shade-grown agroforests demonstrating a smaller change in secondary metabolite profiles compared to tea from adjacent terrace fields. In taking a whole agroecosystem perspective, findings suggest that the management of herbivores, shade, and biodiversity within tea production systems can mitigate the effects of climate variables on tea quality.

Lead Investigators: (1) Field Sampling and Antioxidant Chemistry: Selena Ahmed; (2) Manipulative Experiments / Herbivory / Soils: Colin Orians and Tim Griffin; (3) Volatile Chemistry and Sensory Panel: Albert Robbat and Colin Orians

Tea tasting in China with tea connoisseurs. Photo credit: Selena Ahmed

Tea tasting in China with tea connoisseurs. Photo credit: Selena Ahmed

Determine Consumer Behavior Decisions and Associated Market Implications:

Results from this research were published in the journal Sustainability in September 2019. In this article, Boehm et al. 2019, “Is Agricultural Emissions Mitigation on the Menu for Tea Drinkers?”, found that consumers are willing to pay a significant premium for agricultural mitigation of greenhouse gas emissions. Interestingly, male and lower-income participants, as those in our Midwestern study, were willing to pay a higher premium for agricultural GHG mitigation, relative to females, higher income participants, and those in the Northeastern U.S. Knowledge of climate change and level of concerns for the risks it poses were not significantly associated with increased WTP for agricultural GHG mitigation. A second manuscript is being prepared for the Journal of Sensory Studies and will focus on differences in consumer preference and willingness to pay for teas harvested in the monsoon and pre-monsoon seasons, as well as expert sensory panel ratings of various quality indicators of both the pre-monsoon and monsoon tea samples used in the consumer experiments.

Lead Investigators: (1) Consumer Experiments and Markets: Sean Cash and Tim Griffin; (2) Tea Trader and Connoisseur Surveys: Selena Ahmed 

Tea farmer processing fresh harvested tea leaf in Yunnan Province of China. Photo credit: Selena Ahmed

Tea farmer processing fresh harvested tea leaf in Yunnan Province of China. Photo credit: Selena Ahmed

Elucidate Feedbacks between Farmer Livelihoods, Knowledge and Management Practices:

Our conceptual model (Ahmed and Stepp 2016) has been applied to develop and implement surveys to elucidate farmer perceptions of climate effects on tea quality at the three tea producing sites across agroclimatic

zones in China following an initial survey (Ahmed et al. 2014a). Overall, findings highlight that the majority of farmers interviewed have observed shifts in the occurrence of seasons, the length of seasons, increased temperatures, and changes in rainfall. However, significant variation of these some of these observations was found depending on region and elevation. For example, a significantly greater percentage of farmers in Yunnan and Fujian Provinces have observed changes in rainfall compared to Zhejiang Province, while a significantly greater percentage of farmers in Fujian have also observed increased temperatures. These findings are aligned to climate patterns of these regions. Importantly, farmers identified drought, frost and heavy rainfall as factors that reduce tea quality.

Lead Investigators: Selena Ahmed and Rick Stepp

Organic tea garden management. Photo credit: Selena Ahmed

Organic tea garden management. Photo credit: Selena Ahmed

Develop Tea Production Plans and Policies to Mitigate Climate Risk:

Based on lessons learned from our work, we recommend the following next steps:

  • Carry out farm-level research on the effectiveness of various agricultural practices for climate adaptation and mitigation for tea plants and other food and beverage crops including the cost-effectiveness, replicability, and adaptability for different geographic contexts as well as differing scales and models of production. Findings should be applied to design and disseminate climate resilient agricultural guidelines that should be supported by policy including providing economic and social incentives.
  • Invest in breeding of climate-resilient crop cultivars that includes the evaluation of crop quality to multiple environmental factors and identification of crop quality thresholds.
  • Design more widely agreed upon international standards of crop quality for multiple culturally and economically relevant crops
  • Implement long-term global collaborative projects with shared experimental designs and “big data” sharing to allow for comparison of outcomes across multiple studies on crop quality through space and time. These studies should model system-wide impacts of simultaneous environmental changes on agricultural systems and implications for nutrition and human health to better understand the dynamic feedback loops in the food systems and associated social and ecological long-term implications of climate change.
  • Foster cross-sector collaboration between researchers, practitioners, producers, and policy makers to develop evidence-based adaptation strategies that reduce vulnerability of food systems to shifts in crop quality toward supporting sustainability.

Lead Investigators: (1) Data Integration: All Investigators; (2) Climate Modeling: Corene Matyas; (3) Management Plans and Policies: Tim Griffin and Selena Ahmed       

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