This is second episode of “Harnessing the Power of Science,” a session recorded at Re:co Symposium this past April. The main focus of this session was to learn about new developments in coffee science and explore how Specialty Coffee can engage with the scientific enterprise for the benefit of all of us. If you haven’t listened to episode #30, we strongly recommend going back to listen to it before you continue with this episode.
On this episode of the Re:co Podcast, we are pleased to welcome Professor Selena Ahmed. Selena co-leads the Food and Health Lab at Montana State University where she is a professor in Sustainable Food Systems. At Re:co Symposium this past April, Selena shared her research detailing shares the impact of climate change on two other specialty crops, tea and maple syrup, before exploring how we can harness science to measure the effects of climate change on coffee.
Special Thanks to Toddy
This talk from Re:co Seattle is supported by Toddy. For over 50 years, Toddy brand cold brew systems have delighted baristas, food critics, and regular folks alike. By extracting all the natural and delicious flavors of coffee and tea, Toddy Cold Brew Systems turn your favorite coffee beans and tea leaves into fresh cold brew concentrates, that are ready to serve and enjoy. Learn more about Toddy at http://www.toddycafe.com.
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Episode Table of Contents
3:30 Climate change affects coffee, but also tea and maple syrup. By exploring climate change’s effects on tea and maple syrup, we get a better understanding of how climate change may impact coffee cultivation
4:15 Background explanation of China’s tea production in Yunnan province and Selena’s research
7:00 Climate variability affects tea flavors, yield and livelihoods in Yunnan Province, China
10:45 Droughts and monsoons produce different chemicals in tea, some of which was good for flavor and prices, and others undesirable
13:00 When factoring increased weather variability due to climate change, the outcome on flavors, yield and livelihoods is not one-size-fits-all and very nuanced, depending on the region, with both positive and negative effects
16:30 Maple syrup harvest seasons are changing
17:30 Selena and others documented how flavors changed as the harvest season starts earlier and earlier
20:00 What can farmers do to mitigate the effects of climate change in tea cultivation?
21:45 Final thoughts
Full Episode Transcript
Peter Giuliano: Hello everybody, I’m Peter Giuliano, SCA’s Chief Research Officer. You’re listening to the Re:co podcast, a special episode of the SCA podcast. The Re:co podcast is dedicated to new thinking, discussion, and leadership in Specialty Coffee, featuring talks, discussions, and interviews from Re:co Symposium, SCA’s premier event dedicated to amplifying the voices of those who are driving specialty coffee forward. Check out the show notes for links to our YouTube channel where you can find videos of these talks.
This episode of the Re:co Podcast is supported by Toddy. For over 50 years, Toddy brand cold brew systems have delighted baristas, food critics, and regular folks alike. By extracting all the natural and delicious flavors of coffee and tea, Toddy Cold Brew Systems turn your favorite coffee beans and tea leaves into fresh cold brew concentrates, that are ready to serve and enjoy. Learn more about Toddy at toddycafe.com. Toddy: Cold brewed, simply better.
Today, we’re very happy to present the second episode of “Harnessing the Power of Science,” a session recorded at Re:co Symposium this past April. The main focus of this session was to learn about new developments in coffee science and explore how Specialty Coffee can engage with the scientific enterprise for the benefit of all of us. If you haven’t listened to episode #30, we strongly recommend going back to listen to it before you continue with this episode.
On this episode of the Re:co Podcast, we are pleased to welcome Professor Selena Ahmed. We first heard about Selena from Emma Sage, former science manager from the SCA. Emma returned from a scientific conference in Europe saying “We HAVE to get Selena Ahmed to Re:co”. We were able to get her to come, and we’re so glad we did. Selena co-leads the Food and Health Lab at Montana State University where she is a professor in Sustainable Food Systems. She examines the socio-ecological, phytonutrient, and sensory basis of food systems from production through consumption and waste in the context of global climate change. Selena’s focal study systems are tea, maple syrup, and indigenous foods. Her transdisciplinary research program seeks to identify practices that advance ecological and societal wellbeing while supporting innovative contributions that strengthen our food and drink experience. Selena is a co-founder of Shoots & Roots Bitters, serves as a judge in tea tasting competitions, consults on tea and botanicals, is the author of over four-dozen articles and book chapters, and is a co-author of the book Tea Horse Road: China’s Ancient Trade Road to Tibet as well as the forthcoming Botany at the Bar: The Art and Science of Making Bitters.
At Re:co Symposium this past April, Selena shared her research detailing shares the impact of climate change on two other specialty crops, tea and maple syrup, before exploring how we can harness science to measure the effects of climate change on coffee.
3:30 Selena Ahmed: I’m going to start with a question and the question is: how many of you are alarmed, concern, very concerned about the effects of climate change on coffee? Raise your hands. So pretty much the majority.
Well, I’m not going to speak about effects of climate change on coffee. Today, I’m going to speak about the effects of climate change on two other specialty crops: tea and maple syrup, which I have been studying for over a decade. And this really is to serve as a lens in thinking about how we can harness the power of science in analyzing and measuring how we can measure climate change effects on coffee.
4:15 My research on climate change effects on tea is very much driven by farmer observations and farmer concerns. And I’m going to tell you about that very specific cup of tea that drove my research to thinking about the effects of climate change on tea quality.
This was over one decade ago when I was carrying out research in Yunnan province of southwestern China. Who in this room has been to Yunnan Province? There’s an expanding coffee market over there. And as an ethnobotanist, I’m extremely interested in human interactions with the environment and this interest has driven me into some remote areas around the world where indigenous agricultural practices are still intact. Such as this Aka village over here which grows tea in these wonderful agroforests for hundreds of years.
Tea in these mountains of southwestern China grows in indigenous agroforest and it also grows in wild tea populations. This is the motherland of the tea plant and the center of origin and diversity. And specifically, I was studying the sustainability of tea production systems along a continuum of agricultural intensification. I was comparing these wild tea populations to these indigenous agroforests, all the way to these monocultures systems and looking at sustainability among four dimensions: ecological, economic, social cultural, and human health.
And the indigenous agroforests ran quite well in looking at sustainability. They have rich biological diversity at the landscape, genetic, and plant species level. So as an ethnobotanist or botanist, I would see these different tea land races that grow in one hectare agroforest as Camellia Sinensis variety Assamica. But the farmers that are managing these systems actually have different names for each of these different land bases and our managing these systems and this genetic diversity for different flavor profiles, for a different resistance, to different climate variables, really not putting all of their eggs in one basket even within a small agroforest.
And tea in these systems can grow quite large. Imagine one of these tea leaves unfurling in your tea cup.
Peter Giuliano: Selena is showing a picture of a man holding up two tea leaves either side of this face. They’re literally as tall as his head!
Selena Ahmed: And now I’m going to tell you about that cup of tea that drove my research on climate change effects on tea quality. This was during one of my very first field seasons in Yunnan. And, after a long day of caring out ecological transects in the indigenous agroforest, I was having tea in this farmer’s household. And I was sort of returning every day to drink tea after my fieldwork. And one day Ng says “it has changed. The taste has changed.” And I was really intrigued by what she was speaking about. And she said “yes, it’s changed since just a few days ago.” And what I was speaking about was the onset of the East Asian Monsoon. And so that year and Yunnan, it had been an extraordinary dry year, Yunnan has seen a drought for the past few years in the spring season and then at the same time, it’s actually been seeing more intense and extreme monsoon seasons. And the monsoon seasons were actually getting earlier. And so this was really shifting farmers’ labor schedules as well as the quality of tea and most importantly the livelihoods that farmers are procuring from this tea.
And so this made me think about what is happening in terms of climate change with this increased variability in terms of droughts and monsoons and other environmental factors linked to climate change.
This graph over here shows how the shifts of the monsoon very much matter to farmers. This as prices that farmers receive in this Village for one kilo of tea. So here, let’s say in 2012, the dry season tea, which was undergoing a drought received almost US$400 per kilo. That’s what the farmers were receiving per kilo. And then as soon as the monsoons hit, they evaluate the tea and then they determine a new market price, which is almost 50% less. So less than US$150.
And so this really impacts farmers, when the monsoon seasons are coming earlier or are getting longer, with climate change.
And as I continue to work in the mountains of southwestern China, dozens of farmers began to express these concerns how they were observing all of these different climate factors, that were impacting tea yield, tea quality, and ultimately their livelihoods.
And this led me to develop or initiate a collaborative research project with scientists from all different fields, thinking about how we can look at tea as an indicator species for climate change. And plants such as tea and coffee, make really suitable indicators for assessing climate change. Unlike animals and humans that can run away from a lot of abiotic and biotic stressors. Plants are rooted in place. And so when they’re attacked by predators or there’s extreme sunlight or temperatures are shifting, they can’t simply move away. They actually have evolved this extraordinary pathway of secondary metabolites to defend themselves.
And so all of these different factors are impacting plants and they’re defending themselves with these compounds. These compounds, we as humans can perceive, as flavor compounds or as therapeutic compounds. So in tea, for example, the sort of star antioxidant compounds are actually plant defense compounds that the plants are producing to defend themselves against environmental stress. And so these levels are varying with environmental factors and then depending on an agricultural management practices and climate change, these levels are changing and then we actually as humans can perceive shifts in the concentrations. Which ultimately determines prices.
Are you ready for some really juicy data? Okay, so I became really obsessed with documenting that cup of tea when Ng says that the flavor shifted, I wanted to know physiologically what was happening in tea plants, what was happening phytochemically. And so I decided just to do a seasonal study to see what was actually happening in terms of the key antioxidants and other flavor compounds. And working with my collaborators, using different approaches to get to this question.
And I’m going to just point out one graph over here first.
Peter Giuliano: Selena is has a slide up with six graphs. Each graph is showing how different compounds in tea change depending on what part of the season you’re in. The point to note here is that the Spring Drought period is excellent because it produces lots more of the compounds we want in tea, like anti-oxidants and caffeine. But as the Monsoon arrives, these compounds go down.
Selena Ahmed: On the axis over here, we’re looking at changes in season from our extreme drought, farmers really love the tea during that drought season. If it had become too much of a drought, they would have lost their crop. But the drought levels that were happening that year were perfect for the aromatic compounds of tea. So they were really benefiting from this wonderful tasting tea.
And then this is a monsoon onset and this is the monsoon onset. Here we have the concentrations of EGCG, that’s that star antioxidant compound in tea. It’s a phenolic compound and it’s also associated with different flavor profiles of tea.
And we’re seeing that compound is decreasing more than 50%, just within a two-week period. And it’s not just that compound, its other key compounds, phenolic compounds and also caffeine, that are changing just within this two week period.
And then I began to think about well, can we correlate this with climate change? Can we actually sample tea during different seasons, in different agroclimatic areas where tea is grown, and then link that with temperature and precipitation and CO2 levels. And then begin to model how the flavor profiles of tea are changing with climate change and then do some forecasting of what’s going to happen in the future?
And then my collaborators at Tufts University also measure the same tea samples and they quantified over a hundred volatile aromatic compounds and they also found that there’s changes in the concentrations of those volatile aromatics. Not just in the concentrations, but actually in the presence. And so some of the spring tea samples actually have compounds that are considered very favorable, such as having floral or honey-like flavors. And some of the monsoon teas have compounds that are considered undesirable, such as having more vegetable flavors that are not looked at as favorably.
13:00 And then what does this look like in the context of climate change? And so in this specific area of southwestern China, we see that the spring season is actually predicted to decrease and become more dry. So 4% to 6% percent decrease in precipitation.
Peter Giuliano: Selena has a slide showing that in the part of China she’s studying, climate change is expected to increase the length and depth of the drought period, which might be good for tea farmers because tea plants produce more of the compounds we want during the drought seasons. But, the monsoon season will also be more severe, with more rain, and this is detrimental to tea farmers because the tea plants produce fewer of the compounds want and produce more of the compounds we don’t want.
Selena Ahmed: So based on this graph, where we are seeing that the spring drought has the highest level of antioxidants and then the monsoon season has the lowest, at some part of the year there’s actually some positive things that are happening with these shifts in climate and then in other parts of the year there’s actually detrimental things that are happening.
However, if the plant goes over its threshold in terms of water – all plants have different thresholds in terms of water stress – and if it actually goes above its threshold of that 4% to 6% decrease in precipitation is too much, then there’s going to be crop failure and there’s going to be no crop at all.
And so then how do we begin to model this? And this – we are doing manipulative experiments in the greenhouse to actually see: what does forecasted climate change look on crops? What’s the threshold that plants can tolerate, tea plants specifically, in terms of these different stressors without being too judgmental even in the spring season?
And then what’s really exciting is we also have received a new collaborative grant to continue this work, also looking at the effects of CO2 on tea quality.
And what’s really interesting is we are replicating this work in multiple sites in three different agroclimatic zones in China. And while precipitation is sort of the driving force of impacting tea quality in southwestern Yunnan Province or southwestern China, temperature is actually the key driving force that’s making tea vulnerable in the eastern part of China.
And so we’re really seeing that the specific climate threat really varies depending on geography. It’s not really this one-size-fits-all picture. It’s very subtle and it really depends on where you are.
16:30 And the more I continue to work on this research and speak to different producers, we are recognizing that this trend is not just specific to tea. Since 2012, I’ve also been examining the effects of climate change on maple syrup quality. And it started in a dialogue where I was telling some maple syrup producers in Vermont, about my research on climate change effects on tea quality. And this maple syrup producer runs to her fridge and pulls out these three different samples of maple syrup and says, we’re experiencing the same exact thing with maple syrup.
During my lifetime, I’ve noticed that the maple sap season starts earlier, it also sometimes ends earlier. And most importantly, the high grade maple syrup is decreasing in amount and the more lower-grade maple syrup is increasing and amount due to weather variability.
17:30 And our collaborative research team, we’ve worked with hundreds of producers to sort of document this. And the majority of producers are also expressing that the harvest season for maple syrup is indeed starting earlier. And, very interestingly, the budding of the maple trees is also starting earlier. And as soon as the maple trees begin to bud, there’s off flavors that happen within the tree which is contributing to some off flavors. So very interesting and thinking about quality.
And then we have been sampling across the agroclimatic zone of maple trees for the past four years from the southern range in Virginia all the way to Quebec and then correlating what’s happening with key compounds including sugar compounds and phenolic antioxidants during that period.
And we’re seeing this significant correlation as temperatures decrease, there is a significant decrease in the antioxidant compounds in maple syrup.
And then what does this mean in the future? So this data is really exciting to me. This is looking at the shift and changes of sugar content and sugar yield for maple syrup across its different zone. So if you’re looking at that map of the eastern part of North America, all those are the different sites where we have been collecting maple sap since 2013, and we can see that based on our data, that sugar content of maple is expected to decrease in the next 50 years. And in most of our sites, the yields are also expected to decrease. However in the northern range of maple, yields are expected to increase.
And what’s also really exciting about this in the next phase of this project, we are working with high school students and farmers to do some citizen science where producers and students can actually collect the data, so we can have a larger network of collecting where these changes are happening. And I think this would be really exciting to also see in tea as well as in coffee.
So from the research, I’ve been working on with tea and maple syrup, it’s really obvious that climate change is indeed happening. Now. It’s influencing specialty crops now. The quality and farmer livelihoods and that consumers are able to perceive these differences. I’ve been working with six different sensory panels both in the United States as well as in China to discern these differences.
20:00 And most importantly we know that climate change is happening. But how can we mitigate this risk? Are there actually innovations that are happening? And so the first Innovation that I have been looking at is the indigenous tea agroforest, a practice that’s been in place for hundreds of years.
And this is looking at the total catechin content. This is an index of measuring 12 different secondary catechin compounds in tea. So this is from the same exact mountain using the same landrace of tea in the same in the same region. And quantifying the amount of total catechins and the tea agroforest had more than two times the amount of total catechins compared to the monoculture plantations. And the tea agroforest also support sustainability because there’s no agrochemical input in these systems. They’re relying on the forest structure to provide pollination services, fertility and protection against pests and pathogens.
And what’s really interesting is looking at the changes from that monsoon onset. And so, when the monsoons come, what’s really interesting is that the quality and both the indigenous agroforest and the monoculture plantation do decrease with the onset of the East Asian Monsoon. However, that difference is not as noticeable in the indigenous agroforests.
And so. Really thinking about sustainability practices and helping mitigate against climate risk.
21:45 And so I’m going to leave you with three questions today. Can you discern between climate sensitive tea and maple samples? Tomorrow you’ll have the opportunity. We’re going to set up a sensory boost in the sensory experiences outside. There will be two different samples of spring and monsoon tea. So you can see if you can discern the differences and which ones you prefer.
We’ve actually, through such sensory experiences, found there’s new markets for some of the monsoon teas. And so this is actually very important data collection for me. And then there’s also going to be two samples of maple syrup, one that is higher grade and the other one that is becoming more prevalent with climate change.
How is climate change changing the phytochemicals and flavors of other specialty crops such as coffee? And then what is the role of sustainability practices in mitigating climate risk?
Thank you so much for your time, and I’ll be happy to take questions later. And then in terms of funding I wanted to thank the federal agencies that have supported this research for more than a decade. Thank you.
23:00 That was Selena Ahmed at Re:co Symposium this past April.
Remember to check our show notes to find a link to the YouTube video of this talk and a link to the speaker bios on the Re:co website.
This has been the Re:co Podcast, brought to you by the members of the Specialty Coffee Association, and supported by Toddy.