In the Herbalgram article, titled “Tea and the Taste of Climate Change: Understanding Impacts of Environmental Variation on Botanical Quality,” author Selena Ahmed, PhD, describes her research into the cultivation of tea in China with a focus on Yunnan province in the southwest. Ahmed, who is a postdoctoral fellow at Tufts University, has recently expanded her view to other tea growing regions such as Japan and Hawaii.
Yunnan’s unique geography
Yunnan has long been a source of tea, including the highly regarded Pu-erh variety. The region has an unusual geography that is dominated by high and steep mountain ranges cut into narrow gorges by three great rivers: the Salween, the Mekong and the Yangzte. These gorges act as funnels carrying the warm, moisture-laden air of the monsoon deep into the heart of the continent, giving the river valleys micro-climates that are starkly different from surrounding regions. Climate change seems to be altering the balance of this finely tuned machine, according the the Yunnan Provincial Climate Change Programme, a Chinese government agency. The average number of rainy days in the province has decreased from about 270 in 1950 to about 150 now, and the number of foggy days has decreased from 180 a year to 30, according to a recent agency report.
Bigger precipitation events
The monsoon still comes, but in recent years it has been coming in bigger, more destructive and less predictable chunks, the report said. “In the past ten years, the incidence of extreme climate/weather events in Yunnan was high, with the trend of the increase of extreme precipitation and extreme precipitation events."
Like other botanicals, the quality of tea leaves has always varied by season and by year by year. In her research, Ahmed is attempting to quantify these differences. Ahmed has visited with scores of tea farmers in the course of her multi-year research, and on a anecdotal level, they clearly see shifts in growing conditions, including warmer temperatures, more droughts and paradoxically more intense rains.
“The majority of tea farmers I have interviewed state that climate patterns have shifted noticeably over their lifetimes; such observed changes include warmer temperatures, greater unpredictability of weather such as increased variation of rains, and changing phenology of plants (i.e., the effect of weather patterns on plant growth cycles, including flowering and fruiting seasons, etc.), including earlier bud burst,” Ahmed wrote.
Seasonal variability
Tea harvested in drier months tends to have better flavor and fetch higher prices, whereas tea harvest in wetter times is more plentiful but blander, the growers Ahmed interviewed said. The differences in quality can be attributed to lesser amounts in the well-hydrated leaves of the bitter, tannic compounds that give tea its flavor and impart its antioxidant benefits.
“Initial findings from my field and laboratory sampling during the extreme dry and rainy seasons in southern Yunnan show that tea’s key health compounds can decrease by up to 50% with the onset of the East Asian monsoon, thus validating farmer perceptions of a decrease in tea quality with the rains. . . . It appears that the extreme rains, which are getting more frequent with climate change, may serve to dilute tea phytochemicals and explain the changes that farmers are experiencing,” she wrote.
“Tea could be like a canary in a coal mine, a harbinger of other plants whose chemistries might alter in response to climate change in ways that might desirable or undesirable,” Mark Blumenthal, founder and executive director of ABC told NutraIngredients-USA.
Not all are in agreement
Climate change is a hot potato topic in US politics, and it is no wonder that there is disagreement within the botanical community, too. BI Nutraceuticals sources botanical ingredients from all over the globe, and CEO George Pontiakos said he can’t find evidence in his supply chains to support the concept of global climate change.
“We have been sourcing teas globally since 1975 there has been no significant change in tea quality beyond what is normally to be expected. We have seen variances of course but that just depends on weather patterns. We have seen nothing that we would associate with long term trends,” Pontiakos said.
“If you don’t have data to support your position you are just sound-biting what we think is pseudo science,” he said.
Less supply certainty
Beth Lambert, CEO of Herbalist & Alchemist, a company that focuses on tinctures and other herbal preparations, said she’s not sure about the big issue of climate change, but in the narrow focus of her company’s own supply considerations, complications have multiplied.
“I think it may be a little early to say whether we are seeing wholesale changes in certain regions. But we have seen huge disruptions in supply chains from weather,” Lambert said.
“We had a reliable grower in New York State get taken out by a hurricane. Their fields flooded and they were out of production. They had to rip out all their plants and wait until they could be re-certified organic,” she aid.
“We are seeing more drama than we have before. For example, last year the season was too cold and we could not find an harvestable Indian Pipe. And for almost two years we were not able to find any Chinese Coptus roots that did not have aflatoxin—root rot, basically. To compensate we are having to supply from a wider variety of regions than ever before,” she said.
Tom Tolworthy, CEO of Twinlab, was not willing to hop on the global climate change bandwagon, either. But he did agree with Lambert the supply ground seems to have shifted. Twinlab sources a variety of botanical ingredients for its line of Alavita organic herbal teas and other dietary supplements.
“There is some obvious natural variability. But it is harder to find consistent quality product now than it was six or eight years ago,” he said.
Outlook for the future
Blumenthal said the increasing likelihood of supply variability will put more pressure on brokers, suppliers and manufacturers to keep detailed records to as to have reliable baselines from which to make accurate assessments of long term quality trends.
“You have to keep good chemical profiles of your current supply. For tea there is a flavor issue, but for a lot of botanicals flavor is not an issue. But flavor is an indicator of chemical change,” he said.
Ahmed said different cultivation practices may help growers compensate more effectively for climate variability. One grower she interviewed in Japan did not see evidence of climate change having affected his crop, but she said that might be because his organic farming methods may have produced hardier plants. One issue Ahmed focuses on was how changing weather patterns have given rise to different populations of pests.
“Organic tea farming is more resistant to climate change. Non-organic tea farms have had more problems including high and unstable populations of pests,” Ahmed quotes the grower, Toshiaki Kinezuka, as saying.
In Yunnan, Ahmed said farmers had seen the benefits of keeping the borders of their plantations forested and shying away from a mono-cropping, big agribusiness model.
“(The farmers) believe that tea plants grown in an environment with greater tree canopies and surrounding forests are better able to resist the impacts of climate change. Previous research has documented the numerous benefits of agro-forestry systems,17 including resilience to climate change, maintenance of biodiversity, and higher-quality botanicals,” Ahmed said.