The so-called "tea-belt" comprises a stretch of Asian countries
where the climate is tropical to sub-tropical, and the elevations for the tea gardens are between 3,000 to 6,000 feet. This is necessary because the air is usually cooler, slowing down leaf growth.
The tea plants need anywhere from 80 to 100 inches of rainfall a year, and even though countries in the tea-belt get annual monsoon rains, as long as the storms are not extreme, the tea plants do well. As a matter of fact, the seasonal monsoons help the plants to go through a growth spurt.
Now, climate-change has slowly begun to impact tea growers, with environmental changes affecting not only the taste, aroma, and potential health benefits of the popular beverage, but also the lives of those who grow tea for a living.
In the Assam region of India, the changes in the temperature and rainfall have given rise to added expenses in growing the tea plants. Growers are finding they cannot raise their prices though, because of the competition. Scientists in the north-eastern state of Assam say that temperatures in the region have been creeping up, and with rainfall patterns changing, they are experiencing longer dry periods.
Manish Bagaria, the owner of a tea estate in Dibrugarh, northern Assam, said, "Now, what we have been noticing over the decade is we get a lot of rainfall in one particular month or a couple of months and that erodes the topsoil of the tea garden. While that already affects our production, the dry spell makes our bushes prone to pests, for which we have to use more pesticides and that means higher costs."
Other tea growers in the region have similar stories, and many are now using water pumps, irrigation systems or sprinklers. Almost all the growers
are now battling pests that have been dormant for years. A big fear of many is the rising costs associated with growing their tea.
The Tocklai tea station, in Assam has been keeping records on temperature and rainfall levels for a number of years. and has found minimum temperature across the belts has risen by 1.5°C, while the annual rainfall has dropped by 200mm. The ambient temperatures in the Assam region have risen from 35 degrees C, to as high as 50 degrees C. When the tea leaves reach a temperature of 48 degrees C., the tea leaves stop breathing and the plant will die.
Climate change is also affecting the cultivation of tea in China.
While the Assam tea is a rich, black tea favored by many Briton's, China's green tea also is a favorite tea, with its medicinal properties, it is used by many Asians as the first drink of the day, and by people on weight-loss diets for its antioxidants.
In January of this year, Tufts University biologist Colin Orians, with a grant from the National Science Foundation, started a four year study on the effects of climate change, and how temperature and rainfall alters the concentration of chemical compounds that are responsible for tea’s stimulant, sensory and healthful properties.
“Since the quality of tea is determined by a range of secondary chemicals that depend on climatic conditions, climate change can have significant consequences for tea markets,” says Orians, “People buy and drink tea for certain qualities. If those qualities are not there, then they may not buy the tea.”
Tea is one of the world's most widely consumed beverages. In the U.S., Americans drink 3.6 billion gallons annually and supermarket sales are over $2 billion a year, according to the Tea Association of the USA. In the United Kingdom, 165 million cups of tea are consumed daily, with 96 percent of the tea coming from a tea bag, according to the United Kingdom Tea Council. Another interesting fact on tea in Great Britain is that 98 percent of tea is taken with milk.