[[EDITOR'S NOTE: This very thought-provoking post comes from Steven Owyoung, former Curator of Asian Art at the St Louis Art Museum, and an internationally revered authority on the teas of Pacific Asia. Readers of CHA DAO will remember with pleasure his learned contributions on "Cha 茶 and Ming 茗"; on the Qianlong Emperor's Jade Tea Bowl; and on the Jade Spring. Text and images are published here by his permission. As always, the size of the images may be increased by clicking on them.]]
I have read with some interest your postings on pollution in China and its effects on tea and tea production. In addition to worker hygiene, pesticides, water and air pollution, and global warming, attention needs to turn to another kind of pollutant effect and what is known as "global dimming."
Global dimming is the reduction of sunlight that reaches the earth due to the amount of particulate matter suspended in the atmosphere and the resultant refraction and diffusion of light in the polluted air. The refraction, deflection, and diffusion of light in the atmosphere reduces the amount of sunlight reaching the earth's surface. In moderate to high pollution, the reduction in sunlight caused by global dimming may reach as much as ten to twenty percent.
Sunlight, especially bright late winter sunshine, is crucial to the tea plant, especially the first spring flush. The marked reduction of sun reaching the tea leaves has a pronounced effect on the quality and quantity of production and on the flavor of the tea.
During the winters of 2003 and 2006, Hangzhou was covered by dark, hazy overcast skies. Nearby West Lake, the region known for Dragon Well tea, suffered under the same dim sunlight.
At midday, the nether shores of the lake were nearly invisible and even landmarks in the middle distances were but muddy shadows and dishwater brown. Even in the far south along the Li River in Guilin, the fabulous peaks were layered in a filmy gauze. Back in Shanghai and Suzhou, on the sunniest days, the air was thick with haze. Even by the most lenient standards, the air and skies of China are very polluted.
Given that tea and rare tea are dependent on sunlight and all its constituents, global dimming is a problem and a threat to tea to say nothing of other agricultural products.