A recently published article is the first comprehensive survey of how climate change might affect the availability of some commonly used herbs. “The Effects of Climate Change on Medicinal and Aromatic Plants” by Courtney Cavaliere reports that Arctic or alpine medicinal plants, such as rhodiola (Rhodiola rosea) and snow lotus (Saussurea laniceps), already are being adversely affected.
Jan Salick, Ph.D., curator of ethnobotany at the Missouri Botanical Garden, notes that the Himalaya Mountains are likely to experience some of the most dramatic climate changes, with temperatures increasing by as much as 40 to 42 degrees and precipitation increasing by as much as 30 percent over time. Such climate changes would have a severe impact on the alpine Himalayan plants, and on the traditional Tibetan doctors who use them.
Climate changes appear to be affecting plants in other areas, too. Abnormally hot summers in recent years have prevented chamomile (Matricaria recutita) from reseeding in Germany and Poland. In Hungary, severe flooding over the last two summers has reduced the harvests of fennel and anise seed.
And while the 2008-2009 U.S. winter temperatures averaged “near normal,” a recent study (led by Richard Primack at Boston University) on flowering times in New England showed that many plants now flower more than a week earlier than they did in the time of Henry David Thoreau (1827-1862). Comparing USDA hardiness zone maps of 1990 and 2006 shows a dramatic northward shift of warm zones in the United States.
“As the situation unfolds, climate change may become a more pressing issue for the herbal community,” Cavaliere says. Reading such news might make us cringe, but collecting data from a broad range of studies, as this survey does, is an essential step for shaping public policy that can help prevent or minimize loss.
For more information, see HerbalGram 81, 44-57.
Steven Foster is an author and photographer specializing in medicinal plants.