(Beyond Pesticides, March 29, 2007) While it seems to allergy-sufferers that symptoms get worse year after year, most figure it’s all in our heads. However, research by Lewis Ziska, Ph.D., a plant physiologist with the USDA Agricultural Research Service’s Crop Systems and Global Change Lab and speaker at the upcoming National Pesticide Forum, shows that common pollen allergens – including the troublesome ragweed pollen – may be getting worse as a result of global climate change. The conventional response to unwanted plants is increased pesticide use, which raises concerns among environmental and public health advocates.
According to Dr. Ziska’s research, elevated levels of carbon dioxide (CO2), the top greenhouse gas, and warmer temperatures appear to increase ragweed pollen production. Dr. Ziska’s research uses sealed growth chamber systems to simulate current levels of CO2 (370 parts per million by volume, ppmv) and that projected for the mid-21st century (600 ppmv). The ragweed increased pollen productivity by 131 and 3200% respectively, compared to ragweed grown at pre-industrial CO2 levels (280 ppmv).
A recent two-year real-world observational study of ragweed also found that urbanization-induced increases in CO2 and temperature were associated with increased ragweed growth, pollen production and pollen allergenicity, suggesting a probable link between rising CO2 levels, global climate change and public health. According to Dr. Ziska, while most of the work regarding weeds, pollen production and climate have focused on common ragweed, rising CO2 and/or temperature would also be expected to influence seasonal pollen production of other allergenic plants, including tree and grass species.
Dr. Ziska’s research states, “[I]t is estimated that approximately 10% of the U.S. population-or 30 million people-suffer from hay fever or allergenic rhinitis. Symptoms include sneezing, inflammation of nose and eye membranes, and wheezing. Complications such as nasal polyps or secondary infections of the ears, nose and throat may also be common. Severe complications, such as asthma, permanent bronchial obstructions, and damage to the lungs and heart can occur in extreme cases. Although there are over four dozen plant species that produce allergic reactions, common ragweed, a ubiquitous weed, causes more problems than all other allergenic plants combined.”
Dr. Ziska’s research also examines the impact of climate change on pesticide use and efficacy — especially in relation to glyphosate (RoundUp), crop nutrition, medicinal plants, disease vectors, increases in poison ivy, and more (see also 3/19/07 Daily News post). His full article, “Climate Change, Plant Biology and Public Health,” will be published in the Spring 2007 issue of Pesticides and You.
In addition to significant cuts in fossil fuel emissions, research by Paul Hepperly, Ph.D., of the Rodale Institute and speaker at the National Pesticide Forum, suggests that organic agriculture may also be a powerful tool. The Rodale Institute’s Farming Systems Trial, the world’s longest running study of organic farming, has documented that organic soils actually scrub the atmosphere of global warming gases by capturing atmospheric carbon dioxide and converting it into soil material. This is the first study to differentiate organic farming techniques from conventional agricultural practices for their ability to serve as carbon “sinks.”
Although it’s not a “silver bullet,” carbon sequestration can become a powerful component of a multi-pronged approach to managing the issue of global warming. Since 1981, The Rodale Institute has monitored soil carbon and nitrogen levels in scientifically controlled test fields using organic as well as a wide range of other farming methods. In the organic systems, soil carbon increased 15 to 28 percent.
To find out more about the link between pesticides and global warming effects, as well as to learn about ways that organic agriculture can help sequester carbon, join Beyond Pesticides at our 25th National Pesticide Forum, Changing Course in a Changing Climate: Solutions for health and the environment, June 1-3 in Chicago, IL. Details at www.beyondpesticides.org/forum.