While the Weed Warriors join Mr. Dale in his concern for worsening climate conditions (Letters, July 24), we do not join him in celebrating the role of kudzu in global warming. Mr. Dale states, without offering any evidence, that kudzu “gobbles” up CO2. In fact, the opposite is true. In a 2014 paper in The New Phytologist, Clemson University scientists demonstrate that invasive plants, specifically kudzu and Japanese knotweed, can accelerate global warming by releasing into the atmosphere carbon that had been stored in the soil. Existing stands of kudzu, they found, release an amount of carbon that is equivalent to the amount of carbon stored in 12 million acres of forests. In other research, scientists studying kudzu in Georgia found that kudzu invasions doubled the rate of nitrogen oxide emissions as well as volatile organic compounds. These compounds are the primary contributors to ozone pollution. By killing forests, kudzu also destroys one of our best defenses to climate change. According to the U.S. Forest Service, forests provide 90% of the U.S. carbon sink and sequester about 10% of the U.S. carbon emissions.
Kudzu has invaded more than 7 million acres of land in the U.S. and is spreading at a rate of 120,000 acres each year—far north of its Southern stronghold—into Maine and Ontario. The damage this exotic species has done to croplands and forests is incalculable and indefensible by any standards, but certainly not as a solution to climate change.