Turfgrasses, Carbon Dioxide and Global Warming: Part One of Two
Samples, Thomas J., Landscape & Irrigation
A question often asked of students studying turfgrass science and management is "Which of the following: light, temperature, water ([H.sup.2]0), atmospheric carbon dioxide (C[O.sup.2]) or nutrition is most important for turfgrass survival?" One correct answer is, "All are equally important."
More difficult and complex questions are "What is the capacity of turfgrasses to remove and store, or sequester, carbon (C) from the atmosphere?" and "Does this help prevent global warming?" These questions force students to recall what they've learned about photosynthesis 6C[O.sup.2] + 6 [H.sup.2]O + light energy [C.sup.6][H.sup.12][O.sup.6] + 6[O.sup.2], the ability of turfgrasses to capture and store C, the greenhouse effect, and the oceans' role in C sequestration.
Approximately one-half of the photosynthesis on Earth occurs on land, and the remainder in water (1). Both ocean and land plants share the same basic requirements for photosynthesis and growth. These requirements include light, an appropriate temperature, [H.sup.2]O, C[O.sup.2] and nutrients.
Although nitrogen ([N.sup.2]) and [O.sup.2] account for 78 and 21 percent of the dry atmosphere, respectively, these gases contribute very little to the greenhouse effect. Greenhouse gases in the atmosphere, including C[O.sup.2], hydrofluorocarbons (HFCS), methane (C[H.sup.4]), nitrous oxide ([N.sup.2]O), ozone ([O.sup.3]), perfluorocarbons (PFCS), sulfur hexafluoride (S[F.sup.6]) and water vapor, act as a partial blanket for long-wave radiation coming from the earth's surface. They let energy from the sun in, but don't let all of the heat energy out. This blanketing results in a natural greenhouse effect, warming the earth's surface.
Water vapor and C[O.sup.2] are two very important greenhouse gases. Human activities have had only a small, direct influence on the amount of water vapor in the atmosphere. During the past 20 years, fossil fuel burning has contributed about three-quarters of the atmospheric C[O.sup.2] emissions resulting from human activities (2). For several thousands of years before the Industrial Era, which began about 1750, the atmospheric C[O.sup.2] concentration was 280[+ or -]10 parts per million by volume (ppmv) (2). Since then, it has risen, reaching 379 ppmv in 2005 (3).
Carbon dioxide is soluble in water. Presently, the oceans take up about two billion metric tons of C annually (4). Most of the C[O.sup.2] taken up by the oceans combines with water to form carbonic acid ([H. …