| Carbon terrestrial sinks are seen as a low-cost alternative to fuel switching and reduced fossil fuel use for lowering atmospheric CO2. In this study, meta-regression analysis is used to examine the costs of creating carbon offsets through forestry and through changing agricultural practices. Forestry appears to be relatively inexpensive, with per ton costs ranging from about {dollar}5 to about {dollar}50 depending on type and location of project and whether discount rates are applied to project costs and sequestered carbon. Use of biomass as a substitute for fossil fuels in energy production appears to be the most cost effective option. The viability of agricultural sinks varies by region, with no-till cultivation possibly representing a very low cost option in some regions while coming at costs of {dollar}100 to {dollar}400 per ton of carbon in others. Undercutting these figures, however, is our finding that no-till cultivation may store no carbon at all if measurements are taken at sufficient depth. Carbon sinks may have environmental benefits and can contribute to meeting carbon goals, but questions about the permanence, accounting and monitoring requirements, eventual saturation, leakage, and high transaction costs limit their usefulness. |
