The Impact of Land Use Change for Greenhouse Gas Inventories and State-Level Climate Mediation Policy: A GIS Methodology Applied to Connecticut

Abstract

Greenhouse gas (GHG) inventories conducted at state and regional levels serve to quantify long-term emissions trends and set benchmarks against which to evaluate the effectiveness of state government-mandated emissions reductions. GHG inventories which incompletely account for land use, land change, and forestry (LUCF) due to insufficient measurement tools discount the value of terrestrial carbon (C) sinks. In consequence, sink preservation is often omitted from regional land use planning. This paper proposes an accounting methodology which estimates foregone C sequestration derived LUCF change in the southern New England State of Connecticut (CT). The Natural Capital Project’s InVEST program provided a template for modeling C storage and sequestration for CT’s land class categories. LandSat mapping of long-term land cover patterns in CT conducted by CLEAR at the University of CT served as input data for InVEST computer modeling of C sequestration, both realized and foregone due to LUCF. The results showed that: 1) Land converted from high C density forestland to low density C land cover classes reduced the rate of C sequestration loss at 4.62 times the rate of forest reduction. Forest loss of 3.83% over twenty-five years was responsible for foregone C sequestration equivalent to 17.68% of total 2010 sequestration. 2) Accumulating C stocks pushed total annual sequestration from a 1985 baseline level of 866 MMTCO 2 to 1116 MMTCO 2 by 2010—a 250 MMTCO 2 increment. 3) C sequestration from forest loss since 1985 would have yielded additional sequestration of 53.74 MMTCO 2 by 2010. By 2002, foregone yield surpassed CT’s annual fossil fuel emissions, currently at 40 MMTCO 2 . 4) Preservation of forest C stocks over time becomes the determining factor for influencing biomass C sequestration levels. Deciduous forests have a preponderant influence on CO 2 budgets. The ground-up methodology to quantify land-based C sequestration presented here demonstrates the influence of forest biomass in state-level C mitigation efforts useful to climate-oriented policy makers.