Future Effects of Ozone on Carbon Sequestration and Climate Change Policy Using a Global Biogeochemical Model

Abstract

Exposure of plants to ozone inhibits photosynthesis and therefore reduces vegetation production and carbon sequestration. The reduced carbon storage would then require further reductions in fossil fuel emissions to meet a given CO 2 concentration target, thereby increasing the cost of meeting the target. Simulations with the Terrestrial Ecosystem Model (TEM) for the historical period show the largest damages occur in the Southeast and Midwestern regions of the United States, eastern Europe, and eastern China. The largest reductions in carbon storage for the period 1950-1995, 41%, occur in eastern Europe. Scenarios for the 21st century developed with the MIT Integrated Global Systems Model (IGSM) lead to even greater negative effects on carbon storage in the future. In some regions, current land carbon sinks become carbon sources, and this change leads to carbon sequestration decreases of up to 0.4 Pg C yr −1 due to damage in some regional ozone hot spots. With a climate policy, failing to consider the effects of ozone damage on carbon sequestration would raise the global costs over the next century of stabilizing atmospheric concentrations of CO 2 equivalents at 550 ppm by 6 to 21%. Because stabilization at 550 ppm will reduce emission of other gases that cause ozone, these additional benefits are estimated to be between 5 and 25% of the cost of the climate policy. Tropospheric ozone effects on terrestrial ecosystems thus produce a surprisingly large feedback in estimating climate policy costs that, heretofore, has not been included in cost estimates.

Development and application of earth system models

“…This enhanced IGSM model is nevertheless computationally efficient enough to be used in sensitivity and uncertainty studies with the IGSM (21). In addition, versions that partly couple a 3D atmospheric circulation and chemistry model into the IGSM framework are applied to specific issues (e.g., 22).…”

“…The use of a mosaic scheme within each grid enables a simulation of multiple vegetation types without the need for a very fine-grid resolution. The land model employs three coupled submodels to represent the terrestrial water, energy, and ecosystem processes: the community land model (27) calculates the water and energy balances, including the roles of plants; the terrestrial ecosystems model (TEM) (22,28,29) simulates the carbon and nitrogen cycles in vegetation and soils; and the natural emissions model (6) embedded within the TEM simulates the natural emissions of CH 4 and N 2 O, taking into account climate and ecosystem processes in wetlands and soils around the world.…”

“…The reduced sequestration then forces the need for further reductions in emissions to meet a desired GHG concentration target, and thus increases the cost of attaining the target. The future effects of ozone on carbon sequestration and climate change policy have been estimated using the TEM component of the IGSM (22). Simulations for the period from 1860 to 1995 showed that the largest impacts occurred in the southeastern and midwestern states of the United States, Eastern Europe, and eastern China.…”

Impact of tropospheric ozone on the Euro-Mediterranean vegetation

“…They found a reduction in the net primary production (NPP) ranging from 3% to 16%. Felzer et al (2004Felzer et al ( , 2005 incorporated the algorithms from Reich (1987) and Ollinger et al (1997) for hardwoods, conifers, and crops into a biogeochemical model. Their study across the US indicated a 2.6-6.8% mean reduction in the annual NPP during the late 1980s and early 1990s.…”

Protected areas’ role in climate-change mitigation

“…The model takes into consideration how land carbon dynamics are influenced by multiple environmental factors, both static ones such as soil texture and elevation, and dynamic ones such as CO 2 fertilization, climate change and variability, land-use change, and ozone pollution (Melillo et al 1993(Melillo et al , 2009McGuire et al 2001;Tian et al 2003;Felzer et al 2005). In this study, carbon dynamics are simulated for a mosaic of land-cover cohorts contained within each 0.5°latitude by 0.5°longitude grid cell.…”