Impact of climate variability and land use changes on global biogenic volatile organic compound emissions

Abstract

A biogenic emissions scheme is incorporated in the global dynamic vegetation model ORCHIDEE (Organizing Carbon and Hydrology in Dynamic EcosystEms) in order to calculate global biogenic emissions of isoprene, monoterpenes, methanol, acetone, acetaldehyde, formaldehyde and formic and acetic acids. Important parameters such 5 as the leaf area index are fully determined by the global vegetation model and the influences of light extinction (for isoprene emissions) and leaf age (for isoprene and methanol emissions) are also taken into account. We study the interannual variability of biogenic emissions using the satellite-based climate forcing ISLSCP-II as well as relevant CO 2 atmospheric levels, for the 1983-1995 period. Mean global emis-10 sions of 460 TgC/year for isoprene, 117 TgC/year for monoterpenes, 106 TgC/year for methanol and 42 TgC/year for acetone are predicted. The mean global emission of all biogenic compounds is 752±16 TgC/yr with extremes ranging from 717 TgC/yr in 1986 to 778 TgC/yr in 1995, that is a 8.5% increase between both. This variability differs significantly from one region to another and among the regions studied, biogenic emis-15 sions anomalies were the most variable in Europe and the least variable in Indonesia (isoprene and monoterpenes) and North America (methanol). Year-to-year variability also reveals a strong correlation of emissions in tropical regions with El Niño events, particularly for isoprene, for which the tropical regions are a major source. Two scenarios of land use changes are considered using the 1983 climate and atmospheric 20 CO 2 conditions, to study the sensitivity of biogenic emissions to vegetation alteration, namely tropical deforestation and European afforestation. Global biogenic emissions are highly affected by tropical deforestation, with a 29% decrease in isoprene emission and a 22% increase in methanol emission. Global emissions are not significantly affected by European afforestation, but on a European scale, total biogenic VOCs emis-25 sions increase by 54%. Abstract Introduction Conclusions ReferencesTables 25 penes emissions but also methanol, acetone, acetaldehyde, formaldehyde, formic and acetic acids. In Sect. 2 of this paper, we describe the interactive biogenic emission and vegetation global dynamic vegetation model, Geophys. Res. Lett.

Impact of tropospheric ozone on the Euro-Mediterranean vegetation

“…On the other hand, the vegetation structure and activity has an impact on atmospheric chemistry through deposition of pollutants and emissions of volatile organic compounds (Guenther et al, 2006;Lathiere et al, 2006;Petroff et al, 2008). Hence, there is a strong coupling between O 3 and vegetation: the first one impacts plant productivity that, in turn, can affect the atmospheric O 3 concentration.…”

“…First, O 3 stress leads to a change in stomatal conductance and can affect the dry deposition velocities, and hence the O 3 concentrations in the canopy (Petroff et al, 2008), or, more generally, in the lower atmosphere. Second, a change in stomatal conductance induces changes in BVOC emissions, and it could increase or decrease the O 3 concentration, depending on the NO x levels (Lathiere et al, 2006). Finally, a severe O 3 stress induces a significant decrease in the GPP and, consequently, in the amount of carbon allocated in the biomass.…”

“…Ren et al, 2007), as well as the deposition of pollutants on the canopy (Petroff et al, 2008) and the role of vegetation in BVOC emissions (e.g. Guenther et al, 2006;Lathiere et al, 2006), the vegetation-atmosphere feedbacks are still under investigated.…”

Regionalizing global climate models

“…They therefore have the potential to cause remote regional changes in climate but it is not known if this potential is realised. Emission hot-spots (Figure 2) for isoprene are tropical evergreen and rain-green forests and woodlands (Guenther et al, 1995;Lathière et al, 2006;Arneth et al, 2007). During summer months, the forests of the southeastern US, south and eastern China, parts of southern Europe and central and southeastern Asia are also important sources because these regions contain a relatively large number of high-emitting species (Guenther et al, 1995;Lathière et al, 2006;Arneth et al, 2007).…”

“…Emission hot-spots (Figure 2) for isoprene are tropical evergreen and rain-green forests and woodlands (Guenther et al, 1995;Lathière et al, 2006;Arneth et al, 2007). During summer months, the forests of the southeastern US, south and eastern China, parts of southern Europe and central and southeastern Asia are also important sources because these regions contain a relatively large number of high-emitting species (Guenther et al, 1995;Lathière et al, 2006;Arneth et al, 2007). Monoterpenes tend to have an additional source in coniferous temperate and boreal forests and in Mediterranean and seasonal tropical ecosystems (Guenther et al, 1995;Lathière et al, 2006;Schurgers et al, 2009).…”