University of Vaasa - Vaasan yliopisto

Figure 1 - Impacts of direct and indirect land-use changes on carbon stocks and
global warming
558
The relation between direct and indirect land-use changes and carbon stocks can be
positive or negative. On the one hand, agricultural production, whatever its use may
be (food, feed, energy), is expected to increase in order to ensure the growing world
population needs. This will lead to conversion of wetlands or forests. On the other
hand, new crops implementation on set-aside or degraded land is likely to lead to
carbon stocks expansion, balancing somehow negative effects of deforestation. This
relation is thus indeterminate.
The release of carbon in the atmosphere due to the loss of carbon stocks contributes
to global warming. The relation between carbon stocks and global warming is
inverse.
Direct and Indirect Land-use Changes – Greenhouse Gases
Emissions – Global Warming
GreenHouse Gases (GHG: CO278, CH479, N2O80 and O381)82 come from various
sources and have complicated impacts on each other. Figure 2 83 presents major GHG
sources and direct and indirect relations between main GHG.
EPA (2006) gives figures on major GHG sources. Main CO2 source is fossil fuel
combustion (79%). CH4 is obviously produced by fossil fuel combustion and
extraction (47%) but also by cattle breeding and manure management (34%) and
landfills emissions (24%). Agricultural soil management activities (fertiliser
application) are responsible for 78% of the N2O emissions.
There are two types of ozone (EPA 2003): stratospheric ozone ("good" ozone) and
tropospheric ozone ("bad" ozone). Ground-level or "bad" ozone is not emitted
directly into the air, but is created by chemical reactions in the presence of sunlight
27 Carbon dioxide
28 Methane
29 Nitrous oxide
30 Ozone
31 GHG emissions considered in TEXBIAG project
32 Legend is different for this figure.