Geoscience Reference
In-Depth Information
In fact the stability and predictability of the climate and the
ability of farmers to adapt their practices to changing climatic
conditions will ensure the future of food production and global
food security (Chakravarty and Mallick, 2003). The overall
level of agricultural GHG emissions will continue to rise for the
foreseeable future as agricultural production expands to keep
pace with growing food, feed, fibre and bioenergy demand.
Increasing agricultural efficiency is critical to keep overall
emissions as low as possible and to reduce the level of emis-
sions per unit of agricultural output. Efficient and responsible
production, distribution and use of water, fertilisers and other
inputs are central to achieving these goals. Agricultural systems
can adapt to offset the negative effects of climate change, but
not without costs for changes in technology involving research
and development and farm-level adoption, including possible
physical and human capital investments (Anonymous, 1992;
Rosenberg, 1992; Easterling et  al., 1993; Kaiser et  al., 1993;
Mendelsohn et al., 1994; Easterling, 1996; Adams et al., 1998).
Mitigation is unlikely to occur without action, and higher
emissions are projected in the future if current trends are left
unconstrained. Global population will increase by 50% from
present, reaching nine billion by 2050 (Lutz et al., 2001; Cohen,
2003). This enormous population pressure will require double
production of cereals and other animal-based foods during the
coming decades, which will require more use of N fertiliser and
livestock increasing N 2 O and CH 4 emissions from enteric fer-
mentation unless more efficient fertilisation/management tech-
niques and products can be found (Tilman et al., 2001; Mosier,
2002; Roy et  al., 2002; Galloway, 2003; Green et  al., 2005).
CH 4 and N 2 O emissions vary greatly with land use depending
on trends towards globalisation or regionalisation and on the
emphasis placed on material wealth relative to sustainability
and equity (Strengers et  al., 2004). Trends in GHG emissions
in the agricultural sector depend mainly on the level and rate
of socio-economic development, human population growth and
diet, application of adequate technologies, climate and non-cli-
mate policies and future climate change. Consequently, mitiga-
tion potentials in the agricultural sector are uncertain, making
a consensus difficult to achieve and hindering policy making.
Opportunities for mitigating GHGs in agriculture fall into three
broad categories (Smith et  al., 2007a,b,c; Niggli et  al., 2009)
based on the underlying mechanisms.
Reducing
emissions
The fluxes of GHGs can be reduced by efficient management
of carbon and nitrogen flows in agricultural ecosystems. The
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