Agriculture as a Source of GHGs - Climate Resilient Agriculture for Ensuring Food Security - page 29

manufacturing sectors. The main greenhouse
gases emitted by the agriculture sector are N 2 O,
CH 4 , and CO 2 . Since 1990, GHG emissions from
agricultural soils and enteric fermentation have
decreased slightly, while emissions from manure
have increased slightly. The overall impact has
remained the same.
In 2008, agricultural soils contributed 15 Mt
CO 2 e, principally from N 2 O emissions associated
with the use of fertilizers. Emissions of N 2 O from
soils under cropping systems occur principally
when excess inorganic nitrogen is present in the
form of nitrate. High soil nitrogen levels, particu-
larly under wet soil conditions, are a signifi cant
driver of greenhouse gas emissions associated
with fertilizer use.

and the Caribbean (74 % of total). Manure man-
agement was the only source for which emissions
were higher in the group of developed regions
(52 %) than in developing regions (48 %)
(Fig. 3.3 ) (US-EPA 2006b ).
Globally, agricultural CH 4 and N 2 O emissions
have increased by nearly 17 % from 1990 to
2005, an average annual emission increase of
about 60 Mt CO 2 e/year. During that period, the
fi ve regions composed of Non-Annex I countries
showed a 32 % increase and were, by 2005,
responsible for about three-quarters of total agri-
cultural emissions. The other fi ve regions, mostly
Annex I countries, collectively showed a decrease
of 12 % in the emissions of these gases (high
agreement, much evidence).
Further improvements in productivity will
require higher use of irrigation and fertilizer,
increasing the energy demand for moving water
and manufacturing fertilizer (Schlesinger 1999 ).
Also, irrigation and N fertilization can increase
GHG emissions (Mosier 2001 ).
Growing demand for meat may induce fur-
ther changes in land use (e.g., from forestland
to grassland), often increasing CO 2 emissions
and increased demand for animal feeds (e.g.,
cereals). Larger herds of beef cattle will cause
increased emissions of CH 4 and N 2 O, although
use of intensive systems (with lower emissions
per unit product) is expected to increase faster
than growth in grazing-based systems. This

3.2 Emissions by Agricultural

Source

Most of the (about 74 % of total) greenhouse gas
emissions originate in industrialized countries.
Emissions from rice production and burning of
biomass were heavily concentrated in the group
of developing countries, with 97 % and 92 % of
world totals, respectively. While CH 4 emissions
from rice occurred mostly in South and East Asia,
where it is a dominant food source (82 % of total
emissions), those from biomass burning origi-
nated in Sub-Saharan Africa and Latin America

Fig. 3.3 Greenhouse gas emissions from different countries