Agriculture Reference
In-Depth Information
dioxide, methane, nitrous oxide, SOx, NOx, CO,
soot and particulate matter, ash, aerosols, light
hydrocarbons, volatile organic compounds
(VOCs) such as benzene, and semi-volatile
organic compounds (SVOCs) including polycy-
clic aromatic hydrocarbons (PAHs). The compo-
sition of the gases depends upon the burning
conditions. Burning takes place in two phases:
fl aming and smoldering. During the fl aming
phase, concentration of carbon dioxide is more,
whereas in the smoldering phase, concentration
of carbon monoxide is more.
it will be necessary to stop almost all CO
2
emissions before cumulative emissions reach
one trillion tons of carbon. The world has
already emitted more than half of this quota
since the industrial revolution, and (at current
growth rates for CO
2
emissions) the rest will
be emitted by the middle of this century.
Climate change is a risk management issue - the
longer we take to act and the weaker our actions,
the greater the risk of dangerous outcomes.
3.3.2
Food System Emissions
3.3
Emission Trends (Global
and Regional)
Food system emissions - from production to con-
sumption - contribute 9,800-16,900 million met-
ric tons of carbon dioxide equivalent (MtCO
2
e)
per year, or 19-29 % of total greenhouse gas
emissions (Vermeulen et al.
2012
).
Food production and consumption contribute
19-29 % of total greenhouse gas emissions to
9,800-16,900 MtCO
2
e (million metric tons of
carbon dioxide equivalent at 2008 levels) per
year. This fi gure includes the full supply
chain, including fertilizer manufacture, agri-
culture, processing, transport, retail, house-
hold food management, and waste disposal.
Agriculture makes the greatest contribution to
total food system emissions. It contributes
7,300-12,700 MtCO
2
e per year - equivalent
to 80-86 % of food systems emissions and
14-24 % of total global emissions (Vermeulen
et al.
2012
).
Deforestation and land-use change account
for 2,200-6,600 MtCO
2
e per year to 30-50 %
of agricultural emissions and 4-14 % to total
global emissions.
Direct emissions from agriculture, through,
for example, activities like managing soils,
crops, and livestock, contribute 5,100-6,100
MtCO
2
e per year to 50-70 % of agricultural
emissions and 10-12 % to total global
emissions.
The food chain, excluding agriculture, con-
tributes 14-20 % of food-related emissions
and, at most, 5 % of global emissions.
The proportion of emissions from portions of
the food chain that take place after food leaves
3.3.1
Key Messages
Greenhouse gases (GHGs) infl uence the
earth's climate because they interact with
fl ows of heat energy in the atmosphere.
The main GHGs infl uenced directly by human
activities are carbon dioxide (CO
2
), methane,
nitrous oxide, ozone, and synthetic gases.
Water vapor, although an important GHG, is
not infl uenced directly by human activities.
The amount of warming produced by a given
rise in GHG concentrations depends on “feed-
back” processes in the climate system, which
can either amplify or dampen a change. The
net effect of all climate feedbacks is to amplify
the warming caused by increasing CO
2
and
other GHGs of human origin.
The atmospheric level of CO
2
(the most
important GHG infl uenced by human activi-
ties) rose from about 280 ppm in 1800 to
386 ppm in 2009 and is currently increasing at
nearly 2 ppm per year.
CO
2
levels are rising mainly because of the
burning of fossil fuels and deforestation. Over
half of this CO
2
input to the atmosphere is off-
set by natural CO
2
“sinks” in the land and
oceans, which constitute a massive natural
ecosystem service helping to mitigate human-
ity's emissions.
To have a 50:50 chance of keeping human-
induced average global warming below 2 °C,
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