About the data
3.9
environment
Trends in greenhouse gas emissions Definitions
Greenhouse gases—which include carbon dioxide,
compared. A kilogram of methane is 21 times as
• Carbon dioxide emissions are emissions from
methane, nitrous oxide, hydrofluorocarbons, per-
effective at trapping heat in the earth’s atmosphere
the burning of fossil fuels and the manufacture of
fluorocarbons, and sulfur hexafluoride—contribute
as a kilogram of carbon dioxide within 100 years.
cement and include carbon dioxide produced during
Nitrous oxide emissions are mainly from fossil fuel
consumption of solid, liquid, and gas fuels and gas
Carbon dioxide emissions, largely a byproduct of
combustion, fertilizers, rainforest fires, and animal
flaring. • Methane emissions are emissions from
energy production and use (see table 3.7), account
waste. Nitrous oxide is a powerful greenhouse gas,
human activities such as agriculture and from indus-
for the largest share of greenhouse gases. Anthro-
with an estimated atmospheric lifetime of 114 years,
trial methane production. • Methane emissions from
pogenic carbon dioxide emissions result primarily
compared with 12 years for methane. The per kilo-
energy processes are emissions from the produc-
from fossil fuel combustion and cement manufactur-
gram global warming potential of nitrous oxide is
tion, handling, transmission, and combustion of fos-
ing. Burning oil releases more carbon dioxide than
nearly 310 times that of carbon dioxide within 100
sil fuels and biofuels. • Agricultural methane emis-
burning natural gas, and burning coal releases even
years.
sions are emissions from animals, animal waste, rice
to climate change.
more for the same level of energy use. Cement manu-
Other greenhouse gases covered under the Kyoto
production, agricultural waste burning (nonenergy,
facturing releases about half a metric ton of carbon
Protocol are hydrofluorocarbons, perfluorocarbons,
on-site), and savannah burning. • Nitrous oxide
dioxide for each metric ton of cement produced.
and sulfur hexafluoride. Although emissions of these
emissions are emissions from agricultural biomass
Methane emissions result largely from agricultural
artificial gases are small, they are more powerful
burning, industrial activities, and livestock manage-
activities, industrial production landfills and waste-
greenhouse gases than carbon dioxide, with much
ment. • Nitrous oxide emissions from energy pro-
water treatment, and other sources such as tropi-
higher atmospheric lifetimes and high global warm-
cesses are emissions produced by the combustion
cal forest and other vegetation fires. The emissions
ing potential.
of fossil fuels and biofuels. • Agricultural nitrous
are usually expressed in carbon dioxide equivalents
For a discussion of carbon dioxide sources and
oxide emissions are emissions produced through
using the global warming potential, which allows
the methodology behind emissions calculation, see
fertilizer use (synthetic and animal manure), ani-
the effective contributions of different gases to be
About the data for table 3.8.
mal waste management, agricultural waste burning (nonenergy, on-site), and savannah burning. • Other greenhouse gas emissions include hydrofluorocar-
The six largest contributors to methane emissions account for about 50 percent of emissions
3.9a
bons, perfluorocarbons, and sulfur hexafluoride, which are to be curbed under the Kyoto Protocol.
Methane emissions, 2005 (million metric tons of carbon dioxide equivalent) 1,400
Hydrofluorocarbons, used as a replacement for chlorofluorocarbons, are used mainly in refrigeration and semiconductor manufacturing. Perfluorocarbons,
1,050
also used as a replacement for chlorofluorocarbons in manufacturing semiconductors, are a byproduct of
700
aluminum smelting and uranium enrichment. Sulfur 350
hexafluoride is used largely to insulate high-voltage electric power equipment.
0
China
India
Russian Federation
United States
Brazil
Indonesia
Source: Table 3.9.
The five largest contributors to nitrous oxide emissions account for about 50 percent of emissions
3.9b
Nitrous oxide emissions, 2005 (million metric tons of carbon dioxide equivalent) 500 375
Data sources Data on carbon dioxide emissions are from the
250
Carbon Dioxide Information Analysis Center, Environmental Sciences Division, Oak Ridge National
125
0
Laboratory, Tennessee, United States. Data on methane, nitrous oxide, and other greenhouse China
Source: Table 3.9.
United States
Brazil
India
Indonesia
gases emissions are compiled by the International Energy Agency.
2011 World Development Indicators
161