Barrons AP Environmental Science

insulation

Halons

65 6,000

Fire

extinguishers

Methane (CH 4 )

15 25

Rice

cultivation,

cattle/sheep

raising,

landfills,

natural gas

leaks,  coal

production

Nitrous Oxide

(N 2 O) 115 300

Burning fossil

fuels,

fertilizers,

livestock

wastes, plastic

manufacturing

Sulfur  Hexafluoride

(SF 6 ) 3,200 24,000

Electrical

industry    as  a

replacement for

PCBs

Tropospheric    Ozone

(O 3 )

Varies

3,000

Combustion  of

fossil  fuels,

photochemical

smog    produced

by  internal-

combustion

engines

Greenhouse Gases by Country

The top carbon dioxide emitters from fossil fuel combustion, cement
manufacturing, and gas flaring are China and the United States. Changes in land
use are also significant contributors of CO 2 as global estimates indicate that

deforestation can account for 5 billion metric tons of CO 2 emissions, or about