Barrons AP Environmental Science

Gas

At the global scale, the key greenhouse gases emitted by human activities are:

■ CARBON    DIOXIDE (CO 2 )—Fossil  fuel    use is  the primary source  of  CO 2 .  The

way in  which   people  use land    is  also    an  important   source  of  CO 2 ,

especially  when    it  involves    deforestation.  Land    can also    remove  CO 2    from

the atmosphere  through reforestation   and the improvement of  soils.

■ METHANE   (CH 4 )—Agricultural    activities, waste   management, and energy

use all contribute  to  CH 4    emissions.

■ NITROUS   OXIDE   (N 2 O)—Agricultural    activities, such    as  fertilizer  use,    are the

primary sources of  N 2 O   emissions.

■ FLUORINATED   GASES   (F-GASES)—Industrial    processes,  refrigeration,  and the

use of  a   variety of  consumer    products    all contribute  to  emissions   of  F-

gases,  which   include hydrofluorocarbons  (HFCs), perfluorocarbons

(PFCs), and sulfur  hexafluoride    (SF 6 ).

■ BLACK CARBON  PMX—Black   carbon  is  a   solid   particle    or  aerosol,    not a   gas,

but it  also    contributes to  the warming of  the atmosphere.