Global Change

INDEX
TOPIC Plobal change DATE 12 . □ 24
.




NOTE
Stratospheris OEone Depletion
-

witnin the stratosphere mostly w 2o km incoming Uu radiation from the sun is involved in the splifting
, ,


and peforming of ozone ( os )
s absorbs aa of the Ur from
radiatiom the san
,
whicn is
rery dangerous
s uV radiation exposure cam cause damage ranging from sumburm to skin cancer and cataracts
-



stratospheric ozone layer protects Eartn by absorbing UV radiation

1 .
UV A

longest length least energetic
-



;

-
can cause some damage to
living cells

-

transmitted to Earth

2 . UVB
-


intermediate wavelengtn
cacuse of ozone
problem
-




3 .
uVC

sbortast
wavelength mostenergetic
-




ozome Formation

0 + 0 ~ → 0

s
-




도
s




0.
No 고
→ 20
bo a
a 0 + 02 →
03
ozone shield : stratospheric ozone tmatabsorbs most( aas ) uV radiation : the 11 . ou B radiation that

reaches skim and damages crops and other
us causes cancer
organisms
-

How ozone is formed in the stratusphere :




UVe radiation splits or molecules into fres oxygen ( o )
.




02 + UVC yoto

some O combines with or to form ozome (o 3)

O + Oa → O 3

Ozone Destruction

oxygen atoms combine with O form
some to O
3 로


O + 037 02 + O일

-


oz absorbs urBand converts to oand Oc

O3 + UVB → 0 + Oc


causes of the Ozone Hole

of CFCs Cchlorofluorucarbons) Gost
s



cause for depletion was the increased 7o
-

ozone use in
primary '


-



CFCS :




s monreactire

snonflammable
s
nontoxis organic molecules

s
normally gaseous ,
but liauefy under
pressure
s were used as
refrigerants and propeslants tconsidered an advancement on carier
refrigerants
such as ammoia c which are toxics

s and
plastic foams , refrigerator , air conditions ,
aerosol cans

4 found become r altitudes
only after widespread use that cFCs unstable at where they
could be exposed to ur radiation from sun


4 pichlorod ' fluorometnane [ R 12
-

on CFC -


12 )
=
most common
prior
to ban

s Chlorod : fluoro methame Ltype of HCFC) → still used as re
frigerant in
developing countries


Anthropogemic ozone Destruction

1) photo -

dissosiation -


sun brealas up moreaule

Tricnlorofiuoromexname D, chlorocfluorolmetnyl anlorime

CFCI 3
→ CCI 2 F + 이

, INDEX
2) cnsorine breaks ozone '
s bonds +
pulls off one atorm of oxygen , forming a Co molecule and Oz




NOTE
O 3
+ CI → C1 O + Or

) Finallay free Ontom Bulls the from Clo liberating chlorine and
creating
3



,
a
oxygen atom ,
the

one oxsgen molecule :




Cloto → al + Oz
↑
( promotes wlo being used up )
acts as a
catalyst ran

s
every chlorine molecule lasts 4 o -
100 yrs in the air I aanbreas down 100 ,
000 0
s
molecules )

Infernational Agreement
1987 : Montreal bamned production of CFCS
pro tocol
-




s black mar kef for CFCS
-

cFCs are only I group of ozone
depleting chemicals

Free Cr stratw peaked around 199 g +
projested to declins for more than century
-

in .
a


wzone loss is projected to dimish slomly but willtake anotner t 00 -wo for full recovery
-




yrs

Beplacing CFCs

-

alteratives developed have their set of problems Lprimarily s most potemt oy δ '
)
own are
very s



1 a 2 Os 1950 s 199 Os 2010 s




1 1 1
λ > "
√
「
\
CFC chorofluurocarbon
'
HcFC :
hydrochlorofluoro carbon HFC Hydrofluorocarbon
:
IFO :
bydrofluoroolefin
-
rozone depletion -

↓ ozone deple tion
-

o ozone depletion -

0 ozone de pletion
-

n σ H potential -

oa σ H potential
-

n σ시 potential
-




very t 5 lH potential
Thc Jreenbouse Effect

earth atmospbere up of and Calong wI smal Cor CH 4 , and
'
s made N 0 water quantities of
-



, , rapor ,
a

number of other trace gases
* Jreem house effeat s natural process by whicn neat is trapped witnin atmosphere by these
green bouse gases
results in earen '
s
s averagetemp .being 33 c warmer than if there was no atmosphere
s
greenbouse gases ast as a thermal blanket around the ear th

Glets
sunlight in

s some solar energy is reflected before it reaches the surface and from the surface ,
but

some is reflested back to the Earth coH σ '
s absorb + release reflected energy , trapping it

in the atmosphere )
-


greenhouse gases act as a thermal blanket around the eartn , letting in sunlignt , but trapping the

heat that would radiate back into
normally space
Olobal
warming
-

fluctuation ' s in surface tem p . are normal ( result of climate shifts )

mid 2 oin century been on global warming
-




since surface temp nas
=
.

,



s consensus
by researcnersslobal warming isa result of r in atmospheric leveis of coz and

other antnropogenic greenbouse gases

Hao plays important part in
keeping eartn '
temp
-


an s stable

7 water inflnenced earth s
'

vapor is by temp ,




.
n in
temp .
=
h water to
erapurate [ can ennance
warming effest of otner JH σ
'
s )

lived
'
.

is
very short unlike other oHo s because water aycles from the atmos . and back
'
sources Of OH 8 s


renicles ), ;combustion o f coalfwoodl oit ; burning
Majorsources of cor : exnaust[ rainforest( carbory sinks )
-




-

Cl 4 major sources :
plant debris ,
landfills ; belching f flatus of cattle ; saturated soils lex ; rice


paddy fields ] : AJREATEST beat -




trapping ability
-


CFCs :
leaking coolant from fridges , leaking coolant from air cons
-


Nitrous oxide :
car exhaust
( BAD ) triggered by exhaust ( smog)
tropospheric
:
ozone car
-