RE: Ozone hole, global warming

[Tuan Pham <tuan.pham@unsw.edu.au>]

Hi Cuong

Xin tra? lo+`i the^m ve^` ozone depletion.

CFC (chlorofluorocarbons) la` nhu+~ng ho+.p cha^'t go^`m C (carbon), 
Cl (chlorine) va F (fluorine), du`ng nhie^`u trong ky~ nghe^. la.nh.
Cha^'t tho^ng du.ng nha^'t la` CFC 12 hay R12. R22 du`ng trong ky~
nghe^., ta'c du.ng huy? ozone ye^'u ho+n. ngoa`i ra co`n ca? chu.c
cha^'t kha'c. Halon la` nhu+~ng cha^'t chu+'a the^m Br (Bromine).

CFC va` Halon la`m gia?m ozone (vi` a?nh hu+o+?ng cu?a Cl va` Br)
nhu+ng ngoa`i ra co`n co' a?nh hu+o+?ng greenhouse warming. 
Ddie^`u na`y i't ngu+o+`i bie^'t vi` mo+'i kha'm pha' ra ga^`n dda^y.

Ozone is a greenhouse gas, so ozone depletion
leads to reduction of greenhouse effect, but CFCs are much more powerful
greenhouse gases (for example 1 kg R12 is equivalent to 8500 kg of CO2)
so overall CFC cause global warming. This is made more serious by
the fact that they absorb wavelengths that are not absorbed by CO2 and
water. An estimate is that 15-20% of global warming is caused by CFCs.
Since Vietnam is a tropical coastal country it will be affected by global
warming in terms of climate changes and sea level rise.

There is a lot of information on the net at these sites:

Greenpeace: http://www.greenpeace.org/~ozone/
http://vest.gu.se:70/1s/ozone
The Ozone Secretariat WWW Home Page: 
  http://www.unep.org/unep/secretar/ozone/home.htm

Ca'i na`y vui mie^.ng no'i the^m -

Ca'c ha~ng ho'a ho.c lo+'n nhu+ Du Pont ddang ga^y a'p lu+.c dde^?
ba'n nhu+~ng mo^i cha^'t la.nh mo+'i cu?a ho., go.i la` HFC (nhu+ 134a), 
nhu+~ng cha^'t na`y ra^'t ma('c va` kho' la`m, va` co' nhie^`u va^'n dde^` 
khi xu+? du.ng o+? ca'c xu+' no'ng va` a^?m nhu+ VN (vi` nha.y a^?m), ne^n
hie^.n ca'c nu+o+'c A^u cha^u ddang quay ve^` nhu+~ng cha^'t hydrocarbon 
(propan, butan) la` nhu+~ng cha^'t ra^'t re? (la^'t tu+` natural gas), la.i 
co' hie^.u na(ng cao ho+n HFC. Ca'c ha~ng ho'a ho.c ddang gu+?i ngu+o+`i 
ddi kha('p the^' gio+'i dde^? co^' ga('ng "be^u xa^'u" hydrocarbons va` 
no'i ra(`ng ra^'t nguy hie^?m vi` de^~ cha'y, no^?. Tuy nhie^n nhie^`u 
independent studies dda~cho tha^'y trong ca'c tu? la.nh du`ng trong nha`,
hoa(*.c ma'y la.nh xe ho+i, hydrocarbon kho^ng nguy hie^?m gi` vi` so^' 
lu+o+.ng ra^'t nho?. Ha~ng Du Pont cu~ng ddang gu+?i ngu+o+`i 
dde^'n Vie^.t Nam dde^? tuye^n truye^`n cho^'ng la.i hydrocarbon!

Cheers
Tuan Pham