5
Recovering
the Ozone
Layer
References
[1] Strahan, S. E., Douglass, A.R., Newman, P. A., Streenrod, S. D.,
(2014). Inorganic chlorine variability in the Antarctic vortex
and implications for ozone recovery.
Journal of Geophysics
Research: Atmosphere
. Volume 119, Issue 24.
[2] Carpenter, L. J., Reimann S., Burkholder, J. B., Clerbaux, C., Hall,
B. D., Hossaini, R., Laube, J. C., Yvon-Lewis, S. A. (2014). Ozone-
Depleting Substances (ODSs) and Other Gases of Interest to
the Montreal Protocol – Report No. 55,
World Meteorological
Organization, Geneva Switzerland
.
[3] Culaba, A. Good News: Ozone Hole Closing. Bad News: It Won’t
Recover Until 2070. Retrieved from
-
recovery-ozone-layer-wont-happen-2070/499477
恢復臭氧層
之路
在
二十世紀末，南極臭氧洞規模飆升，直徑橫跨整
個南極。臭氧損耗不但增加紫外線輻射強度，造成人類健
康風險、對生態和氣象的影響亦不容忽視。在自然界中，平
流層的臭氧、氧氣和遊離氧原子不斷合併重組，吸收紫外
線的輻射能量。破壞臭氧層的物質如氯氟烴（CFC）、氫氯
氟烴（HCFC）和氫氟等，加速臭氧解體為氧氣，減少可循
環的臭氧，成為臭氧損耗的主要原因。
南極上空的臭氧洞極大，主要是因為極度寒冷的溫度。
薄層冰晶因而聚集形成極地平流雲，加劇氯、溴等臭氧消耗
化合物所造成的惡果。這些氣體的積累迅速消耗在平流層
中的最冷區域的臭氧層。
自80年代開始氯氟烴已受全球環境條約「蒙特利爾議
定書」約束而逐漸被淘汰。結果，平流層的臭氣層有緩慢恢
復的跡象。在二零一四年，有地球物理學家假設，只要臭氧
消耗率比天然平流層臭氧生產率低，那麼臭氧層便能自我
修補。科學家預測，南極臭氧洞有望從現在的2,410萬平方
公里，到二零四零年縮小至低於2,000萬平方公里（南極洲
面積約為1,400萬平方公里）[1]。科學家估計直到二十一世
紀中後葉，南極臭氧洞規模才會回復至上世紀八十年代的
大小[2]。
可是，我們是否過於樂觀？過去十年，臭氧洞規模一直
沒有平穩的降幅，甚至在二零零六和二零一一年，錄得最
大的臭氧洞面積！美國航空航天局認為，最簡單的解釋是
氣候變化[3]。事實上，即使有「蒙特利爾議定書」規管，在
過去十年仍能檢驗到大量破壞臭氧層的化合物，顯示有非
法使用的情況。
如果漠視不理，強烈紫外光會持續穿透薄弱的臭氧層，
增加人類患上皮膚癌的可能，亦會破壞生態系統和威脅食
物鏈。幸好通過全球協力，南極臭氧洞沒有增大的趨勢。時
間會告訴大家，臭氧層能否回復至八十年代前的狀況。目前
我們應繼續遏止使用消耗臭氧層的化學物質。
to reduce from 24.1 million km
2
today to less than
20 million km
2
in size by 2040 (the size of Antarctica
is 14 million km
2
in comparison) [1], but it will not be
until after the mid-21
st
century for the ozone layer
to reach the state that it was in before the early
1980s [2].
Unfortunately for us, even this estimate may
be too optimistic. In fact the trend of the ozone
layer has not been a smooth sailing downward
decline over the past decade. While it does seem
that the hole is getting smaller, the largest sizes
were recorded in 2006 and 2011. Scientists at NASA
argue that climate change is to be blamed for
the fluctuating patterns [3]. To further complicate
matters, although the Montreal Protocol did its job
in curbing ozone depleting chemicals, substantial
amount s of these chemical s are s t i l l bei ng
detected during the past decade, indicating that
illegal use still exists.
I f l ef t unat tended, ozone depl et ion wi l l
likely cause higher rates of skin cancer, harm
ecosystems, and threaten marine food chains.
The good news is that the ozone hole does not
seem to be getting any bigger, largely thanks to
a concerted global effort. Only time will tell, if it
will return to its pre-80s glory. For now, we
should continue to strive as
a global force to curb the
use of ozone depleting
chemicals.
By Thomas Lee
李浩賢
