Environmental Engineering Reference
In-Depth Information
The part of the Arctic Messenger's story concerning HCFCs and HFCs strikes a theme
that will reappear again in the chapter on persistent organic pollutants. Having created a
global problem with the original ozone-depleting substances, we have managed to replace
them with substances that in many ways are just as hazardous. We have a knack for choos-
ing the third method for gaining wisdom as described by Confucius in the
Analects
quote
at the beginning of this chapter.
PerhapsthemostencouragingpartsoftheWMO2010reportconcernthestratosphere.
After all, this is where the damage is done. Total chlorine is declining in the troposphere
and stratosphere from peak values reached in the 1990s. Stratospheric bromine is no longer
increasing.Thedeclinesinthesumofstratosphericchlorinearelargestinmid-latitudes and
smallest in Antarctica.
However, in March 2014, Johannes Laube and colleagues published a paper in
Nature
Geoscience
that reminded us that it is unwise to be complacent. Their study reported for
the first time the presence of three CFCs and one HCFC from samples collected in air over
Tasmania (from 1978 to 2012) and from firn snow in Greenland (collected in 2008). The
four substances first appeared in the 1960s and two of them continue to accumulate in the
atmosphere. They are, of course, unmentioned in the Montreal Protocol, but the paper es-
timated a combined total emission of 74,000 tonnes. The source of all four substances is
unknown, but the study demonstrates the importance of monitoring, without which we can
never have the whole story.
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