Geoscience Reference
In-Depth Information
negotiation of the Montreal Protocol on Substances that Deplete the Ozone Layer,
an agreement that aimed to substantially reduce the production and consumption of
CFCs. Since entering into force in January 1989, it has been rati
ed by 196 states,
including all members of the United Nations (and adjusted and amended on ten
occasions). The
cation, the Montreal Protocol
stands as the most successful example of international action to tackle a global air
pollution problem, with 95 % of ozone depleting substances now having been
phased out. But because the overall lifetimes of CFCs are between 50 and
100 years, the stratospheric ozone layer is not expected to recover to its original
levels, nor the
rst treaty to achieve universal rati
'
ozone holes
'
to
nally close, until well into the second half of the
rst century.
61
The replenishment of stratospheric ozone, however, may
exacerbate global warming as it acts as a greenhouse gas
twenty-
—
although there is still
cance.
62
In addition, CFCs and HFCs
are potent greenhouse gases and each contributes to climate change, so in that
respect one harmful chemical has been replaced by another.
If the response to stratospheric ozone depletion by the international community
was relatively swift and effective, progress towards a global agreement to cut
greenhouse gas emissions has been slow in comparison. As early as 1896, the
Swedish scientist Svante Arrhenius
some uncertainty about its potency and signi
rst described how burning coal to fuel the
Industrial Revolution would result in a build-up of carbon dioxide (CO
2
) with the
potential to raise the average temperature of the planet. An idea echoed in 1938 by
the British engineer and amateur climatologist Guy Stewart Callendar, who warned
members of the Royal Meteorological Society in London that CO
2
emissions from
fossil-fuelled human industry were changing the climate. Global warming, how-
ever, was a marginal issue at this time, and Callendar himself thought that a small
rise in global temperature might even be bene
cial for humankind by boosting food
production in some regions of the northern hemisphere. It was not until the late
1970s, when the
rst World Climate Conference met in Geneva, that human-
induced climate change began to emerge as a serious environmental problem.
Organised by the World Meteorological Organisation (WMO) and the United
Nations Environment Programme (UNEP), in 1979 more than 300 scienti
c experts
from 50 countries came together to discuss the possibility that human activities
were causing global warming. They reached a consensus that an increase in
anthropogenic CO
2
emissions could cause signi
cant long-term climate change,
although delegates did not agree about how urgent the need was for preventive
measures to be put in place. And overall the meeting attracted very little media or
public attention.
63
Record high temperatures in 1988 with, for example, heat waves and droughts
reminiscent of the Dust Bowl era in the United States, saw public awareness of
climate change begin to increase (although no single weather event can be
61
Jacobson (
2002
) and United Nations Environment Programme (
2009
).
62
Gao et al. (
2010
).
63
Weart (
2003
) and Kessel (
2006
).
