Environmental Engineering Reference
In-Depth Information
•
accepting that these changes are superimposed on a high degree of
natural year-to-year and decadal variability of climate to which many
human activities are currently poorly adapted
•
maintaining, against an environment of disinterest, the capacity to
observe the climate system
•
improving understanding of specific processes of the climate system
and incorporating this new knowledge into the whole-of-system
climate models
•
accepting that, inevitably, uncertainties will remain and that the best
approach is through integrative risk management where options are
chosen on the basis of overt recognition of risk.
At one extreme (perhaps) there are climatologists and geoscientists who
understand that in the 12 000 years since the end of the last glacial period
and the present, climate warming reflects an increase in global mean tem-
perature of only 5-6°C. In just the last century, however, we have already
observed a warming of the planet of 0.6°C, equivalent to around 10 per cent
of this change. Indeed, the projections of the IPCC for this next century are
for warming of between about 30 per cent and 100 per cent of this glacial-
interglacial temperature change in only 100 years. They also know that the
glacial-interglacial temperature variations caused massive changes in the
distribution of ecosystems (including humans) across the face of the Earth
with impacts that continued for thousands of years. (This is well illustrated
in the topic
The Eternal Frontier
by Tim Flannery (2001), and the reader can
enter the wider scientific literature through Overpeck
et al.
(2003) and Ped-
ersen
et al.
(2003).) Climate scientists, therefore, are more likely to consider
that allowing the Earth to warm by even 1°C or so over such a short period is
'dangerous' in the sense that we have little idea how natural and human
systems can respond to such a relatively large and rapid change.
On the other hand, the majority of the general public who, on a daily and
seasonal basis, experience temperature changes of 10°C or more, are more
likely to respond that a little bit of warming - in Melbourne, for example -
would be good.
We urgently need to examine this issue. It currently divides us, despite the
fact that the wording 'dangerous' is incorporated into the objectives of the
United Nations Framework Convention on Climate Change
(UNFCCC 1994).
A very important component of the future scientific work relates to provid-
ing greater guidance as to what 'dangerous' climate change is. This is needed to
