Present climate and biological change - Climate Change: Biological and Human Aspects - page 223

politicians called for international scientific guidance through the United Nations
(UN). In 1988 two UN agencies - the World Meteorological Organization (WMO)
and the UN Environment Programme (UNEP) - established the IPCC under the
chairmanship of Professor Bert Bolin.
The panel was charged with:
1. assessing the scientific information related to the various components of the cli-
mate change issue, such as the emissions of greenhouse gases and the modification
of the Earth's radiation balance, as well as the science needed to assess environ-
mental and socio-economic consequences;
2. formulating realistic response strategies for the management of climate change
issues.
It needs to be emphasised that there were some (especially in what came to be known
unofficially as the fossil fuel lobby) who did not believe - or perhaps did not wish to
believe - that human-induced climate change was real. This belief still exists among
some energy-related and political quarters today, whereas many in the public are
still uncertain, or unaware, of the science underpinning current climate issues. Some
countries too (again especially those consuming prodigious quantities of fossil fuels)
felt that the issue was overblown. Nonetheless, politicians needed clear unambiguous
guidance. The IPCC aimed to provide this by ascertaining the scientific consensus.
For its first report (1990) the IPCC brought together 170 scientists from 25 countries
through 12 international workshops. A further 200 scientists were involved in the
peer review of the report. Although there was a minority of opinions that could not
be reconciled with the panel's conclusions, the extensive peer review helped ensure
a high degree of consensus among the authors and reviewers. Even so, reaching this
consensus was difficult. One of the ways the panel did this was to present both a best
estimate as well as high and low estimates of the likely changes in global temperature.
Further, they looked at a number of scenarios assuming that politicians introduced
three levels of controls, as well as the B-a-U scenario which supposed that nothing
would be done and that the late-20th-century trend in emissions would continue to
grow. It has to be acknowledged that this methodology was as much to bring the
disparate views of the scientists underpinned by various degrees of climatological
understanding on board as it was to provide margins for error. Consequently, as we
shall see, the difference between the high and low estimates under the B-a-U scenario
for 21st-century warming was greater than the difference between the low estimate
and nothing happening at all (zero climate change). Furthermore, the best estimates
for the various scenarios all fell within the range between the B-a-U scenario's high
and low estimates.
For these reasons the IPCC's 1990 B-a-U estimate (Figure 5.5) was of central
importance to international policy-makers, whose initial problem was whether or
not to acknowledge the problem and then, if so, to establish the environment in
which subsequent detailed climate change policy might be formulated and enacted.
A degree more or less warmer on top of the IPCC's 1990 anticipated 21st-century
warming simply did not figure in policy discussions in the political arena: the high -
low range was just stated and the policy debate in the early 1990s focused on whether
doing anything about such warming actually mattered. Even today policy-makers are