Sustainability and policy - Climate Change: Biological and Human Aspects - page 462

new evolutionary paths, this again would be limited in the human-dominated global
environment. Certainly the diversification and expansion of primates began around
the time of or shortly after the IETM, so in theory at least there could be evolutionary
opportunities. It would also be a little ironic if our species - one current end-point of
this primate diversification - triggered a climatic event analogous to the IETM that
arguably marked the beginning of a new diversification for some other species.
The ecological disruption of an IETM-type event today would in all probability be
more severe (because of our current ecosystem management, which itself is resulting
in biodiversity loss). Equally, as with the IETM itself, there would be winners and
losers. One of the losers would be humanity - more specifically our global culture -
for although we as a species would probably not be completely wiped out, many
of our 7 billion-plus population (and growing) would face dislocation, as parts of
the planet become too hot, and famine, unless we radically adapted our grain crops
(including rice) that currently dominate human calorie provision.
So, how realistic is this nightmare scenario? This picture may well be a longer-
term one than the IPCC's 100-year scenarios. Equally, as the IPCC warn, being
wary of surprises, depending on natural systems' critical thresholds the scenario
might be manifest sooner. There has so far been only informal discussion about this
among researchers but, to date, no analysis has been published in a high-impact,
peer-reviewed journal. Nonetheless, globally, the IPCC (1990) say, we need to reduce
carbon emissions by some 50% of their 1990 value by 2050 to stabilise CO 2 at 50%
above pre-industrial levels (which, we should note, would probably result in a low
probability of an eventual IETM-type event). This in turn necessitates both cutting
fossil carbon emissions per capita today and planning for even greater per-capita
reductions for tomorrow's larger population. In addition, 22 years after the first IPCC
report we have singularly failed to halt growth in emissions. Therefore, it would be
foolish to dismiss this IETM-analogue nightmare scenario out of hand.
As things stand, irrespective of whether or not this worst-case scenario comes
about, we are facing the very real prospect of there being climate change to a regime
not seen at least since the Pliocene 3 mya or more. As such we are likely to lose much
of the fauna and flora that have evolved over this time and see some major changes
in the location and type of many of today's ecosystems.
So, what then are the theoretical prospects of reducing fossil emissions? This
question relates more to the abiotic aspects of human ecology rather than biology per
se and has been covered elsewhere (such as in Cowie, 1998a and by the IPCC Special
Report on Emission Scenarios [SRES] scenarios; IPCC, 2000) and so is only very
briefly summarised in the following subsections and only for the short term to 2050.
8.2.1 Prospectsforsavingsfromchangesinlanduse
As noted towards the end of the last chapter, the IPCC's second assessment report
(IPCC, 1995) estimated that by 2050 some 60-87 GtC could be conserved or
sequestered in forests. Compared to the above-estimated mean 21st-century B-a-
U fossil fuel emissions of 18 GtC year − 1 , this represents an annual saving of around
1.2-1.7 GtC, or around 6-9% of annual emissions. More optimistic estimates (a
number are cited in Cowie, 1998a) increase this saving to over 2 GtC per annum. Due