Sustainability and policy - Climate Change: Biological and Human Aspects - page 523

managed land becomes a nature reserve. However, impose significant climate change
on isolated wildlife reserves, from which species cannot migrate, and extinctions
virtually become inevitable.
That this anthropogenic climate change will, beyond the 21st century, take us to a
global climate regime not seen since before the Quaternary means that species that
have evolved since then, such as in the Pleistocene (or even the Pliocene), will in all
likelihood be most adversely affected. This will be especially so for those species
accustomed to the cooler end of the global climatic spectrum. Indeed, this can already
be seen with some boreal and sub-polar species.
We are therefore going through an extinction event of a magnitude only last
exceeded by the Cretaceous/Tertiary extinction 65.5 mya (Chapter 3 and also
Barnosky et al., 2011). Yet, unlike that event, much of which took place rapidly,
the current extinction arguably began when (some consider) the Anthropocene began
with the extinction of Eurasian megafauna; that is to say, an extinction over thou-
sands of years. This extinction is continuing today slowly but steadily and the size
of the species affected is getting smaller. Future climate change will exacerbate
matters.
Can this extinction be halted? In all probability, no. Can it be slowed and can some
species be conserved? In all probability, yes, although it is impossible to estimate
how many species that will be.
If we are to minimise extinctions then, aside from investment in biological conser-
vation and management, investment will be needed to continue improving our under-
standing of biology and climate interactions. Computer models of global climate
are now increasingly including biological dimensions and they are also becoming
increasingly detailed. However, much still needs to be done. To date much of our
present-day climate change understanding (hence computer modelling) comes from
our knowledge of Holocene and glacial climates discerned from actual biological and
geological evidence. Notwithstanding this, we have still much to learn as to how car-
bon moves between various biosphere sources and sinks. Filling this knowledge gap
is fundamentally important, especially as the 21st century will see the Earth move into
a climatic regime not seen for a few million years. Nonetheless, it is possible, before
the end of this century's first quarter, that in some areas ecological biogeographic
mapping will be sufficiently detailed and the climate models sufficiently accurate,
and we will be able to foresee where and what species are best likely to flourish.
This will greatly facilitate not just wildlife management but management of natural
systems, especially agricultural and forestry systems, and hence generate a financial
return on such investment in research, especially as we have a burgeoning human
population to feed. In short, there is a very real role for whole-organism biological,
ecological and biosphere expertise to address such issues for the foreseeable long-term
future.
8.5.4 Reducingfutureanthropogenicgreenhousegasemissions
Curbing anthropogenic emissions of carbon dioxide, as the principal greenhouse gas,
is the main priority (though not the sole one; Chapter 1). Yet such is human ecology
(Chapter 7), and especially human energy requirements, that reductions are proving