Geoscience Reference
In-Depth Information
At 5°C, 57 endemic frogs and mammals were projected to lose their climatic
habitat altogether, with a further 8 species endangered, and at 7°C, all endemic
vertebrates in the region would lose their climatic habitat. Fitzpatrick et al.
(2008) modeled 100 species of West Australian banksias and found that with
warming of 4.2°C, 91-97 per cent (depending on assumptions about dispersal
ability) would experience climatic range contractions, and 17-24 per cent would
lose their climatic habitat completely.
Ecosystems do not exist in isolation from human systems and the fate of our
biodiversity will also depend on social, demographic, economic and political
factors over the next few decades. Australian population growth is one of the
highest in the developed world (about 1.2 per cent per year), and Australia's
population is projected to grow to 31-43 million by 2056 and to 34-62 million
by 2100, depending on assumptions about fertility, lifespans and net immigration
(ABS, 2008). Increasing demand for food, water and other resources will
continue to pressure Australian biodiversity (SoE, 2011), as will other drivers
of biodiversity loss, such as invasive species. New stresses flowing from climate
change adaptation measures in other sectors, such as shifting agricultural
patterns, changed hazard reduction policies and reallocation of river flows to
promote water security for urban settlements, also have the potential to have
negative impacts on ecosystems.
Global average warming of 4°C will make the earth's climate hotter than it
has been during the period over which most present day species evolved. The
prospect that stabilization of greenhouse gases will occur within a time frame to
'allow ecosystems to adapt naturally to climate change' (UNFCCC, Article 2)
appears increasingly unlikely. Australia's rich biodiversity is already subject to
multiple threats from human activities, and these threats are highly likely to
intensify, leading to transformed landscapes, many of which will be biologically
impoverished compared to present. This prospect alone should be motivation
enough to drive an urgent transition to a low carbon economy within the present
decade.
Note
1
A variety of methods have been used to project the impact of future climate on
biodiversity in Australia and elsewhere. These include extrapolation from the paleo-
record (especially of the last 10,000 years), species distribution modeling, controlled
experiments altering CO
2
and temperature, transplant experiments, observations of
biological change over the past few decades correlated with changing climate, and
risk assessments based on existing understanding of life history attributes that may
affect vulnerability, in combination with estimates of exposure to future change and
predicted adaptive capacity. These approaches differ markedly in both the scale of
application, and the picture they provide of the future (see
Table 4.2
).
