Current warming and likely future impacts - Climate Change: Biological and Human Aspects - page 323

The flora and fauna of Australia and New Zealand have a high degree of endemism
(80-100% in many taxa). Many species are at risk from rapid climate change because
they are restricted in geographical and climatic range. Most species are well-adapted
to short-term climate variability, but not to longer-term shifts in mean climate and
increased frequency or intensity of extreme events. Many reserved areas are small
and isolated, particularly in the New Zealand lowlands and in the agricultural areas of
Australia (IPCC, 2007b). Major changes are expected in all vegetation communities.
In the Australian rangelands (75% of total continental land area) shifts in rainfall
patterns are likely to favour establishment of woody vegetation and encroachment of
unpalatable woody shrubs.
The following are examples of key climate-induced ecological impacts likely in
the 21st century:
bleaching of the Great Barrier Reef,
decrease in Australian wet tropical habitat,
risk of 200-300 indigenous New Zealand alpine plant species becoming extinct,
montane tropical rainforest impacts in northern Australia.
Then there are the species migration and phenological issues, which I have covered
previously in reference to other parts of the world. An example of the latter from
Australasia, one of a number, is that of a shift in the emergence date of the common
brownbutterfly( Heteronympha merope ) in response to regional warming in the south-
east Australian city of Melbourne. The mean emergence date for the common brown
has shifted 21.5 days decade − 1 over a 65-year period with a concurrent increase in
local air temperatures of approximately 0.16 ◦ C decade − 1 (Kearney et al., 2010).
This chapter's UK, Australasian and North American case studies illustrate the
types of terrestrial biological change that are taking place and the likely threats
due to current climate change. For a summary map of key Australasian areas of
climate change see Figure 6.10. Other than temperature, central to the changes in
climate factors affecting biology is water availability. This also applies to many
other terrestrial areas subject to climate change outside these global regions. For
instance, one example is that the arid desert biome of northern Africa may extend and
jump the Mediterranean into Spain. In 2005 the Spanish Government reported, when
announcing a £50 million programme to combat desertification, that more than 90%
of the land between Almeria in the south to Tarragona in the north east is considered
at risk. This includes the provinces of Murcia, Valencia and southern Catalonia.
Over-grazing and development pressures have exacerbated the problems.
Spain, though, is not alone in facing both climate and development pressures
given both a warming world and growing global population. Access to water will
become a far bigger issue as the century progresses. Indeed, not only will African hot
dry biomes probably spread across the Mediterranean, deserts are likely to spread
within parts of Africa. This is even though the balance between deserts spreading
and areas of high rainfall spreading, or rain getting more intense over a similar land
area, remains uncertain. Nonetheless, there is some evidence to suggest that areas
that were previously drier and more sandy during (geologically) previous climatic
regimens may once more become desert. In 2005 researchers from Oxford and
Salford in Britain looked at southern Africa's dune systems, much of which today