Geoscience Reference
In-Depth Information
marine ecosystems such as coral reefs are economically important as tourism
destinations, including in Australia. Marine systems will be affected not only by
gradual changes in surface sea temperature but also by temperature fluctuations,
which can cause heat stress and bleaching in coral reefs. Ocean acidification
will affect marine species reproduction and survival. As with terrestrial systems,
where marine ecosystems and species have already been affected by human
activity and their resilience compromised, their vulnerability to climate-related
and other pressures will be increased. Australia's major reefs - the Great Barrier
Reef and Ningaloo - will decline precipitously. And as with land-based plants,
animals and ecosystems, changes and extinctions will result.
Agriculture
Over half of Australia is farmed for crops and livestock. Predicted changes to
temperature and rainfall patterns, to weather extremes, and other aspects of
climatic variability, will have profound effects upon agriculture. Droughts will
likely increase in frequency, area and intensity, with the possibility of droughts
becoming five times more frequent in the south and west of Australia. By 2070,
what was a 1-in-20 year drought during the 20th century will become a 1-10 year
drought for the Murray-Darling Basin, Victoria, east New South Wales, Tasmania
and south-west Western Australia. These changes will alter the location and type
of cropping. The Murray-Darling Basin, Australia's principal farming region, will
be especially hard hit. Estimates suggest that farm production in the Basin will
decline - the extreme estimates are for declines up to 90 per cent due to water
shortages alone. Large areas will become unsuited to current farming use. The
presence and impact of pests, diseases and weeds affecting production, and the
yields obtained, will change. Some will likely decline in impact and some get
worse. Australia, which has long been an exporter of surplus grain, meat and
wool, could become insecure in its ability to feed its domestic population under
certain combinations of high population growth and high climate change. For
example, Australia's population growth is projected to increase from 23 million
in 2013 to between 31 million and 42.5 million in 2056, and to between 33.7
million and 62.2 million by 2101 (ABS, 2008). Meeting these needs will reduce
exports. While the impacts of global warming on farming might be ameliorated
by changes in crop varieties, livestock breeds, farming locations and methods,
these impacts would nevertheless have significant regional social and economic
consequences. Farm produce was valued at some AUD$46 billion in 2011, and so
economic losses could amount to some AUD$30 billion in export revenue alone,
based on 2011-12 figures (ABS, 2012).
Health
The likely changes and disruptions to the natural environment, social conditions
and effective governance in a Four Degree World will hugely escalate risks to the
population's health, many of which cannot be yet clearly foreseen. The greater
frequency and severity of extreme climatic events will intensify increasing and
ongoing pressures on human health. For instance, yearly temperature-related
