In the past the Earth's climate has gone through
many cycles that have caused significant changes to the Earth's
More recently it has been acknowledged that human
activities over the past 200 years have significantly altered the
Earth’s atmosphere (CSIRO 2001) and have lead to a warming of
the Earth’s surface.
The cause of the recent change in climate is
mainly due to an increase in greenhouse gas emissions. Because
greenhouse gas emissions are continuing to increase, this warming
will also continue (CSIRO 2001).
Greenhouse effect | What does this mean | Tropical
savannas and climate change | References |
Carbon dioxide (CO2) and other 'greenhouse gases'
including methane and nitrous oxide are released into the
atmosphere from the use of fossil fuels. Stored carbon has also
been released through the clearing of vegetation. It is thought
that increasing the amount of greenhouse gases in the atmosphere
increases the atmosphere's ability to absorb heat energy. This is
termed the 'greenhouse effect'. Projections indicate that annual
average temperatures in Australia could be 0.4–2.0 degrees
higher by 2030 and 1.0–6.0 degrees higher by 2070. These
estimates are based on world emissions scenarios produced by the
Intergovernmental Panel on Climate Change (IPCC).
Using global climate model simulations, the CSIRO has predicted
the following changes in Australia’s climate in the
- An increase in average annual temperature of 1–6 °C
by 2070 over most of Australia.
- An increase in the average number of extreme hot days and
decrease in the average number of extreme cold days.
- A decrease in annual average rainfall in the south-west and in
parts of the south-east and in Queensland.
- An overall drying trend for Australia due to increased
temperatures and evaporation and changes in rainfall, and
- Rising sea level, stronger tropical cyclones and increasing
associated oceanic storm surges.
Climate change will have ecological, social, economic impacts.
All of our natural ecosystems are vulnerable to climate change. In
the tropical savannas region those ecosystems most at risk include
coral reefs, mangroves and wetlands, tropical forests, savannas and
remnant native grasslands.
Industries based around agriculture, fisheries, forests and
water are likely to be affected as these resources are sensitive to
climate change. The speed at which changes in ecosystems will occur
in response to climate change will determine in part how
successfully ecosystems will adapt to these changes.
However many natural systems will have difficulty adapting to
climate change (CSIRO 2001).
Drier conditions could threaten many eucalypt species, often the
dominant plants in many native forests and woodlands.
The expansive wetlands of the tropical savannas are certainly
vulnerable to climate change and sea level rise. If sea-levels rise
significantly, the vast freshwater floodplains of the region will
be subject to significant saltwater inundation (CSIRO 2001).
Within the coastal region of the tropical savnnas is also the
world’s largest reef system. Rising sea level by itself may
not be such a problem to the reef. However the combination of sea
level rise with other threats may place much of this ecosystem at
risk. These threats include increasing atmospheric carbon dioxide
which leads to a decrease in coral growth, increasing sea
temperatures which leads to coral bleaching, possible increased
river outflow causing low salinity and high pollution and damage
from tropical cyclones (ABS 2006).
Feral animals and weeds currently threaten the ecosystems of the
tropical savannas region. Climate change is likely to increase the
number of severe weather events the region experiences, including
fire, floods and cyclones. As the vegetation becomes more stressed
from these events, it is also likely to become more vulnerable to
weeds and the actions of feral animal.
These severe weather events will also affect people in coastal
communities in a number of ways. A study has shown that the number
of tropical cyclones around Cairns in northern Queensland could
increase by up to 20% by about 2050. Downpours of rain that occur
after cyclones, along with the wind generated waves and storm surge
will likely increase the occurrence of widespread flooding.
People’s health may be impacted by a change in climate.
Parts of the tropical savannas may become more favourable for
mosquitoes as temperatures rise. The warm weather will also
encourage people to spend more time outdoors, and at the same time
expand the mosquitoes range and extend their breeding season.
Unfortunately the warmer temperatures will also reduce the
incubation period for the viruses that mosquitoes carry.
- Rising sea-level, stronger tropical cyclones and increased
intensity of oceanic storm surges are likely with climate
- In the tropical savannas the majority of people live in small
coastal towns and communities. An increase in severe weather events
such as cyclones, storm surges and flooding of rivers will
obviously have a large impact on people living in this region.
- If sea-levels rise significantly, the vast freshwater
floodplains of northern Australia will be subject to significant
change due to saltwater intrusion.
- Various industries are likely to be affected. Agriculture,
fisheries, forests and water resources will be sensitive to climate
- More extreme events like fires and floods are likely to
increase the vulnerability of natural systems to invasion of exotic
- With climate change, parts of Australia may become more
favourable for mosquitoes, thereby increasing the potential for
mosquito-borne disease outbreaks (e.g. Dengue fever and Ross River
- In the tropical savannas there are finely balanced
relationships between the flora and fauna that make up communities.
Climate change and an increase in carbon dioxide will change this
balance, and is likely to change the current distribution of plants
Australian Bureau of Statistics 2006. 1301.0
Year Book Australia, 2006
Living with climate change: An Overview of
Potential Climate Change Impacts on Australia, Australian
Climate Change - An Australian Guide to the
Science and Potential Impacts, Australian Greenhouse
CSIRO 2001. Climate Change: Impacts for