Long-Term
Climate Variability in Australia
Variation
in Australian Climate
Long-Term
Global Climate Variations
Long-Term
Temperature Variations in Australia
Long-Term
Rainfall Variations in Australia
Other
Climate Variations in Australia
Long-Term
Global Climate Variations
Australia's long-term
climate trends are influenced by what is happening to the global climate.
The global temperature record can be reconstructed for thousands of
years using paleoclimate data gathered from ice-cores, pollen records,
tree-rings and corals. These records indicate that the globe has had
numerous ice-ages and warm periods in the past. Some of these variations
are thought to be associated with extremely slow cycles in the earth's
orbit around the sun. These changes in orbit alter the amount of solar
energy reaching the earth and result in subtle changes in atmospheric
temperature. The amount of solar energy reaching the earth's surface
is also influenced by volcanic eruptions that emit aerosols into the
upper atmosphere, effectively blocking some of the sun's rays.
 Ocean
Currents
The world's oceans play an important role in global climate
variability. Slow moving currents driven by differences in temperature
and salinity link the major sources of heating and cooling across the
ocean basins. Long-term variations in this broad scale ocean circulation
are believed to modify regional sea-surface temperatures, which in turn
influence land temperatures and precipitation throughout the globe.
Very slow changes
in the extent of sea-ice in polar regions are also believed to be linked
to long-term variations in the global climate. The balance of evidence
suggests a discernible human influence on global climate. Increases
in atmospheric greenhouse gases, largely due to the burning of fossil
fuels and land-use changes, alter the earth's natural balances and may
be leading to global climate change. As well as these physical mechanisms
of climate change, there are also random, unpredictable fluctuations
within the climate system which account for a significant proportion
of climate variability.
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