Australian Bureau
of Meteorology, State of the Climate 2018,
December 2018:
“Australia's
weather and climate are changing in response to a warming global climate. Australia
has warmed just over 1 °C since 1910, with most warming since 1950. This
warming has seen an increase in the frequency of extreme heat events and
increased the severity of drought conditions during periods of below-average
rainfall. Eight of Australia’s top ten warmest years on record have occurred
since 2005.
The
year-to-year changes in Australia’s climate are mostly associated with natural
climate variability such as El Niño and La Niña in the tropical Pacific Ocean
and phases of the Indian Ocean Dipole in the Indian Ocean. This natural
variability now occurs on top of the warming trend, which can modify the impact
of these natural drivers on the Australian climate.
Increases in
temperature are observed across Australia in all seasons with both day and
night-time temperatures showing warming. The shift to a warmer climate in
Australia is accompanied by more extreme daily heat events. Record-warm monthly
and seasonal temperatures have been observed in recent years, made more likely
by climate change.”
Report
at a glance
The Bureau of
Meteorology and CSIRO play an important role in monitoring, analysing and
communicating observed changes in Australia's climate.
This fifth,
biennial State of the Climate report draws on the latest monitoring, science
and projection information to describe variability and changes in Australia’s
climate. Observations and climate modelling paint a consistent picture of
ongoing, long term climate change interacting with underlying natural
variability.
These changes
affect many Australians, particularly the changes associated with increases in
the frequency or intensity of heat events, fire weather and drought. Australia
will need to plan for and adapt to some level of climate change. This report is
a synthesis of the science informing our understanding of climate in Australia
and includes new information about Australia’s climate of the past, present and
future. The science underpinning this report will help inform a range of
economic, environmental and social decision-making and local vulnerability
assessments, by government, industry and communities.
Key points
Australia
·
Australia's climate has warmed just over 1 °C since 1910
leading to an increase in the frequency of extreme heat events.
·
Oceans around Australia have warmed by around 1 °C
since 1910, contributing to longer and more frequent marine heatwaves.
·
Sea levels are rising around Australia, increasing the risk of
inundation.
·
The oceans around Australia are acidifying (the pH is decreasing).
·
April to October rainfall has decreased in the southwest of
Australia. Across the same region May–July rainfall has seen the largest
decrease, by around 20 per cent since 1970.
·
There has been a decline of around 11 per cent in April–October
rainfall in the southeast of Australia since the late 1990s.
·
Rainfall has increased across parts of northern Australia since
the 1970s.
·
Streamflow has decreased across southern Australia. Streamflow has
increased in northern Australia where rainfall has increased.
·
There has been a long-term increase in extreme fire weather, and
in the length of the fire season, across large parts of Australia.
Global
·
Concentrations of all the major long-lived greenhouse gases in the
atmosphere continue to increase, with carbon dioxide (CO2)
concentrations rising above 400 ppm since 2016 and the CO2 equivalent
(CO2-e) of all gases reaching 500 ppm for the first time in at
least 800,000 years.
·
Emissions from fossil fuels continue to increase and are the main
contributor to the observed growth in atmospheric CO2.
·
The world’s oceans, especially in the southern hemisphere, are
taking up more than 90 per cent of the extra energy stored by the planet as a
result of enhanced greenhouse gas concentrations.
·
Global sea level has risen by over 20 cm since 1880, and the
rate has been accelerating in recent decades.
·
Globally averaged air temperature has warmed by over 1 °C
since records began in 1850, and each of the last four decades has been
warmer than the previous one.
Future
Australia is
projected to experience:
·
Further increases in sea and air temperatures, with more hot days
and marine heatwaves, and fewer cool extremes.
·
Further sea level rise and ocean acidification.
·
Decreases in rainfall across southern Australia with more time in
drought, but an increase in intense heavy rainfall throughout Australia.
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