Emily Hanna, Science, Technology,
Environment and Resources
The impacts of human-influenced changes to the climate are already occurring and are expected to continue and intensify in the future. The issue of climate change and its impacts has significant implications for government policy across a range of portfolios and industries.
Nearly 200 national and international scientific
bodies, as well as over 97 per cent of recently published climate scientists,
agree that the Earth is
warming and that humans are contributing to the
change in climate.
Global climate change
Since its first
assessment in 1990, the Intergovernmental
Panel on Climate Change (IPCC) has expressed growing
certainty that global warming is underway and that human activity is a
principal cause. In its latest report on climate change, the Fifth
Assessment Report in 2014, the IPCC stated:
Warming of the climate
system is unequivocal, and since the 1950s, many of the observed changes are
unprecedented over decades to millennia. The atmosphere and ocean have warmed,
the amounts of snow and ice have diminished, and sea level has risen.
Globally, the average temperature (combined land
and ocean surfaces) has increased 0.85 °C between 1880 and 2012, according
to the IPCC.
Most of this heat is stored in the oceans, with the top 75 metres of water
warming an average of 0.11 °C per decade globally over the four decades
states that average sea level has already risen around 20 centimetres since
1901 and is forecast to continue rising at a faster rate. Sea water has also
become more acidic, with surface ocean water 26 per cent more acidic than it
was in pre-industrial times.
These changes are expected to continue this
century, with the average temperature projected to increase, the average sea
level continuing to rise and the ocean becoming warmer and more acidic.
While these increases may sound minor, small changes in average
temperature can lead to big changes in the climate system. For example, the IPCC expects extreme weather events such as
heatwaves, bushfires, floods and droughts to become more frequent and more
It is not currently possible to state that an
individual extreme weather event (such as a drought) is definitely attributable
to climate change. However, it is now possible to determine how much more likely
it is that a particular extreme temperature event is due to climate change.
For example, the autumn heatwaves in Australia in 2014 were found to be 23
times more likely to occur with climate change, compared to conditions
without human contribution to climate change.
What is causing climate change?
The climate is affected by the rise in greenhouse
gas emissions. Greenhouse
gases (GHGs) ‘trap’ heat in the lower parts of the atmosphere around Earth
(by absorbing infrared energy coming off the Earth’s surface which could
otherwise escape). GHGs include both natural compounds (such as carbon dioxide
(CO2) and methane) and synthetic compounds (such as
Some fluctuations in the levels of natural GHGs are
normal. However, the increasing trend in GHG concentration and the rate of
change is beyond the normal variation seen over millennia. Atmospheric GHG
concentrations have increased dramatically since industrial times began in the
mid-19th century, driven by the burning of fossil fuels and land
clearing. For example, CO2 concentrations recently hit
400 ppm (see Figure 1) after not going above
approximately 280 ppm in the last 400,000 years.
Figure 1: Atmospheric levels of CO2
Source: National Oceanic and Atmospheric
Administration (NOAA), NOAA Climate.gov
Human influence on the climate system is
clear, and recent anthropogenic emissions of greenhouse gases are the highest
in history ... It is extremely
likely that more than half of the observed increase in global average
surface temperature from 1951 to 2010 was caused by the anthropogenic increase
in GHG concentrations.
The higher sea levels are a consequence of increased temperature. This
is caused by two processes: melting ice sheets (for example, Antarctica and
Greenland) and glaciers, as well as the warmer water increasing in volume due
to thermal expansion. The rise in ocean acidity
is also caused by higher atmospheric levels of CO2. As these levels
increase, ocean absorption of CO2 becomes greater. The CO2
then undergoes a chemical reaction with the water to form carbonic acid, thus
increasing the level of acidity in the marine waters.
change in Australia
Australia has become 0.9 °C warmer since
1910. The increase
in sea surface temperature varies by location. Since 1950,
it has risen approximately 0.12 °C per decade in north-west and south-west
Australia, while the average temperature rise in south-eastern Australia has
been approximately 0.2 °C per decade. The 30 year period from 1985–2014
experienced the warmest average temperature in the last millennium
compared to other 30 year periods. Australia’s
average temperature is virtually certain to continue rising this century,
with inland areas forecast to increase more than coastal areas.
rainfall is also changing, decreasing in winter in south-western Australia
and in autumn in south-eastern Australia. In contrast, average annual rainfall
has increased in north-western Australia. Weather extremes are also changing,
with fewer cold extremes while hot extremes rise in number and temperature.
Heatwaves are occurring more often and droughts will become more common in
southern Australia. As much of southern Australia becomes hotter and drier, the
risk of bushfires is also projected to increase.
The IPCC outlined a range of specific risks for
Australia from climate change that could affect the country this century. These
- greater flood damage
limited water resources in southern Australia
- greater impacts from heat waves on infrastructure and human health
and mortality and
- worse harm from bushfires in southern Australia including possible
greater human mortality, damaged ecosystems and economic losses.
These risks, and the changes in climate described, have
significant implications for Australia across a range of policy areas. It is
also worth noting that these threats are not simply theoretical but are already
In 2012, the Productivity
Commission found that all governments should ‘embed
consideration of climate change’ in risk management strategies and ensure that
regulatory and policy settings allow the risks of climate change to be managed.
Some examples of the policy implications of climate change for Australia are
set out below.
Climate change is likely to affect
human health in a number of ways. For example, there is
likely to be an increase in heat-related illnesses such as heatstroke and an
increased risk of some infectious diseases (such as those spread by mosquitoes
due to mosquitoes’ changing distribution). In turn, this has implications for
our health system and policy. The Climate
and Health Alliance recently called
for a national strategy on ‘Climate, Health and Wellbeing’.
Climate change also presents challenges
for agriculture, which is likely to be affected by changes
to water availability, changes in growing seasons and the effects of projected
increases in extreme weather events. In turn, this may disrupt crop yields,
reduce stock numbers, and erode the productivity of farms, threatening their
long-term sustainability and viability. While moderate warming may benefit some
crops (as long as they are not water stressed) and some colder locations,
production levels are projected
to decline over much of southern Australia as a result of climate change.
Infrastructure, including residential and commercial buildings,
roads, railways and industry, is also at increasing risk of damage from climate
infrastructure is particularly vulnerable, mainly due to an
increased risk of flooding from rising sea levels, storm surges, and a higher
chance of erosion. This has wide-reaching implications, particularly given that
most of Australia’s capital cities are near the coast, along with more than 85% of our
population. Many critical services, including hospitals and wastewater
treatment, are on the coast and likely to be affected. Indeed, the impact of
climate change on coastal communities was the subject of a 2009 parliamentary
councils around Australia recently called for
the Australian Government to implement the inquiry’s recommendations.
Environment policy and
Climate change is increasing the extinction
risk faced by non-human species and ecosystems. Many
species, especially plants and small mammals, are unlikely to be able to move
their geographical range fast enough to keep up with the current and forecast
changes to climate. Climate change is also affecting habitat (for example, habitat
loss caused by erosion and rising sea levels), food sources, reproduction and
migration—all of which can adversely affect the survival of individuals and
These risks are demonstrated by the recent extinction of the
Bramble Cay melomys (Melomys rubicola),
a type of native rat which lived on Bramble Cay in the Torres Strait,
Australia. It is believed to be the first mammal species globally driven to
extinction by anthropogenic climate change.
Marine environment, fisheries
Climate change also affects the marine environment, including
fisheries (which in turn can affect food security). Along with increased water
temperatures, marine species need to cope with increasing acidification and
lower levels of oxygen in the water. Climate change is already causing
bleaching and loss of diversity in coral
reefs, as evidenced by the recent severe bleaching
event in the Great Barrier Reef (see the article on the
Great Barrier Reef). These events are likely to become more common in the
future. This threatens not only the species that depend on those ecosystems, but
may also impact on Australia’s tourism industry.
The projected increase in extreme weather events also has
implications for the insurance industry, as well as emergency management
disaster relief and recovery arrangements.
Commentators have also pointed to the risk that climate change
will cause large movements of people—especially from inundated coastal areas or
regions affected by extreme weather events and food and water insecurity. This
may in turn either trigger or exacerbate international conflict. Both issues
have implications for Australia’s immigration, foreign affairs and defence
policies. For example, in light of the impact of climate change on islands in
the Pacific region, there have been calls for Australia to expand
labour mobility opportunities for Pacific Islanders.
While all these risks can be minimised by reducing GHG emissions (climate
‘mitigation’), some level of change is now inevitable. This means we also need
to prepare for the effects of climate change, which is referred to as climate ‘adaptation’.
In 2007, the Council of Australian Governments endorsed a
Climate Change Adaptation Framework. In 2015,
the Australian Government released a National
Climate Resilience and Adaptation Strategy. The
Strategy looks at a range of initiatives across key sectors (such as
agriculture and health) and identifies principles to guide
The Government also established the National
Climate Change Adaptation Research Facility (NCCARF)
in 2008, with $47 million funding. This funding initially ended in June 2013,
but in 2014
the Coalition Government provided
funding of $9 million to allow NCCARF to continue until 2017.
CSIRO and the Bureau of Meteorology are working together on
climate change science
as well as adaptation
to help Australia better prepare for climate change. However, concerns
have been expressed about the capacity of CSIRO to continue its climate
science work as a result of a recent controversial restructure.
A Talberg and S Power, ‘What the latest IPCC report says about Australia’, FlagPost, Parliamentary Library blog, 8 October 2013.
Productivity Commission, Barriers to Effective Climate Change Adaptation
, September 2012.
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