Climate change: the case for action
Dr Julie
Styles
Science, Technology, Environment and Resources Section
Contents
List of figures
Executive Summary
- Scientific evidence demonstrates unequivocally that the climate
is changing. Furthermore, the overwhelming weight of evidence
suggests that most of this change is very likely due to human
influences on the climate system. The likely consequences of
unmitigated climate change present serious risks to our environment
and consequently to our socioeconomic productivity, security, and
health. These risks can be reduced to manageable levels with
mitigation action.
- The climate system responds slowly to small changes in its
driving forces, such as the changes in atmospheric composition and
energy balance that it is now experiencing. Therefore, the Earth
and its inhabitants will continue to experience the effects of
current and previous greenhouse gas emissions for centuries to
come. Delaying action to mitigate climate change increases the risk
that adverse climate change impacts, including possibly
irreversible changes, will occur before greenhouse gas
concentrations can be stabilised at a desired level.
- Delaying action to mitigate climate change may preclude the
successful realisation of more ambitious greenhouse gas
stabilisation targets over the next century, as continued
investment in long–lived, emissions–intensive
technologies commits us to continued high rates of emissions.
- Delaying action will require more drastic measures to achieve a
desired mitigation target than early action. Early action enables
businesses and industries to adjust gradually and allows time for
new technologies to emerge and be commercially deployed.
- The costs of unmitigated climate change are likely to be
substantially higher over the next century than the costs of
mitigation. Mitigation action is likely to cause a net cost to GNP
growth in the first half of the century, but a net benefit in the
second half.
- Australia is particularly vulnerable to the impacts of climate
change, both environmentally and economically. It is in
Australia’s interests to do all we can to secure an effective
international agreement to mitigate climate change. Through
existing agreements, Australia has committed to contributing our
fair share of global responsibility in reducing greenhouse gas
emissions. In implementing effective domestic action, Australia
would demonstrate this commitment while facilitating the process of
reaching an international agreement, easing the integration of our
economy into an international mitigation framework, and
safeguarding the future of our country and planet.
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Glossary of terms and acronyms
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Albedo
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The proportion of light (or other forms of
electromagnetic radiation, such as infrared) that is reflected off
a surface. An ideal, perfectly reflective, white surface would have
an albedo of 1. A perfectly absorptive, black, non–reflective
surface would have an albedo of 0. All real materials have an
albedo between 0 and 1.
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Aerosol
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A suspension of fine particles or droplets in
the air. Atmospheric aerosols scatter and absorb sunlight, and
affect the Earth’s energy balance by reflecting sunlight back
into space and through indirect effects on cloud formation and
atmospheric chemistry. Aerosols are produced from both natural and
human processes such as volcanic eruptions, forest fires, desert
dust storms, and burning of coal and oil.
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Anthropogenic
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Human–induced.
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Carbon
capture and storage (CCS)
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The capture of carbon dioxide (e.g. from power
station effluent) and its transport and storage in a long term
reservoir such as a geological basin.
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Carbon
dioxide equivalent (CO2e)
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CO2–equivalents account for
the abilities of different greenhouse gases to absorb infrared
radiation over a given timeframe, which determines their relative
warming effect compared to CO2. For example, over a
100–year timeframe, methane is 25 times more potent than
CO2 per unit of mass, and nitrous oxide is 298 times
more potent than CO2.
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Carbon
Pollution Reduction Scheme (CPRS)
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The Government’s proposed emissions
trading scheme.
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Carbon
sequestration
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The absorption of CO2 from the
atmosphere or at the source of emissions and its long–term
storage in ‘carbon sinks’. Various potential sinks have
been identified that can be utilised or enhanced for carbon
storage, including forests, soils, geological reservoirs, oceans
and minerals.
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Chlorofluorocarbons (CFCs)
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Compounds that contain carbon, fluorine and
chlorine. Chlorofluorocarbons have been used as refrigerants,
propellants and solvents. Their use has been banned by the Montreal
Protocol on Substances that Deplete the Ozone Layer. They are also
powerful greenhouse gases.
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CPRS–5
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Treasury modelling scenario based on the CPRS
with a 5 per cent emissions reduction target by 2020, consistent
with a greenhouse gas stabilisation target of 550 ppm
CO2e by 2100.
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CPRS–15
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Treasury modelling scenario based on the CPRS
with a 15 per cent emissions reduction target by 2020, consistent
with a greenhouse gas stabilisation target of 510 ppm
CO2e by 2100.
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Greenhouse gases
(GHGs)
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Gases in the
atmosphere that absorb and emit infrared radiation, causing heat to
be trapped in the lower atmosphere. The dominant greenhouse gas is
carbon dioxide, but other important greenhouse gases include
methane, nitrous oxide, and halocarbons.
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Gross
domestic product (GDP)
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The value of all final goods and services
produced in a country in one year.
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Gross
national product (GNP)
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The value of all goods and services produced
in a country in one year, plus income that residents receive from
abroad, minus income received by non–residents.
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Halocarbons
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Compounds consisting of carbon and one or more
halogens, with the remainder of the carbon bonds, if any, attached
to hydrogen atoms. Halogens include fluorine, chlorine, bromine and
iodine. Halocarbons are used, among other things, as refrigerants
and pesticides.
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Hydrochlorofluoro–carbons (HCFCs)
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Compounds containing hydrogen, carbon,
fluorine and chlorine. They are being used to replace
chlorofluorocarbons, but are subject to caps in their production
and consumption, and a phase–out schedule. They contain
chlorine and thus are an ozone–depleting substance, but to a
much lesser extent than chlorofluorocarbons. They are also a strong
greenhouse gas.
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Hydrofluorocarbons (HFCs)
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Compounds containing carbon, hydrogen and
fluorine. These synthetic molecules are up to 14 000 times
more powerful per unit of mass than carbon dioxide as greenhouse
gases over a 100–year time frame.
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Hydrofluoroethers (HFEs)
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Otherwise known as fluorinated ethers. They
are chemical compounds that consist of an ether group (an oxygen
atom connecting two hydrocarbon chains) with fluorine atoms
attached. These compounds do not deplete the ozone layer but are
very strong greenhouse gases with long lifetimes in the
atmosphere.
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Infrared
radiation
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Radiation in the range 750 nm to 1 mm. Far
infrared radiation (at the longer end of the infrared wavelength
spectrum) is thermal, and we experience it as heat. Infrared
radiation represents a significant portion of the sun’s solar
radiation spectrum, and most of the radiation emitted from the
Earth.
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Intergovernmental Panel on Climate Change (IPCC)
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The IPCC was established in 1988 to provide a
comprehensive, objective, open and transparent assessment of the
latest scientific, technical and socio–economic literature
produced worldwide relevant to climate change and its risks and
impacts, and options for mitigation and adaptation. Participation
in the IPCC is open to all member countries of the World
Meteorological Organisation and the United Nations Environment
Programme (more than 180 countries in total). Governments
participate in review of the IPCC reports and plenary sessions
where the reports are approved and accepted. Thousands of
scientists contribute to the IPCC Assessment Reports.
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Kyoto Protocol
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A protocol to
the United Nations Framework Convention on Climate Change that
establishes legally binding commitments for greenhouse gas
emissions reductions over the commitment period (2008–2012)
for Annex I parties (consisting of developed countries and
countries with economies in transition), and general commitments
for non–Annex I parties (developing countries).
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Long–lived greenhouse gases (LLGHGs)
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Those greenhouse gases that are only slowly
removed from the atmosphere by natural processes. They include
carbon dioxide, methane, nitrous oxide, chlorofluorocarbons,
hydrochlorofluorocarbons, hydrofluorocarbons, hydrofluoroethers,
perfluorocarbons and other halocarbons.
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Organisation for Economic Cooperation and Development
(OECD)
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An international organisation consisting of
governments of countries committed to democracy and the market
economy. Most members are high income economies and are considered
developed countries.
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Ozone
(O3)
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A molecule consisting of three atoms of
oxygen. In the lower atmosphere it is a pollutant produced from
emissions of other compounds during fuel combustion. It is toxic to
animals and plants, and damages human respiratory systems. However,
ozone in the upper atmosphere occurs naturally and acts to reduce
the amount of dangerous ultraviolet radiation reaching the
Earth’s surface.
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Perfluorocarbons (PFCs)
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Compounds consisting of carbon and fluorine.
They do not deplete the ozone layer but are very strong greenhouse
gases with long lifetimes in the atmosphere.
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ppm
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Parts per million by volume—a unit that
measures concentration of gases in the atmosphere.
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Radiation
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The emission or transmission of energy as
waves or as particles. Radiation is classified according to the
frequency or wavelength of the wave, and includes radio waves,
microwaves, infrared radiation, visible light, ultraviolet
radiation, x-rays and gamma rays (from longest to shortest
wavelengths). Radiation is emitted from all objects with a
temperature above absolute zero (absolute zero on the Celsius
temperature scale is –273.15°C).
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Radiative forcing
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Radiative forcing refers to the influence on
the Earth’s climate of various radiative components. These
components include the amount of solar radiation reaching the
atmosphere and the Earth’s surface, as well as the influence
of individual greenhouse gases within the atmosphere and their
warming contribution through their ability to absorb infrared
radiation emitted from the Earth’s surface. Radiative forcing
is measured as the change in net (down minus up) irradiance at the
top of the lower part of the Earth’s atmosphere, in units of
Watts per square metre (W m-2).
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Solar radiation
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The spectrum
of radiation emitted from the sun, which includes ultraviolet (100
to 400 nanometres or nm; 1 nm = 10-9 m), visible (400 to
700 nm) and infrared radiation (700 nm to 1 mm), with the peak of
the emission spectrum in the visible range. Solar radiation is the
main energy source for life on Earth, and it drives the
Earth’s atmospheric and oceanic circulation patterns.
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Ultraviolet (UV) radiation
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Radiation emitted from the sun in the range
100 to 400 nm. Almost all of the higher frequency UV radiation
(UV–B and UV–C) is absorbed by ozone in the upper
atmosphere. UV–B radiation reaching the Earth’s surface
can be very damaging to living organisms. It damages DNA, which in
humans can lead to skin cancer and eye damage.
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United
Nations Framework Convention on Climate Change (UNFCCC)
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The UNFCCC is an international treaty that
entered into force in 1994. It sets out a framework for
intergovernmental efforts to address the issue of climate change
and act to stabilise greenhouse gas concentration levels in the
atmosphere. Parties to the UNFCCC submit information on national
greenhouse gas emissions and implement strategies for mitigating
emissions, adapting to anticipated climate change impacts, and
providing assistance to developing countries.
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Introduction
Climate change is an issue
that scientists first raised and seriously considered decades ago,
and it has been hotly debated ever since. Considerable effort and
resources have been invested in observing and understanding the
climate system both past and present, and we are now at the point
where the results of these efforts paint a clear picture of the
changes in climate that are currently occurring and the likely
causes of these changes.
There is no doubt that the climate has changed
over the past 150 years. These changes are documented by an
enormous range of data analysed by scientists in many different
countries and institutions. The evidence tells us with a high
degree of confidence that human activities are responsible for most
of the changes in climate that have been observed over recent
decades, and that the most powerful influence has been the
alteration of the composition of the atmosphere caused by emissions
of greenhouse gases since the industrial revolution.
The changes to climate are having effects on
ecosystems and other environmental processes and functions that
directly impinge on human society. These changes are occurring
already, and are projected to continue and intensify. There is
increasing recognition that climate change poses a real and present
threat to the social and economic structure of human society, as
well as to the environmental and ecosystem functions upon which we
depend.
The scientific evidence demonstrating the
reality of climate change and the leading role of humans in driving
this change in recent decades is so compelling that the
overwhelming majority of scientists in the relevant disciplines do
not doubt that greenhouse gas emissions from human activities are
causing the climate to change. It has taken decades, but the weight
of the climate change debate has finally moved on to the economics
and politics associated with the challenges of mitigation and
adaptation. This acceptance of the problem and challenge is
multi–partisan, multi–national and at all levels of
government. It has been explicitly acknowledged and emphasised by
the Australian Government and Opposition as well as every
Australian state and territory government. [1]
Given the overwhelming acceptance of the
reality of human–induced climate change, this paper is not
about proving, once again, the scientific case. Rather, it
discusses the scientific, economic and moral imperatives for
Australia and the world to act, and act soon, to mitigate climate
change and reduce the risks of damaging or even catastrophic
consequences that may result from inaction. Presented first is an
overview of the science of climate change and the human
contribution, followed by implications of delaying or avoiding
action, then a discussion of Australia’s situation and
responsibilities in the global context.
There is increasing evidence of human
influence on the climate system. [2] Human activities are directly affecting the
composition of the atmosphere, by increasing the concentration of
the naturally occurring greenhouse gases, by adding new greenhouse
gases, and also by changing the mix of suspended particles and
droplets (aerosols) in the atmosphere. We are also changing the
reflectivity (known as the albedo) of parts of the Earth’s
surface, which influences how much of the arriving solar radiation
is absorbed. The two main human activities that are contributing to
climate change are emissions of greenhouse gases and aerosols, and
land use and land conversion practices. These are discussed in turn
below, followed by a summary of evidence showing that these
activities have caused clearly discernible changes in climate over
the past century.
Increasing levels of greenhouse gases in the
atmosphere is by far the most influential amongst the factors
causing contemporary climate change. [3] Greenhouse gas emissions from human
activity derive mainly from combustion of fossil fuels (coal, oil
and natural gas), with additional significant contributions from
industrial processes, agriculture, and land use change. Changes in
levels of black carbon particulates (for example from soot), snow
albedo (from settling dust and particulates), and some atmospheric
pollutants have small additional impacts on global warming. These
factors all tend to act as warming agents, but other factors that
can act as cooling agents are changes in cloud albedo, aerosols,
land albedo change, and, periodically, dust from volcanic
eruptions.
Global warming is a result of the atmospheric
‘greenhouse effect’. [4] This is the process by which solar radiation
passes through the atmosphere relatively freely but infrared
radiation (or heat) emitted from the Earth’s surface is
absorbed and re–radiated by greenhouse gases. Some of this
re–radiated heat escapes to space, but some is
re–absorbed by the atmosphere or Earth’s surface, so
the net effect is to trap heat within the Earth–atmosphere
system. This leads to a higher temperature at the surface than
would otherwise be experienced.
The greenhouse effect is a natural phenomenon
on Earth, brought about by the presence of low concentrations of
carbon dioxide and water vapour in the atmosphere, and is
responsible for maintaining the Earth’s temperature at a
habitable level. However, greenhouse gases emitted or generated by
human activities are enhancing the natural greenhouse effect. The
main such gases are carbon dioxide (CO2), methane
(CH4), nitrous oxide (N2O), halocarbons
(including chlorofluorocarbons, hydrofluorocarbons,
hydrochlorofluorocarbons, perfluorocarbons, and hydrofluoroethers),
and ozone (O3).
The relative contribution of each of the
greenhouse gases to the enhanced greenhouse effect depends on their
infrared radiation absorption characteristics, as well as on their
lifetime and concentration in the atmosphere—the impact of
many of these gases is accentuated owing to their long–lived
nature in the atmosphere. The rate at which we are emitting
greenhouse gases currently far exceeds the rate at which those
gases are removed from the atmosphere by natural processes.
CO2 is responsible for most of the enhanced warming
effect because it is emitted in the largest volume, followed by
methane, combined halocarbons and nitrous oxide, which all have a
much greater warming effect than CO2 for a given mass
but are emitted in smaller quantities. The global warming potential
of different greenhouse gases is compared by using a common scale
of ‘CO2–equivalents’
(CO2e).
Ozone is also a powerful greenhouse gas but is
not classified as a long–lived greenhouse gas (LLGHG) because
in the upper atmosphere it is constantly being broken down by
ultraviolet (UV) radiation and reformed by natural processes. The
absorption of UV radiation in the upper atmosphere by ozone is a
vital process that protects life on Earth from damaging influences
of high levels of UV. In the lower atmosphere, ozone is produced as
a result of human activities. It is formed by chemical reactions
between atmospheric oxygen and ‘precursor’ gases such
as volatile organic compounds and nitrogen oxides that are emitted
from burning of fossil fuels and biomass, and other industrial
processes. It is the additional ozone in the lower atmosphere that
contributes to the enhanced greenhouse effect.
As a result of burning of fossil fuels and
changes in land use practices, carbon dioxide, methane and nitrous
oxide concentrations have all grown steeply in the last century
relative to earlier levels, as shown in Figure 1 (halocarbon
records show similar trends). These increases in concentration are
accompanied by increases in the contribution of these gases to
radiative forcing. The term ‘radiative forcing’ refers
to changes in the overall amount of solar radiation absorbed by the
Earth’s surface and atmosphere, or to the amount of heat
radiated to space. Greenhouse gases affect the latter process,
trapping heat within the lower atmosphere.
The disturbing trend in CO2
concentrations was first observed in the 1960s in pioneering work
at Mauna Loa in Hawaii, where the first reliable long–term
measurements of atmospheric CO2 concentrations were
established. This work was instrumental in demonstrating the
influence of fossil fuel emissions on atmospheric concentrations,
and establishing the basis for concern that human activities could
alter the climate system. [5]
Figure 1
: Trends in the main greenhouse gas concentrations in the
atmosphere in the last 1000 years
Source: Bureau of Meteorology, The
greenhouse effect and climate change, 2003, Figure 26, p. 19,
viewed 18 March 2009, <http://www.bom.gov.au/info/GreenhouseEffectAndClimateChange.pdf>.
Through farming, harvesting of natural
resources and urbanisation, humans have significantly modified the
Earth’s landscape from its natural state, and the rate of
modification has accelerated dramatically since the industrial
revolution. Such changes can reduce or increase the ability of soil
and vegetation to absorb, store and release carbon. [6] In addition, the way in
which we use the land and change the type and extent of vegetation
alters the albedo of the planet’s surface, which affects the
amount of solar energy absorbed by the surface and hence the
temperature.
Plants absorb carbon dioxide from the
atmosphere during photosynthesis, and forests represent a
significant ongoing carbon sink while they are actively growing.
This may continue for hundreds of years, until the trees and forest
ecosystem reach an age where losses of carbon through shedding of
leaves and limbs and decaying dead woody debris above and below
ground may start to exceed the gains of carbon through new growth.
Deforestation and land clearing releases much of the carbon that
was stored in the plant biomass, either quickly if the slash and
burn approach is used, or slowly as the plant matter decays over
time.
Since 1850, deforestation is estimated to have
reduced the total global forest area by about 17 per cent, but the
percentage is much higher in some regions. [7] The issue is of particular interest to
Australia because of the high deforestation rates in our
neighbouring countries, as well as our own record of deforestation
and potential for carbon sequestration through reforestation.
[8] Indonesia has one
of the fastest deforestation rates in the world, and the rate has
been accelerating; half of the forests existing in Indonesia in
1950 have since been cleared. [9] Deforestation in Papua New Guinea (PNG) has also
been accelerating in recent years, with an annual loss rate of 1.4
per cent. Fifteen per cent of PNG’s forests existing in 1972
were cleared in the following 30 years, and it is projected that
more than half will be lost or seriously degraded by 2021. [10] In Australia,
deforestation rates have declined since the early 1990s, but it is
estimated that about 25 per cent of the total forest area that
existed before European settlement has been cleared, and much of
the remaining forest area has been substantially modified and
fragmented. [11]
Figure 2 illustrates the
global extent of conversion of land to crops and pasture between
1750 and 1990.
Figure 2
: Anthropogenic changes in land cover from 1750 to
1990
Notes: Anthropogenic (human) modifications of
land cover up between 1750 (top panel) and 1990 (bottom
panel)—reconstructions from the History Database of the
Environment. Source: ‘Chapter 2 Changes in atmospheric
constituents and in radiative forcing’, in IPCC, Climate
change 2007: the physical science basis, contribution of
Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change, Cambridge University
Press, Cambridge, 2007, Figure 2.15, p. 181.
Activities associated with agriculture, such
as land clearing, burning, deforestation and tillage, change the
reflectivity, texture and composition of the land surface, which in
turn change the level of absorbed radiation and the amount of
evaporation. In addition, deforestation tends to degrade the land,
by removing organic matter and nutrients and disturbing the soil
structure, which reduces the capacity of the land to
re–establish a healthy ecosystem with strong plant growth and
carbon uptake. Removal of vegetation also reduces the ability of
soils to retain moisture and may make it harder for rainwater to
infiltrate, commonly exacerbating erosion.
The soil is thought to contain three times
more carbon than the atmosphere. Agricultural practices causing
changes in soil structure, soil moisture loss and
over–cultivation reduce soil organic content by reducing the
density of soil organisms and accelerating oxidation of organic
carbon compounds to produce carbon dioxide. It is estimated that
most agricultural soils have lost 50 to 70 per cent of the soil
organic carbon pool that existed before their conversion and
cultivation. However, modified farming practices can help retain
soil carbon and hence maximise the potential of soil to act as a
carbon sink. [12]
It is estimated that about 15 per cent of current global emissions
from agricultural soils can be mitigated at no additional cost by
reducing or eliminating tillage to maintain higher soil organic
carbon content, and optimising timing and application of
fertilisers to reduce nitrous oxide emissions. [13]
In the past century, the average surface
temperature of the Earth has warmed by over 0.7°C. [14] Much of that warming
has been in the past three decades. The temperature rise varies
regionally and seasonally. Regional climate change in some areas,
therefore, has been more dramatic—Arctic sea ice is melting
rapidly and is 40 per cent thinner than it was in the 1970s. Most
of the world’s glaciers have been retreating since the 1850s,
and the rate of retreat has increased since 1990. The movement of
glaciers in Greenland and in much of the world is also speeding up,
apparently lubricated by melt water seeping down to the
ice–rock boundary and in some cases by loss or reduction of
ice shelves at their outlet, which is accelerating the loss of ice
mass.
The sea level is also rising. [15] This is partly from
thermal expansion as the surface layers of water heat up (water
occupies more volume when it is warmer), and partly from ice loss
from glaciers and ice caps. Ice losses from the huge ice masses in
the Greenland and Antarctic ice sheets have also contributed
significantly to sea level rise, and observations show that loss
from these ice sheets is accelerating.
Though an average global temperature increase
of 0.7°C may not seem dramatic, an increase in mean
temperature also has implications for the temperature extremes that
we experience. Most temperature recording stations around the world
show that average night–time minimum and day–time
maximum temperatures have both increased over the last few decades.
Periods of sustained and unusually high temperatures are becoming
more common in some places, such as the 2003 heatwaves in central
Europe thought to be responsible for the premature deaths of up to
35 000 (mainly elderly) people, and the 2003 pre–monsoon
heatwave in India which had severe impacts on human health and
contributed to the deaths of 1400 people.
Although any individual weather event cannot
be attributed unequivocally to climate change, the probability of
such high temperature events increases with the underlying trend of
rising mean temperature.
The estimated relative contribution of human
and natural factors to global warming is illustrated in Figure 3 .
The contribution is measured in terms of radiative forcing, with a
positive change representing a warming effect and a negative change
representing a cooling effect.
Figure 3
: Globally and annually averaged radiative forcing due to
various agents since 1850
Notes: This is
an illustrative example of the forcings as implemented and computed
in one of the climate models participating in the IPCC Fourth
Assessment Report. Note that there could be differences in the
radiative forcings among models. Most models simulate roughly
similar evolution of the long–lived greenhouse gases’
radiative forcing. Source: ‘Chapter 2 Changes in atmospheric
constituents and radiative forcing’, in IPCC, Climate
change 2007: the physical science basis, contribution of
Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change, Cambridge University
Press, Cambridge, 2007, Figure 2.23, p. 208.
The concentrations of long–lived
greenhouse gases (LLGHGs) have increased rapidly over the past 20
years. These contribute the most to radiative forcing, exceeding
the level of contribution from all other anthropogenic agents
throughout the latter half of the 20th century. The black line in
Figure 3 indicates the net effect of all greenhouse gases, aerosols
and land use.
The input from solar effects (the sun varying
slightly in its output of radiation) is around 20 per cent of
the combined effect of all anthropogenic agents, and about ten
times less than the total greenhouse gas contribution. Volcanic
eruptions have a large but transitory effect, which is usually
negative (i.e. cooling).
Scientists are confident that natural factors
cannot account for the observed warming in recent decades. Figure 4
demonstrates that when climate models incorporate only these
natural factors (see bottom panel), they are able to reproduce the
general pattern of global temperature up until about 1960. The
cooling influence of volcanic eruptions (marked with vertical lines
and labelled in the figure for each volcano) is also clearly
discernible—these cause large emissions of aerosols into the
atmosphere that act to reflect incoming sunlight. Models
incorporating only natural factors, however, are not able to
reproduce the pronounced rise in temperature observed since 1960.
Note that the high variability in observed temperature from year to
year is not well simulated, because this arises from random and
unpredictable processes in the climate system that cannot be
effectively modelled. The models are more concerned with accurate
simulation of the trend in temperature over several decades.
[16] As shown in
the top panel of Figure 4 , in order to reproduce the warming of
the past several decades, anthropogenic forcing (the change in
radiative balance due mainly to greenhouse gas emissions from human
activities) must be included.
This result presents some of the most
convincing evidence that human activities are causing global
warming—there are no known natural processes that can account
for the observed warming, and the increase in greenhouse gas
concentrations due to human activities is necessary and sufficient
to explain the observations. This and other evidence led the Fourth
Assessment Report of the Intergovernmental Panel on Climate Change
(IPCC) to conclude that natural processes have played little or no
contributing role in driving climate change over the last 50 years.
[17]
Figure 4
: Global mean surface temperature anomaly observations
(black lines), simulations with combined natural and anthropogenic
forcing (red line) and simulations with natural forcing only (blue
line)
Notes: Comparison between global mean surface
temperature anomalies (°C) from observations (black) and
atmosphere–ocean general circulation model simulations forced
with (a) both anthropogenic and natural forcing and (b) natural
forcing only. All data are shown as global mean temperature
anomalies relative to the period 1901 to 1950, as observed (black,
Hadley Centre/Climatic Research Unit gridded surface temperature
data set (HadCRUT3)) and, in (a) as obtained from 58 simulations
produced by 14 models with both anthropogenic and natural forcing.
Significant volcanic eruptions are indicated by grey vertical lines
with labels. Source: ‘Chapter 9 Understanding and attributing
climate change’, in IPCC, Climate change 2007—the
physical science basis, contribution of Working Group I to the
Fourth Assessment Report of the Intergovernmental Panel on Climate
Change, Cambridge University Press, Cambridge, 2007,
Figure 9.5, p. 684.
To summarise, a wide range of evidence from a
number of sources covering trends over the last two centuries and
comparing those to trends over timescales ranging from millennia to
several hundred thousand years demonstrate that the rate and extent
of recent changes in climate are unprecedented in human history.
[18] Furthermore,
there is a strong consensus within the scientific community that
recent climate change has been largely, or possibly wholly, driven
by human activities since the industrial revolution, particularly
emissions of greenhouse gases from fossil fuel combustion and land
use change.
If we take as a starting point the premise
that climate change is occurring and is caused mainly by human
activities, as is argued in the previous section, we then come to
the issue of what, if anything, should be done about it. An
assessment of whether climate change mitigation action is necessary
and urgent requires answers to the following questions:
- How much is the climate likely to change if we do nothing, and
how much will this change be moderated if we do something (with
‘something’ quantified through one or more scenarios
involving specified mitigation action)?
- What are the likely impacts of climate change on our economy,
society and environment?
- How may these impacts be moderated or exacerbated under
mitigation or no–mitigation scenarios and how are they
affected by the timing of mitigation action?
There have been a number of studies addressing
these questions, examining the economics and science of climate
change, and reviewing the knowledge that has accumulated over the
past several decades. Of particular note for their comprehensive
and widely–sourced information are the Intergovernmental
Panel on Climate Change (IPCC) Assessment Reports, the Stern
review on the economics of climate change, and the Garnaut
climate change review. [19]
The IPCC was established in 1988 to provide a
comprehensive, objective, open and transparent assessment of the
latest scientific, technical and socio–economic literature
produced worldwide relevant to climate change and its risks and
impacts, and options for mitigation and adaptation. Since its
establishment, it has delivered four comprehensive assessment
reports, in 1990, 1995, 2001 and 2007. It has also published many
special and technical reports covering topics such as socioeconomic
emissions scenarios and emissions from land use practices. The
Fourth Assessment Report, in 2007, includes three volumes dealing
respectively with the physical science basis; impacts, adaptation
and vulnerability; and mitigation of climate change. More than 1200
authors and 2500 expert reviewers examined the full body of work on
climate science to produce the Fourth Assessment Report, and its
Summary for Policymakers was agreed to line by line by government
representatives of each of the more than 100 participating member
countries. [20]
In 2005, Sir Nicholas Stern was commissioned
by the British Chancellor of the Exchequer to assess the economic
challenges of climate change in the UK and globally, and advise on
how these challenges may best be met. The Stern Review, released in
October 2006, became the most comprehensive and widely known report
of its kind. [21]
In April 2007, Professor Ross Garnaut was
commissioned by then opposition leader Kevin Rudd and the Premiers
and Chief Ministers of Australia’s states and territories to
examine the impacts of climate change on the Australian economy and
recommend policy measures to support Australia’s
long–term prosperity in the face of these impacts. The final
report of the Garnaut Review was released in September 2008. The
Garnaut Review was essentially an Australian version of the Stern
Review, but significant advances in the science and economics had
emerged in the intervening period, notably the release of the
IPCC’s Fourth Assessment Report in 2007. The Garnaut Review
currently represents the most comprehensive and
up–to–date scientific and economic assessment of
climate change available, and as an Australian study, it is of
particular relevance to the Australian situation. [22]
The following sections draw heavily from these
sources, particularly the IPCC Fourth Assessment Report and the
Garnaut Review, to address the questions posed above. While many
additional studies, both economic and scientific, have been
published, the above–mentioned sources are unique in their
treatment of the issue. Firstly, they are unique in the
comprehensive nature of their assessment, which covers all or
nearly all aspects of the complex and interacting scientific and
socioeconomic implications of climate change. Secondly, they are
not motivated by particular interest groups or industry
perspectives: they are independent reviews of all the available
evidence, and their projections and recommendations are a result of
the objective application of the best available models and
interpretation of their output. Thirdly, as a corollary to the
second point, in reviewing and incorporating information from a
large range of sources, they represent ‘moderate’
assessments of the impacts and challenges presented by climate
change: they are not able to ‘cherry pick’ data or
studies to either downplay or exaggerate the risks of climate
change. Of course, there exist many studies, interest groups and
individuals who disagree with the findings of the above reviews.
The fact that these disagreements are fairly evenly distributed in
both directions along the spectrum of climate change risk level
assessment suggests that the reviews took a fairly moderate
position.
Below, the questions posed at the beginning of
this section regarding the importance and timing of global
mitigation action are addressed by consideration of environmental
and economic aspects in turn.
Before human industrial development, the
concentration of carbon dioxide in the atmosphere was about 280
ppm. The burning of hydrocarbon fuels, notably coal and oil,
together with activities such as large scale deforestation, has
caused the atmospheric CO2 concentration to increase to
its current level of over 380 ppm. In addition to this increase in
CO2 in the atmosphere, emissions of
non–CO2 greenhouse gases, some of which were
absent from the atmosphere in pre–industrial times, has
brought current total greenhouse gas concentrations to more than
450 ppm CO2e. Furthermore, the rate of CO2
and other greenhouse gas emissions has been accelerating over
recent years. [23]
While most developed countries are in the process of stabilising or
slightly reducing their emissions, the rapidly expanding economies
of large, populous countries such as China and India are causing a
concurrent rapid growth in emissions from those countries. [24] Achieving significant
global emissions reductions will, in the first instance, require
substantial action on the part of developed countries, which have
the greatest capacity to implement these reductions. Ultimately
though, it will require a concerted global effort involving all
countries.
The longer that action to mitigate climate
change is delayed, the more drastic will be the measures required
to stabilise atmospheric greenhouse gas concentrations at a given
level, and the more likely that the ultimate stabilisation level
will be higher. Conversely, achieving lower stabilisation levels
will require almost immediate action: for example, it has been
estimated that to stabilise at around 450 ppm CO2e,
global emissions will need to have peaked and be starting to
decline by 2015. Table 1 illustrates the implications of different
greenhouse gas stabilisation targets in terms of what those targets
correspond to in CO2 levels alone (compare columns 2 and
3), the best estimate and likely range of warming that would result
(columns 4 and 5), and the timing and magnitude of emissions
reductions required to achieve those targets (columns 6 and 7).
Table 1
: Properties of emissions pathways for alternative ranges
of CO2 and CO2e stabilization
targets
|
Mitigation class
|
Multi–gas concentration level (ppm
CO2e)
|
Stabilization level for CO2 only, consistent
with multi–gas level (ppm CO2)
|
Global mean temperature C increase above
pre–industrial at equilibrium, using best estimate of climate
sensitivityc)
|
Likely range of global mean temperature C increase above
preindustrial at equilibriuma)
|
Peaking year for CO2
emissionsb)
|
Change in global emissions in 2050 (% of 2000
emissions)b)
|
|
I
|
445–490
|
350–400
|
2.0–2.4
|
1.4–3.6
|
2000–2015
|
-85 to -50
|
|
II
|
490–535
|
400–440
|
2.4–2.8
|
1.6–4.2
|
2000–2020
|
-60 to -30
|
|
III
|
535–590
|
440–485
|
2.8–3.2
|
1.9–4.9
|
2010–2030
|
-30 to +5
|
|
IV
|
590–710
|
485–570
|
3.2–4.0
|
2.2–6.1
|
2020–2060
|
+10 to +60
|
|
V
|
710–855
|
570–660
|
4.0–4.9
|
2.7–7.3
|
2050–2080
|
+25 to +85
|
|
VI
|
855–1130
|
660–790
|
4.9–6.1
|
3.2–8.5
|
2060–2090
|
+90 to +140
|
Notes: Estimates are
based on 177 independent scenario studies, most (118) corresponding
to a doubling of CO2 concentrations from
pre–industrial or current levels (class IV, 590–710 ppm
CO2e).
a. Warming for each
stabilization class is calculated based on the variation of climate
sensitivity between 2ºC–4.5ºC, which corresponds to
the likely range of climate sensitivity
b. Ranges correspond
to the 70% percentile of the post–Third Assessment Report
scenario distribution.
c. ‘Best
estimate’ refers to the most likely value of climate
sensitivity
Source:
‘Chapter 3 Issues related to mitigation in the long-term
context’, in IPCC, Climate Change 2007: Mitigation of
Climate Change, Contribution of Working Group III to the
Fourth Assessment Report of the Intergovernmental Panel on Climate
Change, Cambridge University Press, Cambridge, 2007, Table 3.10, p.
229.
The Stern Review found that to achieve a
stabilisation level of 550 ppm CO2e, if global emissions
peak by 2015, then a reduction rate of 1 per cent each year should
be sufficient. If, however, the peak in emissions is delayed by 15
years, until 2030, then the reduction required per year is more
than doubled, to between 2.5 per cent and 4.0 per cent per year,
depending on the height of the peak. [25] Stern notes:
Pathways involving a late peak in emissions may
effectively rule out lower stabilisation trajectories and give less
margin for error, making the world more vulnerable to unforeseen
changes in the Earth’s system... [O]vershooting paths lead to
particularly high risks, as temperatures rise more rapidly and to a
higher level than if the target were approached from below.
[26]
The Garnaut Review notes it is increasingly
recognised that it will be impossible to achieve ambitious
stabilisation targets such as 450 ppm CO2e without
initial overshooting of the target. The potential adverse impacts
of this overshooting (the amount of additional warming and other
changes in climate that will result) will depend on the length of
time the concentrations stay above the target and how far above the
target concentrations rise:
… due to inertia in the climate system, a
large and lengthy overshooting will influence the transient
temperature response, while a small, short one will not. [27]
It is clear that a higher greenhouse gas
concentration stabilisation level will result in warmer mean global
temperatures, as shown in Figure 5 . The figure shows the likely
temperature range resulting from different stabilisation targets,
which are grouped into different mitigation classes corresponding
to the mitigation classes in Table 1 .
Figure 5
: Relationship between global mean equilibrium temperature
change and stabilization concentration of greenhouse
gases
Notes: Results from: (i) ‘best
estimate’ climate sensitivity of 3°C (black), (ii) upper
boundary of likely range of climate sensitivity of 4.5°C
(red), (iii) lower boundary of likely range of climate sensitivity
of 2°C (blue). Roman numerals in coloured blocks refer to
classes of emissions pathways as described in Table 1 . Source:
IPCC, Climate Change 2007: Mitigation of Climate Change,
Contribution of Working Group III to the Fourth Assessment Report
of the Intergovernmental Panel on Climate Change, Cambridge
University Press, Cambridge, 2007, Figure 3.38, p. 228.
These temperature increases, along with
associated sea level rise and other changes in the climate system,
will not happen immediately, but will continue to occur over the
next several centuries. This is because some aspects of the climate
system respond slowly to changes in radiative forcing caused by
changes in greenhouse gas concentrations (i.e., they have high
inertia). The oceans have an enormous heat capacity, and heat
absorbed into the oceans from the atmosphere is redistributed from
one region to another and between deep and shallow waters through
large–scale circulation patterns over thousands of years.
[28] Other
processes in the climate system may respond more quickly, but as
Figure 6 illustrates, the impacts of emissions taking place now and
in the next few decades will be felt for many centuries to
come.
Figure 6
: Inertia in the climate system
Source: R Garnaut, The Garnaut climate
change review: final report, Cambridge University Press,
Cambridge, 2008, Figure 2.6, p. 42.
In considering the likely warming and other
climate change impacts of higher atmospheric greenhouse gas
concentrations, the Garnaut Review considers two mitigation cases
as well as a no–mitigation case:
- Under the no–mitigation case, atmospheric greenhouse gas
concentrations are projected to reach over 1550 ppm CO2e
by 2100.
- Under the 550 mitigation case, emissions peak and decline
steadily so that atmospheric concentrations stabilise at around 550
ppm CO2e by 2100.
- Under the 450 mitigation case, emissions are immediately
reduced and decline more rapidly than the 550 case. Concentrations
overshoot to about 530 ppm CO2e in mid–century
before stabilising at around 450 ppm CO2e early in the
22nd century.
Figure 7 shows the projected temperature
increase under each of these scenarios out to 2200.
Figure 7
: Projected temperature increases to 2200 above 1990 levels
for the three Garnaut emissions cases
Source: R Garnaut, The Garnaut climate
change review: final report, Cambridge University Press,
Cambridge, 2008, Figure 4.7, p. 92.
Higher temperatures present greater risks to
the environment, both regionally and globally, and consequently to
our socioeconomic productivity, security and health. The IPCC
report lists key vulnerabilities relating to a given increase in
global mean temperature as shown in Table 2 . [29] The table also indicates the
approximate stabilisation levels of greenhouse gas concentrations
in the atmosphere corresponding to each temperature increase.
Table 2
: Key vulnerabilities corresponding to given ranges of
temperature increase
|
Temperature
increase
|
Stabilisation
target
|
Vulnerabilities
|
|
>4°C
|
>700 ppm
CO2e
|
Near–total
deglaciation; at least 35 per cent of species committed to
extinction; increase in severity of floods, droughts, erosion and
deterioration in water quality; decline in global food production;
increased frequency and intensity of extreme weather events and
fire risk.
|
|
3–4°C
|
>590 ppm
CO2e
|
Widespread to
near–total deglaciation, 2–7 metre sea level rise over
centuries to millennia; global vegetation becomes a net source of
CO2; extended salinisation of ground water, decreasing
freshwater availability in coastal areas.
|
|
2–3°C
|
>450 ppm
CO2e
|
Lower risk of
near–total deglaciation; 20 to 50 per cent of species
committed to extinction; hundreds of millions of people would face
reduced water supplies; global food production peaks and
declines.
|
|
1–2°C
|
<450 ppm
CO2e
|
Localised deglaciation;
10–40 per cent of species committed to extinction; increased
flooding and drought severity; reduced low latitude food
production, increased high latitude production; increased fire
frequency and intensity.
|
|
0–1°C
|
<450 ppm
CO2e
|
Lower risk over all
vulnerabilities.
|
Source: IPCC, Climate change 2007:
mitigation of climate change, contribution of Working Group
III to the Fourth Assessment Report of the Intergovernmental Panel
on Climate Change, Cambridge University Press, Cambridge, 2007,
Table 3.101 p. 230.
The Garnaut Review finds significant
reductions in environmental risks and damages could be achieved
with global mitigation action. For example, the Garnaut Review
suggests that the percentage of species at risk of extinction under
the no mitigation case is 88 per cent, which is reduced to 12 per
cent under the 550 scenario and 7 per cent under the 450 scenario.
Large–scale melting of the Greenland ice sheet is certain to
be initiated with no mitigation, but the likelihood is reduced to
26 per cent under the 550 scenario and 10 per cent under the 450
scenario. [30]
The recent climate change science congress in
Copenhagen in March 2009 highlighted the importance of implementing
rapid and substantial measures to respond to the changes in climate
that we are continuing to observe. The congress was convened to
provide a synthesis of existing and emerging scientific knowledge
since the IPCC Fourth Assessment Report, to help inform
policymakers at the UNFCCC climate change conference in Copenhagen
in December 2009. [31] A full synthesis report from the science congress will
be published in June 2009. The following points list some of the
key messages that emerged: [32]
- Recent observations show that climate change is proceeding at
rates corresponding to the worst–case scenarios of the
IPCC Fourth Assessment Report, or worse. These include observations
of temperatures, sea level rise and extreme climatic events.
- There is more information available now that suggests our
societies, particularly those of poor nations, will struggle to
adjust to climate change even at moderate levels of change.
- Rapid action is required to effectively mitigate the risks of
climate change. Committing to weak emissions reduction targets for
2020 will increase the risk of irreversible damaging climate change
and make it more difficult to meet substantial targets in
2050.
The Garnaut Review assessed the relative costs
of likely climate change impacts and mitigation measures. It
considered four types of costs of climate change:
- Type 1 costs are the expected market impacts of climate change
that can be assessed quantitatively through general equilibrium
economic models. Garnaut focuses on impacts on primary production,
human health, infrastructure, tropical cyclone damage, and
international trade. The costs are realised through their effects
on GDP or consumption.
- Type 2 costs are market impacts that are not currently readily
measurable. These impacts are similar in nature to Type 1, but
there are insufficient data at present for detailed modelling of
Type 2 costs. However, Garnaut provides a rough estimate of the
likely magnitude of these costs based on available knowledge. An
example is the impact on the tourism industry.
- Type 3 costs relate to the insurance value provided by
mitigation, for avoided risks. Garnaut poses the question of how
much we would be willing to pay to avoid a small probability of a
catastrophic outcome. Such catastrophic events with potentially
highly damaging consequences to human society include irreversible
melting of the Greenland and West Antarctic ice sheets, each
contributing a 7–metre rise in sea level; melting of the
summer Arctic sea ice; disruption of the Atlantic circulation
system (which includes the Gulf Stream and the North Atlantic
Drift); disruption of the Indian monsoon; disruption of the El
Niño–Southern Oscillation; disruption of the
Sahara/Sahel and West African monsoon; dieback of the Amazon
rainforest; and dieback of high–latitude forest. For example,
the tipping point of melting of the Greenland ice sheet has been
put at a temperature increase of between 1.9°C and 4.6°C
above pre–industrial levels. [33] Thus, the Greenland ice sheet could
begin to melt irreversibly, leading to its complete loss over the
next centuries, even under the most stringent stabilisation targets
(see temperature projections corresponding to stabilisation targets
in Table 1 ). Other major impacts are considered likely to occur
only under relatively high stabilisation levels (see Table 2 ). The
desire to avoid or substantially reduce the risk of such events
occurring presents a compelling argument for strong and early
mitigation action.
- Type 4 costs relate to non–market impacts, or a reduction
in the utility of non–monetary services such as environmental
amenity (e.g. the value that Australians place on the integrity of
the Great Barrier Reef, Kakadu, coastal ecosystems, biodiversity
and species conservation), longevity, health and welfare of people
in other countries. Although in principle monetary values can be
assigned to such outcomes, the Garnaut Review assesses this type of
cost qualitatively.
All of the four cost types are important. All
four are costs that Australia would want to avoid if at all
possible, even though only types 1 and 2 can be quantified with any
accuracy.
The Garnaut Review’s findings clearly
indicate that the costs of no action would be considerably higher
than the costs of action in the long term, as illustrated in Figure
8 , which shows the cumulative cost of mitigation or no mitigation
compared to the reference case in which there are no adverse
climate change impacts. Figure 9 shows that after an initial shock
to GNP growth of around 0.8 per cent and a slight reduction in GNP
growth over the next 50 years compared to the no–mitigation
case, in the later part of the century mitigation results in a net
increase in GNP growth as the avoided damaging climate change
impacts outweigh the costs of mitigation.
Figure 8
: A comparison of the modelled expected market costs for
Australia of unmitigated and mitigated climate change up to
2100
Note: includes Type 1 costs only. Source: R
Garnaut, The Garnaut climate change review: final report,
Cambridge University Press, Cambridge, 2008, Figure 11.6, p.
267.
Figure 9
: Change in annual Australian GNP growth (percentage points
lost or gained) due to net mitigation costs under the 550 scenario
compared to no mitigation, 2013–2100
Notes: Modelled results from Type 1 costs,
adjusted to incorporate Type 2 costs, which are estimated at about
30 per cent of Type 1 GNP costs. Source: R Garnaut, The Garnaut
climate change review: final report, Cambridge University
Press, Cambridge, 2008, Figure 11.4, p. 265.
The Australian Treasury undertook a similar
analysis of the costs of mitigating climate change, comparing the
two Garnaut mitigation scenarios (labelled Garnaut–10 and
Garnaut–25, corresponding to stabilisation targets of 450 and
550 ppm CO2e, respectively, and emissions reductions
targets of 10 per cent and 20 per cent by 2020, respectively), as
well as two scenarios corresponding to the framework of the Carbon
Pollution Reduction Scheme (CPRS) with 5 per cent (scenario
CPRS–5) and 25 per cent (scenario CPRS–25) emissions
reduction targets by 2020, respectively. It is important to note
that unlike the Garnaut projections, the Treasury modelling
projects only the costs of mitigation compared to a reference case
that excludes the risks and impacts of climate change and its
associated costs. Furthermore, the Treasury projections extend only
to 2050. Like the Garnaut scenarios, the Treasury scenarios assume
coordinated global action is established. The Treasury scenarios
assume that developed countries take comparable action, and that
developing countries join the scheme over the period 2015 to
2025.
Figure 10 illustrates that under all
mitigation scenarios, the Treasury modelling projects that GNP
continues to grow, but the cumulative difference between the
mitigation scenarios and the reference case amounts to between 5
per cent and 7 per cent of GNP by 2050. The Treasury modelling also
examined the effect of delaying global mitigation action by seven
years (from 2013 to 2020) but retaining a stabilisation target of
550 ppm CO2e by 2100. The analysis found that under
delayed action, global costs were about 10 per cent higher in 2050
and remained higher to 2100. [34]
Figure 10
: Treasury modelling of GNP per capita as (a) change from
reference scenario and (b) levels, 2010 to 2050, for the
CPRS–5, CPRS–15, Garnaut–10 and Garnaut–25
scenarios
Source: Australian Treasury,
Australia’s low pollution future: the economics of
climate change mitigation—report, Commonwealth of
Australia, 2008, Chart 6.9, p. 144.
In relation to the no–mitigation case,
the Garnaut Review concludes:
…[T]emperature increases of the order of
magnitude associated with no mitigation—an expected increase
by 2100 of 5.1°C, a 6.6°C warming at the top of the
likely band, and a smaller probability of a double–digit
temperature increase—would not lead to a marginal reduction
in human welfare. Their impacts on human civilisation and most
ecosystems are likely to be catastrophic. [35]
While the science is clear that any delay in
implementing effective and substantial mitigation measures
increases the risks of damaging climate change, it is also clear
that the costs of mitigation will be higher the longer we wait.
Acting early enables businesses and industries to adjust gradually
to make the transition to a low–carbon economy, with time for
new technologies to emerge and compete to replace old
carbon–intensive technologies. Such effort will take time,
and will only be justified with the aid of the economic incentives
provided by mitigation measures. Such measures, of which emissions
trading is likely to be central, can be introduced with, for
example, gradually increasing carbon prices so as to ease the
transition while stimulating innovation and development. [36]
Regarding paths to stabilisation levels and
timing of mitigation action, Stern notes:
Early abatement may imply lower long–term
costs through limiting the accumulation of carbon–intensive
capital stock in the short term. Delaying action risks getting
‘locked into’ long–lived high carbon
technologies. It is crucial to invest early in low carbon
technologies. [37]
As an example illustrating this point,
Australia, like many other countries including the US and China,
relies heavily on coal to meet its energy needs, and it is
unrealistic to expect that Australia will be able to abruptly end
this reliance. However, in order for the coal industry to remain
viable in a carbon–constrained world, much effort will need
to be invested in developing and commercialising clean coal
technologies and carbon capture and storage (CCS), to improve
efficiency of coal–fired power stations and eventually reduce
their emissions to near zero. In the absence of mitigation
measures, Treasury modelling projects coal production to increase
by 82 per cent by 2050 (from 2008 production levels). With an
emissions trading scheme and in the absence of CCS, however, coal
production is projected to decrease by 18 per cent by 2050. With
CCS, production is lower than in the no–mitigation scenario,
but increases by 42 per cent by 2050. [38] The Garnaut Review projects that
under a global emissions trading scheme, zero–leakage (i.e.,
100% efficient) CCS would result in an increase in global
electricity generation from coal from current levels of around 10
gigawatt–hours (GWh) to over 100 GWh by 2100 to meet the
increase in electricity demand. [39] Australian coal production would be expected to
increase in line with global demand for exports. [40] If CCS is only 90% efficient,
Garnaut projects electricity production from coal to peak by about
2070 and then decline.
These results clearly demonstrate that the
future of Australia’s coal industry is highly dependent on
market responses to both domestic and international carbon trading
and the development of zero–emission technologies. In the
short to medium term, to begin the transformation of our energy
industry that will be required under a low–carbon economy,
the most painless path may involve domestic investment in
implementing clean coal technologies and bringing carbon capture
and storage technologies into fruition. [41]
Many other industries, including aluminium and
agriculture, will similarly need time to adjust to market changes
resulting from emissions trading. This will be necessary to
minimise abrupt disruptions, which may include job losses and
hardship in local communities that depend on these industries.
Though developing countries are projected to
account for an increasingly significant share of global emissions
as their economies expand to meet their development needs,
developed countries are responsible for the majority of greenhouse
gas emissions to date, and have a greater capacity to implement
mitigation and adaptation strategies. Climate change is a global
problem that will require a global solution, but in order to
achieve a global agreement on emissions reduction targets, each
country has a responsibility to commit to and implement mitigation
measures commensurate with its level of economic development.
The United Nations Framework Convention on
Climate Change (UNFCCC) recognises the differentiated
responsibilities of developed and developing countries. The UNFCCC
has been ratified by 192 countries (including Australia and the
US). Parties to the UNFCCC agreed that developed countries should
take the lead in combating climate change and its impacts, and
provide financial assistance to developing countries to facilitate
sustainable development and to build resilience against adverse
impacts of climate change. [42] The Kyoto Protocol builds on these principles,
and commits developed countries and countries with economies in
transition to specific emissions targets, while establishing the
Clean Development Mechanism to encourage developed countries to
invest in emissions reduction activities in developing countries:
[43]
Recognizing that developed countries are
principally responsible for the current high levels of [greenhouse
gas] emissions in the atmosphere as a result of more than 150 years
of industrial activity, the Protocol places a heavier burden on
developed nations under the principle of ‘common but
differentiated responsibilities.’ [44]
Although home to only 0.3 per cent of the
world’s population, Australia’s greenhouse gas
emissions contribute about 1.5 per cent of the world total.
Australia’s emissions per capita are the highest in the
Organisation for Economic Co–operation and Development (OECD)
and among the highest in the world. [45] This is largely due to
Australia’s high reliance on coal for electricity production,
as well as its high agricultural production per capita. The amount
of carbon burned per dollar of wealth created in Australia is
higher than the US and nearly double that of Europe and Japan. The
average growth rate of Australia’s emissions over the last 25
years was twice that for the US and Japan, and five times that for
Europe. [46]
Garnaut notes that the costs of mitigation are
relatively higher when they are carried by the poor than when they
are carried by the rich, because an increment of money is generally
more valuable to the poor than the rich. He supports greater
mitigation efforts by developed countries than developing countries
and further notes that this is in Australia’s interest
because:
Australia has a strong interest in the burden
of mitigation being borne equitably across countries and therefore
disproportionately by developed economies, as Australia’s
terms of trade would be damaged most by any setback to income
growth in developing countries. [47]
Garnaut highlights the role Australia can play
in facilitating an international agreement. He notes that action so
far by individual countries and states within countries such as
Australia have helped gather momentum and provide the impetus for
and confidence in such an agreement, and that:
Pending international agreement, it will be
helpful for individual countries to move forward unilaterally, so
long as this is within policy frameworks that are designed to
integrate productively with an emerging international agreement.
[48]
Australia has a disproportionately high stake
in ensuring that an international effort to reduce greenhouse gas
emissions is realised for the following reasons: [49]
- Australia has very high climate variability compared to other
developed nations and our ecosystems and livelihoods are
particularly vulnerable to the potential adverse impacts of climate
change. An international agreement is urgent and absolutely
necessary to avoid damaging environmental impacts and associated
consequences of climate change, and such an agreement will only be
possible if individual countries, including Australia, attach
enough importance to it.
- With our large aluminium export industry and as the
world’s largest exporter of coal, which is the most
emissions–intensive major energy source, Australia is also
particularly vulnerable to the risks of economic distortion that
may result from domestic assistance to trade–exposed
emissions–intensive industries in the absence of an
international agreement.
- An effective international agreement lowers the cost of
Australian mitigation, and allows more ambitious emissions
reduction targets to be achieved with correspondingly lower risks
of adverse impacts.
- Unchecked global climate change would cause significant
economic damage to Australia’s major trading partners, in
both developed and developing nations. As a trading nation, it is
in Australia’s long term economic interests to minimise this
damage through an effective international greenhouse gas emissions
control agreement, thereby maintaining its overseas markets.
In summary, of all the developed countries,
Australia stands to lose the most if an international agreement to
reduce global emissions is not achieved. It would be difficult for
Australia to justify any other position than playing its full and
fair part in committing to mitigate emissions. Implementing our own
domestic measures consistent with that responsibility will both
facilitate the successful realisation of an effective international
agreement and ease the integration of our economy and industries
into a carbon–constrained world. Australia is also likely to
benefit from continuing to work with regional and international
partners to develop and maintain mutual capacities to anticipate
and respond to the challenges posed by climate change. [50]
Understanding climate change and its risks and
reaching a consensus on whether and what action is required to
mitigate climate change is an enormous challenge. As noted earlier,
there is a strong consensus within the scientific community on the
fundamental reality of anthropogenic climate change. However, the
climate system is complex, and some aspects are not well
understood. [51]
The complexities and uncertainties are often amplified, distorted,
misrepresented and perpetuated through the media and interest
groups, whose vested interests, corporate ideology, personal
beliefs or desire to garner attention lead them to publicise
extreme views or incomplete evidence to sensationalise or deny the
reality of climate change.
Another powerful force driving the nature of
the debate and public opinion is government attitude. At its
extreme, this has stifled scientific research and censored
publication of findings, with the recent Bush administration in the
US being criticised as an example of such practices. As James
McCarthy, President of the American Association for the Advancement
of Science recently said:
I think many people don’t realise how
difficult it was for this science community in the United States
over the last eight years, seeing five years ago the need to really
publicly call into question the scientific integrity of the United
States administration; government scientists who were not permitted
to talk to the press, the reports that were edited by people who
had no scientific credentials whatsoever, the testimonies that had
large segments deleted or altered before they could be made public.
[52]
It is increasingly recognised, however, that
climate change is real and here to stay, and that substantial
ongoing mitigation measures must be implemented within a short
timeframe in order to reduce the risks of adverse impacts over the
next century and beyond to manageable levels. The US and Australia,
the two countries among developed economies notable for their
intransigence during and in the decade following the Kyoto
negotiations, have now both had changes in government with new
administrations prepared to act more decisively, and opposition
parties in both countries are also changing their stance. [53]
Committing to action will not be an easy
process, however. It essentially requires us to value lifestyles,
wealth and commodities a hundred years from now over those we enjoy
at present. But many economists argue that the ‘discount
rate’, which determines the relative value of future utility
or economic status relative to the present in economic modelling,
should be set at zero, giving equal value to the future. Ross
Garnaut judged a near–zero discount rate to be appropriate,
because:
The only reason for a positive rate of pure
time preference is the risk of human extinction in any one year.
[54]
For most people, the issue of whether to value
future utility does not require economic arguments. Our commitment
to our children and grandchildren, to the continued social
wellbeing of the human race, and to doing what we can to reduce
human suffering is strongly embedded in our psyche. Witness the
enormous outpouring of public support and donations in response to
natural disasters that frequently occur throughout the world, and
the culture of philanthropy embedded in many of our societies in
both developed and developing countries.
Furthermore, polls repeatedly indicate that
Australians are deeply concerned about climate change and that most
people are prepared to make sacrifices to minimise the risks of
disastrous consequences. [55] The 2007 Australian election has been described as the
first climate change election, and the Labor Party’s
perceived progressiveness on the issue was thought to be a major
factor contributing to its success in gaining government. [56]
Public concern and individual preparedness to
act are not sufficient to address the challenge of climate change,
however. The challenge requires an integrated, directed effort to
transform our energy industry and carbon–intensive way of
life. Mitigating the threat presented by climate change requires
immediate and substantial action now—action that in its
initial form may prove to be suboptimal, but that if it retains
enough flexibility should ultimately pave the way to a sustainable
future. The challenge we face also presents us with an opportunity:
if we act early, our businesses, industries and economy can undergo
the transformations that will be necessary to maintain or gain a
competitive advantage and grow sustainably in a
carbon–constrained world.
Prime Minister Rudd has described climate
change as the great moral challenge of our generation. [57] Professor Ross Garnaut
described it as a diabolical problem. [58] Little doubt remains, however, that
the problem will persist and worsen until we act to address it. It
seems sensible to conclude, therefore, that Australia should act
urgently to initiate a framework of climate change mitigation so
that our people, our industries and our nation will be ready to
integrate into the international framework that will be required to
slow and eventually halt global climate change.
About the author
Dr Julie Styles has been a research scientist
in the broad area of climate change for over 15 years, working in
Australia, Germany, Siberia and the US. Her PhD and much of her
research dealt with understanding the role of forests and other
land ecosystems in absorbing carbon dioxide from the atmosphere and
mitigating anthropogenic emissions. Julie’s research appears
in international peer–reviewed journals and she has presented
her work at more than 20 international scientific conferences and
meetings. She has served as a review panel member for NASA, and has
been awarded grants amounting to over $1 million to fund her
research. Julie joined the Parliamentary Library in mid–2008
as a senior researcher and is an author and editor of the
Library’s climate change web publication (http://www.aph.gov.au/Library/pubs/ClimateChange/).
Acknowledgements
The author wishes to thank Professor Will
Steffen (Australian National University), and Les Nielson and Roger
Beckmann (Parliamentary Library) for improvements to this paper
facilitated by their careful reviews of earlier versions. The
author also thanks the more than ten participants in a workshop on
the paper for their comments and suggestions. Helpful assistance
with readability and editorial matters from Paula Pyburne and Ann Rann
(Parliamentary Library) is also gratefully acknowledged.
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