Chapter 2
The potential impacts of global warming
(Part a)
The balance of evidence, from changes in global mean surface air temperature
and from changes in geographical, seasonal and vertical patterns of atmospheric
temperature, suggests a discernible human influence on global climate.
[1]
2.1 This chapter sets out the current state of knowledge about climate
change and predictions of future climate change, including at a regional
level. The chapter includes a discussion of scientific opinion on the
potential for stabilising the global climate system, current areas of
uncertainty in relation to the operations of the global climate system,
and the predictive ability of climate change models. The chapter concludes
with a discussion of the need for further research, particularly in relation
to climate change in Australasia and its potential impact on Australia's
environment, biodiversity and economy.
Introduction
2.2 The reality of human-induced (`anthropogenic') global warming is
now widely accepted in the international community. The Australian Government's
National Greenhouse Strategy (NGS) states that:
The world's climate scientists have provided us with a clear message
- that the balance of evidence suggests a discernible human influence
on global climate. Scientists have further reported that climate is
expected to change in the future as concentrations of greenhouse gases
in the atmosphere increase, and that for many regions the effects are
likely to be adverse. These findings… have been accepted and endorsed
by Australia. [2]
2.3 Greenhouse gases (carbon dioxide CO2, water vapour H2O, methane CH4,
nitrous oxide N2O, and ozone) are naturally present in the atmosphere
and have the effect of trapping solar radiation, bringing the average
temperature of the Earth to about 15ºC. Since the 1950s, scientists
have sought to establish whether human activities are changing the volume
and composition of these gases in the atmosphere. By comparing contemporary
measurements of atmospheric CO2 with the analysis of air recovered from
polar ice cores, it has been possible to establish that concentrations
of the major greenhouse gases are increasing. [3]
2.4 A number of synthetic gases also impact on climate change, including
hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride
(SF6). Some of these gases have been used as substitutes for ozone depleting
substances like CFCs and HCFCs in airconditioners and refrigeration, while
SF6 is used in aluminium, magnesium and semiconductor manufacture. While
the quantities of emissions of these gases are currently comparatively
low their global warming potency is thousands of times more than carbon
dioxide [4] and their use is projected to grow.
[5]
2.5 The IPCC cautions that `stabilisation of the concentrations of very
long-lived gases, such as SF6 or perfluorocarbons, can only be achieved
effectively by stopping emissions'. [6] The
NGS (Measure 7.2) calls for the development of environmental management
strategies for synthetic gases through coordinated action by all jurisdictions
in consultation with industry. It states that, `Governments will work
with industry to develop environmental management strategies for each
of the synthetic gases included in the Kyoto Protocol - HFCs, PFCs and
SF6. The Strategy for HFCs will address the use of HFCs in non-refillable
containers'. [7]
2.6 A 1960s study by the Massachusetts Institute of Technology first
documented concerns about climate change and, in the 1970s, the United
Nations Secretary General made reference to the possibility of a `catastrophic
warming event' in his report on the environment. Scientific research and
international action then began to gather pace with the 1979 World Climate
Conference and the establishment of the Intergovernmental Panel on Climate
Change (IPCC). [8]
2.7 The IPCC is an international group of over 300 independent scientists
and experts that was established to provide the most authoritative assessments
of the state of knowledge of global climate change. It was given a mandate
to assess the state of existing knowledge about the world's climate system
and climate change; the environmental, economic, and social impacts of
climate change; and the possible response strategies.
2.8 The First Assessment Report of the IPCC, published in 1990, laid
the scientific and technical base for the negotiation of the United Nations
Framework Convention on Climate Change (UNFCCC). Later work of the IPCC
seeks to provide `scientific, technical and socio-economic information'
that will help policymakers interpret and respond to the basic objective
of the UNFCCC, as described in Article 2:
... stabilization of greenhouse gas concentrations in the atmosphere
at a level that would prevent dangerous anthropogenic interference with
the climate system. Such a level should be achieved within a timeframe
sufficient to allow ecosystems to adapt naturally to climate change,
to ensure that food production is not threatened and to enable economic
development to proceed in a sustainable manner. [9]
2.9 The IPCC's reports are drafted by leading scientists, and subject
to rigorous and exhaustive peer review. The reports provide `state of
the art reviews of the scientific literature in each of the specialised
fields of climate science relevant to the determination future climate
change'. [10] The draft reports are also reviewed
by UNFCCC member governments, and approved at meetings of the IPCC where
member governments, intergovernmental and non-governmental organisations
are also present. For example, the process of drafting the Second Assessment
Report, approved in December 1995, was as follows:
Following a resolution of the Executive Council of the World Meteorological
Organization (July 1992), the IPCC decided to include an examination
of approaches to Article 2, the Objective of the UN Framework Convention
on Climate Change (UNFCCC), in its work programme. It organized a workshop
on the subject in October 1994 in Fortaleza, Brazil, at the invitation
of the Government of Brazil. Thereafter, the IPCC Chairman assembled
a team of lead authors… under his chairmanship to draft the Synthesis.
The team produced the draft which was submitted for expert and government
review and comment. The final draft Synthesis was approved line by line
by the IPCC at its eleventh session (Rome, 1115 December 1995),
where representatives of 116 governments were present as well as 13
intergovernmental and 25 nongovernmental organizations. It may
be noted for information that all Member States of the World Meteorological
Organization and of the United Nations are Members of the IPCC and can
attend its sessions and those of its Working Groups. [11]
2.10 The IPCC assessment reports remain the most authoritative account
of the state of greenhouse science and of the possible impacts of global
climate change. The 1996 Second Assessment Report states that the IPCC's
task `is to provide a sound scientific basis that would enable policymakers
to better interpret dangerous anthropogenic interference with the climate
system'. The IPCC's reports seek to:
Highlight what we know about the vulnerabilities of ecosystems and
human communities to likely climate changes, especially in regard to
agriculture and food production and to other factors such as water availability,
health and the impact of sea-level rise which are important considerations
for sustainable development. [12]
2.11 During its inquiry, the Committee heard evidence from a number of
climate change scientists and organisations, both international and local.
International witnesses included the Chairman of the IPCC, Dr Robert Watson;
the Hadley Centre for Climate Change Prediction and Research (UK); and
the Potsdam Institute for Climate Impacts Research (Germany).
2.12 Within Australia, the Committee heard scientists from the CSIRO
Division of Atmospheric Research, the Commonwealth Bureau of Meteorology,
Monash University, and the Antarctic Co-operative Research Centre at the
University of Tasmania. The Committee also visited the CSIRO's Atmospheric
Research Division in Melbourne.
The First and Second IPCC Assessment Reports
2.13 The IPCC has released two major assessments of the state of climate
change research, in 1990 and 1995. A third is currently being drafted
and reviewed, and is due to be released in 2001. The Committee was also
able to hear evidence about some of the possible conclusions of the third
assessment. [13]
2.14 The key finding of the First Assessment Report was that atmospheric
levels of greenhouse gases were rising due to human activities and that,
if they were to continue rising unchecked, global average temperature
would rise at around 0.3ºC per decade (3ºC by 2100). This would
represent the fastest sustained global rate of temperature change seen
for the last ten thousand years. Within a century such warming could take
the Earth to temperatures not experienced since the warm period before
the last ice age, over one hundred thousand years ago. [14]
2.15 The Second Assessment Report updated and refined the first assessment
based on the growth of scientific research and evidence since 1990, along
with improvements to climate change models. In particular, the Report
described:
- anthropogenic interference with the climate system, both in terms
of interference to the present day and possible consequences of future
interference;
- sensitivity and adaptation of systems to climate change, including
terrestrial and aquatic ecosystems, hydrology and water resources management,
agriculture and forestry, human infrastructure, human health, and technology
and policy options for adaptation;
- an analytical approach to the stabilization of atmospheric concentration
of greenhouse gases;
- technology and policy options for mitigation;
- equity and social considerations; and
- sustainable paths of economic development, including the social, adaptation
and mitigation costs of climate change. [15]
Human-induced climate change to the present day
2.16 The Second Assessment Report stated that atmospheric concentrations
of greenhouse gases have grown significantly since preindustrial
times: carbon dioxide (CO2) from about 280 to almost 360 parts per million
by volume (ppmv3); methane (CH4) from 700 to 1720 parts per billion by
volume (ppbv); and nitrous oxide (N2O) from about 275 to about 310 ppbv.
[16]
2.17 The Report also stated that global mean surface temperature has
risen by between 0.3ºC and 0.6ºC since the late 19th century,
and that global sea levels have risen by between 10 and 25 cm over the
past 100 years. Much of this rise, it said, `may be related to the global
mean temperature'. These temperature and sea level changes, the Report
concluded:
… [are ]unlikely to be entirely natural in origin. The balance
of evidence, from changes in global mean surface air temperature and
from changes in geographical, seasonal and vertical patterns of atmospheric
temperature, suggests a discernible human influence on global climate.
There are uncertainties in key factors, including the magnitude and
patterns of long term natural variability. [17]
2.18 The rise in atmospheric concentrations of greenhouse gases, said
the Report, `can be attributed largely to human activities, mostly fossil
fuel use, land use change and agriculture. Concentrations of other anthropogenic
greenhouse gases have also increased. An increase of greenhouse gas concentrations
leads on average to an additional warming of the atmosphere and the Earth's
surface. Many greenhouse gases remain in the atmosphere - and affect climate
- for a long time'. [18]
2.19 The Report also acknowledged that while there were high levels of
certainty about global trends, it was more difficult to assess patterns
of variability or changes at regional scales:
There are inadequate data to determine whether consistent global changes
in climate variability or weather extremes have occurred over the 20th
century. On regional scales there is clear evidence of changes in some
extremes and climate variability indicators. Some of these changes have
been toward greater variability, some have been toward lower variability.
However, to date it has not been possible to firmly establish a clear
connection between these regional changes and human activities. [19]
2.20 The CSIRO also outlined a range of significant observed changes
in climate over the past century. These included:
- the Atlantic, the Pacific and the Indian ocean basins now show warming
over the past 20 years;
- the upper atmosphere (lower stratosphere) is showing a cooling trend,
consistent with a `greenhouse' signal;
- a widespread retreat of glaciers in the tropics and mid-latitude regions;
- a record published in 1998 of the recent temperature record in the
context of the past 1000 years, shows that 20th century warming counters
a millennial-scale cooling trend due to gradual changes in the Earth's
orbit;
- precipitation (measured over land) has increased about 1 per cent
since the beginning of the 20th century, which is considered statistically
significant;
- consistent with the increase in precipitation is an increase in cloud
cover and a decrease in the difference between day and night temperatures;
- heavy extreme precipitation has generally increased in areas where
average precipitation has risen;
- the pressure at high altitude observations is increasing consistent
with surface warming; and
- the temperature profiles down bore-holes in the earth's crust indicate
recent global warming. [20]
Possible consequences of future interference
2.21 The IPCC's Second Assessment Report refined previous models and
developed six global warming scenarios (IS92a-f), with projections based
on an assumption of little or no abatement action. The models differ according
to a graded range of assumptions about population and economic growth,
land-use, technological change, energy availability and fuel use. They
predict emissions increases between 1990 and 2100. The scenarios predict
that by 2100 CO2 emissions would range from approximately six billion
tonnes (similar to present levels) assuming low population and economic
growth, to as much as 36 billion tonnes. [21]
2.22 A summary of the assumptions used by the IPCC in developing these
models is listed below:
Table 2.1
The 1992 IPCC Scenarios - Summary of Assumptions [22]
| Scenario |
Population |
Economic Growth |
Energy Supplies |
| IS92a,b |
World Bank 1991
11.3 billion by 2100
|
1990-2025: 2.9% 1990-2100: 2.3% |
12,000 EJ conventional oil 13,000 EJ natural gas Solar
costs fall to $0.075/kWh 191 EJ of biofuels available at $70/barrel |
| IS92c |
UN MediumLow Case 6.4 billion by 2100 |
1990-2025: 2.0% 1990-2100: 1.2% |
8,000 EJ conventional oil Nuclear costs decline by 0.4%
annually |
| IS92d |
UN MediumLow Case 6.4 billion by 2100 |
1990-2025: 2.7% 1990-2100: 2.0% |
Oil and gas same as IS92c Solar costs fall to $0.065/kWh
272 EJ of biofuels available at $50/barrel |
| IS92e |
World Bank 1991
11.3 billion by 2100
|
1990-2025: 3.5% 1990-2100: 3.0% |
18,400 EJ conventional oil Gas same as IS92a,b Phase
out nuclear by 2075 |
| IS92f |
UN MediumHigh Case 17.6 billion by 2100 |
1990-2025: 2.9% 1990-2100: 2.3% |
Oil and gas same as IS92e Solar costs fall to $0.083/kWh
Nuclear costs increase to $0.09/kWh |
2.23 Low range emissions scenarios (IS92c) combined with low values for
climate sensitivity predict a temperature increase of 1ºC by 2100,
the mid-range scenario (IS92a) predicts 2ºC and the highest range
(IS92e) scenarios 3.5ºC. The IPCC stated that in all cases the rate
of warming would be greater than the last ten thousand years, and that
only 50 to 90 per cent of the total temperature change would have been
realised by 2100 owing to the thermal inertia of the oceans. Temperatures
would continue to increase beyond that time, even if the level of greenhouse
gases had been stabilised. [23]
2.24 The same models also predict possible sea-level rises due to thermal
expansion of the oceans and the melting of glaciers and ice-sheets. The
mid-range IS92a scenario predicts a rise of 50 cm by 2100, whilst the
highest emissions scenario projects a rise of 95 cm. Again, these rises
would continue beyond 2100 even if emissions were stabilised. The IPCC
states that models built on the scale of hemispheres or continents produce
more certainty, while regional level changes are less easy to model, and
that there is greater confidence in temperature projections than hydrological
changes. [24]
2.25 In summary, the IPCC explained that:
All model simulations… show the following features: greater surface
warming of the land than the sea in winter; a maximum surface warming
in high northern latitudes in winter; little surface warming over the
Arctic in summer; an enhanced global mean hydrological cycle; and increased
precipitation and soil moisture in high latitudes in winter… .
Warmer temperatures will lead to a more vigorous hydrological cycle;
this translates into prospects for more severe droughts and/or floods
in some places and less severe droughts and or floods in other places.
Several models indicate an increase in precipitation intensity, suggesting
a possibility for more extreme rainfall events. Knowledge is currently
insufficient to say whether there will be any changes in the occurrence
or geographical distribution of severe storms such as tropical cyclones.
[25]
2.26 The Second Assessment Report also sought to predict the impacts
of these trends on ecosystems and human communities. Reviewing the available
scientific studies, the IPCC suggested that global warming could have
the following natural effects:
- a reduction in biodiversity;
- altered growing seasons and boundary changes between grasslands, shrublands
and forests;
- major changes in the vegetation types of one third of the world's
forests, with the greatest changes at high latitudes and the least in
the tropics. Entire forest types could disappear while new ecosystems
are established. During such periods of high forest mortality large
amounts of CO2 could be released into the atmosphere;
- higher temperatures in deserts, threatening sensitive organisms, and
increased desertification in arid and semi-arid areas;
- the extinction of some high altitude species due to loss of habitat;
- a geographical redistribution of wetlands, and increased risks to
sensitive coastal ecosystems such as saltwater marshes, mangroves, beaches,
coral reefs and river deltas; and
- the extinction of aquatic species at the low-latitude boundaries of
cold and cool water species ranges. [26]
2.27 Possible effects on human communities and productivity include radical
and hard-to-predict changes to crop yields and productivity, which could
vary markedly across localities. While the IPCC thought that mean global
production levels could be maintained in the face of climate change, the
potential effect of increased pests or possible climate variabilities
has not been factored into existing studies. There were serious concerns
about the regional level impacts of climate change on food production
and nutrition. [27]
2.28 The IPCC clearly stated that there was increased risk of hunger
and famine in some locations. The world's poorest people, especially those
living in tropical and sub-tropical areas or dependent on isolated agricultural
systems in arid and semi-arid regions, were most at risk. The IPCC also
said that warming would exacerbate other trends in reducing the availability
of global wood supplies. [28]
2.29 Other projections indicate very serious potential impacts in the
form of flooding, storms and land losses. Coastal populations are most
at risk. With a 50 cm rise in sea-level, the numbers of people currently
at risk from flooding as a result of storm surges would increase from
46 million per year to 92 million. A 100 cm rise would increase the vulnerable
to 118 million, and while this is at the extreme end of IPCC estimates,
they point out that sea-level rise will continue beyond 2100. They state
that studies using the one metre projection indicate serious risks for
small islands and deltas, which is of particular concern to some Pacific
island nations. [29]
2.30 The IPCC estimates that land losses from sea-level rise would range
from 0.05 per cent in Uruguay, one per cent for Egypt, six per cent for
the Netherlands, 17.5 per cent in Bangladesh to 80 per cent in Majura
Atoll in the Marshall islands. The IPCC stated that countries with higher
population densities would be more vulnerable and that, in some cases,
flooding `could threaten entire cultures'. In such cases, `sea-level rise
could force internal or international migration of populations'. [30]
2.31 The assessment also stated that `climate change is likely to have
wide-ranging and mostly adverse effects on human health, with significant
loss of life'. These include:
- increases in mortality and illness from the higher intensity and duration
of heatwaves, with cardio-respiratory illness the most likely danger;
- fewer cold-related deaths due to temperature rises in cold regions;
- indirect effects such as potential for increased incidence of vector-borne
disease (malaria, dengue, yellow fever and viral encephalitis), because
of the extended geographical and temperature range for vector organisms
such as mosquitos;
- some increases in non-vector borne diseases like cholera, giardia
and salmonella through higher temperatures and flooding; and
- a potential reduction in fresh water supplies and nutritious food,
and increased air pollution. [31]
More Recent Scientific Findings
2.32 In the course of its inquiry, the Committee heard from a number
of leading international and Australian scientists and scientific organisations
on the latest global warming trends and impacts. A number of these witnesses
are lead authors for the IPCC Third Assessment Report to be completed
in 2001. The Committee was told that most research since the IPCC Second
Assessment Report strengthens the conclusion that the balance of evidence
suggests a discernible human influence on climate. Climate scientists
believe that attempts to quantify the anthropogenic influence indicate
that it may account for a substantial fraction of the observed global
temperature change over the 20th century.
2.33 In recent years, estimation of anthropogenic signals has been improved
through the use of newer climate models, ensemble simulations and the
inclusion of additional anthropogenic and natural factors. Statistical
techniques have been extended, in particular applying optimal detection
methods and estimating both natural and anthropogenic signals based on
spatial and temporal information. The robustness of results to the use
of different assumptions and different model data has been improved. [32]
2.34 Most studies indicate that some human influence is needed to explain
20th century temperature changes. Regression techniques in a number of
studies suggest that model estimates of anthropogenic temperature changes
are broadly consistent with observed changes. [33]
2.35 The Director of the Australian Bureau of Meteorology, Professor
John Zillman, told the Committee that the forthcoming Third Assessment
Report of the IPCC `strengthens the conclusion that `the balance of evidence
suggests a discernible human influence on global climate'. He listed a
number of key messages coming out of the drafting process for the Report:
The first is that the evidence for sustained global warming over the
past century, but particularly since 1945, is stronger than at the time
of the finalisation of the Second Assessment Report of the IPCC in 1995.
Most of the earlier discrepancies that have been debated between satellite
measurements and surface measurements of temperature in the atmosphere
appear to have been resolved. Also… new reconstructions of the
temperature trends over the Northern Hemisphere for the past 1,000 years
suggests that the recent warmth - that is in the last two decades -
is unprecedented over this time frame.
The second key message is that both the present atmospheric concentration
of carbon dioxide and its rate of increase during the past 420,000 years
are unprecedented and that the present concentration has probably not
been exceeded during the past 15 million years.
The third message is that most research since the Second Assessment
Report of the IPCC in 1995 strengthens the conclusion that… the
balance of evidence suggests a discernible human influence on global
climate… . Furthermore, it now appears that, on the basis of more
rigorous and comprehensive statistical techniques, human activity may
account for a substantial fraction of the observed global temperature
increase during the 20th century. [34]
2.36 Professor Zillman also cautioned that these strengthening conclusions
were tempered by other uncertainties:
The reliability of these conclusions, however, continues to be limited
by uncertainties in the observation record and in the estimates of the
internal natural variability of the climate system of the radiative
forcing - that is the effects of the greenhouse gases - and of general
climate system response to external influences such as volcanoes and
fluctuations in the energy coming from the sun and so on. [35]
2.37 In evidence to the Committee, Dr Geoff Jenkins of the United Kingdom's
Hadley Centre for Climate Prediction and Research, explained the recent
findings of the Centre's latest climate change model, HADCM3. He argued
that this model has achieved a better representation of climate and climate
change than previous models through a better resolution of the ocean and
the coupling of ocean, atmospheric and land surface measurements, and
has largely confirmed the IPCC's Second Assessment Report climate predictions:
We believe that the prediction in the future is pretty much as we would
have expected, based on past climate change over the past 150 years.
So the predictions in the future are maybe slightly too high, but not
very much too high, and the uncertainty range of 5 per cent to 95 per
cent… is not one million miles away from the IPCC figures of 1.5
to 4.5. So we do believe we have shown… that both the central prediction
and range of predictions are pretty much as IPCC would have it. [36]
2.38 The Committee also heard evidence from the Chairman of the IPCC,
Dr Robert Watson. Although the IPCC has not yet publicly released the
results from its Third Assessment Report, which is currently under peer
review, Dr Watson advised the Committee in general terms that the most
recent modelling largely reinforces its previous findings and those of
other modelling agencies such as the Hadley Centre:
In the Second Assessment Report we came up with a range of plausible
[increases] in global mean surface temperature of one to 3.5ºC.
If you use these more recent emission scenarios, which have yet to be
approved, we are probably going to see a slightly larger range. If you
take both the range of the socioeconomic conditions with the range of
climate sensitivity, I would imagine we are going to see a range of
something like 1ºC to 5ºC. [37]
2.39 Dr Robert Watson then outlined to the Committee the main consequences
of increasing global temperatures over the next 100 years for issues such
as water resources, agriculture, coral reefs, forests, human health and
human settlements. Many of his statements in relation to these issues
mirrored those listed earlier in this chapter, from the IPCC's Second
Assessment Report. In summary, he told the Committee that:
- water resources will be significantly affected. Arid and semi arid
areas of the world, especially in the northern parts of Africa, the
southern parts of Africa, areas in Latin America, the Middle East and
the southern Mediterranean will become considerably drier. These areas,
which suffer from drought today, will also be more adversely affected
by drought in the future;
- water stressed or water scarce areas, which currently occupy less
than 10 per cent of the world today, will probably increase to 50 per
cent by 2050;
- globally, agriculture may not be significantly affected due to the
effects of carbon dioxide fertilisation in some parts of the world.
However, regionally there could be significant changes in agricultural
productivity with significant decreases in Africa, the Middle East and
Latin America, areas where water resources will become more scarce;
- a sustained increase in temperature of 2ºC to 4ºC could
lead to a significant adverse effect on coral reefs around the world;
- one-third of all forest tree species will no longer be viable in a
world with double pre-industrial CO2 levels;
- there will be increases in vector-borne diseases, especially malaria
and dengue fever. Water borne diseases such as cholera will also become
more prevalent, as too will heat stress mortality; and
- tens of millions of people could be displaced, especially from small
island states and deltaic systems in Egypt, Bangladesh and China. [38]
2.40 In particular, Dr Watson stressed that developing countries would
be particularly vulnerable to climate change:
Overall, if one were to try and summarise the impact of likely climate
change, one would say that developing countries are much more vulnerable
than developed countries, largely because they do not have the technical,
economic and institutional capacity to deal with climate change and
to adapt to climate change. The poor in these countries are the most
vulnerable. [39]
2.41 Both Dr Jenkins and Dr Watson told the Committee that considerable
evidence now exists which supports the contention that human activities
are in part responsible for increases in global temperatures over the
latter half of the 20th century:
It is quite clear that human activities are increasing the atmospheric
burden of greenhouse gases, in particular carbon dioxide, primarily
from the combustion of fossil fuels, coal, oil, and gas and through
land use change - [and] primarily at the moment [through] deforestation
in the tropics. [41]
2.42 These conclusions are also shared by Australian climate scientist
Professor David Karoly, Convening Lead Author of the IPCC Third Assessment
Report chapter `Detection of climate change and attribution causes'. Professor
Karoly told the Committee:
In the Second Assessment Report there was a conclusion that was reached
that stated that the balance of evidence suggested discernible human
influence on global climate. The evidence collected since that time…
strengthens the evidence that there has been a discernible human influence
on climate. The attempts to try to quantify that human influence on
climate suggest that a substantial fraction of the global temperature
change over the last century is most likely attributable or due to human
activity. We cannot say exactly how much, but [it is] a substantial
fraction. [42]
2.43 Recently, the robustness of climate change models, such as the Hadley
Centre's HADCM3, have been improved by incorporating important climate
change feedback mechanisms such as the sulphur cycle - the oxidation of
sulphur dioxide into aerosol particles and the subsequent cooling effect
on the atmosphere, and the carbon cycle - the effects of climate change
on the natural carbon cycle.
2.44 In the case of the latter, Dr Jenkins told the Committee that a
`reasonably high positive feedback' will result from the carbon cycle
which will accentuate global warming over the course of the 21st century.
As temperatures rise the amount of carbon stored in soils increases, which
in turn creates more emissions as soil temperatures increase and release
carbon back into the atmosphere. [43]
2.45 In his evidence to the Committee, Professor Karoly also discussed
the effects of feedbacks on climate system. He warned the Committee that
carbon cycle feedbacks actually cause accelerated emissions of carbon
because of the loss of plants in forests and other factors, making it
even harder to achieve stabilisation of emissions. He went on to explain
that:
If those feedbacks are taken into account, we are in an even worse
situation if the climate warms. If there are changes in the natural
carbon cycle which produce natural reductions in carbon uptake, we are
even worse [off] than that, and we have to come down to even lower human
emissions. I think that we have to think of an analogy. We have a tap,
which are the carbon emissions that are still running. Unless we effectively
turn that tap off, the bucket, which is the atmospheric carbon concentrations,
will keep on increasing. So unless that tap is really turned off to
just a trickle, the bucket is going to keep on going up and up and up.
To stabilise carbon dioxide concentrations requires very substantial
reductions in how much that tap is turned on. [44]
2.46 The Hadley Centre's climate change modelling supports the mid-range
sea-level rise predictions made by the IPCC's 1996 assessment: half a
metre over the next 100 years. In addition, Dr Jenkins confirmed the IPCC's
earlier conclusion that sea-level rise would continue beyond 2100, even
if emissions were stabilised. In a recent Hadley Centre climate change
model experiment, the effects of global warming on sea-level rise were
simulated over a 70 year period. Greenhouse gases were allowed to increase
at the rate of 1 per cent per year. After 70 years these gases were then
stabilised at about double pre-industrial concentrations (about 550 ppmv)
and the model was allowed to run for a further 800 years:
We found that due to this penetration of the warming that starts at
the top and penetrates deeper and deeper into the ocean, that the expansion
of the ocean carries on for the whole of this period for many hundreds
of years afterwards, and the melting of land ice carries on for maybe
two or three centuries until basically all the land ice has gone. So
the actual sea level rise over that few hundred year period carries
on and on almost as if the climate change stabilisation after 70 years
had not occurred at all. So you end up with sea level rises of maybe
10 times the original sea level rise even though climate change has
been stabilised. We think that points to a very long commitment over
a very long period with sea level rise that has to be borne in mind.
[45]
2.47 The Committee received similar evidence on the effects of climate
change on sea-level rise over the next few centuries from Dr Watson of
the IPCC:
… even if we stabilise atmospheric concentrations of greenhouse
gases which then maybe 50 years later we would stabilise the earth's
climate, sea-level would continue to rise for many, many centuries…
.[Sea-level rise] would be somewhere between one-half and one-and-a-half
metres over the next 200 or 300 years… . [46]
2.48 Dr Jenkins went on to inform the Committee that the implications
of sea-level rise for small island nations and other states could be very
significant, even if the increase is relatively small:
Some island states and other countries such as India and Bangladesh,
where even a relatively small rise in sea level combined with storm
surges that you get when depressions, storms and cyclones go through,
can produce quite a big change in the frequency of currents, given the
high water levels. Because of the frequency of occurrence of high water
and the high water itself - it is a logarithmic one - you do not have
to change sea level much to get quite a large increase in the frequency
of the occurrence of storm surges in some areas. [47]
Regional Climate Change: Australasia
2.49 According to Australian climate scientist Dr Barrie Pittock, Australia
is the most vulnerable OECD country to the impacts of climate change because
of its low latitudes and naturally occurring high temperatures which are
already above optimum levels. In addition, Australia is relatively arid,
particularly in the more populated parts of southern Australia and although
the tropical north in the monsoon season has a surplus of water, the rest
of Australia, with the exception of Tasmania, often suffers from drought:
The suggestion is that the sort of stresses we have now will get much
worse as a result of climate change. That has to be weighed in to our
policy thinking. It is not an altruistic thing that we are talking about.
It is something which is in our own interests. [48]
2.50 Dr Pittock's conclusions were echoed in evidence to the Committee
by German climate scientist and coordinating lead officer for the IPCC's
synthesis chapter on global vulnerability for the Third Assessment Report,
Professor Dr Hans-Joachim Schellnhuber. Professor Schellnhuber told the
Committee that Australia may be among the most vulnerable regions due
to the isolated evolution of its ecosystems, to aridity and in part due
to its immense coastline. The natural consequence of this was that:
… it seems reasonable [for Australia] to support emissions reductions…
but also to prepare for adapting to the unavoidable climatic change.
Adaptation policy and risk management seem to be a major challenge for
your country. [49]
Earlier regional impact studies
2.51 In 1997 the IPCC reported on its collation of regional level projections
for Australasia and other regions of the world. In addition, the potential
impacts on our region have been the focus of research efforts by the CSIRO.
2.52 In presenting their estimates, as part of an assessment of the potential
impacts of global warming on a number of discrete global regions, the
IPCC qualified their analysis by saying that regional level predictions
were: `necessarily qualitative… because the available studies have
not employed a common set of climate scenarios and methods, and because
of uncertainties regarding the sensitivities and adaptability of natural
and social systems'. [50]
2.53 The IPCC said that `some of the [Australasian] region's ecosystems
appear to be very vulnerable to climate change, at least in the long term,
because alterations to soils, plants and ecosystems are very likely, and
there may be increases in fire occurrence and insect outbreaks'. Possible
impacts of climate change on the region include:
- a `highly likely' reduction of species diversity, despite some adaptation
potential;
- the exacerbation of existing problems of land degradation, weed and
pest infestation;
- changes to river flows, flood frequencies and nutrient and sediment
outputs particularly in drier areas;
- increased bleaching and death of coral due to higher sea temperatures;
- damage to coastal ecosystems and communities, especially indigenous
communities, through sea-level rise, flooding and weather changes;
- vulnerability to falls in the availability of water, especially in
drought prone areas;
- more frequent rainfall events which, while filling dams and replenishing
groundwater, could worsen flooding, landslides and erosion;
- reduced snowpack, a shorter ski season, and further shrinkage of New
Zealand's glaciers;
- a long term trend to increased agricultural vulnerability as initial
growth gains are eroded by rainfall and soil changes, especially with
irrigated crops and range pastoralism, and economic effects through
changed prices of agricultural imports;
- longer maturity times for forests, increasing the financial risks
involved in plantations; and
- other climate-related impacts on air quality, drainage, waste disposal,
mining, insurance and tourism, which will interact with other human
and economic factors. [51]
2.54 The IPCC's predictions about the impact of global warming on coral
reefs were supported by analysis published in 1998 by Professor Ove Hoegh-Guldberg
of the Coral Reef Research Institute at the University of Sydney. It stated
that coral reefs were close to their upper thermal limits, due to an increase
of 1ºC in sea temperatures since 1900, and that 1998 saw some of
the worst bleaching and coral death yet recorded in many reefs around
the world. The report built four simulations from global climate models
which predict that `the thermal tolerances of reef-building corals are
likely to be exceeded within the next few decades'. Bleaching events like
those in 1998 could become commonplace within 20 years and are likely
to occur annually within 50 years. The southern and central parts of the
Great Barrier Reef could be vulnerable to increased bleaching within the
next 20 to 40 years, and northern parts of the reef in 60 years. [52]
2.55 In evidence to the Committee, Professor Hoegh-Guldberg and Dr Peter
Doherty from the Australian Institute of Marine Science (AIMS), said that
1998 saw the warmest sea temperatures on record, both globally and in
Australian waters. Professor Hoegh-Guldberg said that there had been six
mass bleaching events since 1979, events which were largely unknown before
that year and were caused by `higher than normal temperature signals in
the ocean'. During 1998, coral reefs in the Maldives, Okinawa and Palau
were wiped out by bleaching. Areas of the Great Barrier Reef were also
affected and, while some managed to recover within 18 months, two reefs
north of Townsville sustained irreversible damage. Dr Doherty said that
they `were subjected to some of the hottest water for the longest periods,
had the most complete bleaching, and there was substantial death of the
coral subsequently'. [53]
2.56 Dr Hoegh-Guldberg emphasised the economic and environmental importance
of the reefs, both for stabilising coastal ecosystems and tourism:
… there is a possibility that the expected increase in mass bleaching
and mortality may lead to the collapse of coral dominated ecosystems.
If that happens you have to look at what coral reefs are to people in
the world. One hundred million depend directly on coral reefs. In Australia,
there are key fisheries - we have million-dollar industries; we have
got billion-dollar tourism; and, of course, if we look at the state
of Queensland, entire coastlines are stabilised by coral reefs. [54]
2.57 In November 1996 the CSIRO published a summary of its own research
on the regional impact of global warming. In doing so, it used the assumptions
underpinning the IPCC's 1996 Assessment Report and combined them with
regional climate change models. Regional scenarios were then matched with
the IPCC's range of possible changes (IS92a-f). The changes they discussed
included:
- regional temperature increases;
- changes in precipitation;
- tropical cyclones; and
- soil moisture and runoff. [55]
2.58 Regional sea-level changes are the subject of continuing research,
and no special estimates were included in the 1996 paper. Temperature
changes were plotted for three broad regions (the coast north of 25ºS,
the coast south of 25ºS, and inland), and for high to low change
scenarios. [56]
2.59 Inland temperatures were predicted to rise from between 0.4ºC
and 1.4ºC by 2030, and from 0.7ºC to 3.8ºC by 2070. On
the northern coast, increases range from 0.3ºC to 1ºC by 2030
and 0.6ºC to 2.7ºC by 2070. On the southern coasts, increases
range from 0.3ºC to 1.3ºC by 2030 and 0.6ºC to 3.4ºC
by 2070. These figures can be compared with the IPCC's global mean estimates
of between 1ºC to 3.5ºC temperature increase by 2100. [57]
2.60 Precipitation changes were modelled using both `coupled' (atmosphere
plus ocean circulation temperature) and `slab' (atmosphere plus surface
ocean temperature only) models. It is believed that fully coupled models
produce more reliable results, but results from slab models have also
been developed because of uncertainties about coupled models and because,
in the Australian region, the two models sometimes produce very different
results. [58] Future rainfall patterns could
also be affected by difficult-to-model local changes in ocean circulation,
in large-scale atmospheric circulation (due to high sulphate aerosols
in Asia) and changes in El Nino-Southern Oscillation (ENSO) behaviour.
Rainfall changes were projected for winter across three broad regions
and, in summer, for two broad regions. [59]
Figure 2.1
CSIRO Scenarios of precipitation change for the Australian region
based on `coupled' models
Figures not available in Htm Version
Winter Summer
| Winter |
| Location |
Response per degree of global warming |
Change in 2030 |
Change in 2070 |
| Region A |
-10 to 0% |
-8 to 0% |
-20 to 0% |
| Region B |
-5 to +5% |
-4 to +4% |
-10 to +10% |
| Region C |
0 to +10% |
0 to +8% |
0 to +20% |
| Summer |
| Location |
Response per degree of global warming |
Change in 2030 |
Change in 2070 |
| Region A |
-10 to 0% |
-8 to 0% |
-20 to 0% |
| Region B |
-5 to +5% |
-4 to +4% |
-10 to +10% |
2.61 In both models, areas that had very low rainfall in winter, in the
north and centre of Australia, would remain dry. Coupled models predicted
the following changes:
- In winter, the area comprising most of the south and east,
but not the Queensland coast, would see falls of between zero and 8
per cent by 2030 and zero and 20 per cent by 2070. The Queensland coast,
parts of Tasmania and seas to the south of Australia would see a range
from a fall of 4 per cent to an 8 per cent increase by 2030, and a fall
of 10 per cent to an increase of 10 per cent by 2070. Northeast Tasmania
and the Southern Ocean would see increases of between zero and 8 per
cent by 2030 and zero and 20 per cent by 2070.
- In summer, south, central and northern Australia (excluding
the southwest of Western Australia and including Tasmania) would see
falls of between zero and 8 per cent by 2030 and of zero to 20 per cent
by 2070. In the eastern states south of Cairns, there would be a range
of –4 to +4 per cent by 2030 and –10 to +10 per cent by 2070.
[60]
2.62 Using slab models, the predicted changes were:
- In winter, in the band from Shark Bay in Western Australia
around to Cairns and the Victorian coast, falls of between zero and
4 per cent by 2030, and of between zero and 10 per cent by 2070. Southwest
Western Australia, the northern part of the Southern Ocean and southern
Victoria could experience a changes of –2 to +2 per cent by 2030
and –5 to +5 per cent by 2070. In the Southern Ocean and Tasmania
there could be increases of between zero and 4 per cent by 2030 and
zero and 10 per cent by 2070.
- In summer, the western half of the continent would see increases
from 2 to 12 per cent by 2030 and from 4 to 30 per cent by 2070. The
eastern half would see increases of between zero and 8 per cent by 2030
and zero to 20 per cent by 2070. [61]
Figure 2.2
CSIRO Scenarios for precipitation change for the Australian region
based on `slab' models
Figures not available in Htm Version
Winter Summer
| Winter |
| Location |
Response per degree of global warming |
Change in 2030 |
Change in 2070 |
| Region A |
-5 to 0% |
-4 to 0% |
-10 to 0% |
| Region B |
-2.5 to +2.5% |
-2 to +2% |
-5 to +5% |
| Region C |
0 to +5% |
0 to +4% |
0 to +10% |
| Summer |
| Location |
Response per degree of global warming |
Change in 2030 |
Change in 2070 |
| Region A |
+5 to 15% |
+2 to +12% |
+4 to +30% |
| Region B |
0 to +10% |
0 to +8% |
0 to +20% |
2.63 The CSIRO also commented that where models simulated an increase
in average rainfall, this would be accompanied by an increase in intensity,
leading to heavier and more frequent rain. Where falls in rainfall were
simulated this tendency was less marked or absent. [62]
2.64 Notwithstanding the manifest uncertainties regarding exact predictions
between models and in some regions, in general the models predict large
changes in rainfall in a relatively short period. The CSIRO also states
that `significantly larger or smaller changes would apply at the local
scale, particularly in locations where topography still controls weather
patterns'. [63] Should precipitation changes
approach the extreme end of these predictions, substantial changes to
Australian climate, agriculture, flooding patterns, vegetation and biodiversity
could be expected.
2.65 The CSIRO stated that tropical cyclones were difficult to model
and continued to be a research priority. Present indications were that
their region of origin would be unchanged, that there may be some increase
in intensity, that their paths may change and that their location and
frequency were also affected by ENSO patterns. [64]
2.66 Soil moisture and runoff are particularly important for agriculture
and biodiversity. They are sensitive to changes in temperature (increasing
evaporation) and changes in rainfall. The CSIRO stated that uncertainties
remain about quantifying the exact hydrological response for a given climate
change scenario. [65]
Footnotes
[1] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 2.4.
[2] Australian Greenhouse Office, The National
Greenhouse Strategy: Strategic Framework for Advancing Australia's Greenhouse
Response, 1998, p 1.
[3] Dr Chris Mitchell, `Greenhouse and the Science
of uncertainty', ABC Online, http://www.abc.net.au/ science/earth/climate/uncertain.htm,
1997.
[4] The Global Warming Potentials (GWPs) are:
HFC-23 11,700, HFC-134a 1,300, Perfluoromethane 6,500, Perfluoroethane
9,200, Perfluoropropane 7,000 and Sulphur Hexaflouride SF6 23,900. Australian
Greenhouse Office, Synthetic Gas Use in Non-Montreal Protocol Industries,
April 2000, p 3.
[5] IPCC Working Group 1, Summary for Policymakers:
The Science of Climate Change, http://www.ipcc.ch/pub/sarsum1.htm
(01/09/00).
[6] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 4.15.
[7] Australian Greenhouse Office, The National
Greenhouse Strategy: Strategic Framework for Advancing Australia's Greenhouse
Response, 1998, p 85.
[8] Michael Grubb, The Kyoto Protocol: A
Guide and Assessment, The Royal Institute of International Affairs,
London, 1999, pp 3-4.
[9] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 1.4.
[10] Commonwealth Bureau of Meteorology, Submission
207, p 2492.
[11] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 1.1.
[12] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 1.6.
[13] Commonwealth Bureau of Meteorology, Submission
207, p 2492.
[14] Michael Grubb, The Kyoto Protocol:
A Guide and Assessment, The Royal Institute of International Affairs,
London, 1999, p 6.
[15] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change.
[16] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 2.2.
[17] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 2.4.
[18] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 2.2.
[19] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 2.5.
[20] CSIRO, Submission 206, p 2463.
[21] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 2.6.
[22] Source: IPCC Working Group 11, Summary
for Policymakers: Scientific Technical Analyses of Impacts, Adaptations
and Mitigation of Climate Change, section 1.
[23] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 2.7.
[24] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 2.8.
[25] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clauses 2.10-2.12.
[26] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clauses 3.6-3.10.
[27] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 3.13.
[28] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 3.13.
[29] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 3.14.
[30] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clause 3.14.
[31] Intergovernmental Panel on Climate Change,
IPCC Second Assessment Synthesis of Scientific-Technical Information
Relevant to Interpreting Article 2 of the UN Framework Convention on Climate
Change, clauses 3.14-3.16.
[32] Professor David Karoly, Submission 204,
p 2.
[33] Professor David Karoly, Submission 204,
p 2.
[34] Proof Committee Hansard, Melbourne,
20 March 2000, p 129.
[35] Proof Committee Hansard, Melbourne,
20 March 2000, p 129.
[36] Official Committee Hansard, Canberra,
9 March 2000, p 22.
[37] Official Committee Hansard, Canberra,
9 March 2000, p 35.
[38] Official Committee Hansard, Canberra,
9 March 2000, p 35.
[39] Official Committee Hansard, Canberra,
9 March 2000, p 35.
[40] Official Committee Hansard, Canberra,
9 March 2000, p 22.
[41] Official Committee Hansard, Canberra,
9 March 2000, p 34.
[42] Official Committee Hansard, Canberra,
9 March 2000, p 40.
[43] Official Committee Hansard, Canberra,
9 March 2000, p 23.
[44] Official Committee Hansard, Canberra,
9 March 2000, p 43.
[45] Official Committee Hansard, Canberra,
9 March 2000, p 24.
[46] Official Committee Hansard, Canberra,
9 March 2000, p 38.
[47] Official Committee Hansard, Canberra,
9 March 2000, p 26.
[48] Dr Barrie Pittock, Proof Committee
Hansard, Canberra, 22 June 2000, p 736.
[49] Professor Dr Hans-Joachim Schellnhuber,
Proof Committee Hansard, Canberra, 22 June 2000, p 733.
[50] Robert Watson, Marufu Zinyowera, Richard
Moss, David Dokken ed. The Regional Impacts of Climate change: An Assessment
of Vulnerability, Summary for Policymakers, Intergovernmental Panel
on Climate Change, 1997, p 2.
[51] Robert Watson, Marufu Zinyowera, Richard
Moss, David Dokken ed., The Regional Impacts of Climate change: An
Assessment of Vulnerability, Summary for Policymakers, Intergovernmental
Panel on Climate Change, 1997, pp 9-10.
[52] Professor Ove Hoegh-Guldberg, Climate
Change, Coral Bleaching and the Future of the World's Coral Reefs,
Coral Reef Research Institute, Sydney, 1998.
[53] Proof Committee Hansard, Brisbane,
26 May 2000, pp 642-29.
[54] Proof Committee Hansard, Brisbane,
26 May 2000, p 643.
[55] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996.
[56] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, p 2.
[57] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, p 3.
[58] The CSIRO states that, over Australia,
coupled models tend to produce summer rainfall decreases and slab models
summer rainfall increases. They also show that rainfall changes differ
between the models because the coupled models include a strong delay in
warming in the higher latitudes of the southern hemisphere. However, there
is considerable uncertainty about the ocean processes which lead to this
result. There are also conflicts between coupled model simulations and
observed 20th Century trends in some aspects of warming in the southern
hemisphere, although there are some doubts whether this is greenhouse
related. Climate Impact Group, Climate Change Scenarios for the Australian
Region, CSIRO Division of Atmospheric Research, Melbourne, 1996, p
4.
[59] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, pp 3-4.
[60] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, pp 3-4.
[61] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, pp 3-4.
[62] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, p 5.
[63] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, p 5.
[64] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, p 5.
[65] Climate Impact Group, Climate Change
Scenarios for the Australian Region, CSIRO Division of Atmospheric
Research, Melbourne, 1996, p 6.
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