 |
Responses to Questions
& Objections |
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|
Dr Brett Parris Monash Lecturer, School of International & Political Studies Deakin University |
1. The IPCC is a
political body and its reports are scientifically unreliable
4. We should wait
until there is more evidence before reducing greenhouse gas emissions.
8. It was warmer
during medieval times
9. Climate models are
unreliable
11. Global warming
ended around 1998 anyway – it’s been cooling since then.
12. Our best strategy
is simply to adapt to climate change.
15. CO2 is
not a pollutant – it is completely natural and essential for life.
16. Any warming is
the Sun’s fault.
17. Climate change is
due to the effects of cosmic rays.
20. Antarctica is
cooling, so that proves the global climate isn’t warming
21. Action on climate
change would ruin our economies
Download this file as a pdf here.
Introduction
This
paper grew out of my work at both
For
the
poor and for today’s children who will inherit our legacy, these are
not
abstract debates. They are not opportunities for political point
scoring, or
for fighting left-right culture wars. The science of climate change
matters and
it deserves to be taken seriously.
When
the
British economist John Maynard Keynes was derided for changing his
position on
economic policy he replied: “When the facts change, I change my
position. What
do you do, sir?” Keynes’ response reflects the open-minded attitude of
a
genuine inquirer, a true skeptic, willing to change his mind when new
information emerges, or when the weight of evidence, the balance of
probabilities and the risks and consequences of being wrong become
overwhelming.
Not
everyone approaches the issue of climate change in this open-minded
way. Some
come to the science through the lenses of political ideologies or
economic
interests, maintaining positions dogmatically in the face of
overwhelming
evidence to the contrary, and endlessly recycling views that have been
repeatedly debunked by scientists.
We
have seen this approach before with those who continue to deny the moon
landings, the link between HIV and AIDS and the link between smoking
and
cancer.[1]
Some continue to try to convince
the public and governments that there is a raging debate among
scientists about
the main drivers of climate change. There isn’t. As Nicholas Stern, author
of The Stern Review on
the
climate change for
the British Government[2],
wrote recently:
The argument for inaction, or for weak or
delayed action, would make sense on the basis of reservations about the
science
only if one could assert that we know for certain that the risks are
small. In
the face of the evidence we now have, that is a complacent, ignorant
and
dangerous position to take. It is not healthy skepticism or an openness
of
mind; it is a denial of evidence and reason.[3]
This document discusses some of that evidence and responds to some of the most common objections. It is not intended to be comprehensive and the interested reader is referred to the reference list and the ‘Useful Resources’ section at the end for more comprehensive websites and other materials. Please send any constructive comments or suggestions for improvements to:
Brett [dot] Parris [at] buseco.monash.edu.au
1.
The IPCC is a political body
and its reports are scientifically unreliable
False.
There
are many misconceptions about the Intergovernmental Panel on Climate
Change
(IPCC). Some people appear to believe the IPCC’s reports are concocted
by a
small band of ‘UN scientists’ in collaboration with (presumably)
left-wing
governments intent on deceiving the world. Nothing could be further
from the
truth. The IPCC is a scientific intergovernmental body created in 1988
by the
World Meteorological Organization (
The
IPCC does not conduct its own research or
climate monitoring. Instead it undertakes a comprehensive review and
distillation of many thousands of published peer-reviewed papers and
reports,
representing the work of the overwhelming majority of the world’s
climate
scientists and produces assessment reports publishing these findings. A good summary of the
nature of the IPCC’s
work was given by Rik Leemans: “a scientific assessment applies the judgment of experts to existing
knowledge to provide
scientifically credible answers to policy-relevant questions.”[5]
The
three working groups of the Fourth Assessment
Report, published in
2007, produced reports on The Physical
Science Basis, Impacts, Adaptation
and Vulnerability and Mitigation of
Climate Change, as well as a Synthesis
Report. Drafts of the chapters attracted more than 30,000
comments, which
were taken into account in producing the final reports.[6]
Each
of the reports includes a Summary for
Policymakers. Unlike the chapters making up the substance of
the reports on
which these summaries are based, the summaries are agreed line-by-line
by
government delegates, which includes all governments who are members of
the
Some
have interpreted the government approval of
the summaries as proof that the IPCC reports are ‘political’ and
therefore
unreliable. Usually those making this charge are implying that the IPCC
reports
are unnecessarily ‘alarmist’ and are being driven by radical left-wing
government agendas. A moment’s thought should show that this is
nonsense:
Sitting around the table approving the Summaries
for Policymakers for the 2007 Fourth
Assessment Report were: the conservative government of
Australia, the
world’s largest coal exporter, under John Howard, the United States
under the
conservative administration of George W. Bush, the governments of Saudi
Arabia,
the other OPEC states and Russia, all major oil and gas producers, and
the
government of China, the fastest growing greenhouse gas emitter in the
world.
If anything the influence of some governments served to make the final
summary
texts more conservative than the scientists would have preferred.
A
couple of examples are useful here: For the Summary
for Policymakers of Working
Group II, the text that had been submitted to the final government
review was:
Roughly 20-30% of species are likely to be
at high risk of irreversible extinction if global average temperature
exceeds
1.5-2.5°C.[8]
The
actual paper which formed one of the main bases
for this statement had used the phrase “committed to extinction”.[9]
So during discussions the statement was
modified to:
Twenty to thirty percent of species will be
committed to extinction if increases in global temperature exceed
1.5-2.5°C.[10]
The
final text approved by the governments however
watered down the notion that species were “committed to extinction”,
preferring
the far more vague “likely to be at increased risk of extinction”:
Approximately 20-30% of plant and animal
species assessed so far are likely to be at increased risk of
extinction if
increases in global average temperature exceed 1.5-2.5°C.[11]
This
phrasing is far more difficult to interpret
than the original wording. “At increased risk …” – from what baseline?
An
“increased risk of extinction” from 0% to 5% would meet that criterion,
which
is far from the sense of the original idea of species being “committed
to
extinction”.
David
Biello cited another case where government
intervention resulted in a more conservative stance than scientists
would have
preferred:
For
example, after objections by
There
are two other ways in which the IPCC reports
tend to be conservative:
Firstly,
because of the lengthy process of
assessment, review, drafting and approval, the reports published in
2007 could
really only assess papers published up to late 2005 to early 2006,
often based
on work undertaken a year or more previously because of the time it
takes for
findings to be published. This means that inevitably, the Assessment Reports are somewhat out of
date when they are published
and tend not to adequately represent some of the more worrying findings
that
were only just being discovered or had not had time to become widely
accepted.
Secondly,
some of the findings are presented in a
way that inadvertently obscures some worrying implications. For
example, Table 5.1
from the IPCC’s Synthesis Report
presents a range of possible CO2 stabilization
levels and likely
associated temperature and sea-level rises.[13]
Tucked
away in the footnotes to the table are two critical pieces of
information: the
emissions reductions required to achieve particular CO2
stabilization levels could be underestimated because many of the models
do not
include carbon-cycle feedbacks (natural processes reinforcing and
exacerbating
climate change) (note a) and the contributions to sea-level rise of
melting ice
sheets, glaciers and ice caps are ignored (note f).
Similarly,
the Summary
for Policymakers of Working Group I on the science of climate
change
presented a table (Table SPM.3, p. 13) which showed the estimated upper
limit
of likely sea-level rise from the worst climate change scenario by 2100
as 59
cm.[14]
The
column heading included the caveat “Model-based
range excluding rapid dynamical changes in ice flow” and on the next
page the
report emphasised: “Models used to date do not include
uncertainties in
climate-carbon cycle feedback nor do they include the full effects of
changes
in ice sheet flow. … Larger values cannot be excluded, but
understanding of
these effects is too limited to assess their likelihood or provide a
best
estimate or an upper bound for sea level rise.” Despite these caveats,
many
people only looked at the table and took 59 cm as the IPCC’s
upper-bound
estimate, when it was actually simply the upper bound of what
then-current
models were capable of representing.
In
summary, far from being unreliable, the IPCC
reports represent the best assessment of the published peer-reviewed
scientific
consensus up to about a year before their publication. Any political
influence
during the process of government approval of the summaries tends to
make the
reports err on the side of conservatism rather than radicalism. Since
2006 when
the reports were being written, scientists have become increasingly
concerned
by the pace and extent of climate change.[17]
2. Science is not about consensus – Galileo was
ridiculed by the authorities and the scientific establishment
True
– but
misleading.
This argument is used to suggest that the
agreement of the vast majority of qualified climate scientists is
irrelevant.
Not so. On the edge of every scientific field, for every true Galileo
who was
proven right, there are usually hundreds of people who would like to
think of
themselves as a Galileo. Their odds are not good.[18] It
is perfectly sensible for lay-people to take the overwhelming agreement
of the
vast majority of qualified climate scientists as a strong indication
that the
scientists are probably right – particularly since the evidence has
been
painstakingly built up over many years from many different fields.
‘Consensus’
does not mean that climate scientists
agree on every single detail of climate change and its implications. Of
course
there is disagreement and uncertainty about a range of issues. But one
of the
most useful features of the presentation of the IPCC reports was the
fact that
the most important statements came with an indication of the level of
confidence the scientists had in them. On the main features of climate
change,
and on the dangers posed by rising greenhouse gas emissions, there is
very
strong agreement.
It
is important to emphasise that this is not
simply an argument from authority. An argument from authority is weak
because
it asserts that we should believe something simply
because an authority figure says it is true. That is not what is going
on here.
No-one is saying that we should believe the IPCC simply because of its
status
as an international institution. The reasons for confidence in the
statements
of the IPCC and the world’s leading scientific bodies do not rest not
on their
status as authoritative institutions but on the evidence for their
statements.
This evidence has already been through the wringer of peer-review
publication
and has survived post-publication scrutiny by the international
scientific
community.
So,
far from being able to be dismissed simplistically
as an argument from authority, giving due weight to the strong
consensus among
climate scientists is an entirely appropriate acknowledgement of the
rigorous
process of evidence gathering and sifting that the international
community of
climate scientists has undertaken over many decades.
3.
There’s no consensus - 31,000
scientists signed a petition denying the link between greenhouse gas
emissions
and climate change
There
is and they didn’t. Some
of
those who denied the link between greenhouse gases and climate change
didn’t
have much confidence themselves in the argument that the scientific
consensus
was irrelevant, so they tried to gather signatures from professional
scientists
for statements asserting that humans are not one of the main causes of
climate
change. As a result of these efforts, it
is often claimed for example, that 31,000
or more scientists have signed a petition denying the link between
greenhouse
gas emissions and climate change. But it is well known that the great
majority
of people on these kinds of lists are not practising research
scientists with
PhDs, and of those who are, very few are climate scientists.[19]
Science encompasses a broad range of
fields, many of which are quite unrelated to climate science. When the
views of
climate scientists are considered, very few remain unconvinced that
greenhouse
gases emitted by human activities are contributing to climate change,
and will
continue to do so in the coming decades.
So
is it true that the vast majority of qualified
scientists agree that humans are significantly contributing to climate
change?
Yes it is. Aside from the work of the Intergovernmental Panel on
Climate
Change, strong statements affirming the reality of human contribution
to
climate change have been released by the National Academies of Science
of many
countries, including: Australia, Belgium, Brazil, Canada, the
Caribbean, China,
France, Germany, India, Indonesia, Ireland, Italy, Japan, Malaysia,
Mexico, New
Zealand, Russia, South Africa, Sweden, the US and UK.[20]
Reviews
have also been undertaken of the scientific literature and again and
again the
finding is that the vast majority of qualified scientists with
expertise in the
relevant areas support the view that humans are influencing the climate.[21]
A
large number of professional scientific bodies
and associations have also affirmed the reality of human influence on
the
climate, including, in the United States, the National Oceanic and
Atmospheric
Administration, the Environmental Protection Agency, NASA's Goddard
Institute
of Space Studies, the American Geophysical Union, the American
Institute of
Physics, the National Center for Atmospheric Research, the American
Meteorological Society, the American Association for the Advancement of
Science, as well as the Royal Society of the UK, the Canadian
Meteorological
and Oceanographic Society, and Australia’s CSIRO.
In
a recent survey of Earth scientists,
predominantly from the
1.
When
compared with pre-1800s levels, do you think
that mean global temperatures have generally risen, fallen, or remained
relatively constant?
2.
Do
you think human activity is a significant
contributing factor in changing mean global temperatures?
Of
the 10,257 invited to participate, 3146 individuals
responded, 90% of whom answered ‘risen’ to question 1 and 82% answered
‘Yes’ to
question 2. Earth science of course takes in a broad range of fields,
not all
of which have a close familiarity with climate science. It is a common
misperception among the public that just because someone has a PhD and
is a
scientist in one field, it somehow gives them a privileged insight into
other
fields. It may, if they have closely followed that field and have kept
up with
the scientific literature, but it does not necessarily. We should not
imagine
for example, that a researcher in electrical engineering would
necessarily have
a highly developed up-to-date understanding of developments in
aeronautical
engineering. Equally, just because someone is a qualified tradesman,
like a
plumber, that does not make them an expert on carpentry. It is
therefore
important to sift the respondents to see what those with particular
expertise
in climate science believe.
Of
the respondents, 79 scientists had expertise in
climate science and had published more than 50% of their recent
peer-reviewed
papers on the subject of climate change. Of these 79 scientists, 96.2%
(76 out
of 79) answered ‘risen’ to question 1 and 97.4% (75 out of 77) answered
‘Yes’ to
question 2.[22]
The
authors of the survey concluded:
It
seems that
the debate on the authenticity of global warming and the role played by
human
activity is largely nonexistent among those who understand the nuances
and
scientific basis of long-term climate processes. The challenge, rather,
appears
to be how to effectively communicate this fact to policy makers and to
a public
that continues to mistakenly perceive debate among scientists.[23]
There
is rarely total unanimity on anything very
complex in the Earth sciences, so by any measure, the agreement of more
than
96% of scientists with demonstrated expertise in the field, plus the
backing of
all of the world’s major national academies of science and major
professional
scientific associations represents an extremely strong professional
consensus
on the core issue that the climate is warming and that humans are
contributing
to the problem through excessive greenhouse gas emissions.
4. We should wait until there is more evidence
before reducing greenhouse gas emissions.
We’ve
already done that and the evidence is in. The
basic physics of the warming potential
of the greenhouse gases was worked out more than a century ago by John
Tyndall[24]
and Svante Arrhenius,[25]
and in 1938, G.S. Callendar solved a set of
equations linking carbon dioxide to climate change.[26]
In
modern times, scientists became
increasingly concerned about the possibility of climate change. In 1988
the
Intergovernmental Panel on Climate Change (IPCC) was set up by the UN
Environment Program and the World Meteorological Organization in
response to
growing scientific concern, exemplified by NASA scientist James
Hanson’s
testimony before the US Congress that year that global warming was a
reality.[27]
The
IPCC produced its First
Assessment Report in 1990 and the UN Framework Convention on Climate
Change
(UNFCCC) was produced in 1992. By 1995 the IPCC had
concluded in its Second Assessment
Report:
“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.”[28]
The
Kyoto Protocol was adopted in 1997, the IPCC produced its Third Assessment Report in 2001 and its Fourth Assessment Report in 2007,
concluding: “Warming of the
climate system is unequivocal”[29]
and
“The understanding of anthropogenic warming and cooling influences on
climate
has improved since the
In
short, we now know enough to know that drastic reductions in emissions
are
needed. What’s more, we also know that the climate system is a highly
complex,
nonlinear system with considerable momentum. We have already had about
0.76ºC
of warming[31];
we
have about another 0.6ºC above 1980-99 levels guaranteed by 2100 from
past
emissions[32],
plus
another 0.4ºC from emissions over the next couple of decades as we try
to bring
our emissions under control.[33] So
we
are guaranteed at least 1.8ºC warming above pre-industrial levels.
Another
recent study however, revealed that the warming we are committed to,
due to
past greenhouse gas emissions, could already be around 2.4°C, much
higher than
previously suspected, and that the effect of the greenhouse gases was
being
masked by aerosols – fine pollutant particles in the atmosphere which
reflect
the sun’s heat:
The observed increase in the
concentration of greenhouse gases (GHGs) since the preindustrial era
has most
likely committed the world to a warming of 2.4°C (1.4°C to 4.3°C) above
the
preindustrial surface temperatures. The committed warming is inferred
from the
most recent Intergovernmental Panel on Climate Change (IPCC) estimates
of the
greenhouse forcing and climate sensitivity. The estimated warming of
2.4°C is
the equilibrium warming above preindustrial temperatures that the world
will
observe even if GHG concentrations are held fixed at their 2005
concentration
levels but without any other anthropogenic forcing such as the cooling
effect
of aerosols. The range of 1.4°C to 4.3°C in the committed warming
overlaps and
surpasses the currently perceived threshold range of 1°C to 3°C for
dangerous
anthropogenic interference with many of the climate-tipping elements
such as
the summer arctic sea ice, Himalayan–Tibetan glaciers, and the
Greenland Ice
Sheet. IPCC models suggest that ~25% (0.6°C) of the committed warming
has been
realized as of now. About 90% or more of the rest of the committed
warming of
1.6°C will unfold during the 21st century, determined by the rate of
the
unmasking of the aerosol cooling effect by air pollution abatement laws
and by
the rate of release of the GHGs-forcing stored in the oceans.[34]
The
climate system is like driving a fully-laden semi-trailer down a
mountain road.
We need to brake when we see the bend in the road coming. If we wait
until
we’re heading into the bend before we brake, we’re going over the
cliff. In his
Review conducted for the Australian Government, economist Ross Garnaut
warned:
[T]he
science, and the realities of emissions growth in the absence of
mitigation,
show that we do not have time. The world is rapidly approaching points
at which
high risks of dangerous climate change are no longer avoidable. We
would delude
ourselves if we thought that scientific uncertainties were cause for
delay.
Such an approach would eliminate attractive lower-cost options, and
diminish
the chance of avoiding dangerous climate change.[35]
5. Climate change has been happening throughout
geological and human history. What is happening now is not outside the
bounds
of natural climatic variability.
Mostly
true – but irrelevant.
Climate changes have certainly
happened throughout history, but with differing degrees of severity and
different rates: Between around 130,000
to 118,000 years ago for example, at the height of the last
interglaciation
(the period between ice ages) the sea levels were some four to seven
metres
higher than they are now.[36] This is around the
same
increase in level that would occur if the Greenland Ice Sheet were to
melt. But
more extreme levels have also occurred in the past. Sea levels were
around 70
metres higher 45 million years ago when CO2
levels were around 1000
to 1500 ppm and there was no permanent ice on the planet. More
recently, they were
around 130 metres lower during the Last Glacial Maximum 21,000 years
ago when
CO2 levels were around 185 ppm.[37]
Local
and regional temperatures have also increased rapidly in the past. In
Paleoclimatic
records show that large, widespread, abrupt climate changes have
affected much
or all of the earth repeatedly over the last ice-age cycle as well as
earlier –
and these changes sometimes have occurred in periods as short as a few
years.
Perturbations in some regions were spectacularly large: some had
temperature
increases of up to 16°C and doubling of precipitation within decades,
or even
single years.[40]
Intense,
abrupt warming episodes appeared more than 20 times in the
Sea-levels
have also risen rapidly in the past, with average rates of sea-level
rise
during the last interglacial period of around 1.6 m per century, and
peak rates
of up to 5 m per century.[42]
Most
of
the strong climate changes of the past however, were either local or
regional
or, if global, took at least many thousands of years. As the IPCC
emphasised:
The
largest temperature changes of the past million years are the glacial
cycles,
during which the global mean temperature changed by 4°C to 7°C between
ice ages
and warm interglacial periods (local changes were much larger, for
example near
the continental ice sheets). However, the data indicate that the global
warming
at the end of an ice age was a gradual process taking about 5,000 years
… It is
thus clear that the current rate of global climate change is much more
rapid
and very unusual in the context of past changes. The much-discussed
abrupt
climate shifts during glacial times … are not counter-examples, since
they were
probably due to changes in ocean heat transport, which would be
unlikely to
affect the global mean temperature. … although large climate changes
have
occurred in the past, there is no evidence that these took place at a
faster
rate than present warming. If projections of approximately 5°C warming
in this
century … are realised, then the Earth will have experienced about the
same
amount of global mean warming as it did at the end of the last ice age;
there
is no evidence that this rate of possible future global change was
matched by
any comparable global temperature increase of the last 50 million years.[43]
In
summary, the past global ‘natural variability’ of sea levels, rates of
sea-level rise, temperature changes and so on, cover an enormous range,
and the
extremes are outside the experience of human civilizations. There
is also no evidence of a global
temperature increase of 5°C
(which would be
accompanied by much larger regional increases) in a single century for
the past
50 million years. Neither human social systems nor many
eco-systems, nor
many eco-systems, could adapt to some of these changes, so the fact
that some
are of similar magnitude to those in the past is hardly comforting and
does not
provide a reason for inaction.
6. Because what is happening now is within the
realms of natural variability, we can’t say that humans are
contributing to
climate change.
False. It
is sometimes asserted that if climates
changed in the past from natural causes without any human influence,
then any
climate change occurring now must also be entirely due to natural
causes. This
is simply an error of logic. The fact that lightning strikes caused
bushfires
in the distant past, and continue to do so today, does not imply that
arsonists
never cause bushfires. The same event can have a number of different
possible
causes and no fire investigator in her right mind would rule out arson
simply
because the natural explanation of lightning strikes was adequate to
explain
the outbreak of bushfires in general. She is not interested in past
bushfires
in general – she is interested in how particular
bushfires started. In the same way, the fact that past climate changes
were
entirely natural in no way rules out the possibility that humans are
contributing to the current changes – particularly if, as we know,
humans are
now emitting gases on an epic scale which have strongly influenced the
climate
in the past. We are interested in the causes of this particular episode
of
climate change, not past climate changes in general.
The
overwhelming, broad consensus of the world’s climate scientists is that
we
cannot explain observed climate changes without taking into account
human
influence.[44] A
recent comprehensive study of
the polar regions concluded for example,
[T]he observed changes in
Substantial
changes in the climate of the
They
found that the models could produce the observed trends in temperature,
snowpack, and river flow of the past few decades only when they
included the
actual amounts of human-made greenhouse gases and pollutant hazes. Run
without
them, the models poked along, warming and cooling without a long-term
trend. “There’s
no way we can make a natural-variability explanation for what we’ve
seen” in
the West, said Barnett. “I’d put the odds at between one in 100 and one
in 1000
that we were fooled. Quite frankly, it’s us.”[46]
Similarly,
the warming of the world’s oceans cannot be explained without taking
into
account human influence:
A
warming signal has penetrated into the world's oceans over the past 40
years.
The signal is complex, with a vertical structure that varies widely by
ocean;
it cannot be explained by natural internal climate variability or solar
and
volcanic forcing, but is well simulated by two anthropogenically forced
climate
models. We conclude that it is of human origin, a conclusion robust to
observational sampling and model differences.[47]
In
2003 a heatwave in
Using
a threshold for mean summer temperature that was exceeded in 2003, but
in no
other year since the start of the instrumental record in 1851, we
estimate it
is very likely (confidence level >90%) that human influence has
at least
doubled the risk of a heatwave exceeding this threshold magnitude.[49]
Judith
Lean and David Rind undertook a statistical regression analysis of the
influences on temperature of both natural influences, such as solar
variation,
volcanoes and the El Niño
Southern Oscillation (
Figure
1. Natural
and anthropogenic contributions to temperature change
Source: Lean
& Rind (2008), Figure 2, p. 2. Caption: “Reconstructions
of the contributions to monthly mean global surface
temperatures by individual natural and anthropogenic influences (at
appropriate
lags) are shown. The right hand ordinates give the native scales of
each
influence and the left hand ordinates give the corresponding
temperature change
determined from the multiple regression analysis. The grey lines are
trends for
the whole interval. The inset in Figure 2d shows the individual
greenhouse
gases, tropospheric aerosols and the land surface plus snow albedo
components
that combine to give the net anthropogenic forcing.”
Overall
both empirical and theoretical studies are in agreement that greenhouse
gas
emissions from human activities must be taken into account to explain
the
warming we have witnessed:
Natural changes cannot account for the
significant long-term warming in the historical global surface
temperature
anomalies. Linear trends in temperature attributed to
7. Because what is happening now is within the
realms of natural variability, it is not something to worry about.
Species have
always adapted.
False.
Sea levels have been more than 70 metres
higher in the past.[51]
Melting of the
The
world experienced several mass extinctions in the past where 50-90% of
species
became extinct with temperature changes of around 5°C.[54] The
Permian-Triassic
extinction around 251 million years ago, for example, is thought to
have
extinguished 95% of the world’s species in existence at the time. Under
today’s
circumstance with possible migration routes blocked by fences, human
settlements and degraded habitats (such as isolated pockets of forest
surrounded by cleared farmland), it is wishful thinking to imagine that
species
can simply migrate and adapt to any climate change.[55]
8.
It was warmer during medieval
times
Probably
false, but irrelevant anyway. Many
of those who most strenuously deny any link between
greenhouse gas emissions and climate change make a great deal of the
period
from roughly 800 to 1300 AD, when it is possible that temperatures may
have
been slightly warmer than at present – at least in northern Europe. The
argument runs that if temperatures were warmer then, and CO2
levels
were lower, then (somehow) that is supposed to show that rising
greenhouse gas
levels are nothing to worry about because natural variability can lead
to
warming. There are a few problems with this logic.
Firstly,
even if temperatures
were slightly higher in medieval times, that is irrelevant to our
current
situation. No-one claims that rising greenhouse gas levels are the only
factor
that has ever led to higher temperatures. Changes in solar intensity,
variations in ocean currents and a number of other factors can
influence
temperatures. In this case a persistent positive North Atlantic
Oscillation
from 1050 to 1400 seems to have played an important role.[56]
The fact that temperatures appear to have
been warm during medieval times in certain regions does not necessarily
imply
that the warming in our current era can be explained by similar
factors. The
main reason scientists are so concerned is because they cannot explain
the
changes over the past century without taking into account rising
greenhouse gas
levels.
Second,
recent research suggests
that the ‘Medieval Climate Anomaly’ as it now increasingly described by
scientists, was warmer than the Little Ice Age, which lasted from
around 1500
to 1850, but globally it was probably slightly cooler than the last 30
years.
It was also most likely a regional, rather than a global phenomenon.[57]
Third,
as David Archer has
warned, “Beware the bait and switch!”[58]
The projections for global
climate change for the current century and beyond do not depict a
fraction of a
degree increase in temperatures that would usher in a benign era of
more
pleasant winters and balmy summer evenings. Instead, projections show
that even
2ºC
above pre-industrial temperatures would
bring major adverse impacts. As Figure 2 shows, on current trajectories
we
could see average global temperature increases of 6ºC
or more by 2100, which would lead to a humanitarian
catastrophe and a dramatically different planet.
Figure
2: Past and projected future temperature variations
Source:
UNEP (2009), p. 26.
9. Climate models are unreliable
False.
No-one claims that climate models are
perfect, but they are based on sound science and have been able to
replicate
past observations to a good degree of accuracy and have also
anticipated
effects such as the global cooling effects resulting from major
volcanic
eruptions such as Mt Agung in Bali in 1963[59]
and Mt Pinatubo in the
Philippines in 1991,[60] as
well as the more recent
partial offsetting of the effects of rising greenhouse gas levels by
natural
internal variability.[61]
Some
commentators however, misunderstand or deliberately misrepresent the
purpose of
modeling complex systems such as the climate. For any chaotic or
complex system
it is not possible to construct a simulation that will precisely
predict the
future time path of the system, except under very strict conditions
such as
complete, accurate knowledge of all initial parameters and a short
prediction
horizon. That is why the weather is so hard to forecast over more than
a few
days. In an overview of chaotic complex systems, the authors asked
their
readers to imagine an idealised
game of billiards where the balls move across a frictionless surface
and
collide with negligible loss of energy. They then asked us to guess for
how
long an expert player with perfect strike control could precisely
predict the cue ball’s trajectory. Their answer: “If the
player ignored an effect even as miniscule as the gravitational
attraction of
an electron at the edge of the galaxy, the prediction would become
wrong after
one minute!”[62]
The
future trajectories of complex nonlinear systems like the climate are
extremely
sensitive to initial conditions. Long-term modeling of complex systems
therefore focuses, not on a precise single ‘prediction’ of a system’s
future
time path, but on modeling suites of possible scenarios across a range
of
parameter values using hundreds or thousands of simulation runs. This
process
yields a set of scenarios within which the future path of the system is
highly
likely to lie. If the system is well understood, the set of likely
scenarios
will be relatively narrow and there will be high confidence that the
evolution
of the actual system’s path will fall within that set of scenarios. All
complex
systems scientists understand this approach as it is common across a
range of
scientific disciplines.[63]
When
people
disparage climate models because they have not ‘predicted’ the
evolution of the
temperature path in one particular locality, they reveal that they do
not
understand climate modelling or complex systems modeling more
generally. It is
also extremely misleading to give people the impression that because
models
can’t necessarily ‘predict’ the future temperature paths precisely,
that the
models are therefore useless as guides for policy. If, as is the case
currently, a large number of model scenarios from a large number of
different
models all yield dire projections for future climate scenarios, then it
strongly suggests we have a problem.[64]
It
should also be noted that it is not possible for anyone, including
those who
deny the human influence on climate, to make assertions about the
future
relationship between greenhouse gases and global climate without some
explicit
or implicit reference to a model of how the world’s climate works. So
when someone
asserts definitively that greenhouse gases will have no effect on
climate, or
only a minor effect that is not worth worrying about, we are entitled
to ask:
How do they know? They can only make that assertion based on some more
or less
sophisticated understanding of how the climate system works – in other
words, a
model. But where are these climate models? Where are the models which
show that
human greenhouse emissions will have little or no effect on the world’s
climate?
Lastly,
it is also worth mentioning how striking it is that so often the same
people
who deny the validity of climate models, place so much faith in the
minority of
economic models which suggest that mitigating climate change would be
terrible
for our economies. Most economic models in fact have far less claim to
scientific validity than climate models.[65]
10. There was a consensus among climate
scientists in the 1970s that we would soon be heading into another ice
age
False.
This is one of those persistent assertions
that is repeated endlessly, but which has little basis in fact. The
implication
of the statement is that if scientists were wrong in the 1970s, there’s
no
reason to believe them now when they warn of climate change. But it is
a
complete myth that there was any kind of consensus among climate
scientists in
the 1970s that we were heading into a cool period – in fact there was
far more
concern about warming. The most thorough recent debunking of this myth
was
given in a 2008 paper in the Bulletin of
the American Meteorological Society.[66]
The authors undertook a review
of climate science publications and found 7 papers “predicting,
implying, or
providing supporting evidence for future global cooling”, 20 that were
neutral
and 44 supporting future warming. From their publication date to 1983,
“The
cooling papers received a total of 325 citations, neutral 424, and
warming
2,043” (p. 1333). The
authors concluded (p. 1326):
A review of the climate science
literature from 1965 to 1979 shows this myth to be false. The myth’s
basis lies
in a selective misreading of the texts both by some members of the
media at the
time and by some observers today. In fact, emphasis on greenhouse
warming
dominated the scientific literature even then.
11. Global warming ended around 1998 anyway –
it’s
been cooling since then.
False.
There are a couple of issues
that need to be addressed here: the cherry-picking of data and the
complex
relationship between emissions and temperatures.
Firstly,
the cherry-picking:
Choosing particular years, like 1998, to derive ‘trends’ that are not
representative of the data is called cherry-picking. The years
1997-1998 saw a
major temperature spike from the strong El Niño in the Pacific, so if
we take a
big El Niño year like 1998 as a starting point, then of course the
years
immediately following it during the neutral and La Niña phases are
going to be
relatively cooler.
To
see why such cherry picking is
so silly (or deliberately deceptive), consider the following: As Figure
3
shows, the 2005 global temperature was statistically indistinguishable
from
1998 (they were both very warm years), and the NASA GISS data, which
also takes
into account Arctic temperatures, put 2005 as slightly warmer than
1998, which
in the NASA data tied with 2007.[67] So
if we took either 1997 or
1999 as our starting year rather than 1998, we’d be able to show a
strong
warming trend between those years and 2005. Even taking the period 1999
to 2008
would show a strong, statistically significant, warming trend.
Figure
3. ‘Plateaus’ and ‘cooling’ within the recent warming trend
Scientists
don’t cherry pick data
like that because it is meaningless to try to pick major long-term
climate
trends based on just a few years of data. If we look back through the 20th
century and most recent years, or forwards through the simulations
produced by
climate models, we see a number of periods where temperatures were flat
or even
cooled for a period of a few years – but all within a long-term warming
trend.
For example, as Figure 3 also shows, if we took either of the periods
1977-1985
or 1981-1989 we would see no significant trend at all, even though both
periods
fall within the period 1975 to 2008 which showed a strong overall
warming
trend.[68]
Australia’s
Garnaut Review, commissioned by the
Australian Government to
examined the science and economics of climate change, investigated the
assertion that warming had finished, using experts in the analysis of
time
series data. They concluded: “Viewed from the perspective of 30 or 50
years
ago, the temperatures recorded in most of the last decade lie above the
confidence band produced by any model that does not allow for a warming
trend.”[69]
From a scientific, statistical perspective,
there is no justification for asserting that the warming trend
witnessed in the
late-20th century has ended.[70]
Second,
the relationship between
emissions and temperatures is complex. One of the most persistent
misunderstandings among the general public, and one of the most willful
misrepresentations by those who deny the human influence on climate, is
that
climate scientists are claiming that atmospheric temperatures will
increase
relentlessly, year after year, in lock-step with CO2
levels. This is
simply incorrect. For one thing, atmospheric temperatures are only part
of the story
– as Figure 4 shows, an enormous amount of energy has actually gone
into
warming the oceans since the 1950s.[71]
Figure
4. Heat content of the oceans, 1955-2008
Source:
Levitus et al. (2009),
Figure 1, p. 2. Caption: “Time series of yearly ocean heat
content (1022J)
for the 0-700 m layer from this study (solid) and from Levitus et al.
[2005]
(dashed). Each yearly estimate is plotted at the midpoint of the year.
Reference period is 1957-1990.”
But
leaving ocean temperatures
aside, surface temperatures are not just governed by greenhouse gas
levels.
Variations in solar radiation over the 11-year solar cycle play a role,
and
declining solar activity in the waning of the previous solar cycle are
thought
to have countered much of the warming due to greenhouse gas emissions
from 2002
to 2008.[72]
Major volcanic eruptions, such
as Mt Pinatubo in the
Natural
influences also
alter surface temperatures, producing as much as 0.2ºC
global warming during major
The
coupling and synchronization of modes in nonlinear systems gets
complicated, to
say the least.[76]
There
seems to be some evidence that major climate shifts from warming
periods, such
as those from around 1910-1940 and after about 1975, and temperature
stabilizations or slight cooling periods, such as that from the 1940s
to mid-1970s,
are influenced by the degree of coupling and synchronization between
major
climatic modes.[77] Temperatures have been relatively stable so
far this century
and so while not enough years have yet passed to make a statistically
significant judgement, it is not impossible that changes in these
natural
couplings have begun to temper the strong warming trend we have
experienced
since the 1970s. It may even be possible that we will see a cooling
trend for
some years before the resumption of warming. That would bring welcome
relief,
but we should not delude ourselves that these natural reorganizations
of heat
transfer within the global climate system somehow invalidate the
well-established evidence for human influence on the long-term warming
trend.
It would be particularly unfortunate, scientifically irresponsible and
counter-productive for global climate change mitigation efforts, if a
possible
series of cool years in the coming decade were seized on as evidence
that the
century-long warming trend has ‘stopped’ or ‘gone into reverse’ so that
we can
just carry on pumping out greenhouse gases as before. As Swanson and
Tsonis
emphasized in concluding their study on these effects:
Finally,
it is vital to note that there is no comfort to be gained by having a
climate
with a significant degree of internal variability, even if it results
in a
near-term cessation of global warming. It is straightforward to argue
that a
climate with significant internal variability is a climate that is very
sensitive to applied anthropogenic radiative anomalies … If the role of
internal variability in the climate system is as large as this analysis
would
seem to suggest, warming over the 21st century may well be larger than
that
predicted by the current generation of models, given the propensity of
those
models to underestimate climate internal variability.[78]
In
summary, cherry-picking data
is poor scientific practice, it cannot yet be concluded statistically
that the
warming trend since the late 1970s has ended, and greenhouse gas
increases were
never expected to lead to a relentless year-after-year increase in
temperatures
in any case. Temperatures have zigzagged up
and down due to the complex natural internal variability of
the climate system, and they will continue to do so. But despite these
year-to-year variations, we have every reason to believe, based on the
science
of the climate system, that the long-term warming trend experienced
since the
early 20th century will continue, even if for
certain periods
temperatures stabilize or even cool for a while.
12. Our best strategy is simply to adapt to
climate change.
False.
This approach greatly underestimates the
risks from unmitigated climate change and also presumes that the
climate will
settle into a new stable state that we can adapt to. But
the Earth’s
climate is a highly complex nonlinear system with the potential to
cross
thresholds or tipping points and lurch from one stable state to another.[79] We
cannot simply assume that the world’s climate will settle into a new
state that
is both stable and suitable enough to prevent catastrophic consequences
for
ecological and human systems. As one recent study put it:
“Palaeoclimate data
show that the Earth’s climate is remarkably sensitive to global
forcings.
Positive feedbacks predominate. This allows the entire planet to be
whipsawed
between climate states.”[80]
The
emergence from the last ice age for example, was characterised by
dramatic
oscillations, or ‘flickering’ between cold and warm periods.[81]
The
humanitarian, economic and security implications
of unmitigated climate change would also be staggering.[82] In
The
recommendation to just let climate change run
its course and adapt to it seems to come only from those who either do
not
believe the climate is warming, or if it is, do not believe anything
can be
done. I am not aware of a single expert in humanitarian aid,
geopolitics,
economics or international security who believes human societies and
economies
could adapt smoothly or peacefully to unmitigated climate change. Those who place so much
emphasis on the short-term
economic costs of investing to reducing greenhouse gas emissions should
consider
the dire economic, humanitarian and security implications of
unmitigated
climate change.
13.
CO2 exists only in
very low concentrations in the atmosphere, therefore it cannot have
significant
effects.
False.
The
concentration of CO2 in the atmosphere has risen
from around 280 ppm
(parts per million) at the start of the industrial revolution in about
1750 to
around 388 ppm today – a 39% increase. Nevertheless, 388 ppm
constitutes just
0.0388% of the atmosphere by volume and it is sometimes asserted that
the
increase in concentration can’t possibly have any significant effect –
simply
because it is such a low concentration. This assertion
is simply an error of logic, since it presumes that, by definition, a
small
cause cannot have a large impact, which is demonstrably false. To take
just one
example, a drop of the nerve agent VX around the size of a grain of
sand is
enough to kill an adult.[86] It
cannot be asserted that just because the concentration of a substance
is low,
it therefore cannot have major effects on the system it is interacting
with. The potential
impact of the
substance on the system must be examined and understood before any
comment can
be made on the likely effects of different concentrations.
Why
then do
scientists believe that CO2 and other greenhouse
gases could be
warming the planet? Isn’t water vapour the most important greenhouse
gas? Yes
it is, by a long way. But direct human influence on the concentration
of water
vapour in the atmosphere is negligible – it is largely a feedback
response to
temperature changes, since warmer air can hold more moisture. The warm
tropics
therefore already experience a strong greenhouse effect, so adding more
greenhouse gases impacts the drier polar regions more than the humid
tropics. At the
poles, the warmer air
can hold significantly more water vapour than before, which acts to
reinforce
the warming due to the addition of other greenhouse gases such as CO2.[87]
If
water vapour is
the main greenhouse gas, then what role does CO2
play? To answer
this question, a brief discussion of the basic physics of the
greenhouse effect
is needed. The sun emits most of its radiation, including the
ultraviolet,
visible light and near-infrared light, with wavelengths of around
0.2-4 μm (micro-metres).
The longwave
radiation that is reflected back from Earth as heat is emitted at
wavelengths
of 4-100 μm. [88]
Our
atmosphere consists overwhelmingly of simple gas molecules in the
proportions:
Nitrogen, N2, (78.08%), Oxygen, O2,
(20.95%) and Argon,
Ar, (0.93%). The greenhouse gases in the atmosphere – water vapour (H2O),
carbon-dioxide (CO2), methane (CH4),
nitrous oxide (N2O),
ozone (O3) and others – absorb some of the
radiation from the
surface, emitting some of it back to the surface, which causes more
warming,
and emitting the rest back to space. If it were not for the greenhouse
effect
of these gases, the average temperature of the Earth would be around
-18ºC,
rather than 15ºC.[89]
Adding
more
greenhouse gases to the atmosphere increases the altitude from which
heat
radiation escapes back into space. At the higher altitude, temperatures
are
cooler and so emission temperatures and rates of radiation emission to
space
will be lower than they would have been without the additional
greenhouse gas.
To restore thermal equilibrium, temperatures in the lower atmosphere
(troposphere) and the Earth’s surface increase until the incoming solar
radiation is once again balanced with the outgoing heat radiation.[90]
The
effectiveness
of a greenhouse gas depends on a number of factors, including the
wavelength at
which the gas absorbs radiation, the gas concentration, the strength of
the
absorption per molecule and also whether other gases are already
strongly
absorbing at that particular wavelength. These factors are important
because it
means that different gases absorb radiation at different wavelengths,
as Figure
5 shows.
Figure
5. Radiation transmitted by the atmosphere showing greenhouse gas
absorption
bands. Source: http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png
Water
vapour for
example, absorbs across a large number of bands, but particularly
strongly near
6.3 μm
and
2.7 μm
due
to changes in molecular vibrational energy, and also at wavelengths
greater
than 18 μm
because of changes in rotational energy. CO2 on
the other hand, absorbs around 4.3 μm,
only weakly between 8-12 μm
and
most strongly in the 13-17 μm
zone, centred on 15 μm
(but
also with significant absorption at 13.9 μm
and 16.2 μm),
which is right near the peak of the longwave radiation spectrum and
causes more
than 90% of the warming due to CO2.[91]
From
about 7.7 μm
to 12 μm,
the so called “atmospheric window”, absorption
by water vapour and CO2 is weak and other trace
gases such as ozone
(with a peak around 9.6 μm),
methane (7.7 μm)
and nitrous
oxide (7.8 μm)
absorb more strongly, despite their low concentrations.[92]
Other
greenhouse gases such as the chlorofluorocarbons are present only in
low
concentrations but they are very powerful greenhouse gases and they
absorb
strongly in the atmospheric window where water
vapour and CO2 are weak, at wavelengths such as
8.7 μm,
9.1 μm,
9.2 μm,
10.9μm
and
11.8 μm.[93]
It
is important to
emphasise that the atmospheric physics of the various greenhouse gases,
including their effects on different wavelengths of outgoing longwave
radiation, is well established both empirically and theoretically. [94] It
is
simply incorrect to assert that gases such as CO2
must have little
effect because of their low concentrations compared to the main
atmospheric
gases.
14. CO2 is a weak
greenhouse
gas. Doubling of CO2
from its
pre-industrial levels of 280 ppm to 560 ppm would only bring warming of
about
1ºC.
False
- twice.
The warming effect of CO2 in the
atmosphere diminishes logarithmically as its concentration increases,
as Svante
Arrhenius confirmed in 1896.[95] It
has
been claimed by some who accept this logarithmic relationship, that a
doubling
of CO2 would only bring warming of around 1ºC
and that since we have
already experienced about 0.76°C of warming there is only a very small
amount
of benign warming still to come. But this claim is false in two
different ways:
Firstly,
basic
radiation calculations show that for a doubling of CO2,
surface
temperatures would warm by around 1.2ºC (not 1ºC) if, and only if, the
structure of the atmosphere and all other factors remained fixed.[96] So
the
assertion that doubling CO2 would bring warming
of only 1ºC is
already about 0.2 ºC wide of the mark in this purely theoretical
calculation.
Far
more serious
is the second way in which this assertion is false, namely that in the
real
world, the structure of the atmosphere and a host of other factors are
not
fixed at all. There are a large number of feedbacks in the climate
system which
reinforce the warming. If the logarithmic relation between CO2
concentration increases and temperature increases is accepted, and it
is
accepted that the 35% increase in CO2
concentrations from 280 to 379
ppm up to 2005 led to the approximately 0.76°C warming we have already
experienced since pre-industrial times, then it is easily shown that a
doubling
of CO2 from pre-industrial levels would likely
lead to at least
about 1.74ºC of warming.[97]
This
calculation
however, presumes that we have already experienced the full effects of
the
increase in CO2 concentrations to 379 ppm. We
haven’t. We have
experienced some of the feedbacks from this increase, but by no means
all. The
climate system has momentum and delayed feedbacks, due to factors such
as the
immense volume of the oceans which take a long time to warm up. So
there would
have been a further ‘committed warming’ already guaranteed from the
increase to
379 ppm even if all emissions had ceased in 2005. In other words, the
1.74ºC
figure applies only if we ignore the committed warming we will get from
past
emissions and their feedbacks on the climate system – or if we presume
(on the
basis of a climate model?) that the feedbacks cancel out. Once those
feedbacks
are properly taken into account however, the temperature increase
resulting
from a doubling of pre-industrial CO2 levels
(referred to as the
‘climate sensitivity’) is “likely to be in the range 2 to 4.5°C with a
best
estimate of about 3°C, and is very unlikely to be less than 1.5°C.”[98]
The
most recent
assessment of climate sensitivity by James Hansen and his team, based
on
empirical geological evidence, is even more disturbing.[99] Hansen argues that the
figure of 3°C for the sensitivity of the climate
to a doubling of CO2
used
in most climate
models only accounts for ‘fast’ feedback effects, such as cloud
formation,
water vapour, and sea ice. Once
‘slow’ feedback effects are accounted
for (on timescales of centuries or less), such as ice sheet
disintegration,
vegetation changes, and CO2 and methane releases
from soils, tundra
and ocean sediments, the climate sensitivity for a doubling of CO2
above pre-industrial levels is likely to be more like 6°C. This higher
climate
sensitivity suggests that a 300-325 ppm CO2
target is what we need
for a safe climate with sea ice restored to its area of 25 years ago.[100]
Since
CO2 levels are now approaching 390 ppm, this
implies not only
drastically reduced emissions but an extended period of actually
removing CO2
from the atmosphere.
Furthermore,
even
ignoring these feedback effects, emissions projections at current
trajectories
are likely to see CO2 levels
of 1000 ppm by 2100, leading in turn to temperatures well over 3°C.[101] What
is the highest level of CO2 that those who are
opposed to strong
emissions reductions would consider safe? Is
there any level of CO2
concentration they would agree is too high?
Let’s
allow for
the moment the argument that human greenhouse gas emissions have not
contributed much at all to warming so far, and that the warming we’ve
seen
(which is not in dispute) is mostly of natural origin: What then is the
policy
implication? Well, the evidence from both theoretical physics and
empirical
data collected over more than 100 years show that these gases do
contribute to
warming, so if we’re already being subjected to natural warming, does
that in
any way lessen the case for reducing our emissions? Hardly. That
argument only
follows if, for sound theoretical reasons, we believe that the
greenhouse gases
we emit will have no significant impact on the climate. But such a
judgement
has no sound basis in science and could only be arrived at by use of a
climate
model, none of which show negligible impact from rising greenhouse
gases.
It
should be remembered
then, that when critics spurn climate models as ‘voodoo science’,
asserting
that the sensitivity of the climate to a doubling of CO2
is just 1ºC
or less, they must be implicitly adopting a climate model which either
ignores
all feedback effects, or which presumes that the feedbacks cancel out.
To say
anything about the effects of greenhouse gases on climate, there is no
alternative but to use some kind of model – and any model that
arbitrarily
assumes either that there are no feedback effects or that they all
cancel out,
is scientifically unjustifiable. As Reto Knutti from the Institute for
Atmospheric and Climate Science in
No credible
model has been produced that questions the strong anthropogenic
influence on
climate in the past and future. I, therefore, argue that the
large-scale model
projections are very likely robust and accurate within the stated
uncertainties.[102]
15. CO2 is not a
pollutant – it is
completely natural and essential for life.
Misleading.
In
general, whether something is a pollutant or not depends not on whether
it is
natural, but whether its concentration
has increased sufficiently to adversely affect an ecosystem or human or
animal
health. Manure is natural and highly beneficial as a fertilizer on
fields – but
only up to a certain point. Even at current concentrations CO2
is
already a pollutant, adversely affecting human and natural systems.
Those
who make this argument often also imply that
greenhouse gases in general aren’t pollutants. In doing so, they ignore
the
other main greenhouse gases released by human activities like CH4
(methane) and N2O (nitrous oxide), plus around
60 other gases under
the broad categories of CFCs (chlorofluorocarbons), HCFCs
(hydrochlorofluorocarbons), HFCs (hydrofluorocarbons), PFCs
(perfluorinated
compounds) such as SF6 (sulfur hexafluoride),
fluorinated ethers,
perfluoropolyethers, halocarbons and other various other compounds.[103]
Many
of these synthetic gases are extremely potent greenhouse gases and
contribute
significantly to the overall human influence on the climate.
16. Any warming is the Sun’s fault.
False.
No-one
claims that increased greenhouse gas emissions are the only
cause of climate change. Fluctuations in solar activity also
influence the world’s climate, but their effects are taken into account
by
climate scientists and they are not enough to explain the changes we
are seeing.[104] A
number of recent studies have debunked the notion that solar variations
are responsible
for the recent warming rather than greenhouse gases produced by humans,
concluding:
After 1980 … the Earth's temperature
exhibits a remarkably steep rise, while the Sun's irradiance displays
at the
most a weak secular trend. Hence the Sun cannot be the dominant source
of this
latest temperature increase, with man-made greenhouse gases being the
likely
dominant alternative.[105]
Variations in the Sun's total energy output
(luminosity) are caused by changing dark (sunspot) and bright
structures on the
solar disk during the 11-year sunspot cycle. The variations measured
from
spacecraft since 1978 are too small to have contributed appreciably to
accelerated global warming over the past 30 years.[106]
This
comparison shows without requiring any recourse to modeling that since
roughly
1970 the solar influence on climate (through the channels considered
here)
cannot have been dominant. In particular, the Sun cannot have
contributed more
than 30% to the steep temperature increase that has taken place since
then,
irrespective of which of the three considered channels is the dominant
one
determining Sun-climate interactions: tropospheric heating caused by
changes in
total solar irradiance, stratospheric chemistry influenced by changes
in the
solar UV spectrum, or cloud coverage affected by the cosmic ray flux.[107]
[O]ver the past 20 years, all the trends in
the Sun that could have had an influence on the Earth's climate have
been in
the opposite direction to that required to explain the observed rise in
global
mean temperatures.[108]
[E]ven large solar irradiance change
combined with realistic volcanic forcing over past centuries could not
explain
the late 20th century warming without inclusion of greenhouse gas
forcing.
Although solar and volcanic effects appear to dominate most of the slow
climate
variations within the past thousand years, the impacts of greenhouse
gases have
dominated since the second half of the last century.[109]
[T]he
energy content of the climate system increased between about 1955 and
1995 by
about 2 x 1023 J, equivalent to an energy
imbalance at the top of the
atmosphere of 0.3 W/m2. Because incoming solar
energy … has not
changed, the
imbalance must result from increased absorption of outgoing energy,
such as by
increased greenhouse gases.[110]
Lean
and Rind concluded that there was no chance
that variation in solar radiation was primarily responsible for the
warming
witnessed in the 20th century:
For the ninety years from 1906 to 1996, the
average slope of the anthropogenic–related temperature change … is
0.045 K per
decade … Solar-induced warming is almost an order of magnitude smaller.
It
contributes 10%, not 65% … of surface warming in the past 100 years
and, if
anything, a very slight overall cooling in the past 25 years … not
20–30% of
the warming.[111]
It
has also been shown that solar influences are
not well correlated with long-term climatic changes, based on a 9000
year
dataset.[112]
As
Figure 6 shows, there is no strong trend in
solar activity that could explain recent warming, so the variation in
radiative
forcing (in
Figure
6. Total solar irradiance
Source:
Forster et
al. (2007),
Fig. 2.17, p. 190. Caption: “Reconstructions of the total solar
irradiance time
series starting as early as 1600. The upper envelope of the shaded
regions
shows irradiance variations arising from the 11-year activity cycle.
The lower
envelope is the total irradiance reconstructed by Lean (2000), in which
the
long-term trend was inferred from brightness changes in Sun-like stars.
In
comparison, the recent reconstruction of Y. Wang et al. (2005) is based
on
solar considerations alone, using a flux transport model to simulate
the long-term
evolution of the closed flux that generates bright faculae.”
17. Climate change is due to the effects of
cosmic rays.
False.
Cosmic
rays are not really rays, but high-energy particles such as protons and
helium
nuclei (alpha particles) from the sun and other stars which enter the
Earth’s
atmosphere.
Some
studies have purported to show a degree of correlation in some parts of
the
world between cosmic ray fluxes and increases in low-level cloud cover.
From
these correlations, some have concluded that cosmic rays are a primary
cause of
increased cloud cover, which would have a cooling effect due to their
greater
reflectivity (albedo). When the Sun is more active, its magnetic field
deflects
more of these fast-moving particles away from the Earth, and so it is
postulated that the influence of solar activity has been significantly
underestimated since a more active sun would lead to fewer particles,
fewer
clouds and more warming. Other studies however have shown no
correlation
between cosmic ray fluxes and cloud cover. For example, an analysis of
US data
from 1900-1987 found that while solar irradiance variations were
correlated
with cloud cover changes, cosmic rays were not.[113] Similarly,
a 2002 review of the issue concluded:
No meaningful relationship is found between
cosmic ray intensity and cloud cover over tropical and extratropical
land areas
back to the 1950s. The high cosmic ray-cloud cover correlation in the
period
1983–1991 over the
In
discussing this issue, the Royal Society
concluded:
[O]bservations of clouds and galactic cosmic
rays show that, at most, the possible link between cosmic rays and
clouds only
produces a small effect. Even if cosmic rays were shown to have a more
substantial impact, the level of solar activity has changed so little
over the
last few decades the process could not explain the recent rises in
temperature
that we have seen.[115]
In
somewhat more detail, the IPCC concluded:
[T]he cosmic ray time series does not
correspond to global total cloud cover after 1991 or to global
low-level cloud
cover after 1994 … without unproven de-trending … Furthermore, the
correlation
is significant with low-level cloud cover based only on infrared (not
visible)
detection. Nor do multi-decadal (1952 to 1997) time series of cloud
cover from
ship synoptic reports exhibit a relationship to cosmic ray flux.
However, there
appears to be a small but statistically significant positive
correlation
between cloud over the
Moreover,
in assessing the scientific evidence for
various climate forcing agents, the IPCC ranked cosmic rays as having
‘insufficient evidence’, ‘insufficient consensus’ and a ‘very low’
level of
scientific understanding and a ‘General lack/doubt regarding the
physical
mechanism; dependence on correlation studies’.[117]
More
recently, the first calculations of the
magnitude of the cosmic ray effect on clouds were published, with the
authors
concluding that the effect of cosmic rays was about 100 times too small
to
account for the observed changes in cloud properties: “Consequently we
conclude
that the hypothesized effect is too small to play a significant role in
current
climate change.”[118]
It
is possible then that cosmic rays do have some
minor effects on the climate. But some people give enormous weight to
the supposed
effects of cosmic rays, despite their speculative foundations,
inadequate
evidence and a general view among scientists that they are unlikely to
be very
important in determining recent and projected climate changes. This
stands in
stark contrast to the often emphatic rejection of the warming effects
of
long-lived greenhouse gases by the same people, despite the fact that
these
gases are given the highest grades possible in each category of the
IPCC’s
assessment: ‘strong evidence’ for their warming impacts, a ‘good deal
of
consensus’ among the scientific community and a ‘high’ level of
scientific
understanding.[119]
This
‘uneven’ approach to the scientific evidence on cosmic rays compared
with
greenhouse gases appears to betray a pre-determined conclusion in a
search of
support, rather than an honest and rigorous appraisal of the weight of
the available
scientific evidence.[120]
18. Lack of warming in the tropical troposphere
(lower atmosphere) proves anthropogenic global warming is a myth.
False.
For
some years an apparent discrepancy existed between the predictions by
climate
models that the tropical troposphere would be warming, and certain
satellite
data which suggested it was not. When a paper by Douglass et al. (2008) was published online in
2007, it was hailed by some
as a knock-out blow for climate models in general and even the whole
phenomenon
of anthropogenic (human-caused) climate change. But a more recent
assessment of
the issue found serious flaws in the Douglass paper including a failure
to account
for natural variability and a flawed statistical test. Santer et al. (2008) concluded that “There is
no longer a serious and fundamental discrepancy between modelled
and observed trends”.[121]
19. Coming out of the ice ages, the changes in
CO2 happened after the warming began, so CO2
doesn’t
affect atmospheric temperatures.
Half-true
but a
false conclusion.
At the end of the ice ages, variations in the
Earth’s orbit and the angle of its axis warmed the planet again.
Temperatures
began to increase, followed 200 to 2000 years later by rising CO2
concentrations. The fact that warming generally preceded the CO2
increases has often been misrepresented as somehow proving that
increases in CO2
do not contribute to global warming. In fact it proves nothing of the
sort.
What it demonstrates is that CO2 was not the
forcing that drove the initial
warming after periods of glaciation. The initial phase of warming
however, is
only a fraction of the total warming period. For example, during the
so-called
‘Termination
20.
Antarctica is cooling, so
that proves
the global climate isn’t warming
False.
While
parts of
The
climate in
Here
we show that significant warming extends well beyond the
The
Another
team used satellite observations from 1992
to 2006 covering 86% of
In
East Antarctica, small glacier losses in Wilkes Land and glacier gains
at the
mouths of the Filchner and Ross ice shelves combine to a near-zero loss
of 4±61
Gt yr-1. In
One of the authors of
this
study, Eric Rignot, emphasised that, “Without doubt,
Another
recent study found that mountain glaciers
and ice caps in
One
apparent paradox that is that Antarctic sea ice
cover increased since the late
1970s,
particularly during autumn, despite warming in both the atmosphere and
ocean.
The increase has not been uniform. Increases in the
The
model shows that an increase in surface air temperature and downward
longwave
radiation results in an increase in the upper-ocean temperature and a
decrease
in sea ice growth, leading to a decrease in salt rejection from ice, in
the
upper-ocean salinity, and in the upper-ocean density. The reduced salt
rejection and upper-ocean density and the enhanced thermohaline
stratification
tend to suppress convective overturning, leading to a decrease in the
upward
ocean heat transport and the ocean heat flux available to melt sea ice.
The ice
melting from ocean heat flux decreases faster than the ice growth does
in the
weakly stratified Southern Ocean, leading to an increase in the net ice
production and hence an increase in ice mass. This mechanism is the
main reason
why the Antarctic sea ice has increased in spite of warming conditions
both
above and below during the period 1979–2004 and the extended period
1948–2004.[131]
In
other words, two opposing factors seem to be at
work: The first factor is that warmer temperatures tend to reduce
sea-ice
growth. The second factor is that the reduction in sea-ice growth
reduces salt
rejection from the ice, which in turn reduces the salinity (and
therefore the
density) of the upper-ocean. The less dense upper-ocean water then
impedes the
upwelling of warmer waters to melt the ice from below. This second
factor,
impeding the upwelling heat available to melt the sea ice, has been
stronger
than the first factor, the warmer temperatures impeding ice growth. As
a
result, there has been a net increase in ice mass.
21. Action on climate change would ruin our
economies
False.
Quite the
opposite in fact, for five main reasons:
21.1 The conventional
economic estimates of the ‘costs’ of addressing climate change are small
The
IPCC noted that “In 2030 macro-economic
costs for multi-gas mitigation, consistent with
emissions trajectories towards stabilization between 445 and 710 ppm CO2-eq,
are estimated at between a 3% decrease of global
The
Australian Treasury found
similar figures for
Elsewhere,
for 2020, the Australian
Government’s White Paper states:
GNP is 1.3 per cent to
1.7 per cent below the reference case in 2020 in the CPRS [Carbon
Pollution
Reduction Scheme] scenarios, and up to 2.0 per cent below the reference
case in
the Garnaut Final Report scenarios. These
impacts are equivalent to about four months of economic growth,
implying
that the level of economic activity achieved in January 2020 in the
reference
case would be achieved in April 2020 in the CPRS scenarios.[134]
So
the
Australian Government’s modelling concluded that even reaching a target
of 25%
emissions reductions below 2000 levels by 2020 (which translates to 24%
below
1990 levels – the usual baseline used in international negotiations)
the net
economic impact would be likely to be only 0.1 percentage points
foregone from
real per capita GNP growth. To put that figure into some context, by
1942-43
If
we
accept the IPCC’s and Treasury’s modelling then, there are no serious
economic
impediments to strong action on climate change. But are there reasons
to doubt
this type of modelling? Yes – but these doubts only make the case for
action
even more compelling.
21.2 The conventional
economic estimates of the ‘costs’ of addressing climate change are not
the ‘net
costs’ – i.e. costs vs. benefits
The
key to the IPCC’s and Treasury’s framework is
the ‘baseline’ projections for GNP growth that are used to provide a
benchmark
against which to compare the ‘costs’ of mitigating climate change.
Regrettably,
these baselines generally do not take into account the economic costs
of
letting climate change run its course. The computable-general
equilibrium (CGE)
models used for this analysis are rarely well-integrated with dynamic
climate
models.[136]
For
example, in the OECD Environmental Outlook to
2030, some
of the most important sentences in the
whole report for understanding the implications of the economic models
are
tucked away in an appendix:
The OECD Environmental
Outlook …
shows the impact of the global economy’s development on the physical
world;
i.e. the environment. It does not, however, reflect the environmental
impact
back on the economy. Failing to provide this fully integrated picture
has two
implications. First, the Baseline fails to reflect
The
‘Baseline’
projection then, with which all policy responses are compared, does not
take into account the likely effects of climate change on the global
economy.
In Australia, the Garnaut
Review and Treasury analysis in Australia’s
Low Pollution Future, both used a ‘Garnaut-Treasury Reference
Case’ in
which emissions and GNP growth were projected as far as 2100.[138] . Critically,
as
Figure 7 shows, the likely impacts of unmitigated climate change on the
economy
are again not taken into account in
the reference case.
Figure
7. Chart 1
from the Australian Treasury’s analysis
Source: Australian
Government (2008a), pp. xii.
Box and arrow added.
For
example, Treasury says,
The
modelling does not include the economic impacts of climate change
itself,
so does not assess the benefits of reducing climate change risks
through
mitigation.[139]
The
reference scenario … presents a plausible future path for economic
growth, population levels, energy consumption and greenhouse gas
emissions in a
world without climate change. The reference scenario is not a
prediction and
does not include risks arising from climate change itself.[140]
Nor
apparently, are the constraints of natural
resources or sinks considered, since global output in the reference
case is
projected to be 17 times current levels by 2100.[141]
The
Garnaut Review further noted that, “By the end of the century, the
concentration of long-lived greenhouse gases is 1565 ppm CO2-e,
and
carbon dioxide concentrations are over 1000 ppm – more than 3.5 times
higher
than pre-industrial concentrations.”[142]
The
consequences of such a drastic rise in emissions have no impact on
economic
growth in the reference case.
While
it is useful to conduct such a modelling
exercise to get a sense of where global economic and emissions trends
are
leading us, it is quite another matter to suggest that comparison with
such a
‘reference case’ constitutes a useful basis for estimating the ‘costs’
of
mitigating climate change. The Garnaut
Review, to its credit, acknowledged this problem and tried to
estimate the
costs of climate change on the economy, distinguishing four types of
costs,
only the first of which could be estimated with any confidence.[143]
The
Treasury analysis did not do this, instead presenting results as
“Overall
mitigation cost, 2010-2050” (p. xii) for the various scenarios, with
the
‘costs’ of mitigation presented as being around 0.1 percentage points
of annual
GNP per capita growth. It
also asserts:
All
scenarios show
The
introduction of emission pricing will reduce
These
statements however, are quite misleading
presentations of the results. While it is true that in the context of
the
model, emissions pricing reduces GNP relative to the reference
scenario, this
result cannot be transferred to the real world with any great relevance
beyond
the first few years. It cannot be asserted for example, on the basis of
this
modelling exercise, that
The
methodology used in the Treasury analysis
guarantees by assumption that any
serious mitigation efforts will look like a net cost because they are
being
compared with an imaginary economic growth trajectory in which climate
change
does not exist. In fact, the modelling approach used does not allow us
to say
anything about the real world net costs of
mitigation since the exercise must be viewed over a multi-decade time
frame, during
which unchecked climate change would certainly lead to major economic
impacts.
The baseline ‘reference case’ cannot occur because it ignores the
impacts of
climate change on the economy. A model that fully integrated the global
economic and climate systems would be far more likely to show that
strong
mitigation action is the only way to prevent catastrophic climate
change and so
ensure that we retain a living standard even comparable to today, let
alone
global output being 17 times greater than today and Australian incomes
per
capita being US$137,000 in 2100 compared with US$36,000 in 2005 as the Garnaut Review envisages.[147]
In
summary, projecting a reference case for
economic growth out to 2050 or 2100 based on past experience and
‘business as
usual projections’, as if climate change was not happening, does not
constitute
an adequate basis for comparing the costs and benefits of mitigation
measures.
It is like deciding whether or not to hose a house down based purely on
the
cost of the water, ignoring the fact that the house is on fire.
21.3 Much economic analysis
tends to grossly underestimate the likely costs of unmitigated climate
change.
Most
economic analysis of climate change simply presumes that economic
growth will
continue onward and upward, regardless of any impacts climate change
might have
on economies and societies. Most economic models are not well
integrated with
biophysical, political or financial models. So they cannot, for
example,
examine the effects of famines and mass migrations on the stability of
governments, the likelihood of conflict and the impacts on investment
decisions
and financial markets. Neither can they account for the impacts of
sea-level
rise on coastal property values, financial markets and insurance
markets.
For
example,
once ice sheet dynamics are taken into account, sea-levels are likely
to rise
at least 0.8 m and possibly even 2 metres by 2100.[148]
Even a
one metre sea-level rise would impact around 105 million people in
Most
of
Figure
8. Likely climate impacts in
The
sea-level issue is particularly important since it is often assumed
that
sea-level rise represents a slow, progressive inundation that is
relatively
straightforward to manage. But one of the greatest dangers from higher
seas are
the storm surges which accompany tropical storms and which can often be
5-7
metres high. The storm surge accompanying cyclone Nargis in
As
the
science relating to sea-level rise continues to consolidate over the
next
decade, the potential for future sea level rises and associated
shoreline
erosion and storm surges are likely to have very serious implications
for
coastal property values and insurance premiums around the world. A
critical point
is that the sea-level rises do not have to have taken place yet for
projected
rises to have immediate economic effects. Properties used for loan
collateral
may be devalued by lenders and land taxes may become delinked from
falling
property values. Over time insurance premiums may also climb across
entire
economies if losses in coastal areas and from extreme weather events
are
cross-subsidised by insurance companies from elsewhere. These climate
system-financial market links do not appear to be captured by current
modeling.
Questions
are already being raised in
Other
major international impacts noted by
Key
Australian export markets are projected to have significantly lower
economic
activity as a result of climate change. This is likely to feed back
into
significantly lower Australian export prices and terms of trade.[155]
Weather
extremes and large fluctuations in rainfall and temperatures have the
capacity
to refashion
Climate
change can generate security risks through infectious disease. … A
study by the
World Health Organization (2002) estimated that 154 000 deaths annually
were
already attributable to the ancillary effects of climate change due
mainly to
malaria and malnutrition. The study suggests that this number could
nearly
double by 2020.[157]
In
the future … climate refugees could constitute the fastest-growing
proportion
of refugees globally, with serious consequences for international
security.[158]
The
geopolitical implications of water projections in
The
Consultative Group on International Agricultural Research (2002) has
predicted
that food production in
In
2008
there were food riots in more than 30 countries as the price of food
staples
skyrocketed due to several factors that included reduced harvests due
to
drought and diversion of land to first-generation biofuels. Food prices
are
closely tied to economic and political stability and so can have major
economic
impacts beyond their first-round effects.
The
IPCC also noted that
The
gross per capita water availability in India will decline from about
1,820 m3/yr
in 2001 to as low as about 1,140 m3/yr in 2050 …
India will reach a
state of water stress before 2025 when the availability falls below
1000 m3
per capita.[163]
There
is substantial potential for tension between
There
are enormous humanitarian and security implications of probable
widespread
water shortages across
Like
most economic analyses which are unable to incorporate the nonlinear
effects of
major conflicts into their economic models, the Garnaut
Review noted these concerns, but downplayed their likely
economic impacts:
Climate
change may lead to geopolitical instability, which will require an
increase in
the capability and requirements of
It
is
of course extremely difficult to envisage the economic and social
consequences
of geopolitical instability, but the outlook is sobering. Island states
of the
Pacific face increasing pressures, and in
On
balance it is likely that the total economic costs of future
geopolitical
tensions in
21.4 Industries tend to
overestimate the costs of adjustment to emissions reduction policies
Another
reason much of the discussion about the economic costs of addressing
climate
change are likely to be overestimated is because the industries
lobbying
against the changes have every incentive to overestimate the impacts in
order
to persuade governments to be less stringent with regulations and more
generous
with assistance packages. Around the world as governments have prepared
to
introduce emissions trading schemes or carbon taxes, industries have
lined up
to explain why such measures would ruin them. It is instructive to
analyse what
actually happened to industries in the past when such measures were
introduced.
In
While
fighting the introduction of a new law, companies have every inventive
to
overstate the compliance costs. Once a new law is introduced resources
are at
least partially switched to innovating to minimize compliance costs.
21.5 Current markets and
industrial structures are distorted by two centuries of misleading
price
signals
Some
policymakers and elected
officials are concerned that measures to address climate change could
be
‘market distorting’ and therefore ‘inefficient’. This perspective needs
to be
challenged because it rests on an unspoken assumption that the current
market
environment is efficient. In fact, the entire problem of anthropogenic
climate
change has been caused by the most colossal market failure in history –
the
failure of prices to reflect the true costs of emissions for the last
200
years. Our markets and our entire industrial structure are currently
distorted
by this long-term market failure and also by explicit subsidies to
emission-intensive
fuels and industries.[170]
Markets
do not exist in a vacuum.
They rest on complex legal foundations that include standards,
regulations,
contract and employment law, human rights law, dispute resolution
mechanisms
and so on.[171]
Real-world markets are also
characterized by imperfect information and information asymmetries,
principal-agent problems (eg. lack of incentives for landlords to
improve
energy efficiency for tenants), imperfect credit and risk markets,
coordination
failures, rent-seeking by firms, rapidly evolving technologies, and
natural
monopolies (such as rail or fibre-optic network infrastructure).
Today,
new low-carbon industries are
trying to establish themselves and compete with established
emissions-intensive
industries on a playing field that is severely distorted in favour of
heavy
emitters. It is entirely appropriate that a raft of policy measures be
used to
correct this distortion. Such measures should include market measures
such as
emissions trading, but in the context of a highly distorted market,
policymakers should not assume that others measures are ‘market
distorting’ or
‘sub-market’.
Measures
such as higher efficiency
standards, subsidies for low-emissions renewable technologies, public
investment in network infrastructure and so on would, in fact, make the
market
more efficient by enabling the price signals it sends to better reflect
the
true costs of emissions.
Current
markets and industrial
structures are highly distorted by the pervasive externality of the
historic
failure of prices to reflect the true costs of emissions. Correction of
these
distortions through a combination of market-measures, regulations,
subsidies
and standards should not be viewed as ‘market-distorting’ but ‘market
correcting’, ensuring that prices better reflect the true costs of
emissions.
As
the
true costs of greenhouse gas emissions come to be better reflected in
prices,
and as energy efficiency standards are tightened we see the emergence
of a
clean industrial revolution with thousands of new jobs being created.
Many of
these are labour-intensive, blue collar jobs – both in rural and urban
areas:
building new distributed renewable energy systems and smart power
grids,
retrofitting buildings and homes, building new mass transit
infrastructure,
installing renewable energy systems at large and small scales, and so
on.[172]
General remarks
In
June
2009 the US Government released a comprehensive assessment of the
impacts of
climate change on the
It is
clear that climate
change is happening now. The observed climate changes we report are not
opinions to be debated. They are facts to be dealt with.[174]
Many
who describe themselves as ‘skeptics’ however,
continue to distort the public debate on climate change, portraying
themselves
as a courageous band of level-headed rebels struggling against a vast
global
conspiracy to deceive the world and take away our freedom. If only it
were
true. If any one of them had been able to offer convincing evidence
that
anthropogenic greenhouse emissions were not contributing to climate
change they
would have received the Nobel Prize instead of the IPCC, along with the
thanks
of a grateful world.
Instead,
those who contest the link between
anthropogenic emissions and climate change tend to concentrate on CO2,
ignoring
the other very potent greenhouse gases human beings have released. They
also,
bizarrely, frequently attribute this fixation to climate scientists,
accusing
them of focusing solely on CO2 and ignoring
factors such as water
vapour. Even a cursory examination of the IPCC’s Fourth
Assessment Report shows this to be nonsense. They also tend
to make a great deal of minor discrepancies in atmospheric temperature
data and
year-to-year fluctuations, largely ignoring the huge body of other
evidence for
climate change and its impacts such as:
·
The
widespread melting of glaciers[175]
·
The
accelerated melting of the
·
Unexpectedly
rapid sea-level rise[177]
·
Tens
of thousands of observed changes in species
ranges and timing of annual ecosystem events[178]
·
Rapid
Arctic ice melting, well ahead of
expectations[179]
·
The
warming of the oceans[180]
·
The
acidification of the oceans due to CO2
absorption[181]
·
The
spread of oxygen-starved dead zones in the
oceans[182]
·
Changing
hydrological and rainfall patterns with
more extreme rainfall events[183]
·
Changes
in the height of the tropopause, the
boundary between the troposphere and stratosphere[184]
·
The
cooling of the stratosphere due to more heat
being trapped in the troposphere below[185]
·
The
expansion of the Earth’s tropical belt, and
consequent movement of the subtropical dry zones and jet-streams
towards the
poles[186]
·
The
greater intensity of cyclones[187]
·
Influence
of CO2 levels on past climate
changes[188]
Those
opposed to strong emissions reductions also
seem remarkably cavalier about the possibilities of long-term
consequences,
many of which are irreversible, including:
·
Sudden
shifts in the climate system[189]
·
Dramatic
oscillations in the climate system[190]
·
A
decline in the effectiveness of natural CO2
sinks, accelerating atmospheric CO2 accumulation[191]
·
A
reinforcement of human-induced emissions by
carbon-cycle feedbacks[192]
·
The
potential for large releases of methane from
melting permafrost and marine deposits[193]
·
Multi-metre
sea-level rises as warming continues
after 2100[194]
·
The
high probability that warming induced by our
emissions would last for many thousands of years[195]
·
The
likelihood of significantly greater insect
predation on forests and food supplies[196]
·
The
likely expansion of the world’s deserts[197]
·
Threats
to global food security[198]
·
Threats
to global freshwater supplies[199]
·
Threats
to human health[200]
·
Species
extinctions and threats to biodiversity[201]
·
The
commitment of ecosystems to further
deterioration, such as the dieback of the Amazon, for decades after
temperatures are stabilised[202]
·
A
significant, potentially permanent, deterioration
in international security and the emergence of major conflicts[203]
·
A
legacy that could amount to the greatest
wholesale violation of the rights of children in human history.[204]
In
their
book Poles Apart: Beyond the Shouting,
Who’s Right About Climate Change, authors Gareth Morgan and
John McCrystal
set out to weigh the evidence on human contributions to climate change.
Trying
to be as fair as possible to different views, they engaged two separate
panels
of expert advisers, one representing mainstream climate scientists, and
the
other the skeptics,
to
guide them through the best evidence on both sides.
Their conclusion, though polite, was damning:
The Alarmists were right, and we shouldn’t
call them alarmists any more – or at least not all of them! And
further, it has
to be said that only a few of the Sceptics are actually sceptics: too
many are
mere gadflies and deniers.[205]
Perhaps
the most forceful recent condemnation of those who continue to deny
that
greenhouse gas emissions from human activities are contributing to
climate
change came from the winner of the 2008 Nobel Prize in economics,
Professor
Paul Krugman. Writing after the vote on the Waxman-Markey climate
change bill
in the US Congress, Krugman considered the implications of unmitigated
climate
change for the
So the
House passed the
Waxman-Markey climate-change bill. In political terms, it was a
remarkable
achievement. But 212 representatives voted no. A handful of these no
votes came
from representatives who considered the bill too weak, but most
rejected the
bill because they rejected the whole notion that we have to do
something about
greenhouse gases. And as I watched the deniers make their arguments, I
couldn’t
help thinking that I was watching a form of treason – treason against
the
planet. To fully appreciate the irresponsibility and immorality of
climate-change denial, you need to know about the grim turn taken by
the latest
climate research. The fact is that the planet is changing faster than
even
pessimists expected: ice caps are shrinking, arid zones spreading, at a
terrifying rate. And according to a number of recent studies,
catastrophe – a
rise in temperature so large as to be almost unthinkable – can no
longer be
considered a mere possibility. It is, instead, the most likely outcome
if we
continue along our present course. …
… if
you watched the debate
on Friday, you didn’t see people who’ve thought hard about a crucial
issue, and
are trying to do the right thing. What you saw, instead, were people
who show
no sign of being interested in the truth. They don’t like the political
and
policy implications of climate change, so they’ve decided not to
believe in it
– and they’ll grab any argument, no matter how disreputable, that feeds
their
denial. …
…
Still, is it fair to call
climate denial a form of treason? Isn’t it politics as usual? Yes, it
is – and
that’s why it’s unforgivable. … the existential threat from climate
change is
all too real. Yet the deniers are choosing, willfully, to ignore that
threat,
placing future generations of Americans in grave danger, simply because
it’s in
their political interest to pretend that there’s nothing to worry
about. If
that’s not betrayal, I don’t know what is.[206]
Strong
language indeed. But when we consider, as Krugman does, the fact that
the most
recent scientific projections are considerably more dire than even a
few years
ago, strong language is justified. The team at the Massachusetts
Institute of
Technology for example, recently undertook a comprehensive reassessment
of the
likely outcomes if we do not act decisively to rein in emissions. In
2003 they
had concluded that the median likely outcome (with 50% of projections
above and
below the median) was 2.4°C
of warming above 1990 levels, or 2.9°C
above pre-industrial levels.[207] In
their recent
reassessment, based on a significantly improved model and improved
input
parameters, they increased this median projection to 5.2°C,
with a 90% probability range of
3.5°C to
7.4°C above 1990
levels, or equivalently a 5.7°C median with a 90% range of 4.0°C to
7.9°C above
pre-industrial levels.[208]
The word ‘disaster’ hardly begins to
capture the consequences of warming anywhere close to 5.7°C
above pre-industrial levels, let alone 7.9°C.
Science
is driven by genuine inquiry and genuine
skepticism. But continued denial of overwhelming evidence from multiple
sources
is not genuine skepticism. Denial is understandable from a
psychological point
of view – no-one wants the projections of severe climate change to be
true. But
dressing up denial in scientific obfuscation does not contribute
constructively
to the public policy debate. Like those who continued to deny the links
between
smoking and cancer and between HIV and AIDS long after the evidence was
in,
those continuing to deny the links between greenhouse gas emissions and
climate
change are using specious arguments that have been repeatedly shown to
be
false, weak or irrelevant in the peer-reviewed scientific literature in
order
to try to thwart action. Those earlier cases of denial were serious
enough. But
when we consider what now is at stake for our societies, for the poor,
for our
children, for the other species on our planet, and for future
generations,
strong language is not inappropriate. It is time to listen to the
warnings of
the scientists and to pull together to prevent a catastrophe
unparalleled in
human history.
Acknowledgments
I
am grateful to Roger Jones, John Finnigan,
Christian Jakob, Neville Nichols, Kamal Siddiqui, Brett Inder, Will
Steffen, Jeff
McLean, Ed Lockhart, Simon Angus, Behrooz Hassani-M., Dave Batten,
Simon Angus,
Roger Bradbury, Anne-Marie Grisogono, Rachel Coghlan, Gerard Finnigan,
Bill
Pheasant, Melanie Gow, Paul Ronalds, Tim Costello and David Lansley for
useful
discussions and particularly to Barry Brook, Andrew Glickson, Dave
Griggs,
Greame Pearman, Tony Kevin, Mike Raupach, Beth Fulton, Michael Ashley,
Chris
Shore and Julie Tanaka for comments on an earlier draft. None are
responsible
for the opinions expressed here, or for any remaining errors.
Author
Note
Dr
Brett Parris is a
Research Fellow at
http://www-personal.buseco.monash.edu.au/~BParris/
