Transcript U3A-ClimChange01 4442KB Oct 07 2012

CLIMATE CHANGE
THE GREAT DEBATE
Session 1
IS CLIMATE WARMING?
• There is tremendous short term variation in
climate
• This means that we need long-term records
to show a warming trend
• Most long-term records are from stations
that are located in cities
• Since the beginning of the industrial
revolution cities have experienced rapid
increases in local warming from heat
generated by industrial, domestic and
transport sources
• Can we trust such records?
BELIEVERS AND SCEPTICS
• Believers say that we are seeing the
onset of very rapid climatic warming
that is being caused by the emission of
large amounts of greenhouse gases
and that urgent action is required to
deal with it
• Sceptics say that climate is always
changing and that the present rate of
change is not unusual compared with
others in recent history
AUSTRALIAN BELIEVERS
• Dr Berry Pittock is a climatologist with
CSIRO and author of the book: Climate
Change – turning up the heat
• Dr Tim Flannery is a zoologist who has
recently retired as Director of the South
Australian Museum. He is a prolific
author and has written the book: We
are the Weather Makers
Tim Flannery in full flight!
AN AUSTRALIAN SCEPTIC
• Ian Plimer is a geologist and professor
at the School of Earth & Environmental
Sciences at the University of Adelaide.
• He is author of the book: Heaven and
Earth (Global warming: the Missing
Science).
• He has received many honours and has
always been heavily involved in the
mining industry. He even had a mineral
named after him: plimerite
CLIMATE CHANGE – A
POLITICAL FOOTBALL?
• The Australian Labour Party strongly
supports the believers and has
introduced the Carbon Tax in an
attempt to rein in the ever growing use
of fossil fuels
• The Liberal Party, supported by the
mining industry, strongly opposes the
introduction of such a tax and
frequently quote the work of Ian Plimer
who denies that human activities are
responsible for climate change
WHAT TO BELIEVE?
• Much of the temperature increase since
1880 may be due to growing urban heat
islands
• Not all recent temperature changes can
be due to CO2 increase in atmosphere
because temperatures dropped
between 1940 and 1970 while CO2
content was increasing
Climate at Puntas Arenas shows a cooling trend
Why should that be?
WHAT HAPPENED?
• Why has the temperature in Punta
Arenas cooled between 1888 and 2004
while world temperatures appear to
have been rising?
• Could temperature changes in the
Southern Hemisphere be out of phase
with the Northern Hemisphere?
• If Punta Arenas is getting cooler why
are the glaciers in the Antarctic
Peninsula retreating rapidly?
Three rural stations
in New York state
also show a decline
in mean annual
temperature between
1930 and 2000
But what about
New York City?
The climate in New York City is getting warmer!
PARADIGM
• What is a paradigm? In science, the
word describes distinct concepts or
thought patterns in any scientific
discipline (Wikipedia)
• The vast majority of climate scientists
subscribe to the paradigm that any
increase in greenhouse gases in the
atmosphere causes climatic warming
WHAT ARE GREENHOUSE
GASES?
• The earth radiates long-wave (infrared)
radiation and some of that radiation is
intercepted by certain gases in the
atmosphere and stored as heat energy
• Naturally occurring greenhouse gases are
water vapour, carbon dioxide and methane.
• Carbon dioxide and methane concentrations
have increased dramatically since the
beginning of the industrial revolution
CARBON DIOXIDE
• Large amounts of carbon dioxide are
produced by the burning of fossil fuels
such as coal, oil and natural gas
• Burning of natural vegetation has also
made a significant contribution
• Concentration in the atmosphere has
increased from 280 ppm(v) in 1800 to
392 ppm(v) in 2012
• Seasonal changes are due to variations
in vegetation activity in the Northern
Hemisphere
METHANE
• Methane is produced in swamps, by grazing
animals, burning fossil fuels, wet rice
cultivation and decomposition of organic
matter in landfills
• Concentration in the atmosphere has
increased from 700 ppb(v) in 1800 to 1840
ppb(v) in 2012 but the increase has slowed
since about the year 2000
• It is a more powerful greenhouse gas than
carbon dioxide but breaks down slowly in the
atmosphere
A TEMPLE FOR BELIEVERS
• The Intergovernmental Panel on
Climate Change (IPCC) is the leading
international body for the assessment
of climate change established by UNEP
and WMO to provide the world with a
clear scientific view on the current
state of knowledge in climate change
and its potential environmental and
socio-economic impacts (their words)
IPPC
• It is a scientific body. It reviews and
assesses the most recent scientific,
technical and socio-economic
information produced worldwide
relevant to the understanding of
climatic change. It does not conduct
any research nor does it monitor
climate related data or parameters
• Currently 195 countries are members
GOVERNMENT SUPPORT
• By supporting the IPCC financially most
governments can be seen to be doing
something about climatic warming without
necessarily making hard decisions such as
introducing a carbon tax which would impact
on the standard of living of their populations
• Australia is one of the few exceptions but it
produces only 1.3% of the world’s carbon
dioxide emissions and it remains to be seen
whether the tax will be effective
PREDICTING CLIMATE CHANGE
• Computer models use the latest super
computers to try and predict climatic
warming over the next few decades
• Sceptics point out that these models
are a far cry from the complexity of the
real Earth especially as they vary only
the input of greenhouse gases and
neglect the effects of many other
processes that affect the Earth’s
climate over time
PAST CLIMATE CHANGE
• By studying past climate change we
can expect to improve our
understanding of the multitude of
processes involved and how they may
effect the Earth’s climate in the future
• We will look at three different time
scales: total Earth history, the
Quaternary Ice Age and the Holocene