We greatly enjoyed the huge response to
our article about climate change. It
is clear that there is both a great deal of interest and a
great deal of confusion about the science of climate change,
write Doug Mackie, Hugh Doyle and Paul Young.
We have compiled some of the most common scientific claims
taken from the 940 submissions made about the Emissions
Trading Scheme and we invite comments and questions.
If this is successful we will add more claims later but for
now we will only respond to comments that are on topic. We
have excluded non-scientific claims (eg"It is all a hoax"),
but can come back if there is interest.
Please click on the image above for a clear view of the
graphic.
Not since.
This was the topic of our last article and is the idea that
"the slight warming that occurred between 1979 and 1998 has
been followed by stasis and, since 2002, cooling."
To the right are the graphs we used to show this claim is
invalid because such short time periods are weather, not
climate.
2. Natural cycle.
This is the idea that climate
varies naturally and that current variation is due to changes
in a stated factor (such as solar output or El Nino). We
agree climate varies naturally.
However, natural changes and human-induced changes are not
exclusive.
Please click on the image above for a clear view of the
graphic.
The current change in atmospheric CO2 is superimposed
over and above natural changes. Furthermore, the rate of
current change is unprecedented for at least the last 8 "ice
ages", further suggesting it is not natural. At the end of an
ice age CO2 typically goes up by about 100 parts per million
(ppm) over about 10,000-15,000 years (i.e. less than 0.01 ppm
per year). Currently CO2 is increasing at more than 2 ppm per
year. This is over 200 times faster than changes associated
with the natural CO2 cycle.
3. Carbon cycle
We included this because it has
increased hugely in popularity; 18th in 2008 to 12th in
February 2009 to 4th place in October 2009. This claim states
agricultural emissions are a closed cycle and do not require
regulation because grass takes up CO2, cows eat grass and
belch methane and then the methane is oxidised to CO2 and
taken up by the grass.
However, this neglects the fact that methane is better at
trapping heat than CO2 and until the methane is oxidised
(about 8 years) it causes extra warming.
It is like saying because you borrowed $100,000 at 9% for 8
years and then earned 4% interest on $100,000 saved for 8
years that your finances are balanced.
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