Human Activity and Climate Change
+ Cardinal George Pell, Archbishop of Sydney
31 Jan 2010
In 2007 the Vatican sponsored a meeting in Rome on climate change and opinion was divided between believers and sceptics.
All Christians acknowledge the duty to respect creation and preserve the environment for future generations as well as not burdening them with huge, unnecessary debts.
All Catholics should seek the truth, but there is no church line on the role of human activity in rising or falling temperatures. We can agree to disagree.
We need more scientific debate as we strive to separate the central issues from the distractions and judge conflicting claims.
The issue is too important and the measures proposed too expensive for us to leave everything to the scientists and politicians. The rest of us also need to inform ourselves.
As always it is useful to try to identify points of agreement before listing the disputes.
The world's climate has changed drastically over the millennia. Our planet has experienced Ice Ages (is one overdue?) and warmer centuries, while unpredictable change continues.
Temperatures have increased by less than one degree Celsius since the middle of the nineteenth century. For a few hundred years beforehand there was a cooler period, a little Ice Age.
In the same period with the coming of the Industrial Revolution carbon dioxide has increased by 30 per cent.
Carbon dioxide is not a pollutant, but part of the stuff of life, and constitutes only a minute percentage of the atmosphere. It is a minor greenhouse gas with methane and nitrous oxide, which inhibit cooling, but water vapour and high clouds are the major greenhouse substances.
The debate centres on the claims that humanly produced rising carbon dioxide levels will raise temperatures to dangerous levels.
There is no scientific consensus on this issue, despite contrary bluster and more and more plausible evidence to the contrary. Science is decided by evidence and the hypotheses which best explain the evidence.
One major scandal is the implication that the existence of some warming, some greenhouse effect, necessarily implies a catastrophe. We have coped with this before as London was able to produce grapes in some eras while at other times the Thames river was frozen regularly. I would not want Sydney weather to change too much, but a Tasmanian climate like Brisbane's would be an improvement.
Most computer models failed to anticipate the absence of warming over the past decade.
Next week I shall continue the story.
