Physics, Power and Climate Change

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Speaker: Professor David Jamieson (University of Melbourne)
Date: 6th May 2011

Although the human responses to climate change are volatile, the laws of Physics are not.  Since the 1905 Chemistry Noble laureate Svante Arrhenius first modelled the greenhouse effect on the temperature of our planet little has changed from his prediction of a 2.1 degree Celsius temperature rise for a doubling of the 1905 CO2 levels in the atmosphere.  Today, with greatly improved physical models, the prediction is between 2 and 4.5 degrees under the same scenario.  Physics helps us understand the past, present and future scenarios for the climate of our planet.  The Physics tells us very clearly that continuing with our present high carbon emission and energy intensive lifestyle will cause significant climate change.  The numbers also tell us about who is most vulnerable to climate change and that they are not the present high energy users.  The Garnaut report recommends we reduce our carbon emissions by 80 percent or more by the middle of the century.  Just as you would not attempt to buy a house without carefully looking at your financial budget and future earning capacity, working out what to do about our emissions and climate change requires us to look at our present and future energy budget.  More serious is the confusion between energy and power.  It is power that drives our civilisation, not energy.  The path from energy to power is via the second law of thermodynamics which constrains alternative sources of power despite apparently abundant energy in those sources.  Yet even among numerically literate Physicists there is little understanding of the numbers of Joules consumed by a major Australian city each year or the number of Watts needed for mundane tasks like driving a car, flying in a 747 or running a University.  Without reference to the numbers there are many options.  With reference to the numbers the options greatly narrow.  As this lecture describes, it will be a challenge for present and future Physicists to overcome these difficulties and chart the uncertain future.