Tim Flannery: The coal conundrum

Last March, James Hansen, arguably the world’s leading climate scientist, and eight colleagues, claimed earth’s climate system was about twice as sensitive to carbon dioxide pollution as the Intergovernmental Panel on Climate Change had found. This implies that there is already enough greenhouse gas pollution in the atmosphere to cause 2 degrees of warming, bringing about conditions not seen on earth for 2 to 3 million years and constituting, according to the authors, “a degree of warming that would surely yield dangerous climate impacts”.

Hansen and his colleagues summarise the challenge as follows: “If humanity wishes to preserve a planet similar to that on which civilisation developed and to which life on earth is adapted, palaeoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385ppm [parts per million] to at most 350ppm.” This, they argue, can only be achieved by phasing out all conventional coal burning by 2030, and by aggressively reducing the amount of CO2 in the atmosphere by capturing it in growing tropical forests and in agricultural soils. That a rapid phase-out of coal is in itself not enough is elegantly illustrated by the fact that the concentration of CO2 in the atmosphere would remain above 350ppm for 200 years were a coal phase-out to be achieved within the next decade or two, and nothing else done. Yet the point of no return is, in all probability, less than 20 to 40 years away.

So just how large is the task of replacing the current fossil fuel-based energy supply (in particular, conventional coal burning) with other non-polluting fuel sources? On April 3, the researchers Roger Pielke, Tom Wigley and Christopher Green published a study examining the IPCC projections that guide current thinking on the extent to which emissions need to be reduced. Shockingly, they discovered that the IPCC projections underestimate the scale of the task by two-thirds.

The reason for this is that the lion’s share of the emissions reductions required in the future are already “built in” to the IPCC scenarios. In other words, the IPCC assumes that these reductions will occur anyway, even in the absence of specific policies aimed at producing the shift. While such an assumption may seem remarkable, it was based on the observation that improvements in technologies – and in particular in their efficiency – occur over time.

Thus internal combustion engines have become more efficient, as have refrigerators and countless electrical appliances. But can we expect that such efficiencies will lead to a slowing in the overall rate of greenhouse-gas pollution, regardless of government policy? The answer came when the researchers examined the relevant changes in the real world that had occurred over the first eight years of the 21st century. Dismayingly, they discovered that no “built-in” emissions reductions were occurring; in fact, exactly the reverse was happening, for the efficiency of global energy use (measured as energy intensity) and carbon intensity (pollution) have both risen over the period.

Sydney Morning Herald