The publication of the new report by the Intergovernmental Panel on Climate Change is a landmark moment. The report states that the UN-backed body of international scientists is 95% certain that half of the global warming seen in the years covered by the report is man-made. The other 50% of the warming effect is presumably perfectly natural and is therefore acceptable. This natural warming is to be borne with gritted teeth and a sigh of weary acceptance. If sea level does eventually rise by a metre, then I shall curse the man-made half of the rise, but I will try to enjoy the other half of the sea level rise, like I might enjoy a lovely natural organic hummus wholemeal baguette.
It might not come as a surprise to regular readers of this column, but I must count myself among the sceptics about the new report. I wonder though, for a start, about the 5% of doubt that remains about global warming. Does that mean that 5% of the scientists are 100% sceptical about the theory, or that perhaps 15% are 33% sceptical? This quantification of scepticality is a mystery to me: I wonder what are the units used in measurement? Was there an online survey? I must have missed it. It sounds to me like they waved their hands around and plucked that number from the air.
Although it seems that the planet has been warming slowly for the last few hundred years (since before the Industrial Revolution - go figure), we seem to have arrived at a bit of a plateau. The report largely glosses over the increasingly lengthy pause (or 'hiatus' as the report prefers to call it) in global average temperatures, which have remained within 0.1°C - within the bounds of measurement error - for the last 16 years. During the same period, global average temperature were forecast to rise by up to 0.9°C (see the chart at the right, from the Global Warming Policy Foundation). Please forgive my naivety, but it seems to me that the models used to make the forecasts are plainly wrong since they have failed to correctly predict what would happen (as my childhood anti-hero Molesworth might have written, "As any fule kno"). My bewilderment at the wrongness of the models leads me to ask, 'In what way are they wrong?' Could it be that the models have forgotten to include some important physical process that could hide the extra heat? In fact, the IPCC suggests that the 'extra' heat that their models suggested would have shown up by now has somehow been conveyed into the deep oceans, where there are (in)conveniently few measurement probes to prove or disprove the theory. The physical means of mixing the heat into the deep oceans has additionally yet to be specified.
Could it be that the models have understated other important physical processes that might provide a negative feedback on global warming, or have overstated their warming potential? Perhaps chief among these is the role of water vapour in the atmosphere, which accounts for between a third and two thirds of the greenhouse effect1. With more water vapour in the atmosphere due to warming, we might expect to have more radiation-reflecting clouds, reducing the overall warming effect. Water vapour is the elephant in the room - it's big, but nobody is talking about it.
And finally, I wondered if CO2, the millstone that has been hung around the neck of global energy-intensive industry, is quite the problem that it has been made out to be. I put this out there for discussion: what if the global warming models are too sensitive to the concentration of CO2 in the atmosphere? After all, there has been a steady increase in measured CO2 concentrations (I'm not denying that - just look at the graph) but there has been no corresponding increase in global average temperature (at least not for the last 16 years). As one Australian professor recently said to me, "CO2 is plant food, after all!" What if the significance of CO2 to climate change has been overplayed? In that case, surely, the cost of carbon emission credits should be even lower than it is today, making suggested mitigation efforts like carbon capture and storage (CCS) even less economic.
We all need to look after the planet and conserve our resources: by 2050 there will be 9 billion of us on the planet. However, I have the feeling that when we look back in 25 years' time at the current decarbonisation 'war' on industry, we will all scratch our heads and ask ourselves, "What was all that about?"
1: http://en.wikipedia.org/wiki/Greenhouse_gas#Role_of_water_vapor
