TCS Daily


'Technically Unsound'

By Hans H.J. Labohm - February 24, 2003 12:00 AM

Question: How can science prove that the apocalypse will happen in a century from now? Answer: Use models, introduce some small biases in the beginning and because of the logic of compounded interest one will surely end up with the apocalypse in due time.

Question: Has this approach already been successful in the past? Answer: Yes, very successful indeed! According to the first Report to the Club of Rome, we should have been in the middle of the apocalypse by now.

Why should one want to alarm the public in that way? Stephan Schneider, a prominent spokesman for the Intergovernmental Panel on Climate Change (IPCC) provides the answer: 'On the one hand, we are ethically bound to the scientific method, in effect promising to tell the truth, the whole truth, and nothing but ... which means that we must include all the doubts, caveats, ifs, and buts. On the other hand, we are not just scientists, but human beings as well. And like most people we'd like to see the world a better place, which in this context translates into our working to reduce the risk of potentially disastrous climatic change. To do that we have to get some broad-based support, to capture the public's imagination. That, of course, entails getting loads of media coverage. So we have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have.'

In a nutshell this has been the guiding principle of the United Nations' Intergovernmental Panel on Climate Change (IPCC). It has 'projected' an increase in the globally averaged surface temperature by 1.4 to 5.8 C over the period 1990 to 2100. Given the recent weather conditions on the east coast of the United States, many Americans would perhaps love that idea, but the higher end of the range is expected to produce all kinds of harmful effects for mankind worldwide.

Are the IPCC scenarios based on science? And is the science really settled? Well ... eh .... not exactly. Hidden in a footnote of one of the recent IPCC reports it is acknowledged that climate is a non-linear stochastic system. This is scientific slang which in everyday language implies that prediction is impossible. Or, in the words of Dr. James Hansen, who is reputed to have invented the notion of man-made global warming, but subsequently changed his mind: 'The forcings that drive long-term climate change are not known with an accuracy sufficient to define future climate change.' And this of course also applies to man-made CO2 emissions.

How does one calculate future man-made CO2 emissions? Since these emissions are linked to worldwide economic growth another set of models is required: economic models this time, the outcomes of which are used as inputs into the climate models.

What are the growth projections for the next century? Fortunately, they are excellent, as a recent issue of the Economist (February 13th 2003) dryly reveals: '[...] even for the lowest emission scenarios, the average income of South Africans will have overtaken that of Americans by a very wide margin by the end of the century. In fact America's per capita income will then have been surpassed not only by South Africa's, but also by that of other emerging economic powerhouses, including Algeria, Argentina, Libya, Turkey and North Korea.'

Enter two distinguished commentators - Ian Castles of the National Centre for Development Studies at Australian National University, formerly the head of Australia's national office of statistics, and David Henderson of the Westminster Business School, formerly the chief economist of the OECD - who have put together a critique of the IPPC's Special Report on Emissions Scenarios. Their main criticism is that the scenario-builders have based their projections of future output on national GDP estimates which have been converted to a common measure using market exchange rates. This procedure leads them to overstate the initial gaps in average incomes between rich and poor countries - because prices tend to be much lower in poor countries. Therefore, they should have been based on purchasing power parities instead. Those gaps are in turn crucial for the IPCC's projections, because the method used in the scenarios assumes not only that the rich countries will continue to get richer but also, in most of the 40 scenarios considered, that the greater part of the (overstated) initial gaps between rich and poor will be closed by the end of the century. And the Economist concludes that the combination of overstated gaps and of built-in assumptions about the extent of convergence in the average incomes of rich and poor countries yields projections of GDP for developing regions which are improbably high. Castles and Henderson's overall verdict is that the IPCC document was 'technically unsound'. This is diplomatic slang
for 'worthless'.

All in all, the latest batch of criticism confirms what should have been clear all along: the IPCC has done an outstanding job in perfecting the art of spindoctoring.
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