terça-feira, 1 de março de 2011

Freeman Dyson no debate sobre o «aquecimento global»

  • «First, the computer models are very good at solving the equations of fluid dynamics but very bad at describing the real world. The real world is full of things like clouds and vegetation and soil and dust which the models describe very poorly. Second, we do not know whether the recent changes in climate are on balance doing more harm than good. The strongest warming is in cold places like Greenland. More people die from cold in winter than die from heat in summer. Third, there are many other causes of climate change besides human activities, as we know from studying the past. Fourth, the carbon dioxide in the atmosphere is strongly coupled with other carbon reservoirs in the biosphere, vegetation and top-soil, which are as large or larger. It is misleading to consider only the atmosphere and ocean, as the climate models do, and ignore the other reservoirs. Fifth, the biological effects of CO2 in the atmosphere are beneficial, both to food crops and to natural vegetation. The biological effects are better known and probably more important than the climatic effects. Sixth, summing up the other five reasons, the climate of the earth is an immensely complicated system and nobody is close to understanding it.» (Freeman Dyson no The Independent)
Dyson está a responder às seguintes alegações: a) que os modelos computacionais bastam para provar que a subida das temperaturas atmosféricas só pode ser explicada pelo aumento da concentração de CO2 na atmosfera; b) que não existe outra explicação possível; c) que temos mesmo que «fazer alguma coisa».