I seemed to have ruffled some feathers with my claim in my previous post that global warming is confusing to the public--and it's the fault of those providing the information not the receivers. By pure coincidence I received the latest edition of The Economist today and they are talking about climate change. So here's a challenge. Take the following introduction to a story on climate change and show it to someone with only a passing interest in climate change. Then ask that person: Is there a scientific consensus on 1) whether global warming exists and 2) the possible causes and effects of such warming?
FOR most of the Earth's history, the planet has been either very cold, by our standards, or very hot. Fifty million years ago there was no ice on the poles and crocodiles lived in Wyoming. Eighteen thousand years ago there was ice two miles thick in Scotland and, because of the size of the ice sheets, the sea level was 130m lower. Ice-core studies show that in some places dramatic changes happened remarkably swiftly: temperatures rose by as much as 20°C in a decade. Then, 10,000 years ago, the wild fluctuations stopped, and the climate settled down to the balmy, stable state that the world has enjoyed since then. At about that time, perhaps coincidentally, perhaps not, mankind started to progress.
Man-made greenhouse gases now threaten this stability. Climate change is complicated and uncertain, but, as our survey this week explains, the underlying calculation is fairly straightforward. The global average temperature is expected to increase by between 1.4°C and 5.8°C this century. The bottom end of the range would make life a little more comfortable for northern areas and a little less pleasant for southern ones. Anything much higher than that could lead to catastrophic rises in sea levels, increases in extreme weather events such as hurricanes, flooding and drought, falling agricultural production and, perhaps, famine and mass population movement.
Nobody knows which is likelier, for the climate is a system of almost infinite complexity. Predicting how much hotter a particular level of carbon dioxide will make the world is impossible. It's not just that the precise effect of greenhouse gases on temperature is unclear. It's also that warming has countless indirect effects. It may set off mechanisms that tend to cool things down (clouds which block out sunlight, for instance) or ones that heat the world further (by melting soils in which greenhouse gases are frozen, for instance). The system could right itself or spin out of human control.
Source: "Climate change: The heat is on," Sep 7th 2006 From The Economist print edition
