The North-West Passage

There are reports (Arctic Ocean shipping routes to open ‘for months’) that the Arctic Ocean may be ice-free for long periods of the year. Actually, this is no more than a further projection of the consequences of global warming at high latitudes. We have previously seen the complete melting of the ice cap predicted to have happened before now, but this time they could be right.

To quote the opening of this piece on the BBC website: ‘Shipping routes across the Arctic are going to open up significantly this century even with a best-case reduction in CO2 emissions, a new study suggests.’ What we don’t find out until later is, of course, that this study is simply a use of computer models to make predictions. Given their failure to project the pattern of average temperature evolution this century, we should perhaps not take this latest pronouncement too seriously.

We are very much in ‘what if’ territory: the authors claim to have tuned several models to reflect the current distribution of ice and then set them running. However, they will still be based on the assumption that there is a positive feedback loop increasing the impact of a given rise in carbon dioxide levels. In the real world, there is no hard evidence that this is true. Until we have a much better understanding of global climate systems, reports such as this should be considered simply as speculation.

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