Climate of fear

Steuart Campbell’s letter (“Climate chaos”, 3 January) makes much of a paper in the magazine Nature to spell gloom and doom.

The authors of this paper have been trying to estimate the sensitivity of some 43 general circulation models of climate to a doubling of carbon dioxide and claim that it will be in a higher range rather than lower range based on some observations of the troposphere. However, the paper was accompanied by a critical commentary in the same edition of Nature.

This pointed out that the claims in the paper were inconsistent with other data, ignored other modelling approaches which give much lower estimates of temperature change, and suggested that the results could be skewed by common errors found in most computer models among many other criticisms.

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In the latest Intergovernmental Panel on Climate Change (IPCC) document, the consensus rate of increase of temperature has been downgraded to about 0.1C per decade, largely in agreement with what can be observed over the past 100 years.

It is generally recognised that the computer-generated circulation models used in the paper above have been predicting a temperature rise at least twice as much as observed in the last 25 years.

Also, they have not predicted the present stasis in temperature starting in 2000.

Until the errors in these models are sorted and start to cohere with actual observation it would be unwise for assumptions to be made over any future temperatures.

Science progresses by the production of hypotheses which are then tested against the actual data.

Mr Campbell confuses normal scientific debate with supposed realistic future predictions.

(Prof) Tony Trewavas

Scientific Alliance 

North St David Street