Pleased to see Carol back on our screens

me the same courtesy!

One section of his letter begins: “Mr Curnow further appears not to understand the basic statistical concept of a mean value as a measure of central tendency.”

He goes on: “The fact that not all places on earth have seen identical changes in temperature during the instrumental record does not throw any doubt on the finding that average temperature for the globe as a whole has risen by 1.1ºC since preindustrial times.”

This rather implies that I was suggesting the opposite, but I was not. What I was suggesting was that we do not, in fact, have truly comparable records for the present and the ‘pre-industrial’ – this is obviously so in the case of satellite records, but it is also true of temperature measurements taken by thermometer at various times and in various places.

There are some places which provide a continuous record, going back over many years, but for a large portion of the globe a temperature figure would not be a record of an actual reading, but a figure constructed from known readings in other locations – such calculations provide the only way of constructing a ‘record’ for the past and, like it or not, such calculations will involve many assumptions, especially when the work involves proxies.

There is a difference between ‘raw data’ – actual measurements of some property – and ‘adjusted data’. This is a distinction which needs to be remembered when discussing the ‘temperature record’, and I think it is always worth asking: “Why is it thought the data needs to be adjusted?”

Howard Curnow Lifton, Devon

IT is great to see popular weather forecaster Carol Kirkwood back on