Journalism and maths – the adventure continues:

Although in fact, here the issue is not really numeracy: it’s a more abstract one of conceptualisation – confusing a temperature of 2.5C with a difference in temperature of 2.5C. A sum has been calculated correctly; it’s just not the appropriate sum. (If global temperatures rise by 36F, even air conditioning isn’t going to help.)
And I’m afraid, at the Tribune, this has happened quite often:




It’s not clear why we struggle with temperature like this when we navigate other conversions successfully and, as has been said elsewhere, sub-editors are capable of making much finer distinctions than this when it comes to language. I think it may have something to do with the fact that the zeroes on the two scales are so far apart and signify different things (whereas, for example, 0 mph and 0 kph signify the same thing, and the scales diverge after starting at a common point).
The classic formula for converting an actual temperature in celsius to fahrenheit is
(<temp in C> x 1.8) + 32 = <temp in F>
and it’s that addition of the constant, the 32, that causes the trouble when you are trying to calculate a difference in temperature. If you subtract 32 from all the erring totals (where given) in the corrections above, you get the right answer (or close to it, given some of the original fahrenheit totals have been rounded). So the correct C to F conversion for a difference in temperature is simply
<temp difference in C> x 1.8 = <temp difference in F>
and similarly the other way, for a difference in temperature:
<temp difference in F> x 0.5555 = <temp difference in C>
In such a critical decade for climate change policy, we may find ourselves needing to do these sums more and more often.
With thanks to the Tribune’s chief revise sub for spotting this one – a man who has seen too many improbable-looking pound-to-yen conversions (really, that many zeroes?) to let any figure in parentheses pass unscrutinised.