Firstly, because it shows an increase (whatever the amount). This is
useful
information.

Secondly, because any scientific prediction is based on probabilities.
Virtually no prediction is certain. Scientists are used to working with
probabilities. Knowing probabilities is very useful to a scientist.

Do they know the probablity distribution of the huge range of
temperatures quoted? If so, why not tell us? I have not seen any
quoted probabilities, or a time scale, and without these the figures
are quite meaningless.

Tudor Hughes