Here we have 28 pages of goodness – a very compact users' guide for reading scientific product.
Put crudely, scientists tend to think science is about things we don't know fully. Journalists and politicians (and to a large extent, many people) think it is about things we do know, and they're impatient with ‘maybe's.
The problem here is that not all scientific knowledge is the same, so treating it as though it were is misleading
For your reference library.