As Anthony Watts says, this does seem to represent a "sea change" in climate journalism.
While this started out as a suggestion from him to the Guardian's James Randerson that "if the Guardian truly wishes to engage climate skeptics" it would stop using the derogatively term deniers to describe them.
It appears that this has been discussed within the newspaper's environment team and it has gone public with the outcome.
We have been discussing such terminology, and some of my colleagues have suggested that Guardian style might be amended to stop referring to “climate change deniers” in favour of, perhaps, “climate sceptics”.
The editor of our environment website explains: “The former has nasty connotations with Holocaust denial and tends to polarise debate. On the other hand there are some who are literally in denial about the evidence. Also, some are reluctant to lend the honourable tradition of scepticism to people who may not be truly ’sceptical’ about the science.” We might help to promote a more constructive debate, however, by being “as explicit as possible about what we are talking about when we use the term sceptic”.
Most if not all of the environment team – who, after all, are the ones at the sharp end – now favour stopping the use of denier or denialist (which is not, in fact, a word) in news stories, if not opinion pieces.
The Guardian’s environment editor argues: “Sceptics have valid points and we should take them seriously and respect them.” To call such people deniers “is just demeaning and builds differences”. One of his colleagues says he generally favours sceptic for news stories, “but let people use ‘deniers’ in comment pieces should they see fit. The ’sceptics’ label is almost too generous a badge as very few are genuinely sceptical about the science but I think we have to accept the name is now common parlance.”
As Anthony also says, the Guardian should be applauded for this and the gesture reciprocated.