I think a long trend over a number of years is the only thing that will convince the whack jobs that global warming is, well, whacked.
They worked their way into a bind by committing themselves to a ‘demonstrable’ effect of man's activity (warming), and have already begun to back out.
With the term “Climate Change,” they can attribute warming or cooling or even stagnation, if global temperatures do not change (because, they'll say, they should change ‘some’) to man's activity and demand totalitarian control over the people.