So this article has two sources, neither or which were readable on my device because of paywall or such.

Is there any actual stats on how often the DNC talk about climate change?

Even if you think they should talk more, their policy platform has very demonstably, through actions louder than words, been about green power, phasing out gas and coal, and empowering the EPA.

EDIT: Thanks to a source provided by another commenter we can see the number of mentions largely haven't changed by either party in over a decade. LINK HERE