C'mon, they are deniers because they're ignorant..
See their age- they are 70-80+ years old grandpas.
They don't understand anything from the modern world.
Times when the wisest and the most knowledgeable people in the village are grandpas and grandmas, are long time gone.
Regardless, climate change is human-made, or it's f.e. natural increase of power of the Sun (when it'll be turning to red giant and burning Helium-4 more extensively), it's in the best human interest to "do something", and f.e. prevent higher radiation of the Sun by placing mirrors in the cosmic space between the Sun and Earth, to decrease radiation.. and being able to remotely control it when needed.. Without such devices this planet will vaporize and sterilize from living organisms much more quicker..
I would split deniers to "denying human-made climate change but accepting climate change" and "denying any climate change".