Climate change has been happening, by definition, since the earth acquired an atmosphere.
What current changes (ie a warming trend, on the whole) are down to is not fully understood - probably many factors are involved, and the activity of the sun is one of them.
It's a pity that debate has become polarised between those who bang the drum for man-made explanations on the one hand, and so-called 'deniers' on the other.
The argument between fanatics on both sides stands in the way of sensible progress being made, in my view.