The picture is indeed great! @pab.ink rocks! :)

Let's get to the science: In theory, how big is the increase in earth temperature caused by dark matter?

Thanks for the good question. It however works in the opposite way. We know the heat flow originating from the planet (this is measured). If there is a dark matter contribution (because the possibility of such a contribution depends on the details of the dark matter model), then it is part of what we measured. When a theory is built, physicists must then pay attention not to generate too much heat flow from the planet.

Therefore, as said in another comment, this does not affect in any special way the observed temperature variations.