The change may be in Mars (Score 1)

The orientation of the axis of Mars has been about the same as Earth, but it historically has varied by as much as 60 degrees. When the northern pole of Mars has been pointed towards the Sun in the past, the frozen carbon dioxide there melted and produced a greenhouse effect. If this is what is occurring today, then the change is in Mars, instead of the Sun and does not necessarily explain anything about Earth's heating.