Perhaps I could weigh in on the Mars thing because I'm supposed to know some astronomy?
There are natural 'climate cycles' here on earth which are to do with:
1. the Sun (eg sunspots every 11,22, hundred-and-something years)
2. our eccentric orbit/ polar precesion etc (eg polar precession every 26,000 years and others, whose sum-total gives the milankovich 100,000 year cycle)
On top of these is superimposed, what we're doing to the planet.
OK you can see that 1. but not 2. would also have some influence on Mars. Mars will probably have its own equivalent of 2. which (my guess) is the cause of its polar alternating thang.
Right, back to the sun. Its output has been being measured, fairly reliably, for decades. Both from the surface (the chaps who discovered Global Dimming used irradiance time-series) and from space (no dimming, natch).
The upshot: These latter (space-based Sun data) have shown no change which could account for global warming all by itself: we (or possibly something else on the planet) are the culprits. So no blame for the Astronomers