Mars is warming - not my fault

How could people on Earth cause Mars to be warming? it is:

Mars is being hit by rapid climate change and it is happening so fast that the red planet could lose its southern ice cap, writes Jonathan Leake.

Scientists from Nasa say that Mars has warmed by about 0.5C since the 1970s. This is similar to the warming experienced on Earth over approximately the same period.

Since there is no known life on Mars it suggests rapid changes in planetary climates could be natural phenomena.

The mechanism at work on Mars appears, however, to be different from that on Earth. One of the researchers, Lori Fenton, believes variations in radiation and temperature across the surface of the Red Planet are generating strong winds.

From the Times (UK).

How about activity of the Sun? This short article doesn't say if they checked.