A question

Global warming is happening. But I'm not talking about our globe - I'm talking about Mars.

A couple of thoughts:
1) Mars has heated up measurably over the past 30 yers
2) Mars is farther away from the sun than Earth (50% further), meaning any warming effect due to solar radiation should be much weaker.
3) Mars is smaller than Earth (treating it as a disk, it presents about 28% of the profile the Earth would to the sun at the same distance), giving it less surface area to catch and hold the warming effect.

If Mars is heating up because of demonstrable, purely natural causes... could it be the Earth is, too? I don't want to quash debate on global warming, but I want to see it actually take place. I saw headlines galore when the U.S. supreme Court decided that the EPA had to regulate greenhouse gasses because of climate change theories. I had to stumble across one that said that another planet was experiencing the same thing.

Edit: Another, more mainstream news source. Quote to note: "The warming is similar to what the Earth has experienced in the last 100 years."