Time was that denialists relied on rather thinly-sourced evidence of potential warming on Mars to say it's proved, proved I tell you, that the warming that Earth has not even experienced came from the Sun. You saw and heard stuff like this:
I could've sworn that the SUV reference came from Michael Crichton originally, but digging around didn't confirm it. Inhofe was into it, though. Here's the 'scientific' source of the claim:
Habibullo Abdussamatov, head of space research at St. Petersburg's Pulkovo Astronomical Observatory in Russia, says the Mars data is evidence that the current global warming on Earth is being caused by changes in the sun.
"The long-term increase in solar irradiance is heating both Earth and Mars," he said.
So much for that.
To be sure, we don't necessarily know what's happening on Mars, we haven't studied it as long and as closely as Earth. Solar irradiance is well studied though and not the cause of the warming we're seeing on EArth.