They should teach those Rocket Scientists at NASA a little bit about history, and common sense. The Earth has had periods of volcanic activity where the amount of toxic gases in the atmosphere, especially so-called green house gases was hundreds of times higher than it is today...and that was millions of years before man was around. From a bazillion miles away the tree hugger aliens would never know the difference.
Imagine that to write this nonsense about aliens killing us over global warming, they even had to ignore the part where the aliens kill us because we have nuclear weapons!!!
Klaatu look, planet Earth is 4 degrees warmer than uh, Al Gore thinks it should be! (Oh and they had a little thing called WWII but back to that temperature reading....)