Hey, aren’t there tons of Class M planets out there in the galaxy? They found them on Star Trek. (sarcasm , LOL )
On one old episode, they found a life form which was silicon based, not carbon based.
As far as global warming goes, we don’t know if the aliens on these planets have been using coal fired power plants or driving SUVs. (more sarcasm)
Not only were there tons of Class M planets, they were usually populated by hot chicks in 60’s miniskirts, and Captain Kirk took every opportuinty to become very familiar with the indigenous life forms.