At 94 years young, the naturalist's follower count raced to seven figures in four hours 44 minutes on Thursday, according to Guinness World Records.
His debut post said: "Saving our planet is now a communications challenge."
Last October, Friends star Aniston reached the milestone in five hours and 16 minutes.
In his first video, the veteran broadcaster told followers: "I am making this move and exploring this new way of communication to me because, as we all know, the world is in trouble.