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.
"Continents are on fire. Glaciers are melting. Coral reefs are dying. Fish are disappearing from our oceans. The list goes on and on. Saving our planet is now a communications challenge."