With just one video, David Attenborough has burst onto Instagram, gaining more than 2.5 million followers in less than 24 hours.
The British naturalist has launched onto the social media platform with a video explaining why he's joined.
"The world is in trouble," he says in the 1:13 Instagram TV video.
"Continents are on fire, glaciers are melting, coral reefs are dying and fish are disappearing from our oceans, the list goes on and on."
He says he's tackling this "new way for me" of communication because "we know what to do about" the problems facing the world.
In the next few weeks he will be uploading videos explaining what the problems are and how we can deal with them.
You can follow him here.