Swedish teenage climate activist Greta Thunberg endorsed Joe Biden in a tweet Saturday aimed at driving turnout in the election.
Why it matters: The 17-year-old Thunberg is among the world's highest-profile advocates for aggressive steps to combat global warming.
Quick take: Thunberg's backing underscores how left activists are consolidating around Biden, despite some groups' misgivings about his platform.
He's picked up endorsements from groups on the left flank of the green movement, such as Oil Change U.S. and the political arms of 350.org and Friends of the Earth.
Biden's platform has grown more aggressive in recent months, but still doesn't contain elements that many environmental activists want — notably a call to ban fracking.
