She said she was concerned about the health impacts of climate change and was “afraid” of bringing children into the world.
A police spokesman said the bridge was still open to buses during the protest but was closed to cars.
More than a dozen police were at the scene to manage traffic.
Ms Thompson, dressed in purple, received mixed reactions from passers-by, some giving her a thumbs up and others giving her the middle finger.
About 8.40am, police negotiators told the woman she could either hoist herself down or they would begin to dismantle the bamboo while she was still up there.
She lowered herself and waved to supporters as she was taken into a police van about 8.45am. The bridge was re-opened to traffic about 9am.
A statement from the group said it was the first protest of “thousands” expected in the coming days as part of International Rebellion Week, the last of which saw more than 70 people arrested in Brisbane as traffic and police were obstructed.
“All people of privilege need to assess their priorities and take civil disobedience in place of those who cannot, to force rapid systematic change,” the statement read.
Lydia Lynch is a reporter for the Brisbane Times