LONDON (AP) — A 21-year-old free climber who was imprisoned two years ago for climbing the U.K.'s tallest skyscraper has scaled another building in London, this time to draw attention to climate change.

George King-Thompson climbed up the 36-story Stratosphere Tower, a residential block in east London's Stratford neighborhood, unaided Tuesday morning and reached the top in less than half an hour.

The former personal trainer said he picked the skyscraper because he was shocked by the flash floods that recently hit the area. Pudding Mill Lane, a subway station in Stratford, was one of eight stat...