Every time Kelly Ksiazek-Mikenas scrambled onto a new green roof, it was hard to tell exactly where she was. The city below was definitely Berlin or Neubrandenburg, but the expanse of scraggly greens ahead of her looked a lot like the green roofs in Chicago, her home.
The only difference was that the German green roofs were much older than anything found in the United States: three to nine times older. Which is why the Northwestern University Ph.D. student in plant biology spent her summer there a few years ago.
