Activists of environmental organization Robin Wood observe police activities from their tree houses, built in protest against the clearing of a wooded area for a new runway for the airport, in Frankfurt January 20, 2009. Some of the demonstrators have been living in the wooded area slated for clearing as a form of protest for the past 6 months. REUTERS/Kai Pfaffenbach (GERMANY)

- Image ID: 2D1HXT5

Activists of environmental organization Robin Wood observe police activities from their tree houses, built in protest against the clearing of a wooded area for a new runway for the airport, in Frankfurt January 20, 2009. Some of the demonstrators have been living in the wooded area slated for clearing as a form of protest for the past 6 months. REUTERS/Kai Pfaffenbach (GERMANY)

REUTERS / Alamy Stock Photo

Image ID: 2D1HXT5