The image shows a timeline from 1991 when the Brent Spar stopped being used as an oil storage buoy until August 1999 when its decommissioning was complete.

Key dates shown are:

December 1994 - decision taken to dump Brent Spar in North Sea.
April 1995 - Greenpeace occupy the Brent Spar and mount protests at dumping plans.
June 1995 - Shell reconsider disposal options.
January 1998 - Shell announce the dismantling of the Brent Spar rather than its sinking.