Looking back one, two and five years ago today on Worldchanging:

2009
Interview with IRENA Director General Nominee Hans Jǿrgen Koch
Ben Block interviews Hans Jǿrgen Koch on renewable energy...

2008
Seeing the African Challenge in a Single Graph
Our allies at the Global Footprint Network and WWF released a report, "Africa: Ecological Footprint and Human Well-Being," on pathways towards sustainable development and what really hit Alex Steffen was this graph, which seems to sum up the fundamental challenge in one image...

2005
Protecting Genetic Resources on the Deep Ocean Floor
Sam Johnston says it is precisely because deep sea bioprospecting is just getting started that the time is right to create a legal framework for its conduct: Alex Steffen wonders how that can be done and looks to a study produced by the United Nations University's Institute for Advanced Studies for insight...

Other recent "look backs":
June 22
June 23
June 24