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

2009
Special Innovation Zone: Imagination Without Regulation
Alex Steffen looks at the social inertia and institutional, legal and regulatory barriers that many innovative ideas and projects face on the way to realization. Furthermore, he advocates for a place for visionary thinkers to experiment boldly and in public...

2008
The Problem with Big Green
Alex Steffen and Julia Levitt challenge the utility of 'small-steps-green' and explore a recent WWF report, "Weathercocks and Signposts: the Environment Movement at a Crossroads," which launches a major assault on green consumerism and social marketing as avenues to sustainability, and encourages instead a new and more committed values-based approach...

2005
Plankton, El Niño, and Sinking Carbon
James Cascio explores why it's hard to overestimate the importance of phytoplankton to the planet's global ecosystem...

Other recent "look backs":
June 21
June 22
June 23