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

2009
Graphic Series: Earthly Ideas, Algae Energy
This post is part of a series featuring Worldchanging ally Andy Lubershane's original graphics. Use this medium in your classroom, or on your office wall, to help explain ideas to friends and family. This cartoon describes algae-based energy -- one of the promising possibilities for plant-based fuels...

2008
Resource: Watershed Locator
A greater understanding of our regional resources helps us gain perspective when we look at where we fit within the natural world. Ecotrust has developed a new tool -- the watershed locator -- that makes it a cinch for Pacific Northwesterners to find and learn about the watersheds they live and work in. Check it out...

2005
Global Change, Local Effects
James Cascio looks at the "Regional Impacts" section of the the Climate Change Information Resource for the New York Metropolitan Region, or CCIR-NYC, a resource for understanding global and regional effects from climate change...

Other recent "look backs":
May 14
May 18
May 19