Calama

April 22 will mark Earth Day worldwide, an event now in its 42nd year and observed in 175 countries. The original grass-roots environmental action helped spur the Clean Water Act and Clean Air Act in the United States. Gathered here are images of our planet's environment, efforts to utilize renewable alternative sources of energy, and the effects of different forms of pollution. -- Lane Turner and Leanne Burden Seidel (35 photos total)
A ladybug in flight spreads its wings as it flutters from grass blade to grass blade at Rooks Park in Walla Walla, Wash. on April 2, 2012. (Jeff Horner/Walla Walla Union-Bulletin/Associated Press)

The best photos of 2011 from around the globe. Warning: All images in this entry are shown in full, not screened out for graphic content. Some images contain dead bodies, graphic content and tragic events. We consider these images an important part of human history.