Gray smoke rises from Unit No. 3 of the stricken Fukushima Dai-ichi nuclear plant Monday. Though no country is more familiar with nuclear peril than Japan, many Japanese don't connect the nuclear bombings of World War II with the ongoing crisis at Fukushima, says Yale-trained nuclear physicist Sukeyasu Yamamoto, who teaches in Tokyo. AP hide caption

itoggle caption AP

A fishing boat lies on its side in shallow water in the boat basin at Crescent City, Calif., after a tsunami surge withdrew March 11. The surges broke loose and damaged most of the 35 boats that remained in the harbor. Jeff Barnard/AP hide caption

itoggle caption Jeff Barnard/AP

Rising crude oil prices and improved extraction methods have made exploitation of Canada's oil sands more economical. Here, a view of an oil sands mine near Fort McMurray, Alberta. Mark Ralson/AFP/Getty Images hide caption

itoggle caption Mark Ralson/AFP/Getty Images

A production plant on the short of Mellitah, Libya, opened in 2004. Owned by Eni, the Italian oil and gas company, the facility is part of a pipeline that connects Libya to Sicily. Political unrest in the African nation is having effects in the worldwide oil market. Eni Press Office/AP hide caption

itoggle caption Eni Press Office/AP

Teeth from a cremated child were excavated from a site believed to be 11,500 years old. The color differences show uneven burning. The scale is in millimeters. Science/AAAS hide caption

itoggle caption Science/AAAS

Researchers aboard the Atlantis, a research vessel operated by the Woods Hole Oceanographic Institution, examine core samples brought up from the sea floor of the Gulf of Mexico by the deep-sea submersible Alvin on Nov. 24, 2010. The scientific community is conflicted about the lack of direction, coordination and funding in studying the aftermath of the Gulf of Mexico oil spill. Richard Harris/NPR hide caption

itoggle caption Richard Harris/NPR

A mature Atlantic tomcod collected from the Hudson River. These tomcod evolved to handle excessive amounts of industrial pollutants, like PCBs and dioxin, in the water. Science/AAAS hide caption

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This foot bone, the fourth metatarsal, connects the heel to the fourth toe. The 3 million-year-old fossil suggests that Australopithecus — Lucy and her kind — could have been the first upright walkers. Carol Ward and Elizabeth Harman/Science/AAAS hide caption

itoggle caption Carol Ward and Elizabeth Harman/Science/AAAS

Major droughts in 2005 and 2010 cut into the Amazon's ability to absorb carbon dioxide from the atmosphere. Drought reduces carbon-absorbing tree growth, and opens the door to more forest fires, which release carbon into the air. Seen here, a Peruvian section of Amazonia. John W. Poole/NPR hide caption

itoggle caption John W. Poole/NPR

During the 1980s, wildlife managers said striped bass like this one were overfished. Now, it appears that a weather pattern known as the Atlantic Multidecadal Oscillation may have been a contributing factor to the declines. Jay Fleming/Jay Fleming Photography hide caption

itoggle caption Jay Fleming/Jay Fleming Photography