"Halliburton Co. is in talks to buy Baker Hughes Inc. in a deal that would combine two of the largest and oldest names in the energy business as plunging oil prices send the industry into a downturn."

"ANCHORAGE -- Six environmental groups sued Monday to throw out a federal agency rule that concludes oil exploration off Alaska’s northwest coast has a negligible effect on walrus."

"The U.S. State Department must halt plans to expand an oil sands pipeline route from Canada to Wisconsin until possible environmental harm has been closely studied, several green groups said in a lawsuit filed on Wednesday."

"Lightning strikes in the United States will likely increase by nearly 50 percent by the end of the century as the world gets warmer and wetter, a new study says."

"Two years ago, in a preemptive move, Shell sued a host of environmental and advocacy groups to prevent them from suing Shell over its plans to drill for oil in the Arctic. On Wednesday, a federal appeals court called Shell's legal strategy 'novel' and ruled it unconstitutional."

"Legislation to force the approval of the Keystone XL pipeline picked up support Thursday as more Democratic senators signed on to Sen. Mary Landrieu's effort."

"Don Blankenship, the longtime chief executive officer of Massey Energy, was indicted Thursday on charges that he orchestrated the routine violation of key federal mine safety rules at the company’s Upper Big Branch Mine prior to an April 2010 explosion that killed 29 miners."

"Nearly 140 bison originally from Yellowstone National Park that were quarantined on a ranch owned by media mogul Ted Turner to create a herd free of a cattle disease will be transported late on Wednesday to an Indian reservation in Montana."

"Health concerns about oil field fracking have been focused on the mixed brew of chemicals injected into wells. But it is another innocuous-sounding substance — sand — that poses a more serious danger to workers."

"U.S. wildlife authorities listed the Gunnison sage grouse as threatened on Wednesday, disappointing environmental activists who wanted the species given greater protection, and politicians who did not want the federal government involved."