"In a speech to more than 100 heads of state, the president outlines the elements of accord: commitments to limit emissions, a way of monitoring those pledges and aid to help poor nations adapt."

"COPENHAGEN -- President Obama told leaders of 193 nations here Friday that their collective will to address climate change "hangs in the balance" and urged both developed and developing countries to accept a climate change agreement he acknowledged was far from perfect."

"President Barack Obama met other world leaders in a last push for a new global climate deal on Friday, after negotiators failed to reach a deal on carbon cuts in all-night talks."

The effluent stream of an East Chicago, Indiana, wastewater treatment plant is clean enough to fool salmon into spawning there.

"China is preparing to build three times as many nuclear power plants in the coming decade as the rest of the world combined, a breakneck pace with the potential to help slow global warming."

"In 2005 the U.S. Bureau of Land Management offered up thousands of acres of federal land in Colorado to drilling. Because the land was in the heart of an area that supplies drinking water to 55,000 people in the western part of the state, the plan drew stong opposition from local communities."

"Around the world, whenever airborne particles increase, so do deaths from heart and lung diseases. Now new evidence is emerging that some particles may be more dangerous than others. A growing body of research – much of it in New York City – suggests that breathing nickel and other metals may put acute stress on the lungs and heart, resulting in illnesses and deaths at particulate levels below national standards."

"In New Mexico, a tribal attempt to protect Mount Taylor sparks a battle over ancient claims to the land."

"In a little more than a year, a regional push to cap greenhouse gases has raised millions for Maryland energy programs, with supporters calling it a model for easing climate change on a national or even global scale."

"COPENHAGEN -- Mayors of some of the world's largest cities flexed their muscle at the United Nations climate talks Wednesday, warning that 'billions of people' are prepared to cut emissions far beyond whatever agreement world leaders may ink this week."