Montana suspends wolf hunting in the vicinity of Yellowstone National Park after the popular alpha female of the Lamar pack is legally killed by a hunter in neighboring Wyoming. Up to 10 other Yellowstone wolves, 7 of which are wearing radio tracking collars, are also killed.
Low water levels, due to the worst drought in 50 years, threaten to halt barge traffic on the Lower Mississippi River.
A study finds that in the past 20 years, Greenland and Antarctica have lost 4 trillion tons of ice. During that time, global sea levels rose 60 percent more than past rates would have predicted. Another study finds that West Antarctica is warming three times faster than the global average.
The U.S. birth rate declines to 63.2 per every 1,000 women of childbearing age, the lowest ever recorded. The decline is led by a steep drop in the birth rate among immigrant women.
California puts a price on carbon dioxide emissions via a cap-and-trade system. Initial price: $10.09 per metric ton. Within weeks, the price hits $14.50.
The pine marten, thought for 40 years to be extinct in much of Great Britain, is proved to still exist after one is killed by a car in Wales.