President Barack Obama makes California's Pinnacles National Monument the country's 59th national park.
Obama nominates Sally Jewell, the CEO of REI, to be secretary of the Interior Department. She becomes the first cabinet secretary to have climbed the highest mountain in Antarctica.
More than 40,000 people rally in Washington, D.C., to press Obama to reject the proposed Keystone XL pipeline.
The U.S. State Department declares that the pipeline "is unlikely to have a substantial impact" on the rate of tar sands development.
In his State of the Union speech, Obama pledges action on climate change: "If Congress won't act soon to protect future generations, I will."
The U.K. Guardian reports that as of 2010, a secretive funding network known as Donors Trust had contributed $118 million to climate-denial think tanks and activists.
A study in Environmental Research links air pollution to low birth weight. For every increase of 10 micrograms of particles per cubic meter, an infant's risk of being born too small increases by 3 percent.
Asia Pulp and Paper, one of the continent's largest paper companies, agrees to stop clearcutting Indonesia's forests.
Winter inversions trap pollution in Utah's Wasatch Front. The city of Provo scores 172 on the EPA's 0-to-500 air quality index. Anything above 150 is considered unhealthy.
ON THE SAME 0-TO-500 SCALE, air pollution in Beijing hits 755.
Mississippi seeks to ban "human-animal hybrids."
Illustrations by Peter Arkle