Be part of the U.N.'s Plant for the Planet by planting your own tree to mark World Environment Day.

President Barack Obama challenged world leaders to join the United States in fighting global warming. Watch the entire 10-minute speech here.

Actor/activist excited to use new role to share that 'human well-being is intertwined fundamentally with biodiversity'.

The United Nations General Assembly has officially recognized access to safe, clean drinking water as a basic human right.

Is Denver's B-Cycle program nothing but a form of U.N. control of the city? The Mayoral Republican gubernatorial frontrunner thinks so.

Actor teams with Google and the United Nations to collect real-time satellite imagery of war-torn Sudan region.

The world's forests support the planet's diverse creatures, and keeping forests robust also could help humanity achieve some of its biggest goals.

German tree-planting advocate brings his Stop talking. Start planting message to the United Nations.

The head of the U.N.'s World Food Program talks about how we can fix the hunger problem.

Cookstoves that burn more efficiently and channel smoke outside could save millions of lives around the world.

Earth has never hosted 7 billion people all at once before, but according to the U.N., it may reach that spooky milestone by the end of this month.

As humanity hits the 7 billion mark today, a new U.N. report suggests we should focus more on our quality of life than the quantity of it.

The threat of heat waves and heavy precipitation are becoming especially severe, warns the Intergovernmental Panel on Climate Change.

As the Earth heats up and weather grows wilder, meteorologists are on the front lines of an intensifying war with the elements.

Forty years after the first World Environment Day, and 20 years after the original 'Earth Summit,' Brazil is still a flashpoint for environmental politics.

More than 100 world leaders and tens of thousands of protesters will descend on Rio de Janeiro next week for the Rio+20 summit in hopes of overcoming years of d

As world leaders fly into Rio de Janeiro for Rio+20, thousands of people from indigenous tribes, environmental groups, unions and religious organizations gather

Here's a small birthday tribute to Mohandas Karamchand Gandhi, the "great-souled" man who was born 148 years ago today. It's a poignant way to celebrate the man

Health experts argue that banning the preservative could make it difficult for children in developing countries to get life-saving vaccines.

Quinoa is one of the most nutritious foods on the planet, cooked like rice, gluten-free, and loaded with vitamins and minerals.

Discussions about the Russian meteor explosion and Earth's encounter with asteroid 2012 DA14 were high on the Feb. 15 agenda of a UN meeting.

If Western culture can overcome the 'disgust factor,' insect cuisine could help fight global hunger and global warming, a United Nations agency reports.

Mongolia, the host of this year's World Environment Day, is home to Earth's rarest bear. Conservationists hope 2013 will mark the start of its comeback.

Here is a sneak preview of what to expect when the AR5 report is issued next week, based on the leaks so far.

The IPCC report is expected to include summaries on melting glaciers, sea level rise and the impact of human activities on the global climate.

A new international effort will monitor potential asteroid threats and examine how to deflect them before they hit Earth.

An early alert system and rapid space launches are two ways that the UN is coordinating with other agencies to deter asteroids.

Climate change has already taken a serious toll on human well-being and world economies.

While traveling through Antarctica, journalist Charlie Bird had an up-close encounter with some adorable seals that left him giggling.

The island country is currently experiencing a harrowing seasonal infestation of the Malagasy migratory locust.

A young poet from the Marshall Islands reportedly 'brought world leaders to tears' at the U.N. Climate Summit.

With a Global Alliance dedicated to Climate-Smart Agriculture, you’ll be hearing more about this effort with a goal to improve agriculture and food security.

A key focus of this week's Transformational Media Summit is how sharing stories can change attitudes to help us create a more peaceful world.

World leaders can't agree on nixing the leap second, so we’ll just keep adding them until they figure it out.

UNESCO protects more than landmarks and culturally-significant sites. There are intangible parts of culture that are important, too.

The United Nations shares "ONE Life," a new song and music video highlighting the severity of climate change.

Sue Flood's new book on emperor penguins, 'Emperor: The Perfect Penguin,' is the culmination of 9 years of work.

Astrophotographer Andrew McCarthy spent hours creating this breathtakingly detailed composite image of our moon.

Beautiful photos show the desert in Yucca Valley, California, and Joshua Tree National Park covered in snow.

An unusual spike in auroral activity culminated in this mystical aurora borealis display captured by Jingyi Zhang, a photographer and astronomer.

This year's open category winners of the Sony World Photography competition range from a Chinese shadow puppet show to a mesmerizing underwater dance.

Michigan woman has a 'photo booth' to get a glimpse of the personalities of birds that visit her yard.

Photo of hungry sharks wins Underwater Photographer of the Year contest, which also selected winners in more than a dozen categories.

Photographer Oliver Hellowell believes anyone can accomplish their dreams — even if they have Down syndrome.

Photographer Will Burrard-Lucas's new book 'Land of Giants' chronicles some of the last days of this towering gentle giant.

Such a convergence hasn't occurred since March 1981.

Photographers capture landscapes, portraits, wildlife and more for Sony World Photography Awards.

Annual Koch Institute exhibition explores the thought-provoking and stunning visuals behind life sciences and biomedical research at MIT.

Artist Dale Chihuly's whimsical glass art pops up in botanical gardens and museums all around the world.

Dozens of massive president heads sit in a field in Virginia, waiting for a new home in a museum.