Two U.S. astronauts stepped out on a risky spacewalk Friday to complete the repair of an ammonia cooling system at the International Space Station.

Highly toxic ammonia is used to cool electronics at the orbiting outpost, and the thermal system has been plagued by problems.

A drought caused by the El Nino weather phenomenon is worrying farmers in the Colombian Andes who fear for their crop -- one of the world's most prized coffee beans.

"The harvest is about to be lost. We farmers are in total despair," said Raul Fajardo, 56, who grows coffee beans at 1,800 meters (5,900 feet) altitude on the slopes of the Galeras volcano.

A third of China's forests are under threat despite the Communist Party announcing a ban on commercial logging in natural forest, activists said Wednesday.

Vast swathes of woodlands have been destroyed during China's decades-long economic boom, but environmental concerns are rising up the agenda and the measure was included in guidelines the ruling party issued for the country's next five-year plan.

Astronauts celebrated 15 years of circling the Earth aboard the International Space Station Monday, a new milestone for an orbiting space lab that some say deserves the Nobel Peace Prize.

With operations expected to last another decade, the world's space agencies are now looking to the outpost to provide key data on how future space pioneers may withstand the rigors of venturing further, perhaps even to Mars.

A British tree thought to be up to 5,000 years old has started to change sex, a "rare and unusual" phenomenon not fully understood by scientists, a botanist said Monday.

The Fortingall Yew, in Perthshire, central Scotland has for hundreds of years been recorded as male, but has recently begun sprouting berries, suggesting that at least part of the tree is changing gender.

A massive space rock that will shave by Earth on Halloween looks like a dead comet with a skull face, NASA said after gaining a closer look at the spooky space junk.

Astronomers initially thought the object was an asteroid when they spotted it in early October, and named it Asteroid 2015 TB145.

Two NASA astronauts stepped out on a spacewalk Wednesday for upgrades and maintenance at the orbiting International Space Station, the U.S. space agency said.

Spaceflight veteran Scott Kelly, who is in the midst of a year-long stint at the ISS, began the first spacewalk of his career at 8:03 am (1203 GMT), according to a live broadcast on NASA television.

Bracing for a tsunami like the one that devastated Japanese communities during a 2011 mega-earthquake, coastal communities from British Columbia to California have been grappling with how to protect people from a similar catastrophe.

One of those towns is constructing the nation's first structure built as a vertical tsunami refuge.

An international scientific expedition has spotted up to 25 individual specimens of a near-extinct small porpoise in Mexico's Gulf of California, amid efforts to save the critically endangered vaquita marina.

The environment ministry said Monday that the rare sightings of the world's smallest porpoise were made during the first 20 days of the Vaquita Expedition 2015, which started on September 26.

Endangered orangutans are falling victim to a devastating haze crisis that has left them sick, malnourished and severely traumatized as fires rage through Indonesia's forests, reducing their habitat to a charred wasteland.

Rescuers at a center for the great apes on Borneo island are considering an unprecedented mass evacuation of the hundreds in their care, and have deployed teams on hazardous missions to search for stricken animals in the wild.