France will reduce use of fossil fuels by 30 percent by 2030 as part of a strategy to halve overall energy use by 2050, President Francois Hollande announced on Friday.

"Fossil fuels still account for more than 70 percent of our overall energy use," Hollande said, as he unveiled a two-day conference on the environment in Paris.

Hopes of finding life on Mars suffered a setback after new findings from NASA's Curiosity rover detected only trace amounts of methane gas in the Red Planet's atmosphere, a study said Thursday.

In the past decade, scientists have reported large "plumes" of methane in the Martian atmosphere, findings that have remained controversial because they were made on the basis of observations from Earth or an orbiting satellite.

Scientists working on a landmark U.N. report on climate change are struggling to explain why global warming appears to have slowed down in the past 15 years even though greenhouse gas emissions keep rising.

Leaked documents obtained by The Associated Press show there are deep concerns among governments over how to address the issue ahead of next week's meeting of the Intergovernmental Panel on Climate Change.

More than 15,000 residents have fled a volcano that rumbled to life less than a week ago in Indonesia and local airlines have been warned to avoid flying near the mountain as thick ash continues to spew from its crater, an official said Thursday.

The aviation warning was issued Wednesday for small planes serving short-haul flights in the region as small eruptions continue at Mount Sinabung, said Susanto, general manager for air navigation at Kuala Namu airport in North Sumatra's capital Medan. Like many Indonesians, he uses only one name.

Japanese Prime Minister Shinzo Abe Thursday ordered the operator of the crippled Fukushima nuclear plant to work out a schedule for stemming radioactive water leaks as he toured the facility.

Tokyo Electric Power (TEPCO) had "to resolve the leaky water problem by setting a timeline", Abe told journalists traveling with him.

Scientists studying reefs off Australia said Thursday sharks play a fundamental role in the health of coral, and overfishing of them made reefs more vulnerable to global warming and weather disasters.

A research team, led by Mark Meekan from the Australian Institute of Marine Science (AIMS), studied the impact of sharks at the Rowley Shoals and Scott Reefs 300 kilometers (185 miles) off northwest Australia over 10 years.

Orbital Sciences Corp launched the first flight of its unmanned Cygnus cargo ship Wednesday to the International Space Station, as NASA forges ahead with its plan to privatize U.S. space missions.

"This is just the beginning of what we can do to support human space flight," Orbital executive vice president Frank Culbertson, a retired NASA astronaut, told reporters after Cygnus went into orbit around the Earth.

Margaret Buckingham, a Scottish-born biologist, has been awarded one of France's top science prizes, the National Center for Scientific Research (CNRS) announced on Wednesday.

It said it was awarding her its gold medal -- a prize that in the past has singled out several scientists who later won the Nobel -- for pioneering work in gene regulation.

Scientists using a wind tunnel and a full-scale model have shed light on how feathery dinosaurs adapted to the skies, a study said on Wednesday.

A widening consensus among palaeontologists is that birds evolved from small, feathery dinos -- but the question is: how?

Russian coast guards on Wednesday arrested two Greenpeace activists who scaled an oil platform owned by state energy giant Gazprom in the Arctic to protest oil drilling in defiance of warning shots, the environmental group and officials said.

The activists set off before dawn in inflatables launched by Greenpeace mothership the Arctic Sunrise and headed towards Gazprom's Prirazlomnaya oil rig in the Pechora Sea, Greenpeace said in a statement.