U.S. Secretary of State John Kerry has called on American ambassadors around the world to make the fight against climate change a top priority ahead of new U.N. talks next year.

In his first department-wide policy guidance statement since taking office a year ago, he told his 70,000 staff: "The environment has been one of the central causes of my life."

Astronomer Carl Sagan become Mr. Science for a generation after his 1980 series, "Cosmos," took audiences on a groundbreaking TV journey through the universe.

Astrophysicist Neil deGrasse Tyson, host of "Cosmos: A Spacetime Odyssey," the 21st-century edition debuting Sunday, has a head start with a Twitter following of 1.7 million that's just edged by the starry likes of Gwyneth Paltrow and Cee Lo Green.

South Africa's peace icon Desmond Tutu on Friday urged the United States to reject Canada's Keystone XL pipeline, saying the "carbon bomb" would upend the U.S. role fighting climate change.

The Nobel Prize-winning archbishop who fought apartheid led a letter to Secretary of State John Kerry urging him to reject the 1,179-mile (1,897-kilometer) pipeline, which would bring oil from the carbon-intense Alberta tar sands into the United States.

Negotiations over mackerel fishing quotas have fallen apart, Iceland said Thursday, extending a dispute dubbed "the mackerel war" that has been a thorny issue in the country's EU membership bid.

The European Union, Iceland, the Faroe Islands and Norway left a meeting in Edinburgh on Wednesday without reaching an agreement for 2014.

Campaigners warned Thursday of environmental threats from new oil-prospecting projects off Spain's Balearic and Canary Islands, two major tourist destinations.

Campaign group Ecologists in Action said in a report that 10 oil installations were operating off Spanish coasts and new oil-prospecting licences had been granted for the islands that draw millions of tourists every year.

Europe is headed for scorching summers with temperatures well over 40 degrees Celsius (104 deg Fahrenheit) and droughts in the south within the next 40 years, climate scientists said Friday.

Europe is expected to witness some of the most dramatic climatic changes due to global warming, according to research published in the journal Environmental Research Letters.

Graphic on debris and defunct space hardware that currently orbit the earth

Australian scientists said Friday they aim to prevent a real-life version of the space disaster scenario portrayed in Oscar-winning film "Gravity" by removing extraterrestrial debris with lasers.

A new dinosaur species discovered in Portugal dominated the food chain 150 million years ago -- the Tyrannosaurus Rex of its time, researchers said Wednesday.

The new species is the largest land predator discovered in Europe and one of the largest worldwide of the Jurassic era, said authors Christophe Hendrickx and Octavio Mateus of the Universidade Nova de Lisboa and Museu da Lourinha.

Time is running out for Australia's iconic Great Barrier Reef, with climate change set to wreck irreversible damage by 2030 unless immediate action is taken, marine scientists said Thursday.

In a report prepared for this month's Earth Hour global climate change campaign, University of Queensland reef researcher Ove Hoegh-Guldberg said the world heritage site was at a turning point.

Officials in the Marshall Islands blamed climate change Wednesday for severe flooding in the Pacific nation's capital Majuro which has left 1,000 people homeless.

The Marshalls declared a state of emergency in the wake of the flooding, which peaked Monday when surges caused by so-called "king tides" inundated areas of the low-lying capital.