A plan to link the Red Sea with the shrinking Dead Sea could save it from total evaporation and bring desalinated water to thirsty neighbors Israel, Jordan and the Palestinians.

But environmentalists warn that the "Red-Dead" project could have dire consequences, altering the unique chemistry of the landmark inland lake at the lowest point on earth.

Environmental officials and scientists warned Friday that Puerto Rico is dangerously vulnerable to the effects of global climate change and urged it to prepare by better-regulated coastal development, and perhaps even by building artificial reefs.

The storm-caused floods and erosion that have always affected the U.S. Caribbean territory are expected to grow worse as temperatures and seas rise, perhaps by 22 inches (57 centimeters) by 2060, according to a U.S. Army Corps of Engineers study.

Greenpeace said on Saturday it had defied the Russian authorities by sending its icebreaker through an Arctic shipping route to protest against oil drilling in the fragile ecosystem.

Earlier this week the global environmental group said Russia had refused its ship permission to enter the Northern Sea Route on several occasions citing concerns about the icebreaker's ability to withstand thick ice.

A giant panda gave birth to a cub at the U.S. National Zoo on Friday, raising hopes for a rare success after a series of false pregnancies and a death.

"WE HAVE A CUB!!" the zoo announced on Twitter, after the birth was shown live on two Internet webcams from the panda's den.

The man whose research team discovered the wreckage of the Titanic has now turned his attention to the deepest trough of the Caribbean Sea.

Dr. Robert Ballard was aboard a 211-foot (64-meter) research vessel with dozens of other scientists to probe the Cayman Trough this week and collect samples of organisms they say might reveal how life might exist on other planets.

U.S. scientists said Thursday they have built the world's most precise clock, whose ticking rate varies less than two parts in one quintillion, or 10 times better than any other.

The clock, made from the element ytterbium, could be used for technological advancements beyond timekeeping, such as navigation systems, magnetic fields and temperature.

Birds sense posted speed limits on roads and react to avoid collisions, according to a study out Wednesday.

Researchers said birds appear to have adapted to the local speed limits as a feature of their environment, such as the risk of predators.

Since the first test-tube baby was born more than three decades ago, in vitro fertilization has evolved into a highly sophisticated lab procedure. Now, scientists are going back to basics and testing a simpler and cheaper method intended mainly for developing countries.

In the West, many would-be parents spend thousands of dollars for IVF, which involves pricey incubators and extensive screening. But European and American scientists say a simplified version of the entire procedure aimed at developing countries could be done for about 200 euros ($265) with generic fertility drugs and basic lab equipment that would fit inside a shoebox.

Scientists studying the H7N9 bird flu virus that has killed more than 40 people since March said Wednesday they had discovered another H7-type virus lurking in chickens in China.

Dubbed H7N7, the virus was able to infect mammals in a lab experiment, said the team, warning H7 viruses "may pose threats beyond the current outbreak".

Colombia on Wednesday more than doubled the size of a huge nature reserve as it fights to protect the Amazon from deforestation.

Environment Minister Juan Gabriel Uribe said deforestation of the Colombian Amazon is a worrisome problem, mainly because of land being cleared for growing coca leaves, logging, illegal mining and agriculture.