Sea levels may rise as much as 69 centimeters (27 inches) through 2100 as water temperatures rise, glaciers melt in the Andes and Himalayas and ice sheets in Greenland and Antarctica shed water, European scientists said.

The new estimate exceeds a previous forecast of as much as 59 centimeters by the United Nations’ Intergovernmental Panel on Climate Change in 2007, which didn’t fully account for the effects of melting ice, researchers with the independent Ice2sea project of 24 institutions in Europe and Chile said today.

The first humans to live on Mars might not identify as astronauts, but farmers. To establish a sustainable settlement on Earth's solar system neighbor, space travelers will have to learn how to grow food on Mars — a job that could turn out to be one of the most vital, challenging and labor-intensive tasks at hand, experts say.

India's tigers are facing extinction owing to a collapse in the variety of their mating partners, according to new research carried out by scientists at Cardiff University.

India is a refuge for approximately 60% of the world's wild tigers, yet even here their numbers remain low and genetic diversity is declining rapidly making them increasingly vulnerable to extinction.

In a damp Spanish cave, Alistair Pike applies a small grinder to the world's oldest known paintings. Every few minutes, the dentist-drill sound stops and Pike, an archaeologist from the University of Southampton, UK, stands aside so that a party of tourists can admire the simple artwork — hazy red disks, stencilled handprints, the outlines of bison — daubed on the cave wall tens of thousands of years ago. He hopes that the visitors won't notice the small scuff marks he has left.

You, hear me! Give this fire to that old man. Pull the black worm off the bark and give it to the mother. And no spitting in the ashes!

It’s an odd little speech. But if you went back 15,000 years and spoke these words to hunter-gatherers in Asia in any one of hundreds of modern languages, there is a chance they would understand at least some of what you were saying.

That’s because all of the nouns, verbs, adjectives and adverbs in the four sentences are words that have descended largely unchanged from a language that died out as the glaciers retreated at the end of the last Ice Age. Those few words mean the same thing, and sound almost the same, as they did then.

From Ireland to the Balkans, Europeans are basically one big family, closely related to one another for the past thousand years, according to a new study of the DNA of people from across the continent.

The study, co-authored by Graham Coop, a professor of evolution and ecology at the University of California, Davis, will be published May 7 in the journal PLoS Biology.

Scientists searching for signs of life beyond our solar system should keep an open mind, for planets very different than Earth may well be habitable, a prominent researcher says.

While it may seem natural to zero in on "alien Earths," such a narrow focus would exclude many potentially life-supporting exoplanets, whose diversity continues to astound astronomers, says Sara Seager of MIT.

And researchers can't afford to be so picky, she adds, since they'll be able to get in-depth looks at just a handful of alien worlds for the foreseeable future.

On April 27, NASA's Fermi and Swift satellites detected a strong signal from the brightest gamma-ray burst in decades. Because this was relatively close, it was thousands of times brighter than the typical gamma-ray bursts that are seen by Swift every few days. Scientists are now scrambling to learn more.

We already knew that when the biggest stars run out of fuel, they don't fade quietly away. Instead, they explode in a blaze of glory known as a supernova. These stellar explosions are often bright enough to be seen by us even though they are in galaxies billions of light-years from our own Milky Way galaxy home.

NASA's Curiosity rover is back at work in Yellowknife Bay, a rocky area inside Mars' Gale Crater — and if it takes good care of itself, it just might still be at work when humans hit the Red Planet.

At least that's the sentiment voiced by Michael Meyer, lead scientist for NASA's Mars Exploration Program, during this week's Humans to Mars Summit in Washington. "I anticipate the first astronaut we send can go and shake Curiosity's hand," he told Monday's audience at George Washington University. If that astronaut is able to come within hand-shaking distance, the gesture would serve as a thank-you for years of service by the nuclear-powered robot, Meyer said.

Some things you just count on. Like if we ever meet a space alien, it should have eyes (and maybe a head). Like somewhere out there, there are planets like ours. Like we have an ordinary solar system — "ordinary" because you know what it looks like ...

It's got a sun in the middle, little planets on the inside, bigger ones farther out. That's what most of them should look like, no?

Researchers have pinpointed a set of biological markers that could help diagnose PTSD--and, eventually, treat it.

A molecular imaging study has pinpointed a set of biological markers that could help diagnose post-traumatic stress disorder more accurately, and might even lead to a pharmacological treatment in the future.

Smoking cannabis may prevent the development of diabetes, one of the most rapidly rising chronic disorders in the world.

If the link is proved, it could lead to the development of treatments based on the active ingredient of cannabis, tetrahydrocannabinol (THC), without its intoxicating effects.

The helicopter appears as a speck on the horizon, moving slowly on a dead-straight path over the black volcanic island. Beneath it hangs a huge metal cone: an industrial-scale hopper that is sending a steady stream of blue pellets raining down on the scrubby landscape of Pinzón, one of the Galapagos Islands.

Erin Hagen watches through her binoculars. She is standing on the deck of the Sierra Negra, one of three vessels moored just off the island on this morning in November 2012. When the helicopter reaches the rocky shoreline, it changes course, heads across the ocean and hovers just above the boat.