Science Daily

An ancient otter tooth recently discovered in Mexico suggests certain mammals migrated across America during the Miocene geologic epoch, roughly 23 million to 5.3 million years ago. The new hypothesized route questions other theories such as migrations above Canada and through Panama, and has implications for a much larger biologic event -- the Great American Biotic Interchange, when land bridges were formed and animals dispersed to and from North America and South America.

To understand how human activities are affecting the planet, scientists often study the health of animals in the wild. Now a new study finds that the levels of mercury in some polar bears are declining. But rather than heralding a drop in mercury in the environment, the decrease could indicate how climate change has led the animals to shift foraging habits, which has affected their diets and weight.

The Science Team of the Canadian Research Icebreaker CCGS Amundsen has cancelled the first leg of the 2017 Expedition due to complications associated with the southward motion of hazardous Arctic sea ice, caused by climate change.

A new study suggests that roughly 22% of the element xenon found in Earth's atmosphere may have come from comets.

Future climate warming could lead to a re-greening of the southernmost Sahara (Sahel), with decreased dust emissions and changes in land cover. In a recent study, researchers have found that tropical cyclone activity may have increased during past warm climates in connection with a greening of the Sahara.

Unlike other species that migrate successfully to escape the wrath of climate change, a new study shows that dispersal may help sustain global Emperor penguin populations for a limited time, but, as sea ice conditions continue to deteriorate, the 54 colonies that exist today will face devastating declines by the end of this century.

Several methane domes, some 500m wide, have been mapped on the Arctic Ocean floor. They may be signs of soon-to-happen methane expulsions that have previously created massive craters in a near-by area.

The rift in the Larsen C ice shelf in Antarctica has grown by 17km in the last few days and is now only 13km from the ice front, indicating that calving of an iceberg is probably very close, researchers revealed after studying satellite data. The rift is likely to lead to one of the largest icebergs ever recorded.

Hundreds of massive, kilometer-wide craters on the ocean floor in the Arctic were formed by substantial methane expulsions, new research explains.

During the last glacial period -- when the ice in the Antarctic was far thicker and extended further offshore than it does today -- it has been speculated that subglacial lakes existed beneath it. An international team of researchers has now successfully sampled the meter-thick sediment layers left behind by these lakes contemporary on the seafloor.

A new study combining European ice core data and historical records of the infamous Black Death pandemic of 1349-1353 shows metal mining and smelting have polluted the environment for thousands of years, challenging the widespread belief that environmental pollution began with the Industrial Revolution in the 1700s and 1800s.

Arctic warming occurred in the early 20th century due to the warming phases -- 'interdecadal variability mode' -- of both the Pacific and Atlantic oceans, suggests new research.

The discovery of anomalously high levels of mercury in rocks from the Ordivician geological period has led to a new interpretation of the ensuing mass extinction. A sequence of disturbances may have led to catastrophic cooling by reflective sulfate aerosols injected into the atmosphere by massive volcanism. The finding is important since aerosol cooling is under consideration as a way to temper global warming.

Scientists are using new imaging techniques to measure the atomic nanostructure of ancient crystal fragments at meteorite impact sites. The end goal? To understand when impacts ended and life began.

Research based on more than 180 fossil insects preserved in the La Brea Tar Pits of Los Angeles indicate that the climate in what is now southern California has been relatively stable over the past 50,000 years.

Evidence from the age of the dinosaurs to today shows that chemical weathering of rocks is less sensitive to global temperature, and may depend on the steepness of the surface. The results call into question the role of rocks in setting our planet's temperature over millions of years.

In 2013, researchers studying mosses and microbes growing at the southern end of the Antarctic Peninsula documented unprecedented ecological change over the last 50 years, driven by warming temperatures. Now, the same research group has confirmed that those striking changes in the Antarctic are widespread, occurring all across the Peninsula.

Engineers have known for some time that calcium chloride salt, commonly used as deicer, reacts with the calcium hydroxide in concrete to form a chemical byproduct that causes roadways to crumble. A civil engineer is working on a new recipe for concrete, using cast-off products from furnaces, that can hold its own against the forces of chemical erosion.

Temperatures in the Arctic are increasing twice as fast as in the rest of the globe, while the Antarctic is warming at a much slower rate. A new study shows that land height could be a 'game changer' when it comes to explaining why temperatures are rising at such different rates in the two regions.

A Greenland ice core providing a first glimpse at the history of reactive oxidants shows that for big temperature swings in the past 100,000 years, reactive oxidants are actually higher in cold climates. This means that new mechanisms -- not just water vapor, plant and soil emissions -- must affect the concentration of ozone and other oxidants in the atmosphere.