Science Daily

If someone cries 'Eureka!' because it looks like oxygen appeared in Earth's ancient atmosphere long before the body of evidence indicated, be careful. If it was a chromium isotope system reading that caused the enthusiasm, it might need to be curbed.

The glaciers that carved Yosemite Valley left highly polished surfaces on many of the region's rock formations. These smooth, shiny surfaces, known as glacial polish, are common in the Sierra Nevada and other glaciated landscapes. Geologists have now taken a close look at the structure and chemistry of glacial polish and found that it consists of a thin coating smeared onto the rock as the glacier moved over it.

Prehistoric polar forests were built for survival, but were not hardy enough to live in ultra-high concentrations of atmospheric carbon dioxide. A geologist is studying the tree fossil record in Antarctica from a mass extinction 250 million years ago, looking for clues to how greenhouse gases affected plants -- then and now.

The concentration of carbon dioxide (CO2) in the atmosphere determines whether the Earth is in greenhouse or ice age state. Before humans began to have an impact on the amount of CO2 in the air, it depended solely on the interplay of geological and biological processes, the global carbon cycle. This study shows that the break-up of continents - also known as rifting -- contributed significantly to higher CO2 concentrations in the atmosphere.

New research has revealed why the oldest water in the ocean in the North Pacific has remained trapped in a shadow zone around 2km below the sea surface for over 1000 years.

New research shows that climate warming reduced the mass of the Cordilleran Ice Sheet by half in as little as 500 years, indicating the Greenland Ice Sheet could have a similar fate.

When water droplets freeze in clouds, the structure of the ice crystal isn't necessarily the classic hexagonal snowflake structure. Rather, a more disordered ice structure forms more easily than hexagonal ice under certain cloud conditions, allowing the water droplets in clouds to turn to ice more rapidly than previously predicted. The work reconciles theoretical models of clouds with observations of freezing rates.

Analyses of ancient plant leaf wax found in the sediments of the Gulf of Guinea told the researchers about rainfall in Cameroon and the central Sahel-Sahara over the past several millennia and showed a rapid aridification around 5500 years before now.

A new NASA study adds evidence that a geothermal heat source called a mantle plume lies deep below Antarctica's Marie Byrd Land, explaining some of the melting that creates lakes and rivers under the ice sheet. Although the heat source isn't a new or increasing threat to the West Antarctic ice sheet, it may help explain why the ice sheet collapsed rapidly in an earlier era of rapid climate change, and why it is so unstable today.

The newly released Climate Science Special Report describes current trends in the climate globally and for the U.S., and projects trends in temperature, precipitation, sea-level rise and Arctic sea ice for the remainder of this century.

The carbonate shells of tiny marine plankton, foraminifers, are important archives of geochemical records of past climates. Now researchers have discovered that, contrary to long-standing textbook knowledge, these shells do not form as calcite, but instead, are originally formed as the metastable carbonate vaterite and only later transform into calcite. The presence of vaterite instead of calcite in these abundant organisms also means that foraminifer shells are much more susceptible to ocean acidification than has been previously thought.

New maps of Greenland's coastal seafloor and bedrock beneath its massive ice sheet show that two to four times as many coastal glaciers are at risk of accelerated melting as had previously been thought.

Totten Glacier, the largest glacier in East Antarctica, is being melted from below by warm water that reaches the ice when winds over the ocean are strong, according to research. The new findings are a cause for concern because the glacier holds more than 11 feet of sea level rise and acts as a plug that helps lock in the ice of the East Antarctic Ice Sheet.

Major volcanic eruptions in the future have the potential to affect global temperatures and precipitation more dramatically than in the past because of climate change, according to a new study.

Concentrations of carbon dioxide in the atmosphere surged at a record-breaking speed in 2016 to the highest level in 800,000 years, according to a new report. The abrupt changes in the atmosphere witnessed in the past 70 years are without precedent.

Isotopes found in bat guano over the last 1,200 years provide scientists with information on how the climate was and is changing.

A new geological record of the Yellowstone supervolcano's last catastrophic eruption is rewriting the story of what happened 630,000 years ago and how it affected Earth's climate. This eruption formed the vast Yellowstone caldera observed today, the second largest on Earth.

Thousands of marks on the Antarctic seafloor, caused by icebergs which broke free from glaciers more than ten thousand years ago, show how part of the Antarctic Ice Sheet retreated rapidly at the end of the last ice age as it balanced precariously on sloping ground and became unstable.

Volcanic eruptions have been known to cool the global climate, but they can also exacerbate the melting of ice sheets, according to a new paper.

Rising sea levels caused by a warming climate threaten greater future storm damage to New York City, but the paths of stronger future storms may shift offshore, changing the coastal risk for the city, according to a team of climate scientists.