Researchers Find Ancient Evidence of 'Snowball Earth'

LSU scientist Huiming Bao, along with colleagues from UCLA and China, recently discovered some of the first atmospheric evidence in support of the “Snowball Earth” hypothesis. This theory suggests that Earth was entirely covered by ice during the Cryogenian period, which took place from about 790 to 630 million years ago. Their findings were reported in the May 22 issue of Nature.

Bao and his group used a new parameter called “sulfate oxygen-17 anomaly” to measure atmospheric records found in mineral sulphate deposits. “My group specializes in measuring these anomalies – very few other groups do,” said Bao. “This puts us in an extremely good position for uncovering previously unknown information.”

These oxygen-17 anomalies are usually not measured by scientists who study Earth rocks because they were originally believed to be exclusively extra-terrestrial in nature, coming only from specific types of asteroids. Over the years, Bao’s group has worked on many extremely dry deserts on Earth and shown that there are a large range of oxygen-17 anomalies among desert salts that record atmospheric reactions.

All of the previous documented anomalies are positive, meaning that there is an excess in oxygen-17 isotopes. This finding, however, reveals a large depletion in oxygen-17 content in some of the sulfate minerals. These are the first oxygen-17 depletions, or negative anomalies, found in Earth minerals. What is even more striking is the timing of the negative anomalies – there is a spike in the depletion right at the time when a global glaciation came to an abrupt end approximately 635 million years ago.

To account for the data, Bao and his colleagues proposed that this depletion spike was caused by an extremely high atmospheric carbon dioxide concentration at that time, at least 40 times the modern level. That is what the “Snowball Earth” hypothesis predicted when the entire oceans were frozen over for millions of years. Bao and his colleagues will still have to rule out other scenarios before calling their evidence a “smoking gun” for the theory. “But we have found a new way to look into the details of very old glaciations events that other approaches couldn’t,” said Bao. “Using this new parameter, we should be able to read from the rock record the dynamics of the glaciations as well as the impact to biosphere, atmosphere and hydrosphere of our Earth system.”

In light of the increasing environmental stresses humans have placed on Earth, Bao said that there is a critical need to understand how a complex system like Earth’s can be expected to react.

“There is an old saying that the best way to know a person’s character is to put him or her under pressure and see how he reacts,” said Bao. “This is the same situation. The best way to learn more about our Earth system is to see how it responded to extreme conditions in the past.”

Source: LSU

Related stories:

BOSS: The Baryon Oscillation Spectroscopic Survey
The Sloan Digital Sky Survey (SDSS) uses a 2.5-meter telescope with a wider field of view than any other large telescope, located on a mountaintop in New Mexico called Apache Point and devoted solely to mapping the universe. We now know that some three-quarters of the universe consists of dark energy, whose very existence was unsuspected when telescope construction began in 1994 and still controversial when the first Sloan survey started in 2000.
Alternative energy hits the road
Anyone who has walked barefoot across a parking lot on a hot summer day knows that blacktop is exceptionally good at soaking up the sun's warmth. Now, a research team at Worcester Polytechnic Institute (WPI) has found a way to use that heat-soaking property for an alternative energy source.
How drug that blocks cholesterol absorption from the diet works
A new study in the June issue of Cell Metabolism, a Cell Press publication, sheds light on the action of the drug ezetimibe (trade name Zetia), which is used to treat high cholesterol. Ezetimibe is unique among cholesterol-lowering drugs in that it works by cutting the amount of cholesterol taken in from the diet rather than by blocking cholesterol’s manufacture in the body.
Halting methane squanderlust
The pipes that rise from oil fields, topped with burning flames of natural gas, waste fossil fuels and dump carbon dioxide into the air. In new work, researchers have identified the structure of a catalytic material that can turn methane into a safe and easy-to-transport liquid. The insight lays the foundation for converting excess methane into a variety of useful fuels and chemicals.
New findings: The anti-fibrotic mechanism of plant extract Cpd 861
A team led by Dr. Xue-Hai Tan from the Beijing Genomics Institute has determined that the antifibrotic function of Chinese herbal extract Cpd 861 is mediated by both downregulating the synthesis of collagens and upregulating the degradation of collagens. This effect is evidently different from that of Western antifibrogenic drugs and could allow for the development of effective antifibrogenic drugs from Chinese medicinal herbs.
Catalysis discovery takes aim at NOx emissions
A discovery in molecular chemistry may help remove a barrier to widespread use of diesel and other fuel-efficient "lean burn" vehicle engines. Researchers at the Department of Energy's Pacific Northwest National Laboratory have recorded the first observations of how certain catalyst materials used in emission control devices are constructed.
New technique quickly detects cancer indicator
Researchers have developed a new way to detect protein movements inside cells, which signal a variety of cellular changes such as those in cancer cell development. The method could help diagnose cancer in the future.
Researchers develop powerful tool to study the genetics of inflammation
Scientists have known which genes are linked to inflammation, but now researchers at Wake Forest University Baptist Medical Center have organized this information to develop a powerful tool to aid investigators in studying the genetics of inflammatory diseases.

News discussion:

Space & Earth science news