(Press-News.org) New research shows the permanent rise of oxygen in our atmosphere, which set the stage for life as we know it, happened 100 million years later than previously thought.
A significant rise in oxygen occurred about 2.43 billion years ago, marking the start of the Great Oxidation Episode -- a pivotal moment in Earth's history.
An international research team including a UC Riverside scientist analyzed rocks from South Africa formed during this event. Findings, published this week in the journal Nature, include the discovery that oxygen fluctuated dramatically after its early appearance until it became a permanent constituent of the atmosphere much later.
These fluctuations reinforce a direct link between atmospheric oxygen and concentrations of greenhouse gases such as methane, helping to explain some of the most extreme climate changes in the planet's past.
During the same period, ancient Earth experienced four glaciations -- periods when the whole planet was covered with ice and snow for millions of years. According to UC Riverside geologist Andrey Bekker, changes in atmospheric oxygen levels began and ended these events.
Scientists have often wondered how the planet could have emerged from the periods in which ice and snow covered everything, including the oceans. According to Bekker, increases in atmospheric oxygen levels resulted in low concentrations of greenhouse gases, such as methane and carbon dioxide. This ushered in global glaciations by maintaining surface conditions below the water-freezing temperature.
Volcanoes also continued to erupt on the frozen planet, building required high levels of carbon dioxide in the atmosphere to exit from climatic catastrophe by warming the planet and melting the snow and ice.
"Before this work, we all wondered why the fourth glacial event happened if oxygen was already a steady component in the atmosphere," Becker said. "We found it was not steady. The permanent rise of oxygen actually occurred after the fourth, final glaciation in the Paleoproterozoc Era, and not before it, and this solves what had previously been a major puzzle in our understanding."
The Great Oxidation Episode ushered in a 1.5 billion-year period of subsequent environmental stability, which lasted until a second major transitional period, marked by rising atmospheric oxygen and similar climatic changes at the end of the Precambrian time.
"We thought once oxygen increased it wouldn't ever return back to lower levels," Bekker said. "Now we have learned it fluctuated to very low levels and this could have dramatic implications in terms of understanding extinction events and the evolution of life."
Open questions include the reasons for these multiple fluctuations, and whether complex life could have evolved and then died out again in response to them, said Simon Poulton, a biogeochemist at Leeds University who led the research.
"We cannot begin to understand the causes and consequences of atmospheric oxygenation, the most significant control on Earth's habitability, if we do not know when permanent atmospheric oxygenation actually occurred," he said. "Now at last we have that piece of the puzzle."
INFORMATION:
Researchers at the National Institutes of Health have developed a breath test that measures how well patients with methylmalonic acidemia (MMA) respond to receiving liver or combined liver and kidney transplantation. Researchers also used the test to assess the severity of the disease in people and help determine if they would benefit from surgical or experimental genomic therapies that target the liver. The study results were published in Genetics in Medicine. Scientists at the National Human Genome Research Institute (NHGRI) led the project team, with collaborators from the National ...
Rates of prolonged visits for pediatric mental health emergency department (ED) visits increased over a decade, in contrast to non-mental health visits for which visit times remained stable, according to a study published in the journal Pediatrics. From 2005-2015, rates of ED visits lasting over six hours for children presenting for mental health issues jumped from 16 percent to nearly 25 percent, while rates of visits lasting over 12 hours increased from 5 percent to nearly 13 percent.
"The trend of increasingly long ED visits for pediatric mental health problems likely represents worsening access to essential mental health services. This is concerning, especially since during the COVID-19 pandemic we are seeing substantially more children coming ...
BATON ROUGE, La. (March 2021) - Without restoration efforts in coastal Louisiana, marshes in the state could lose half of their current ability to store carbon in the soil over a period of 50 years, according to a new paper published in American Geophysical Union Journal of Geophysical Research Biogeosciences.
"This reduction in capacity could significantly alter the global carbon budget, given that Louisiana's marsh soils account for between 5 and 21 percent of the global soil carbon storage in tidally influenced wetlands," said Melissa Baustian, lead author and coastal ecologist at The Water Institute of the Gulf.
The article, "Long-term carbon sinks in marsh soils of coastal Louisiana are at risk to wetland loss" ...
A new study shows a correlation between the end of solar cycles and a switch from El Nino to La Nina conditions in the Pacific Ocean, suggesting that solar variability can drive seasonal weather variability on Earth.
If the connection outlined in the journal Earth and Space Science holds up, it could significantly improve the predictability of the largest El Nino and La Nina events, which have a number of seasonal climate effects over land. For example, the southern United States tends to be warmer and drier during a La Nina, while the northern U.S. tends to be colder ...
PULLMAN, Wash. - The ability to control your own behavior, known as executive function, might not exist all in your head. A new theory proposes that it develops with many influences from outside the mind.
The theory, detailed in Perspectives on Psychological Science, draws on dynamic systems theory which originated in mathematics and physics and has been used to describe complex organizing phenomena like cloud formation and flying patterns of birds. Now, a research team led by Washington State University human development assistant professor Sammy Perone is applying ...
Tokyo, Japan - Researchers from Tokyo Metropolitan University have shown that skeletal muscle satellite cells, key players in muscle repair, proliferate better in low glucose environments. This is contrary to conventional wisdom that says mammalian cells fare better when there is more sugar to fuel their activities. Because ultra-low glucose environments do not allow other cell types to proliferate, the team could produce pure cultures of satellite cells, potentially a significant boost for biomedical research.
Healthy muscles are an important part of a healthy life. With the wear and tear of everyday use, our muscles continuously repair themselves to keep them in top condition. In recent years, scientists have begun to understand how muscle repair ...
The neurons in our nervous system "talk" to each other by sending and receiving chemical messages called neurotransmitters. This communication is facilitated by cell membrane proteins called receptors, which pick up neurotransmitters and relay them across cells. In a recent study published in Nature Communications, scientists from Japan report their findings on the dynamics of receptors, which can enable understanding of the processes of memory formation and learning.
The regulation of receptor movement and localization within the neuron is important for synaptic plasticity, an important process in the central nervous system. A specific type of ...
DEPRIVATION among society at large is 'driving' Covid-19 disparities among minority ethnic groups - predominantly South Asian and Black African or Caribbean populations - and could be considered the main cause of disproportionate infection rates, hospitalisation and deaths experienced by these populations, according to new analysis from the University of Leicester.
The study, supported by the National Institute for Health Research (NIHR) Leicester Biomedical Research Centre (BRC) comes a day after a government-commissioned review concluded race and racism have become less important factors in explaining social disparities in the UK.
Researchers at the University of Leicester used UK Biobank data of 407,830 South Asian, Black ...
Waiting for your turn can be frustrating, especially when it comes to COVID-19 vaccinations. But prioritizing who receives the limited supply of vaccines available saves lives and reduces spread of infection, according to a study published today in the journal PNAS from the University of California, Davis.
While there is mostly universal agreement that older people should be prioritized, debates are currently underway about prioritizing a variety of other groups. Still others argue against targeting at all.
"Prioritization has benefits because people differ in at least two key ways -- their risk of infection and the likelihood of serious consequences from infection," said senior author ...
Within southeast Michigan's Middle Eastern and North African community, those who worry about deportation or believe they've been treated unfairly are likely to face more adverse conditions associated with poor health, including food insecurity and financial distress.
The MENA people who face several of these barriers are also more likely to report chronic illness and mental health issues as well as worse overall health.
That's according to a new study by the University of Michigan Rogel Cancer Center, the University of Michigan School of Public Health, and the Arab Community Center for ...
