Ancient air pockets changing the history of Earth’s oxygen

Ancient air trapped in rock salt for 813 million years is changing the timeline of atmospheric changes and life on Earth.

Defining past atmospheric compositions is an important yet daunting task for geologists. Most methods for determining past Earth surface conditions rely on indirect proxies gleaned from ancient sedimentary rocks. Further complicating matters, sedimentary rocks are notoriously difficult to date because they contain remnants of other rocks formed at various times.

As a result, oxygenation, or the rise of oxygen in the Earth's atmosphere, has been presumed to occur about 550 million years ago near the boundary between the Precambrian and Paleozoic geologic periods.

The Earth seeen from Apollo 17. By NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans [Public domain or Public domain], via Wikimedia Commons

West Virginia University geologist Kathleen Benison is part of a research team using new direct methods to measure the Earth's oxygenation.

The team's study identifies, for the first time, exactly how much oxygen was in Earth's atmosphere 813 million years ago - 10.9 percent. This finding, they say, demonstrates that oxygenation on Earth occurred 300 million years earlier than previously concluded from indirect measurements.

"Diversity of life emerges right around this time period," Benison said. "We used to think that to have diversity of life we needed specific things, including a certain amount of oxygen. (The findings) show that not as much oxygen is required for organisms to develop."

Fluid inclusions, the microscopic bubbles of liquids and gases in rock salt, can contain trapped air. Analysis of this trapped air allows researchers to understand past surface conditions and how oxygen has changed over the course of geologic history.

The team used a quadrupole mass spectrometer to study the air pockets. Carefully crushing minute rock salt crystals released water and gases into the mass spectrometer, which then analyzed for various compounds of oxygen and other gases.

"There are a lot of different environmental conditions specific from the past that we can find occurring in modern samples," Benison said. "This tells us about the range of conditions on Earth and also has implications for Mars."

For more information visit:

https://www.sciencedaily.com/releases/2016/08/160822174234.htm

http://www.prlabs.co.uk/lab-supplies.php?N=oxygen-sensor&Id=75102

Methane production reduced in ruminants

Livestock farming is responsible for 18 percent of the world's greenhouse gases, and ruminants such as cattle, sheep and goats generate 35 percent of one of these gases - methane, and according to experts they make a significant contribution to climate change.

Researchers at the Spanish National Research Council (CSIC) have taken part in a study of the effect of one molecule, 3-nitrooxypropanol, in inhibiting methane production in ruminants. The work has been published in the magazine, Proceedings of the National Academy of Sciences (PNAS).

Stereo, skeletal formula of methane with some measurements added. By Jynto [Public domain], via Wikimedia Commons.

Ruminants are animals which digest their food through fermentation carried out by microorganisms living in the rumen. This process produces organic acids: acetic acid, propionic acid, and butyric acid, all of which are absorbed and metabolized by the organism as a source of energy. But, in addition, it also produces methane, which escapes into the atmosphere in the form of gas.

How 3-nitrooxypropanol works

By 2014, scientists had demonstrated the effectiveness of this molecule in sheep, but were unaware of how it actually worked. Now, in vivo research, using incubated anaerobic microorganisms from ruminants' digestive systems have revealed how the compound 3-nitrooxypropanol only had an effect on methane producing microorganisms (arqueas methanogens) and not on those which contribute to digestion (bacterias). As David Yáñez, a CSIC researcher at the Zaidin Experimental Research Centre in Granada (southern Spain) explains, "Up until now, no-one had described the mode of action of a compound which can repeatedly reduce (by 30%) methane production in animals without any risks, either to the animal's health, or to their productivity."

The results of this work open up the possibility of reducing methane emissions and of contributing to a reduction in global temperatures which is caused by greenhouse gases. In addition, "We will see an increase in the efficiency of ruminant production systems as better use is made of the energy taken in in animal feed, given that methane production accounts for a loss of up to 12% of the energy an animal ingests" notes Yáñez.

Both the University of Auburn in the USA and the Max Planck Institute in Germany collaborated on this project as did the Swiss company, DSM Nutritional Products, which developed and owns the patent to 3-nitrooxypropanol.

For more information visit:-

https://www.sciencedaily.com/releases/2016/05/160502161108.htm

http://www.prlabs.co.uk/lab-supplies.php?N=bisdiphenylphosphino-methane-for-sy&Id=38134

Carbon emissions 'postpone ice age'

The next ice age may have been delayed by over 50,000 years because of the greenhouse gases put in the atmosphere by humans, scientists in Germany say.

They analysed the trigger conditions for a glaciation, like the one that gripped Earth over 12,000 years ago.

The shape of the planet's orbit around the Sun would be conducive now, they find, but the amount of carbon dioxide currently in the air is far too high.

Earth is set for a prolonged warm phase, they tell the journal Nature.

"In theory, the next ice age could be even further into the future, but there is no real practical importance in discussing whether it starts in 50,000 or 100,000 years from now," Andrey Ganopolski from the Potsdam Institute for Climate Impact Research said.

"The important thing is that it is an illustration that we have a geological power now. We can change the natural sequence of events for tens of thousands of years," he told BBC News.

The Earth seen from space

Earth has been through a cycle of ice ages and warm periods over the past 2.5 million years, referred to as the Quaternary Period.

This has seen ice sheets come and go. At its maximum extent, the last glaciation witnessed a big freeze spread over much of North America, northern Europe, Russia and Asia.

In the south, a vast expanse of what are now Chile and Argentina were also iced up.

A fundamental parameter determining what dips Earth into an ice age is the changing nature of its orbit around the Sun.

The passage around the star is not a perfect circle and over time our planet's axis of rotation also rocks back and forth.

These movements alter the amount of solar radiation falling on the Earth's surface, and if a critical threshold is reached in mid latitudes in the Northern Hemisphere then a glaciation can be initiated.

Dr Ganopolski colleagues confirm this in their modelling but show also the role played by the concentration of greenhouse gases in the atmosphere.

And one of their findings is that Earth probably missed the inception by only a narrow margin a few hundred years ago, just before the industrial revolution took hold.

"We are now in a period when our (northern) summer is furthest from the Sun," the Potsdam researcher explained.

"Under normal circumstances, the interglacial would be terminated, and a new ice age would start. So, in principle, we are in the perfect conditions from an astronomical point of view. If we had a CO2 concentration of 240 parts per million (200 years ago) then an ice age could start, but luckily we had a concentration that was higher, 280ppm." Today, industrial society has taken that concentration to over 400ppm.

The team says that an interglacial climate would probably have been sustained anyway for at least 20,000 years, and, very probably, for 50,000 years, even if CO2 had stayed at its eighteenth century level.

But the almost 500 gigatonnes of carbon that has been released since the Industrial Revolution means we will likely miss the next best astronomical entry point into a glaciation, and with a further 500 gigatonnes of emissions the "probability of glacial inception during the next 100,000 years is notably reduced", the scientists say in their Nature paper.

Add a further 500 Gt C on top of that and the next ice age is virtually guaranteed to be delayed beyond the next 100,000 years.

Commenting on the study, Prof Eric Wolff from the University of Cambridge, UK, said: "There have been previous papers suggesting that the next ice age is many tens of thousands of years away, and that the combination of seasonal solar energy at the latitude where an ice sheet would form, plus CO2, is what determines the onset of an ice age. But this paper goes much further towards quantifying where the limits are.

"It represents a nice confirmation that there is a relatively simple way of estimating the combination of insolation and CO2 to start an ice age," he told the Science Media Centre.

And Prof Chris Rapley, from University College London, added: "This is an interesting result that provides further evidence that we have entered a new geological [Epoch] - 'The Anthropocene' - in which human actions are affecting the very metabolism of the planet."

For more information visit:

http://www.bbc.co.uk/news/science-environment-35307800

http://www.prlabs.co.uk/lab-supplies.php?N=gastube-carbon-dioxide-hr-05-20&Id=11735