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Posts tagged "volcanism"

kenobi-wan-obi:

Did Volcano on Mercury Erupt for a Billion Years?

Extra-terrestrial volcanism is every bit as stellar as its sounds. The Earth puts on its fair share of spectacular eruptions — but it’s Earth’s distant cousins who win the awards. Lava-scarred Venus has more volcanoes than any other planet we know; Olympus Mons, a treble Everest soaring above Mars’ Northern Hemisphere, is the largest active peak in the solar system; while Saturn’s frozen moon, Enceladus, where cryovolcanoes shoot towering streams of water through a crust of solid ice, must surely rank as the strangest.

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thenewenlightenmentage:

Giant Moon-Forming Impact On Early Earth May Have Spawned Magma Ocean

Billions of years ago, the Earth’s atmosphere an opaque and the planet’s surface was a vast magma ocean devoid of life.

This scenario, says Stanford University professor of geophysics Norman Sleep, was what the early Earth looked like just after a cataclysmic impact by a planet-size object that smashed into the infant Earth 4.5 billion years ago andformed the moon. The moon, once fully formed, which would have appeared much larger in the sky at the time, since it was closer to Earth

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shychemist:

Gifford Miller collects vegetation samples on Baffin Island. (Credit: Photo courtesy of Gifford Miller, University of Colorado)

A new international study may answer contentious questions about the onset and persistence of Earth’s Little Ice Age, a period of widespread cooling that lasted for hundreds of years until the late 19th century.

 

The study, led by the University of Colorado Boulder with co-authors at the National Center for Atmospheric Research (NCAR) and other organizations, suggests that an unusual, 50-year-long episode of four massive tropical volcanic eruptions triggered the Little Ice Age between 1275 and 1300 A.D. The persistence of cold summers following the eruptions is best explained by a subsequent expansion of sea ice and a related weakening of Atlantic currents, according to computer simulations conducted for the study.

The study, which used analyses of patterns of dead vegetation, ice and sediment core data, and powerful computer climate models, provides new evidence in a longstanding scientific debate over the onset of the Little Ice Age. Scientists have theorized that the Little Ice Age was caused by decreased summer solar radiation, erupting volcanoes that cooled the planet by ejecting sulfates and other aerosol particles that reflected sunlight back into space, or a combination of the two.

“This is the first time anyone has clearly identified the specific onset of the cold times marking the start of the Little Ice Age,” says lead author Gifford Miller of the University of Colorado Boulder. “We also have provided an understandable climate feedback system that explains how this cold period could be sustained for a long period of time. If the climate system is hit again and again by cold conditions over a relatively short period — in this case, from volcanic eruptions — there appears to be a cumulative cooling effect.”

“Our simulations showed that the volcanic eruptions may have had a profound cooling effect,” says NCAR scientist Bette Otto-Bliesner, a co-author of the study. “The eruptions could have triggered a chain reaction, affecting sea ice and ocean currents in a way that lowered temperatures for centuries.”

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Volcanoes and the Little Ice Age: Not the Smoking Gun?
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There is the tendency in our fast-paced world for lots and lots of articles to get written about science before anyone beyond the researchers and the reviewers actually sees the science. This is mostly thanks to the fact that press releases come out before the actual study – and who has time to read a study when there is a handy press release with all the bits? Yesterday saw an example of just this – a whole lot of “news” without a lot of assessment of the study itself.

The paper itself is called “Abrupt Onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks” by Gifford Miller and a host of coauthors (mostly climatologists) in the Geophysical Research Letters. After seeing a post about it on Dot Earth, I knew that the media would eat this up and wouldn’t you know it, within hours there were dozens of articles mostly telling us what the initial press release already said … and not much else. It took a while for the PDF of the article to appear on the GRL website, but after it did, I sat down with it to see what the “smoking guns” were that they identified.

I’m not going to discuss the climate models or interpretation – more or less, they sampled moss and lake sediment in Canada and Iceland to constrain the dates of the onset of the Little Ice Age. Then, they used climate models and data about volcanic atmospheric sulfur (from Gao et al., 2008, more on this paper in a bit) to model how the atmosphere and oceans would respond and if it correlated with their ages. The long and short is they found that a large sulfur loading in the atmosphere could trigger increased sea ice that would prompt cooler global climate, thus the Little Ice Age.

Continue reading over at Wired.