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Earth's magnetic field is weakening 10 times faster than originally predicted, swarm satellites show

Earth's magnetic field is weakening 10 times faster than originally predicted, swarm satellites show | Jeff Morris | Scoop.it

Earth's magnetic field, which protects the planet from huge blasts of deadly solar radiation, has been weakening over the past six months, according to data collected by a European Space Agency (ESA) satellite array called Swarm.

 

The biggest weak spots in the magnetic field — which extends 370,000 miles (600,000 kilometers) above the planet's surface — have sprung up over the Western Hemisphere, while the field has strengthened over areas like the southern Indian Ocean, according to the magnetometers onboard the Swarm satellites — three separate satellites floating in tandem.

 

The scientists who conducted the study are still unsure why the magnetic field is weakening, but one likely reason is that Earth's magnetic poles are getting ready to flip, said Rune Floberghagen, the ESA's Swarm mission manager. In fact, the data suggest magnetic north is moving toward Siberia.

 

In fact over the past 20 million years, our planet has settled into a pattern of a pole reversal about every 200,000 to 300,000 years; as of 2012, however, it has been more than twice that long since the last reversal. These reversals aren't split-second flips, and instead occur over hundreds or thousands of years. During this lengthy stint, the magnetic poles start to wander away from the region around the spin poles (the axis around which our planet spins), and eventually end up switched around, according to Cornell University astronomers.


Via Dr. Stefan Gruenwald
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Rescooped by Jeff Morris from Amazing Science
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Ancient forests stabilized Earth’s CO2 and climate 24 million years ago

Ancient forests stabilized Earth’s CO2 and climate 24 million years ago | Jeff Morris | Scoop.it

UK researchers have identified a biological mechanism that could explain how the Earth’s atmospheric carbon dioxide and climate were stabilised over the past 24 million years. When CO2 levels became too low for plants to grow properly, forests appear to have kept the climate in check by slowing down the removal of carbon dioxide from the atmosphere. The results are now published in Biogeosciences, an open access journal of the European Geosciences Union (EGU).


“As CO2 concentrations in the atmosphere fall, the Earth loses its greenhouse effect, which can lead to glacial conditions,” explains lead-author Joe Quirk from the University of Sheffield. “Over the last 24 million years, the geologic conditions were such that atmospheric CO2 could have fallen to very low levels – but it did not drop below a minimum concentration of about 180 to 200 parts per million. Why?”


Before fossil fuels, natural processes kept atmospheric carbon dioxide in check. Volcanic eruptions, for example, release CO2, while weathering on the continents removes it from the atmosphere over millions of years. Weathering is the breakdown of minerals within rocks and soils, many of which include silicates. Silicate minerals weather in contact with carbonic acid (rain and atmospheric CO2) in a process that removes carbon dioxide from the atmosphere. Further, the products of these reactions are transported to the oceans in rivers where they ultimately form carbonate rocks like limestone that lock away carbon on the seafloor for millions of years, preventing it from forming carbon dioxide in the atmosphere.

 

Forests increase weathering rates because trees, and the fungi associated with their roots, break down rocks and minerals in the soil to get nutrients for growth. The Sheffield team found that when the CO2 concentration was low – at about 200 parts per million (ppm) – trees and fungi were far less effective at breaking down silicate minerals, which could have reduced the rate of CO2 removal from the atmosphere.

 

“We recreated past environmental conditions by growing trees at low, present-day and high levels of CO2 in controlled-environment growth chambers,” says Quirk. “We used high-resolution digital imaging techniques to map the surfaces of mineral grains and assess how they were broken down and weathered by the fungi associated with the roots of the trees.”

 

As reported in Biogeosciences, the researchers found that low atmospheric CO2 acts as a ‘carbon starvation’ brake. When the concentration of carbon dioxide falls from 1500 ppm to 200 ppm, weathering rates drop by a third, diminishing the capacity of forests to remove CO2 from the atmosphere.


Via Dr. Stefan Gruenwald
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