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IN BRIEF: Greenland is losing 7% more ice than we thought, thanks to an ancient hotspot

9/22/2016

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Researchers have lots of fancy ways of measuring ice loss on Greenland, from precise laser mapping to gravity-measuring satellites. These techniques have yielded a fairly reliable measurement of ice loss from Greenland: 2,500 gigatons per year, since 2003.
Picture
A figure from the study showing the measured rates of uplift (rebounding from the weight of larger ice sheets) and possible models for uplift across the island.
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However, the models these measurements fed all assumed the ground under Greenland was rising, as it rebounds from the great mass of the ice sheets of the Last Glacial Maximum, at a similar global average.

It's not, according to a new study published Science Advances. The crust in an area on the southeast side of Greenland is rebouding up at 12 millimeters per year (compared to a handful of millimeters per year elsewhere on the island). This is probably because this part of Greenland's crust passed over a volcanic hotspot 40 million years ago (the same one now forming Iceland), which made that section of crust more pliable and prone to deformation by the weight of ice sheets.

This means that, if the land is rising faster than expected, more ice must be melting off than previously thought, or the Greenland ice cap would be bulging up in this spot, which it is not doing. Calculations by the study's authors estimate 200 more gigatons (10^7) of ice have been melting off Greenland each year, unaccounted for until now. That is 7% of Greenland's total ice loss.
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VIDEO: MEGA Plate Paints Evolution with Bacteria

9/15/2016

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An 11-day timelapse of breeding bacteria artfully visualizes evolution and antibiotic resistance.
This timelapse of bacteria spreading across a large table of nutrients--laced in increasingly potent strips with an antibiotic--is a clear and beautiful demonstration of evolution. On a stark black background, white bacteria creep across the table, pausing as they encounter a more deadly stripe of antibiotic. When mutant strains emerge that are capable of living in the harsher environment, they surge on to the next boundary.

In only 11 days, bacteria are thriving in antibiotic concentrations 1000 times greater than concentrations that killed their ancestors.

The 2-by-4-foot table was created and filmed for a Harvard Medical School graduate class and proved an effective educational tool. "When shown the video, evolutionary biologists immediately recognize concepts they’ve thought about in the abstract, while non-specialists immediately begin to ask really good questions,” said Tami Lieberman, who is a co-investigator on the project, in the Harvard press release.

The table also revealed a new insight in bacterial evolution. The first mutant strains to reach the highest concentration of antibacterial are not necessarily the strongest. The fittest, most reproductively successful strains might develop resistance to antibiotics later.
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(The demonstration was also inspired by a Hollywood marketing ploy for the film Contagion, that spelled out the movie’s title with spreading bacteria.)
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Contact: HarrisonDreves@gmail.com | (615)-349-7300