Deench

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Familiar fishes found opportunity in mass extinction

For mammals, the mass extinction event at the end of the Cretaceous was the crisis that opened the door to evolutionary success. With so many species gone, like the dominant dinosaurs (minus the ancestors of birds), opportunities were plentiful. Our small, furtive ancestors made the most of those opportunities, giving rise to the diversity of mammals around today.

Perhaps the ray-finned fishes—which include almost every fish you can think of apart from sharks and rays and make up almost half of all modern vertebrate species—found similar opportunities. Researchers knew that this group of fish only took off in the last 100 million years (so since the mid-Cretaceous), but the early details were fuzzy. Scripps Institution of Oceanography’s Elizabeth Sibert and Richard Norris set out to tighten up that history by picking through seafloor mud for tiny fish teeth.

Those seafloor muds came from deep drilling in multiple locations in the Atlantic and Pacific Oceans. Samples of Italian limestone that had been laid down in an ocean long since closed up by plate tectonics rounded out the collection. In all the samples, which spanned from the late Cretaceous (about 75 million years ago) to the mid-Eocene (about 45 million years ago) the researchers sifted out teeth shed by ray-finned fishes and scales belonging to sharks or rays. Both types of fossils are plentiful, as they resist dissolving away on the ocean floor.

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How breaking a glacier makes the Earth quake

In the 1960s, the network of seismometers around the world expanded rapidly. It wasn’t because seismology became a fad—it was because seismometers could detect underground nuclear weapons tests anywhere in the world. Shifting gears from a cold war to the cold science of glaciology, there’s another phenomenon seismometers can pick up: seismic booms from the melting end of glaciers. These “glacial earthquakes” have become increasingly frequent as parts of the Greenland and Antarctic ice sheets shed mass and shrink in volume, contributing to sea level rise.

Glacial earthquakes have much longer periods than actual tectonic earthquakes, with minutes passing between peaks in the wave. As a result, researchers actually have to analyze seismometer data in a different way in order to pick them up. The quakes aren’t trivial in strength though; most release a similar amount of total energy as a magnitude 5 earthquake.

The weird thing is that, even as we've tracked them, we haven’t actually figured out precisely what a glacial earthquake was. They seemed to be related to calving events, where large icebergs break off the floating front of a glacier that reaches the ocean, but what actually shakes the earth? Was the iceberg scraping along bottom? Did it have something to do with the sudden acceleration of the iceberg as it peels away from the rest of the glacier?

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Counting crows’ neurons work just like yours

Crows can do some things we can readily recognize as “intelligent”—like using tools, solving puzzles, and even recognizing human faces. But it has been a long time since a common ancestor of birds and humans walked the Earth, and the two groups’ brains have ended up with significant structural differences. The part of the brain that we (and other primates) use to handle numbers is one of those structures. Still, crows are no slouches at the whole “one, two, or three?” thing, so how do their brains do it?

To find out, University of Tübingen researchers Helen Ditz and Andreas Nieder outfitted a couple carrion crows with surgically implanted neuron sensors. Those crows had been trained to play a little number-based matching game to win little snacks. On a little screen, the crows would be shown a number of dark dots (between one and five) inside a gray circle. After about a second, the screen would go blank for a second, and then a second image would be shown. If the same number of dots was shown again, the crows would tap the screen and get a treat.

The crows weren’t shown a consistent symbol for each number, like the ones on a domino. The diameter of each dot varied randomly, as did their placement within the gray circle. (Although specific shapes, like a line of dots, was sometimes used.) So the birds really did have to recognize the number of dots in each image.

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Pope makes ethical case for action on climate change

We see plenty of news stories about climate science and the politicians who reject that research, but not many people can command international attention by discussing the moral implications of all that science. The Pope is one of those people.

On Thursday, the Vatican released a highly anticipated “encyclical”—a weighty letter from the Pope to the rest of the Roman Catholic Church—on the environment and, yes, climate science. The encyclical was a priority for Pope Francis, who took his name from Saint Francis of Assisi, the patron saint of animals and—as of 1979—ecologists. The pontiff had the assistance of the Pontifical Academy of Sciences in preparing the 184 page document (published in eight languages), which includes some pretty detailed discussions of environmental science.

Although the hype leading up to the document’s release centered on the issue of climate change, it is actually aimed more broadly at the relationship between humanity and our environment. The Pope quotes St. Francis’ description of “our Sister, Mother Earth," and writes, “This sister now cries out to us because of the harm we have inflicted on her by our irresponsible use and abuse of the good with which God has endowed her.”

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Making tiny earthquakes to understand fracking-driven quakes

In some places, notably Ohio and Oklahoma, the injection of used fracking fluid in deep disposal wells appears to have produced a significant uptick in earthquake activity. The earthquakes are mostly much too small to be felt at the surface, but a magnitude 5.6 quake in Oklahoma was large enough to cause some damage in 2011.

This has made lots of news because of its scale, but it’s not our first experience with injection-triggered earthquakes. It’s a concern for geothermal power designs that inject water to depths where it can turn to turbine-driving steam, for example. And in the future, it could be a concern for efforts to store carbon dioxide in underground reservoirs.

Earthquakes occur where two blocks of rock suddenly slip past each other along a fault, releasing energy that causes the shaking that bothers us up at the surface. The blocks are generally stuck in place by friction, but the strain of being pushed (or pulled) in different directions slowly builds. Eventually, that strain overcomes the friction keeping it in place and the rocks slip some distance along a portion of the fault, relieving strain.

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EPA’s draft of four-year fracking study finds no inherent water risks

Back in 2011, the US Environmental Protection Agency (EPA) announced an effort to evaluate the publicly controversial technique of fracking, in which fluid pumped at pressure fractures rock that contains trapped natural gas or oil. Lots of research has been published since then, and the EPA has finally released a draft of its report for public comment and peer review.

The report is a useful summary of the practices being employed in fracking and the available data relating to concerns about contamination. The focus is on contamination of surface water and groundwater—the report doesn’t extend to questions about earthquakes triggered by the injection of used fracking fluid in deep disposal wells, local air quality concerns, or the effects of things like the mining of sand that is added to fracking fluid to prop open fractures.

Water use and recycling

The report touches on every stage of the fracking process, from acquiring the water used to disposing of it afterward. It takes about four million gallons of water to frack a natural gas well, and almost 30,000 new wells are being drilled each year in the US. Overall, this adds up to a pretty insignificant sliver of our water use, but there are some areas where it is problematic. In southern Texas, for example, there is a lot of demand from the dense array of natural gas wells tapping the Eagle Ford Shale, and there isn't much of a water supply available. Groundwater use there is causing some drawdown of the local water table.

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Updated NOAA temperature record shows little global warming slowdown

Creating and maintaining a record of surface temperatures around the world isn’t as easy as it sounds, even if you rightly don’t think that sounds easy. Lots of work goes into combining different kinds of measurements in the most accurate way possible. When new studies provide slightly better accounting for some of the complications involved, the records need to get updated.

An update to the US National Oceanographic and Atmospheric Administration’s temperature record is out this week, and the researchers behind it say it has an impact on discussions about the slower rise of global average surface temperatures in recent years. That is, it doesn’t look much slower.

In this case, the update was spurred by two efforts. The first was simply a new database of weather stations on land that more than doubles the number available by folding in many smaller collections. The second was research into sources of sea surface temperature measurements. A large number of buoys are now dedicated to making these measurements, but commercial ships have also been a major source of data. Those ships haven’t always used the same methods, though, so researchers have to be careful to account for differences between the data those methods produce.

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Did West Antarctica’s ice fall into the sea 120,000 years ago?

One of the bigger risks we’re running with our planetary warming experiment is the melting of the vulnerable West Antarctic Ice Sheet, raising sea levels much more rapidly than we expect. It’s a scenario scientists assess both by studying present conditions and by examining the past.

One time period of particular interest is the previous interglacial—a warm intermission between ice ages—about 120,000 years ago. Sea level appears to have been 5 to 9 meters higher during this time when the configuration of Earth’s orbit made for a little more summer sunshine (and warmer temperatures) in the Northern Hemisphere.

The West Antarctic Ice Sheet is a candidate to have supplied about 3 meters of that sea level rise. Unfortunately, evidence of its history is hard to come by, as the regrowth of the ice sheet destroyed some of it and now conceals even more. Sediment cores show the ice sheet shrank drastically in the past, but it’s unclear when in the past.

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How bad would the ozone hole be if we did nothing?

The “hole” in the ozone layer is sometimes invoked by those who downplay environmental concerns as an example of “sky is falling” warnings that never came to pass. It's an odd example. There's a simple reason ozone problems didn't come to pass: the world came together and agreed to phase out key ozone-depleting chemicals.

It’s a major success story, and one that should be remembered. As we consider the cost of dealing with ongoing environmental problems, it's worth considering: how much better off are we for the action we did take to preserve the ozone layer? Some scientists have now tackled this question.

Ozone gas in the stratosphere is enormously important for life on Earth. Ozone absorbs ultraviolet radiation emitted by the Sun, greatly reducing the amount that reaches the surface. It’s sunscreen for the planet, as UV causes skin cancer and sunburns. In the 1970s and early 1980s, it was discovered that compounds called chlorofluorocarbons (CFCs), commonly used as refrigerants and in aerosol sprays, were breaking down stratospheric ozone.

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Watching two new islands form in the Red Sea

The solid Earth changes very slowly, generally speaking—so slowly that short-lived and fast-changing creatures like ourselves can be forgiven for forgetting that it changes at all. It's hard to imagine the land we live on sitting beneath three kilometers of glacial ice or sitting under open ocean; it's like imagining a painting of a different place.

This is partly what makes volcanic islands so wild. When they erupt, the island changes quickly and obviously. And if you’re extremely lucky, you might even catch the birth of a new island. A place that had long been sea becomes land, and you can watch it happen—no CGI or imagination required. And we now have robotic eyes constantly scanning the globe from space, so we no longer rely on the luck of being in the right place at the right time to observe such an event.

In the Red Sea between Africa and the Arabian Peninsula, there is a small chain of islands, called the Zubair Archipelago, with an interesting history. Just as Africa is slowly splitting apart along the volcanically active East African Rift, the Arabian Peninsula is breaking up with Africa along the Red Sea. In the 1700s and 1800s, the Zubair Archipelago hosted eruptions—the only recorded in the Red Sea—but they went quiet through the 20th century. In 2007, they woke up, with an eruption popping on one of the islands.

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