April 19, 2013
Last year, to celebrate the 42nd Earth Day, we took a look at 10 of the most surprising, disheartening, and exciting things we’d learned about our home planet in the previous year—a list that included discoveries about the role pesticides play in bee colony collapses, the various environmental stresses faced by the world’s oceans and the millions of unknown species are still out in the environment, waiting to be found.
This year, in time for Earth Day on Monday, we’ve done it again, putting together another list of 10 notable discoveries made by scientists since Earth Day 2012—a list that ranges from specific topics (a species of plant, a group of catfish) to broad (the core of planet Earth), and from the alarming (the consequences of climate change) to the awe-inspiring (Earth’s place in the universe).
1. Trash is accumulating everywhere, even in Antarctica. As we’ve explored the most remote stretches of the planet, we’ve consistently left behind a trail of one supply in particular: garbage. Even in Antarctica, a February study found (PDF), abandoned field huts and piles of trash are mounting. Meanwhile, in the fall, a new research expedition went to study the Great Pacific Garbage Patch, counting nearly 70,000 pieces of garbage over the course of a month at sea.
2. Climate change could erode the ozone layer. Until recently, atmospheric scientists viewed climate change and the disintegration of the ozone layer as entirely distinct problems. Then, in July, Harvard researcher Jim Anderson (who won a Smithsonian Ingenuity Award for his work) led a team that published the troubling finding that the two might be linked. Some warm summer storms, they discovered, can pull moisture up into the stratosphere, an atmospheric layer 6 miles up. Through a chain of chemical reactions, this moisture can lead to the disintegration of ozone, which is crucial for protecting us from ultraviolet (UV) radiation. Climate change, unfortunately, is projected to cause more of these sorts of storms.
3. This flower lives on exactly two cliffs in Spain. In September, Spanish scientists told us about one of the most astounding survival stories in the plant kingdom: Borderea chouardii, an extremely rare flowering plant that is found on only two adjacent cliffs in the Pyrenees. The species is believed to be a relic of the Tertiary Period, which ended more than 2 million years ago, and relies on several different local ant species to spread pollen between its two local populations.
4. Some catfish have learned to kill pigeons. In December, a group of French scientists revealed a phenomenon they’d carefully been observing over the previous year: a group of catfish in Southwestern France had learned how to leap onto shore, briefly strand themselves, and swim back into the water to consume their prey. With more than 2,000,000 Youtube views so far, this is clearly one of the year’s most widely enjoyed scientific discoveries.
5. Fracking for natural gas can trigger moderate earthquakes. Scientists have known for a while that whenever oil and gas are extracted from the ground at a large scale, seismic activity can be induced. Over the past few years, evidence has mounted that injecting water, sand and chemicals into bedrock to cause gas and oil to flow upward—a practice commonly known as fracking—can cause earthquakes by lubricating pre-existing faults in the ground. Initially, scientists found correlations between fracking sites and the number of small earthquakes in particular areas. Then, in March, other researchers found evidence that a medium-sized 2011 earthquake in Oklahoma(which registered a 5.7 on the moment magnitude scale) was likely caused by injecting wastewater into wells to extract oil.
6. Our planet’s inner core is more complicated than we thought. Despite decades of research, new data on the iron and nickel ball 3,100 miles beneath our feet continue to upset our assumptions about just how the earth’s core operates. A paper published last May showed that iron in the outer parts of the inner core is losing heat much more quickly than previously estimated
, suggesting that it might hold more radioactive energy than we’d assumed, or that novel and unknown chemical interactions are occurring. Ideas for directly probing the core are widely regarded as pipe dreams, so our only options remains studying it from afar, largely by monitoring seismic waves.
7. The world’s most intense natural color comes from an African fruit. When a team of researchers looked closely at the blue berries of Pollia condensata, a wild plant that grows in East Africa, they found something unexpected: it uses an uncommon structural coloration method to produce the most intense natural color ever measured. Instead of pigments, the fruit’s brilliant blue results from nanoscale-size cellulose strands layered in twisting shapes, which which interact with each other to scatter light in all directions.
8. Climate change will let ships cruise across the North Pole. Climate change is sure to create countless problems for many people around the world, but one specific group is likely to see a significant benefit from it: international shipping companies. A study published last month found that rising temperatures make it probable that during summertime, reinforced ice-breaking ships will be able to sail directly across the North Pole—an area currently covered by up to 65 feet of ice—by the year 2040. This dramatic shift will shorten shipping routes from North America and Europe to Asia.
9. One bacteria species conducts electricity. In October, a group of Danish researchers revealed that the seafloor mud of Aarhus’ harbor was coursing with electricity due to an unlikely source: mutlicellular bacteria that behave like tiny electrical cables. The organisms, the team found, built structures that traveled several centimeters down into the sediment and conduct measurable levels of electricity. The researchers speculate that this seemingly strange behavior is a byproduct of the way of the bacteria harvests energy from the nutrients buried in the soil.
10. Our Earth isn’t alone. Okay, this one might not technically be a discovery about Earth, but over the past year we have learned a tremendous amount about what our Earth isn’t: the only habitable planet in the visible universe. The pace of exoplanet detection has accelerated rapidly, with a total of 866 planets in other solar systems discovered so far. As our methods have become more refined, we’ve been able to detect smaller and smaller planets, and just yesterday, scientists finally discovered a pair of distant planets in the habitable zone of their stars that are relatively close in size to Earth, making it more likely than ever that we might have spied an alien planet that actually supports life.
April 18, 2013
If you weren’t on the East Coast during Hurricane Sandy, you likely experienced the disaster through electronic means: TV, radio, the internet or phone calls. As people across the country tracked the storm by listening to information broadcast through electromagnetic waves, a different kind of wave, produced by the storm itself, was traveling beneath their feet.
Keith Koper and Oner Sufri, a pair of geologists at the University of Utah, recently determined that the crashing of massive waves against Long Island, New York and New Jersey—as well as waves hitting each other offshore—generated measurable seismic waves across much of the U.S., as far away as Seattle. As Sufri will explain in presenting the team’s preliminary findings today during the Seismological Society of America‘s annual meeting, they analyzed data from a nationwide network of seismometers to track microseisms, faint tremors that spread through the earth as a result of the storm waves’ force.
The team constructed a video (below) of the readings coming from 428 seismometers over the course of a few days before and after the storm hit. Initially, as it traveled up roughly parallel to the East Coast , readings remained relatively stable. Then, “as the storm turned west-northwest,” Sufri said in a press statement, “the seismometers lit up.” Skip to about 40 seconds into the video to see the most dramatic seismic shift as the storm hooks toward shore:
The microseisms shown in the video differ from the waves generated by earthquakes. The latter arrive suddenly, in distinct waves, while the microseisms that resulted from Sandy arrived continuously over time, more like a subtle background vibration. That makes converting these waves to the moment magnitude scale used to measure earthquakes somewhat complicated, but Koper says that if the energy from these microseisms was compressed into a single wave, it would register as a 2 or 3 on the scale, comparable to a minor earthquake that can be felt by a few people but causes no damage to buildings.
The seismic activity peaked when Sandy changed direction, the researchers say, triggering a sudden increase in the number of waves running into each other offshore. These created massive standing waves, which sent significant amounts of pressure into the seafloor bottom, shaking the ground.
It’s not uncommon for events other than earthquakes to generate seismic waves—Hurricane Katrina produced shaking that was felt in California, landslides are known to have distinct seismic signatures and the meteor that crashed in Russia in February produced waves as well. One of the reasons the readings from Sandy scientifically interesting, though, is the potential that this type of analysis could someday be used to track a storm in real-time, as a supplement to satellite data.
That possibility is enabled by the fact that a seismometer detects seismic motion in three directions: vertical (up-and-down shaking) as well as North-South and East-West movement. So, for example, if most of the shaking detected by a seismometer in one location is oriented North-South, it indicates that the source of the seismic energy (in this case, a storm) is located either North or South of the device, rather than East or West.
A nationwide network of seismometers—such as Earthscope, the system that was used for this research and is currently still being expanded—could eventually provide the capacity to pinpoint the center of a storm. “If you have enough seismometers, you can get enough data to get arrows to point at the source,” Koper said.
Satellites, of course, can already locate a hurricane’s eye and limbs. But locating the energetic center of the storm and combining it with satellite observations of the storm’s extent could eventually enable scientists to measure the energy being released by a hurricane in real-time, as the storm evolves. Currently, the Saffir-Simpson scale is used to quantify hurricanes, but there are several criticisms of it—it’s solely based on wind speed, so it overlooks the overall size of a storm and the amount of precipitation in produces. Including the raw seismic energy released by a storm could be a way of improving future hurricane classification schemes.
The prospect of seismometers (instruments typically used to detect earthquakes) being employed to supplement satellites in tracking storms is also interesting because of a recent trend in the exact opposite direction. Last month, a satellite data was used for the first time to detect an earthquake by picking up extremely low pitched sound waves that traveled from the epicenter through outer space. The fields of meteorology and geology, it seems, are quickly coming together, reflecting the real-world interaction between the Earth and the atmosphere that surrounds it.
April 12, 2013
If you have long hair, you probably don’t need to look up a weather report to get an idea of how much humidity’s in the air: You can simply grab a fistful of hair and see how it feels. Human hair is extremely sensitive to humidity—so much that some hygrometers (devices that indicate humidity) use a hair as the measuring mechanism, because it changes in length based on the amount of moisture in the air.
Straight hair goes wavy. If you have curly hair, humidity turns it frizzy or even curlier. Taming the frizz has become a mega industry, with different hair smoothing serums promising to “transform” and nourish hair “without weighing hair down.” But just why does humidity have this strange effect on human hair?
Hair’s chemical structure, it turns out, makes it unusually susceptible to changes in the amount of hydrogen present in the air, which is directly linked to humidity. Most of a hair’s bulk is made up of bundles of long keratin proteins, represented as the middle layer of black dots tightly packed together in the cross-section at right.
These keratin proteins can be chemically bonded together in two different ways. Molecules on neighboring keratin strands can form a disulfide bond, in which two sulfur atoms are covalently bonded together. This type of bond is permanent—it’s responsible for the hair’s strength—and isn’t affected by the level of humidity in the air.
But the other type of connection that can form between adjacent keratin proteins, a hydrogen bond, is much weaker and temporary, with hydrogen bonds breaking and new ones forming each time your hair gets wet and dries again. (This is the reason why, if your hair dries in one shape, it tends to remain in roughly that same shape over time.)
Hydrogen bonds occur when molecules on neighboring keratin strands each form a weak attraction with the same water molecule, thereby indirectly bonding the two keratin proteins together. Because humid air has much higher numbers of water molecules than dry air, a given strand of hair can form much higher numbers of hydrogen bonds on a humid day. When many such bonds are formed between the keratin proteins in a strand of hair, it causes the hair to fold back on itself at the molecular level at a greater rate.
On the macro level, this means that naturally curly hair as a whole becomes curlier or frizzier due to humidity. As an analogy, imagine the metal coil of a spring. If you straighten and dry your hair, it’ll be like the metal spring, completely straightened out into a rod. But if it’s a humid day, and your hair is prone to curling, water molecules will steadily be absorbed and incorporated into hydrogen bonds, inevitably pulling the metal rod back into a coiled shape.
April 2, 2013
Step outside after the first storm after a dry spell and it invariably hits you: the sweet, fresh, powerfully evocative smell of fresh rain.
If you’ve ever noticed this mysterious scent and wondered what’s responsible for it, you’re not alone.
Back in 1964, a pair of Australian scientists (Isabel Joy Bear and R. G. Thomas) began the scientific study of rain’s aroma in earnest with an article in Nature titled “Nature of Agrillaceous Odor.” In it, they coined the term petrichor to help explain the phenomenon, combining a pair of Greek roots: petra (stone) and ichor (the blood of gods in ancient myth).
In that study and subsequent research, they determined that one of the main causes of this distinctive smell is a blend of oils secreted by some plants during arid periods. When a rainstorm comes after a drought, compounds from the oils—which accumulate over time in dry rocks and soil—are mixed and released into the air. The duo also observed that the oils inhibit seed germination, and speculated that plants produce them to limit competition for scarce water supplies during dry times.
These airborne oils combine with other compounds to produce the smell. In moist, forested areas in particular, a common substance is geosmin, a chemical produced by a soil-dwelling bacteria known as actinomycetes. The bacteria secrete the compound when they produce spores, then the force of rain landing on the ground sends these spores up into the air, and the moist air conveys the chemical into our noses.
“It’s a very pleasant aroma, sort of a musky smell,” soil specialist Bill Ypsilantis told NPR during an interview on the topic. “You’ll also smell that when you are in your garden and you’re turning over your soil.”
Because these bacteria thrive in wet conditions and produce spores during dry spells, the smell of geosmin is often most pronounced when it rains for the first time in a while, because the largest supply of spores has collected in the soil. Studies have revealed that the human nose is extremely sensitive to geosmin in particular—some people can detect it at concentrations as low as 5 parts per trillion. (Coincidentally, it’s also responsible for the distinctively earthy taste in beets.)
Ozone—O3, the molecule made up of three oxygen atoms bonded together—also plays a role in the smell, especially after thunderstorms. A lightning bolt’s electrical charge can split oxygen and nitrogen molecules in the atmosphere, and they often recombine into nitric oxide (NO), which then interacts with other chemicals in the atmosphere to produce ozone. Sometimes, you can even smell ozone in the air (it has a sharp scent reminiscent of chlorine) before a storm arrives because it can be carried over long distances from high altitudes.
But apart from the specific chemicals responsible, there’s also the deeper question of why we find the smell of rain pleasant in the first place. Some scientists have speculated that it’s a product of evolution.
Anthropologist Diana Young of the University of Queensland in Australia, for example, who studied the culture of Western Australia’s Pitjantjatjara people, has observed that they associate the smell of rain with the color green, hinting at the deep-seated link between a season’s first rain and the expectation of growth and associated game animals, both crucial for their diet. She calls this “cultural synesthesia”—the blending of different sensory experiences on a society-wide scale due to evolutionary history.
It’s not a major leap to imagine how other cultures might similarly have positive associations of rain embedded in their collective consciousness—humans around the world, after all, require either plants or animals to eat, and both are more plentiful in rainy times than during drought. If this hypothesis is correct, then the next time you relish the scent of fresh rain, think of it as a cultural imprint, derived from your ancestors.
March 2, 2013
During the month of July 2011, the United States was seized by a heat wave so severe that roughly 9,000 temperature records were set, 64 people were killed and a total of 200 million Americans were left very sweaty. Temperatures hit 117 degrees Fahrenheit in Shamrock, Texas, and residents of Dallas spent 34 consecutive days stewing in 100-plus-degree weather.
For the past couple of years, we’ve heard that extreme weather like this is tied to climate change, but until now, scientists weren’t sure exactly how the two were related. A new study published yesterday in the journal Proceedings of the National Academy of Sciences reveals the mechanism behind events such as the 2011 heat wave.
What it comes down to, according to scientists at Potsdam Institute for Climate Impact Research (PIK), is that higher temperatures caused by global warming are disrupting the flow of planetary waves that oscillate between Arctic and tropical regions, redistributing the warm and cold air that usually help regulate the Earth’s climate. “When they swing up, these waves suck warm air from the tropics to Europe, Russia, or the US, and when they swing down, they do the same thing with cold air from the Arctic,” lead author Vladimir Petoukhov of PIK explained in a statement.
Under pre-global-warming conditions, the waves might have initiated a short, two-day burst of warm air followed by a rush of cooler air in Northern Europe, for example. But these days, with global temperatures having climbed 1.5 degrees Fahrenheit in the past century and escalating particularly sharply since the 1970s, the waves increasingly stall out, resulting in 20- to 30-day heat waves.
The way it occurs is this: The greater the temperature difference between regions like the Arctic and Northern Europe, the more air circulates between the areas–warm air rises over Europe, cools over the Arctic, and rushes back down to Europe, keeping it chilly. But with global warming heating up the Arctic, the temperature gap between the regions is closing, stanching the flow of air. In addition, land masses warm and cool more easily than oceans. ”These two factors are crucial for the mechanism we detected,” Petoukhov said. “They result in an unnatural pattern of the mid-latitude air flow, so that for extended periods the… waves get trapped.”
The scientists developed models of this phenomenon and then entered daily weather data for the middle latitudes of the Northern Hemisphere during the summers from 1980 to 2012. They found that during several major heat waves and episodes of prolonged rain–which led to floods–the planetary waves had indeed been trapped and amplified.
“Our dynamical analysis helps to explain the increasing number of novel weather extremes,” said Hans Joachim Schellnhuber, director of PIK and co-author of the study. “It complements previous research that already linked such phenomena to climate change, but did not yet identify a mechanism behind it.”
The research joins another recent study (PDF) by scientists at Harvard that highlights how changes to air circulation patterns are spreading drought. As warm tropical air rises, it triggers rains before migrating to higher latitudes. The dry air then descends, heats up and eventually travels again, landing in regions characterized by desert. These dry regions used to be confined to narrow bands spanning the globe. But now, these bands are expanding by several degrees in latitude.
“That’s a big deal, because if you shift where deserts are by just a few degrees, you’re talking about moving the southwestern desert into the grain-producing region of the country, or moving the Sahara into southern Europe,” study author Michael McElroy said in a statement. In this way, climate change threatens national security because drought, heat and other extreme weather events can jeopardize food stocks, destroy roads and bridges, and ultimately lead to political instability, the authors note.
The connection between climate change and extreme weather will be highlighted this summer, if current trends continue. The summer of 2012 was even hotter in the U.S. than that of 2011, and according to the PIK scientists, it was also marked by prolonged, amplified waves in the mid-latitudes of the Northern Hemisphere.
Unfortunately, the frequency of these atmospheric patterns is only expected to increase. When the researchers compared the period from 1980 to 1990 with that from 2002 to 2012, they saw that the incidence of trapped waves had doubled. Bottom line: Heat waves are not only here to stay, they’ll become more frequent and will linger for longer.