August 6, 2012
Hydraulic fracturing (a.k.a. “fracking”) recovery techniques for oil and natural gas are a controversial business. The practice—in which a mix of water, sand and chemicals is injected deep into bedrock at high pressure to create fractures, allowing gas and oil to flow upward—was developed in the late 1990s and has become more and more common across the United States over the past few years, opening up geologic areas such as the Bakken Shale in North Dakota and the Marcellus Shale in Pennsylvania, New York and West Virginia to dramatic increases in gas production.
On the one hand, proponents argue that hydraulic fracturing increases the amount of energy that can be economically produced in the United States, making oil and gas cheaper and reducing our dependency on foreign imports. Opponents, though, note that fracking causes dangerous chemicals to leach into groundwater, releases known carcinogens into the air and increases our contribution to climate change.
Alongside these observed problems, though, a different sort of worry has emerged: the idea that hydraulic fracturing can trigger an earthquake. Scientists have known for decades that injecting fluids into the earth could cause quakes, but we were uncertain just how much of an increase widespread fracking might cause. This past spring, USGS scientists decided that the recent dramatic increase in the number of small quakes in the United States is “almost certainly manmade,” but were unable to conclusively tie it to this particular activity.
Now, the evidence is starting to pile up. A study published today in the Proceedings of the National Academy of Sciences finds a correlation between dozens of small earthquakes in Texas’ Barnett Shale region—the site of intensive hydraulic fracturing activity—and the locations of injection wells used to dispose of the wastes of this process. ”You can’t prove that any one earthquake was caused by an injection well,” says Cliff Frohlich, the University of Texas geologist who conducted the study, “but it’s obvious that wells are enhancing the probability that earthquakes will occur.”
To come to the finding, Frohlich analyzed two years’ worth of data from a network of extremely sensitive seismographs that was installed in the region in 2009. He discovered dozens of small earthquakes that had not been previously reported—and found that all 24 of the quakes for which he was able to establish an accurate epicenter occurred within two miles of an injection well.
One important distinction is that these wells were the disposal sites for waste fluids that had already used to fracture rock, rather than the original wells used to extract the gas. Although the actual gas extraction wells cause many microearthquakes by their very nature (they literally crack the bedrock to release gas and oil), these are far too small to be felt by humans or cause any damage. The fluid disposal wells, though, are more likely to cause earthquakes of significance, because they are sites of injection for a longer duration over time.
The waste fluids may trigger earthquakes by acting as lubricants in pre-existing faults deep underground, allowing masses of rock to slide past each other more easily and relieve built-up pressure. All of the wells that Frohlich found correlated with quakes were home to high rates of injection (more than 150,000 barrels of fluid per month). However, there were other wells in the area with similar rates of injection that did not correlate with increased seismic activity. ”It might be that an injection can only trigger an earthquake if injected fluids reach and relieve friction on a nearby fault that is already ready to slip,” explains Frohlich.
The good news is that all of these earthquakes were still relatively small, with magnitudes of less than 3.0 on the Richter scale, unlikely to cause any damage on the surface. Seismologists, though, are concerned that fluid injection could cause larger quakes if the fluid migrates into older, deeper rock formations beyond the local shale, which are home to larger fault lines. A number of earthquakes that occurred in Ohio last year, including one with a 4.0 magnitude, were linked to disposal of fracking fluids.
Frohlich notes that much more research is needed to help us understand exactly why some wells are more likely to cause earthquakes than others. For those already concerned about fracking, though, his new research adds another major concern to a growing list.
July 18, 2012
Since the Industrial Revolution, ocean acidity has risen by 30 percent as a direct result of fossil-fuel burning and deforestation. And within the last 50 years, human industry has caused the world’s oceans to experience a sharp increase in acidity that rivals levels seen when ancient carbon cycles triggered mass extinctions, which took out more than 90 percent of the oceans’ species and more than 75 percent of terrestrial species.
Rising ocean acidity is now considered to be just as much of a formidable threat to the health of Earth’s environment as the atmospheric climate changes brought on by pumping out greenhouse gases. Scientists are now trying to understand what that means for the future survival of marine and terrestrial organisms.
In June, ScienceNOW reported that out of the 35 billion metric tons of carbon dioxide released annually through fossil fuel use, one-third of those emissions diffuse into the surface layer of the ocean. The effects those emissions will have on the biosphere is sobering, as rising ocean acidity will completely upset the balance of marine life in the world’s oceans and will subsequently affect humans and animals who benefit from the oceans’ food resources.
The damage to marine life is due in large part to the fact that higher acidity dissolves naturally-occurring calcium carbonate that many marine species–including plankton, sea urchins, shellfish and coral–use to construct their shells and external skeletons. Studies conducted off Arctic regions have shown that the combination of melting sea ice, atmospheric carbon dioxide and subsequently hotter, CO2-saturated surface waters has led to the undersaturation of calcium carbonate in ocean waters. The reduction in the amount of calcium carbonate in the ocean spells out disaster for the organisms that rely on those nutrients to build their protective shells and body structures.
The link between ocean acidity and calcium carbonate is a directly inverse relationship, which allows scientists to use the oceans’ calcium carbonate saturation levels to measure just how acidic the waters are. In a study by the University of Hawaii at Manoa published earlier this year, researchers calculated that the level of calcium carbonate saturation in the world’s oceans has fallen faster in the last 200 years than has been seen in the last 21,000 years–signaling an extraordinary rise in ocean acidity to levels higher than would ever occur naturally.
The authors of the study continued on to say that currently only 50 percent of the world’s ocean waters are saturated with enough calcium carbonate to support coral reef growth and maintenance, but by 2100, that proportion is expected to drop to a mere five percent, putting most of the world’s beautiful and diverse coral reef habitats in danger.
In the face of so much mounting and discouraging evidence that the oceans are on a trajectory toward irreparable marine life damage, a new study offers hope that certain species may be able to adapt quick enough to keep pace with the changing make-up of Earth’s waters.
In a study published last week in the journal Nature Climate Change, researchers from the ARC Center of Excellence for Coral Reef Studies found that baby clownfish (Amphiprion melanopus) are able to cope with increased acidity if their parents also lived in higher acidic water, a remarkable finding after a study conducted last year on another clownfish species (Amphiprion percula) suggested acidic waters reduced the fish’s sense of smell, making it likely for the fish to mistakenly swim toward predators.
But the new study will require further research to determine whether or not the adaptive abilities of the clownfish are also present in more environmentally-sensitive marine species.
While the news that at least some baby fish may be able to adapt to changes provides optimism, there is still much to learn about the process. It is unclear through what mechanism clownfish are able to pass along this trait to their offspring so quickly, evolutionarily speaking. Organisms capable of generation-to-generation adaptations could have an advantage in the coming decades, as anthropogenic emissions push Earth to non-natural extremes and place new stresses on the biosphere.
July 2, 2012
The Washington, DC area has seen its fair share of destructive storms–we get hurricanes, tornadoes and even the rare snowpocalypse. But on Friday night we got hit with another type of storm–one that I’d never heard of–called a derecho (pronounced ”deh-REY-cho”).
The storm swept through the area late Friday evening, bringing an incredible amount of thunder and lightning, winds up to 80 mph and sheets of rain. By morning, hundreds of trees had been blown down, millions were left without power and several people were dead. Netflix, Pinterest and Instagram had all been taken down by Amazon server outages caused by the storm. The Smithsonian Folklife Festival had to shut down for a day to clean up the mess. We were all left wondering, “what in the world had happened?”
The stifling heat wave that we’d been suffering through, which had stretched from the Midwest through the mid-Atlantic to the Southeastern United States and brought temperatures in excess of 100 degrees Fahrenheit, was to blame for the fast-moving band of thunderstorms. The Capitol Weather Gang explains:
As this stifling air bubbled northward, clashing with the weather front draped from near Chicago to just north of D.C., thunderstorms erupted. They grew in coverage and intensity as they raced southeast, powered by the roaring upper level winds and fueled by the record-setting heat and oppressive humidity in their path.
The coverage and availability of this heat energy was vast, sustaining the storms on their 600 mile northwest to southeast traverse. The storms continually ingested the hot, humid air and expelled it in violent downdrafts – crashing into the ground at high speeds and spreading out, sometimes accelerating further.
Though unfamiliar to those of us here on the East Coast, derechos occur more commonly in the Corn Belt, which runs from Mississippi into the Ohio Valley, but even there they are relatively infrequent. They can wreak their havoc at any time of the year but are most likely to occur during May, June and July. Derechos get their starts in curved bands of thunderstorms called “bow echoes,” which are perhaps better known for their ability to spawn tornadoes. But instead of rotating cells of winds, derechos blow and travel in straight lines.
Derechos have a long history here in the United States. The term “derecho” was coined by University of Iowa physics professor Gustavus Hinrichs in an 1888 paper in the American Meteorological Journal in which he illustrated the path of such a storm that had crossed over Iowa on July 31, 1877. The storm’s straight path across the state gave Hinrichs the inspiration for the storm’s name–”derecho” means “straight” in Spanish. But path alone isn’t quite enough for a storm to qualify as a derecho; wind speeds must also reach a minimum of 57 mph.
Given that derechos are associated with warmer weather, could they become more common as the United States heats up due to climate change? Tom Kines, senior meteorologist at AccuWeather.com, told the Guardian: “If indeed we are seeing global warming, then it will certainly increase the risk of something like this happening again.”
April 16, 2012
Update on April 16, 2012: A new study by the U.S. Geological Survey to be presented Wednesday indicates that the “remarkable increase” in earthquakes in the continental United States that rate greater than 3 on the Richter Magnitude Scale is “almost certainly manmade.” The authors note that although it is unclear whether new hydrofracturing (a.k.a. fracking) techniques to recover natural gas are to blame, “the increase in seismicity coincides with the injection of wastewater in deep disposal wells.” —Joseph Stromberg
This wasn’t the first case in which the injection of fluids into the earth has been linked with earthquakes. In April, for example, the English seaside resort town of Blackpool shook from a magnitude 2.3 earthquake, one of several quakes now known to have been caused by hydraulic fracturing (or “fracking,” which involves pumping large amounts of fluid into the ground to release natural gas) in the area. The link has been known for decades—a series of quakes in the Denver, Colorado, region in 1967 was caused by fluid injection.
The phenomenon is so well known that Arthur McGarr, a geologist at the U.S. Geological Survey in Menlo Park, California, has developed a method to predict the highest magnitude of an earthquake that could be produced by hydraulic fracturing, carbon sequestration, geothermal power generation or any method that involves injecting fluid deep into the earth. Though the method doesn’t allow scientists to predict the likelihood that such a quake would occur, it will let engineers better plan for worst-case scenarios, McGarr told Nature.
Hydraulic fracturing naturally causes small tremors, but bigger quakes may occur if the liquid migrates beyond the area where it’s injected. The New York Times reports:
The larger earthquakes near Blackpool were thought to be caused the same way that quakes could be set off from disposal wells—by migration of the fluid into rock formations below the shale. Seismologists say that these deeper, older rocks, collectively referred to as the “basement,” are littered with faults that, although under stress, have reached equilibrium over hundreds of millions of years.
“There are plenty of faults,” said Leonardo Seeber, a seismologist with the Lamont-Doherty Earth Observatory. “Conservatively, one should assume that no matter where you drill, the basement is going to have faults that could rupture.”
Earthquakes caused by fracking are of particular interest right now because the number of wells, particularly in the United States, has been skyrocketing (along with reports of nasty environmental consequences, such as flammable water). But this is only one way that humans are causing the earth to quake. Mining (taking weight from the earth), creating lakes with dams (adding weight on top of the earth) and extracting oil and gas from the earth have caused at least 200 earthquakes in the last 160 years, Columbia University earthquake scientist Christian Klose told Popular Science.
Klose’s research has demonstrated that coal mining was responsible for Australia’s most damaging earthquake in recent memory, the magnitude 5.6 Newcastle earthquake of 1989. And in 2009, he was one of several scientists who suggested that the magnitude 7.9 earthquake in China’s Sichuan Province in 2008, which left 80,000 dead, could have have been triggered by the Zipingpu Dam. (That wasn’t the first time a dam was linked to an earthquake—Hoover Dam shook frequently as Lake Mead filled.)
It can be easy to look at our planet and think we’re too small to really do much damage, but the damage we can do can have severe consequences for ourselves. ”In the past, people never thought that human activity could have such a big impact,” Klose told Wired, “but it can.”
February 27, 2012
How do scientists reconstruct the climate of the past? They often turn to ice cores or growth rings from trees or deep-sea corals. But a new study gleans a wealth of weather intel from a largely untapped source: old documents.
Researchers from Spain scoured manuscripts from 9th- and 10th-century Baghdad, in modern-day Iraq, for references to the weather. Baghdad, where the Tigris and Euphrates Rivers meet, was at that time the new and bustling capital of the vast Islamic Empire, which stretched from India to the Atlantic Ocean. Much was written about the city and why it was chosen as the capital, including its population size, agricultural potential and climate.
In the 10 analyzed texts, most of which give exhaustive political histories of the region, the researchers found 55 meteorological citations, many of which were referring to the same event. The study points out that although the social and religious content of the documents is probably biased, the historians weren’t likely to fabricate an off-hand mention of a drought, hail storm or solar eclipse.
The researchers were shocked by the number of references to cold periods in this notoriously hot and dry region. They identified 14 chilly periods in all: five in winter, two in spring, one in summer and two that denoted cold weather for a whole year. Some of the descriptions specified snowfalls, ice and frozen rivers.
For instance, an entry from December 23, 908, noted when “four fingers of snow accumulated on the roofs,” and another, on November 25, 1007, that the snow reached somewhere between 30 and 50 inches. One particularly odd event was in July 920, when it was too cold for people to sleep on their roofs, as they did on most summer nights. This temperature drop could have been caused by a volcanic eruption the previous year, the researchers speculate.
In any case, it seems safe to say that the weather of that Islamic Golden Age was much more variable than it is today. The only time that snow has hit Baghdad in modern memory was on January 11, 2008, melting as soon as it hit the ground.
Images from Domínguez- Castro et al., ”How useful could Arabic documentary sources be for reconstructing past climate?” appearing in Weather, published by Wiley.