August 19, 2015

On Tuesday, August 18, U. S. President Barack Obama outlined a plan to cut methane gas emissions from oil and natural gas drilling. The plan calls on petroleum companies to  capture much of the methane produced when they drill new wells. Currently, some of this methane gets released into the atmosphere. There, it contributes to the greenhouse effect, which drives global warming.

Oil pumps and other types of petroleum-industry equipment may soon be regulated to reduce methane emissions. Credit: © PhotoStock10/Shutterstock

The greenhouse effect is caused by certain gases in the atmosphere that let sunlight pass into the atmosphere but trap heat close to the planet’s surface. Although the greenhouse effective existed long before people evolved, human activity, especially since the Industrial Revolution, has likely added to it. One such activity is the burning of fossil fuels, such as coal, oil, and natural gas. This burning releases large amounts of the greenhouse gas carbon dioxide. But human activities, including drilling for fuel, have also produced emissions of another greenhouse gas—methane.

Methane is a powerful greenhouse gas. A molecule of methane lasts for an average of 12 years in the atmosphere before being broken down by sunlight. This is much shorter than carbon dioxide, which can linger in the atmosphere for thousands of years. The molecular structure of methane, however, makes it much more efficient at trapping heat than carbon dioxide. In fact, methane is 25 times more powerful than is carbon dioxide when it comes to contributing to the greenhouse effect, even with its relatively short lifespan.

The Obama administration and its allies want to cut methane emissions as part of a broader strategy to reduce the amount of greenhouse gases the United States produces. Oil and gas companies and some members of the U. S. Congress oppose the plan, saying it will increase the cost of energy. Some environmental groups also criticized the proposal. They argue that it does not go far enough because it will not hold existing wells to the same high standards.

Other World Book articles:

• Carbon Offsets: Reducing Your Footprint (Special report)
• Methane: Another Greenhouse Troublemaker (Special report)

April 1, 2014

A single-celled organism that was a glutton for nickel may have played a key role in the most devastating mass extinction in Earth’s history. The Permian Extinction took place some 252 million years ago. It is informally known as “The Great Dying” because at least 90 percent of all living species on Earth perished over the short (geologically speaking) period of about 60,000 years. Even insects, which largely escaped other mass extinctions, were hit hard. Scientific theories for the die-off have included global warming, global cooling, meteorite impacts, disease, blasts of radioactive cosmic rays from space, and–the favorite–massive volcanic eruptions. Volcanoes have come under suspicion because of the Siberian Traps, about 480,000 cubic miles (2 million cubic kilometers) of preserved flood basalts (layers of volcanic rock) dating from the end of the Permian Period in western Siberia. In the longest-known continuous volcanic eruption in Earth’s history, Siberian volcanoes spewed out enough lava to cover Earth to a depth of 10 feet (3 meters).

Now a team of researchers headed by Daniel Rothman of the Massachusetts Institute of Technology is arguing that the volcanoes were only “accessories to the crime.” The main cuplrit, they contend, was a group of microbes called Methanosarcina. These methane-producing microbes are archaea, organisms that make up one of three basic divisions of life. According to the researchers, Methanosarcina grew explosively in the oceans, releasing massive amounts of methane. Methane is an even more potent greenhouse gas than carbon dioxide (CO2). In fact, molecule for molecule, methane traps about 25 times as much atmospheric heat as does CO2. The methane from the microbes dramatically changed the chemistry of the atmosphere and the oceans, making Earth’s climate toxic to nearly all species.

Mount Etna is an active volcano on the island of Sicily. Major eruptions of the volcano spew molten lava and endanger nearby villages. The eruption shown here began on July 18, 2001. AP/Wide World

Rothman and his team presented three lines of evidence to support their theory. First, they pointed to a huge increase in CO2 levels in the oceans at the end of the Permian Period. As ocean waters absorbed the CO2, they would have become increasingly acidic. Devastating losses in marine organisms, particularly those with shells, would have resulted. Second, the researchers determined that about 251 million years ago, Methanosarcina picked up a gene from another microbe that enabled it to rapidly convert carbon into methane. Even with practically unlimited amounts of carbon at their disposal, the microbes would still have needed an esssential nutrient–nickel–to support their new lifestyle. According to the scientists, that’s where the Siberian volcanoes came in. Lava from the volcanoes produced the world’s largest nickel deposits. The nickel somehow reached the oceans, causing a feeding frenzy among the microbes. That explosion in atmospheric methane essentially suffocated most of the life on Earth.

After the Permian extinction, life took at least 5 million years to recover–that is, to evolve a wide variety of species. In the oceans, complex mollusks, crustaceans, and fish, which could swim easily from place to place, become more widespread and common. On land, surving plants and animals evolved into a variety of forms, including coniferous trees and insect-eating mammals. The extinctions of Permian animals also paved the way for the dinosaurs.

Additional World Book articles:

• Methane: Another Greenhouse Troublemaker (a Special Report)
• The Biggest Eruptions on Earth (a Special Report)
• The Ocean’s Changing Chemistry: Tipping the Balance? (a Special Report)

October 4, 2013

Hopes that microbes may be living beneath the harsh surface of Mars have been seriously dampened by new findings from the Curiosity rover. Over the past 10 years, Mars-orbiting satellites and telescopes on Earth have produced data showing small but significant amounts of methane gas in the red planet’s atmosphere. Although methane can be produced by geological processes, most of the methane in Earth’s atmosphere is a by-product of animal digestion or comes from decaying plants. Perhaps, scientists thought, the same was true on Mars. However, a study by Curiosity failed to detect any methane at all, scientists at NASA’s Jet Propulsion Laboratory reported.

From October 2012 to June 2013, Curiosity searched for signs of methane in samples of the Martian atmosphere using its Sample Analysis at Mars (SAM) laboratory. The previous research had revealed methane levels of up to 45 parts per billion (ppb). But Curiosity’s data showed nothing above 1.3 ppb, the minimum detectable by the SAM laboratory. Curiosity’s findings suggest that the satellite and telescope readings were incorrect or that the gas has disappeared. But Sushil Atreya of the University of Michigan, Ann Arbor, one of the paper’s co-authors, said, “There’s no known way for methane to disappear quickly from the atmosphere. Methane is persistent. It would last for hundreds of years in the Martian atmosphere. Without a way to take it out of the atmosphere quicker, our measurements indicate there cannot be much methane being put into the atmosphere by any mechanism, whether biology, geology, or by ultraviolet degradation [breakdown] of organics delivered by the fall of meteorites or interplanetary dust particles.” Scientists who reported finding methane argued that more research was needed to rule out the existance of microbial life.

Gravel at this site photographed by Curiosity shows evidence of an ancient streambed. (NASA/JPL-Caltech/MSSS)

The search for existing life on Mars is not quite over, however. Curiosity scientists plan to retune the SAM laboratory to enable it to detect amounts of methane of less than 1 ppb. Moreover, Curiosity’s findings don’t totally rule out the presence of life on Mars. “This important result … reduces the probability of current methane-producing Martian microbes, but … addresses only one type of microbial metabolism. As we know, there are many types of terrestrial microbes that don’t generate methane,” said Michael Meyer, NASA’s chief scientist for Mars exploration.

The SAM laboratory findings also don’t affect efforts to determine whether life existed on Mars in the past. Only two months after landing, Curiosity found direct evidence that billions of years ago, a deep, fast-moving stream of water once flowed across Gale Crater, the rover’s landing site. This discovery showed that Mars had once been capable of supporting life. Whether it did is an open question.

Additional World Book articles:

• Mars Pathfinder
• Mars Science Laboratory
• Space exploration
• The Search for Water on Mars (a special report)

July 24, 2013

The release of large amounts of methane gas from thawing permafrost in the Arctic could have an enormous impact on the world economy, announce scientists in the journal Nature. The researchers estimated that the effects of the release of methane on climates worldwide–through rising sea levels, flooding, and damage to agriculture and human health–could amount to as much $60 trillion, roughly the size of the global economy in 2012.

Scientists have for years warned of the dangers posed by rising temperatures on permafrost. Large amounts of methane gas are concentrated in the frozen Arctic tundra. Methane commonly forms when plants decay in places where there is very little oxygen in the ground, such as tundra. When the ground thaws, the methane is released into the atmosphere.

Methane is released from Arctic tundra as the permafrost melts due to global warming. (© Scott T. Smith, Corbis)

Semi-solid gas hydrates are also concentrated under the world’s oceans. Diminishing ice cover in the Arctic Ocean, especially the East Siberian Sea, is resulting in warmer waters, allowing methane to leach out. Plumes of the gas more than a half mile in diameter have been detected rising from the sea.

The authors of the study estimated that the release of methane from the Arctic at the current rate will likely increase global temperatures by 3.6 Fahrenheit (2 Celsius) degrees in 15 to 35 years. Peter Wadhams of the University of Cambridge warned of the possibly catastrophic effect on global climate: “We are seeing increasing methane in the atmosphere . . . and the place where the increase is happening most is over the Arctic.” One of the authors of the study, Gail Whiteman of Erasmus University in the Netherlands, stated “That’s an economic time bomb that at this stage has not been recognized on the world stage. . . . We think it’s incredibly important for world leaders to really discuss what are the implications of this methane release and what could we indeed do about it to hopefully prevent the whole burst from happening.”

Additional World Book articles:

• Geology 2012 (a Back in Time article)
• Another Greenhouse Troublemaker (a special report)

March 15, 2013

For the first time, scientists have extracted natural gas from methane-hydrate deposits, Japanese researchers announced this week. Methane hydrate is methane gas trapped in frozen water–the substance forms an icelike solid. When burning, methane hydrate looks like ice on fire. Deposits of methane hydrates are found in the Arctic, the Antarctic,and along offshore areas of continents.

A map of the known and inferred methane-hydrate deposits created by the United States Geological Survey. (USGS)

Scientists have been searching for a practical and economical method of extracting methane hydrate. Earth’s deposits of this compound form a larger resource of hydrocarbons than oil, natural gas, and coal combined.  Japan imports a huge amount of fuel for energy, so the ability to extract the methane off of Japan’s coast for energy would be an economic boon to the nation. This is particularly true now that Japan has shut down most of its nuclear power plants after the meltdown and leak of radioactive materials at Fukushima in 2011. Japan has invested hundreds of millions of dollars into research on methane hydrates. In the current successful experiment, scientists used depressurization to release the methane from its hydrate bond.

Environmentalists are concerned about the process of extracting methane in this fashion. Methane is about 20 times as powerful as carbon dioxide as a greenhouse gas.  If a sizable amount of methane gas was freed into the atmosphere during the extraction process, it could have a large and unpredictable effect on Earth’s climate. Geologists are also studying whether mining for methane hydrates could destabilize the seabed, potentially causing tsunamis.

Additional World Book Articles:

• Environment
• Exploring the Ocean Abyss (A Special Report)
• Methane: Another Greenhouse Troublemaker (A Special Report)

December 13, 2012

Evidence of a river in the north polar region of Saturn’s moon Titan has been reported by scientists with NASA’s Cassini mission. The river, which has several smaller tributaries, looks like a smaller version of the Nile River on Earth. As revealed in radar images taken on Sept. 26, the “mini Nile” winds through a river valley more than 200 miles (400 kilometers) from its source to a large sea called Ligeia Mare. The relative straightness of the river indicates that it follows at least one fault (crack) in Titan’s crust (outer layer), similar to the path followed by other rivers running into Ligeia Mare. The Cassini scientists concluded that the river is filled with liquid due to the dark coloration of the surface in the images.

The dark, branching channels in an image of Titan's surface were almost certainly carved by rivers of liquid methane. The image was taken by the probe Huygens as it parachuted to Titan's surface in January 2005. The channels appear to cross a bright plateau (top of image), then descend into a darker area (bottom) which may be a lake bed. (European Space Agency/NASA/JPL/University of Arizona)

Titan is the only other body in the solar system known to have stable liquid on its surface. On Earth, the most abundant surface liquid is water. But because Titan’s atmosphere is extremely cold, no liquid water would be found there. Instead, the liquids on Titan are such hydrocarbons as ethane and methane. These liquids have a very low freezing point. In the past several years, Cassini scientists have found evidence of rainfall, large lakes, and other rivers on Titan. Such evidence supports the theory that Titan has a cycle of hydrocarbons similar to the water cycle on Earth.

Scientists have speculated that the hydrocarbons could possibly form an environment in which life could develop. However, the thick and hazy atmosphere shrouds the moon from most forms of imaging. Detecting life or the evidence of life is not likely to be confirmed or refuted anytime in the near future.

Additional World Book articles:

• Porco, Carolyn
• Satellite
• Close encounters with Saturn (a special report)
• Astronomy 1944 (Back in Time article)
• Astronomy 1988 (Back in Time article)
• Astronomy 2004 (Back in Time article)
  
• Astronomy 2005 (Back in Time article)
• Astronomy 2006 (Back in Time article)
  

April 19, 2012

New rules that would require oil and natural gas companies to capture and contain gas emissions from drilling operations and pipelines were announced on April 18 by the Environmental Protection Agency (EPA). The rules would chiefly affect hydraulic fracturing operations–called “fracking” for short–which have become a widespread source of natural gas in the past decade. Fracking involves drilling deep wells and forcing a chemical-laced fluid through rocks to tease out natural gas trapped within. Although most of the natural gas is captured for sale, some natural gas and other emissions escape into the atmosphere, creating air pollution. The EPA rules would force operators to burn or capture all gas emissions by 2015. After 2015, operators must capture all emissions. The new rules also apply to pipelines that transport natural gas.

Emissions from fracking operations include volatile organic compounds (VOC’s), which contribute to smog and may have both short- and long-term health effects. VOC’s include such carcinogens (cancer-causing compounds) as benzene and hexane. Fracking also releases methane, a potent greenhouse gas that traps heat in Earth’s atmosphere, causing global warming. The EPA estimated that the rules will cut 95 percent of VOC emissions after 2015. The agency also predicted that the rules will reduce greenhouse gas emissions by around 28 million to 44 million tons (25.4 million to 40 million metric tons) per year–equivalent to the amount produced by generating electric power for a few million homes.

Ages ago, the remains of tiny marine organisms sank to the sea floors and were buried by sediments, left. The decaying matter became gas and oil trapped in porous rock under nonporous rock, center. Later, Earth's crust shifted, and dry land appeared over many deposits, right. (World Book diagram by George Suyeoka)

The American Petroleum Institute said that many fracking operations have already complied with the rules. The industry welcomed the delay in enforcing emission capture. The EPA predicted that the new rules will save the oil and gas industry $11 million to $19 million per year above the cost of new equipment because the captured gas can be sold for additional profit.

Addtional World Book articles:

• Natural gas liquids
• Environmental pollution 2011 (Back in Time article)
• Geology 2011 (Back in Time article)