Viruses are well known for attacking humans and animals, but some viruses instead attack bacteria. Texas A&M University researchers are exploring how hungry viruses, armed with transformer-like weapons, attack bacteria, which may aid in the treatment of bacterial infections.

The Texas A&M researchers’ work is published in the journal Nature Structural & Molecular Biology.

The attackers are called phages, or bacteriophages, meaning eaters of bacteria.

The word bacteriophage is derived from the Greek “phagein,” meaning eater of bacteria.

“The phages first attach to the bacteria and then inject their DNA,” says Sun Qingan, coauthor of the article and a doctoral student at Texas A&M. “Then they reproduce inside the cell cytoplasm.”

After more than 100 phage particles have been assembled, the next step is to be released from the bacterial host, so that the progeny virions can find other hosts and repeat the reproduction cycle, Sun adds.

Besides the cell membrane, the phages have another obstacle on their way out — a hard shell called cell wall that protects the bacteria. Only by destroying the cell wall can the phages release their offspring.

But, don’t worry. The phages have a secret weapon — an enzyme that can destroy the wall from inside, thus called endolysin.

“One of the special examples, R21, remains inactive when it is first synthesized and attached to the membrane as demonstrated in our paper,” Sun explains. “But when the enzyme leaves the membrane, it restructures just like a transformer and gains the power to destroy the cell wall.”

The trigger controlling the transformation process is a segment of the enzyme call the SAR domain, according to the Texas A&M team.

“The SAR domain is like the commander — it tells the enzyme when to begin restructuring and destroying the cell wall,” he says. “This finding enables us to better understand the release process and provides us with a possible target when we want to control the destruction of bacteria cell walls or prohibit this action in some infectious diseases.”

Some research has been conducted to explore the possibility of using phages to kill bacteria and thus treating bacterial infections.

Sun and colleagues’ finding unveils one secret of the phages and may be useful in phage therapy and other applications.

ENID, Oklahoma (Reuters) – To the untrained eye, Pollard Farms looks much like any other cattle ranch. Similar looking cows are huddled in similar looking pens. But some of the cattle here don’t just resemble each other. They are literally identical — clear down to their genes.

Of the 400-some cattle in Barry Pollard’s herd of mostly Black Angus cattle there are 22 clones, genetic copies of some of the most productive livestock the world has ever known.

Pollard, a neurosurgeon and owner of Pollard Farms, says such breeding technology is at the forefront of a new era in animal agriculture. “We’re trying to stay on the very top of the heap of quality, genetically, with animals that will gain well and fatten well, produce well and reproduce well,” Pollard told a reporter during a recent visit to his farm.

The U.S. Food and Drug Administration in 2008 approved the sale of food from clones and their offspring, stating the products are indistinguishable from that of their non-clone counterparts. Japan, the European Union, and others have followed suit.

The moves have stirred controversy about whether tinkering with nature is safe, or even ethical, prompting major food companies to swear off food products from cloned animals. But consumers are likely already eating meat and drinking milk from the offspring of clones, which are technically not clones, without even knowing it.

Farmers can now use cloning and other assisted breeding technologies to breed cows that produce bigger, better steaks or massive amounts of milk, and animals that resist diseases or reproduce with clockwork precision. Premier genes can translate to improved feeding efficiency, meaning the ability to convert the least amount of feed into the most meat or milk, which results in a smaller environmental footprint.

“If you don’t need as much corn to feed your cattle, you might be able to cut back on the amount of fertilizer put out there on the countryside that might end up in a river. You can cut the amount of diesel that’s spent raising that corn,” Pollard said. “Just like they improve the genetics of corn, so they can produce more bushels per acre, we’re trying to do that same type of thing by using cloning and superior genetics to produce more meat with less input.”

RISING FOOD DEMAND

The United Nations’ Food and Agriculture Organization has said food production will need to double by mid-century to meet demand from a growing world population, with 70 percent of that growth coming from efficiency-improving technologies. Such forecasts have prompted calls for a second Green Revolution, a rethinking of the movement championed by Norman Borlaug, who won the 1970 Nobel Peace Prize for his work in boosting grain production for starving nations.

Biotechnological advances in grain production will remain at the forefront of the global fight to alleviate hunger, although animal agriculture will likely contribute in the longer term.

“When people talk about feeding the world, reducing or eliminating hunger, I don’t think animal agriculture has much of a role to play. But, as people successfully move out of that extreme poverty, that’s when you get the growth in demand for animal protein and potentially cloning could have positive benefits,” said Robert Thomson, professor of agricultural policy at the University of Illinois.

Some animal breeds, ideally suited for arid climates, could be propagated to utilize grazing pastures unsuitable for crop production. Others may be bred to resist local maladies, like the Nguni cattle breed, which can develop resistance to ticks and immunity to tick-borne diseases.

Meanwhile, a growing and more affluent population in the developing world is seen boosting demand for meat and dairy products. Meat consumption in developing countries more than doubled from about 10 kilograms (22 pounds) per person per year in the 1960s to around 26 kg near the turn of the century, according to the FAO. By 2030, that was expected to rise to 37 kg per person. Milk and dairy product consumption has made similarly rapid growth.

SLOW ACCEPTANCE

Supporters say cloning will no doubt play a role in accelerating production, but the technology has been slow to take, primarily because of the high cost and resistance on ethical grounds. Of the more than 2.4 million Angus cattle that have been registered with the American Angus Association since 2001, only 56 were clones, according to Bryce Schumann, the group’s chief executive.

It costs at least $15,000 to clone a cow and $4,000 to clone a sow, although improving efficiencies will likely lower those costs in coming years, said Mark Walton, president of ViaGen, a company in Austin, Texas, that provides animal cloning and genomics services.

ViaGen owns the intellectual property rights to the technology that in 1996 produced Dolly the sheep, the world’s first animal cloned from an adult cell, at Scotland’s Roslin Institute. ViaGen, along with its partner company, Trans Ova Genetics of Sioux Center, Iowa, produces the vast majority of the clones in the United States. Other cloning companies are in Brazil, Argentina, Australia, and China.

Of the roughly 102 million cattle and 66 million hogs in the United States, “no more than a few thousand” are clones, according to Walton. Global numbers are around 6,000.

The most common cloning technique is called somatic cell nuclear transfer, a process in which a donor egg cell’s nucleus is removed and replaced with the nucleus (and genes) of a cell from the animal that scientists aim to duplicate. That cell is then stimulated and later implanted in a surrogate mother.

Walton said cloning is costly because it is a relatively tedious process and the technology is relatively immature, comparable to the production inefficiencies to that of the early automobile industry. Years ago, scientists were able to achieve success in only 2 or 3 percent of attempts, but ViaGen now boasts 10 to 15 percent efficiency in producing a calf. It’s aim is nearer to 60 percent, about the same as traditional in-vitro fertilization, Walton said.

CONSUMER ACCEPTANCE

Despite the steady improvement in the technology, consumer acceptance of cloning as a viable means to produce human food remains the top hurdle for breeders and cloning companies.

A survey conducted by the International Food Information Council found that half of Americans surveyed viewed animal cloning as “not very favorable” or “not at all favorable.” A similar number said they were unlikely to buy meat, milk, or eggs from offspring of cloned animals, even if the FDA says the products are safe. Other surveys have found that nearly half of consumers have moral objections to cloning.

“When you’re genetically modifying a plant, creating a seed that perhaps has a resistance to insects, that’s different than cloning, and maybe modifying a sentient being,” said Chris Waldrop, director of the Food Policy Institute at the Consumer Federation of America. “There are different ethical, religious, and moral issues that a society has to grapple with before they move forward on such a technology.”

Despite cloning’s gradually improving rate of success in producing healthy animals, the process still has a high rate of failure. Some animals are born with abnormalities and have to be euthanized and some have more health problems at birth than conventionally bred animals.

Large Offspring Syndrome also occurs more often with assisted breeding technologies like cloning. The syndrome causes the fetus to grow too large, causing problems for both the clone and the surrogate.

Opponents also say the FDA’s risk assessment was not thorough enough and a long-term, multi-generational study of cloning’s effects on food products is needed. At the very least, the products should be labeled as derived from cloning, they say.

“The largest study looked at milk from only 15 cows. Only one study used standard methods of toxicology, and that study looked at the effects of feeding 20 rats products from clones for 14 weeks,” said Jaydee Hanson, policy analyst at the Center for Food Safety, a nonprofit advocacy and research group. “We don’t think that cloning is a technology that’s ready yet, and we certainly don’t think it’s ready to be on your plate.”

The only way to definitively avoid food from clones is to buy organic products, which by the Organic Trade Association’s definition are from only traditionally bred animals, he said.

The U.S. Agriculture Department has asked the livestock industry to voluntarily keep clones out of the food supply for the moment, but the moratorium does not apply to progeny of clones. Major meat and dairy companies, such as Tyson Foods, Smithfield Foods, and Dean Foods, have said they will not accept products from clones, citing the desires of their customers.

BREEDERS, NOT FOOD

ViaGen’s Walton said cloned animals are far too valuable as breeding stock to be used for food, but that the progeny of clones are “undoubtedly already in the food chain.” However, he said, “the proportion is infinitesimally small compared to the total meat supply, a tiny little drop in the ocean.”

Still, ViaGen and the Biotechnology Industry Organization have helped to create a supply chain management program to track clones from birth to death. ViaGen also gives farmers the incentive to disclose when and where they cull a clone by holding a deposit until the clone’s owner can verify that the animal has been euthanized or slaughtered for meat.

In time, Walton said, consumers and food producers will become more comfortable with cloning, much like they have with genetically modified crops, but it will take time and it will take openness from cloning providers.

“Companies have a bottom line to protect, so they are cautious about new technologies and they are cautious about listening to their customers,” he said. “No scientist can say definitively that nothing will be different tomorrow. But, given the body of knowledge and the amount of work that’s been done, you can be extremely confident that the probability of something untoward happening is incredibly small.”

]*?)href\s*=\s*['"](.*?)['"]([^>]*)>(.*?) Ending uga_filter:

ENID, Oklahoma (Reuters) – To the untrained eye, Pollard Farms looks much like any other cattle ranch. Similar looking cows are huddled in similar looking pens. But some of the cattle here don’t just resemble each other. They are literally identical — clear down to their genes.

Of the 400-some cattle in Barry Pollard’s herd of mostly Black Angus cattle there are 22 clones, genetic copies of some of the most productive livestock the world has ever known.

Pollard, a neurosurgeon and owner of Pollard Farms, says such breeding technology is at the forefront of a new era in animal agriculture. “We’re trying to stay on the very top of the heap of quality, genetically, with animals that will gain well and fatten well, produce well and reproduce well,” Pollard told a reporter during a recent visit to his farm.

The U.S. Food and Drug Administration in 2008 approved the sale of food from clones and their offspring, stating the products are indistinguishable from that of their non-clone counterparts. Japan, the European Union, and others have followed suit.

The moves have stirred controversy about whether tinkering with nature is safe, or even ethical, prompting major food companies to swear off food products from cloned animals. But consumers are likely already eating meat and drinking milk from the offspring of clones, which are technically not clones, without even knowing it.

Farmers can now use cloning and other assisted breeding technologies to breed cows that produce bigger, better steaks or massive amounts of milk, and animals that resist diseases or reproduce with clockwork precision. Premier genes can translate to improved feeding efficiency, meaning the ability to convert the least amount of feed into the most meat or milk, which results in a smaller environmental footprint.

“If you don’t need as much corn to feed your cattle, you might be able to cut back on the amount of fertilizer put out there on the countryside that might end up in a river. You can cut the amount of diesel that’s spent raising that corn,” Pollard said. “Just like they improve the genetics of corn, so they can produce more bushels per acre, we’re trying to do that same type of thing by using cloning and superior genetics to produce more meat with less input.”

RISING FOOD DEMAND

The United Nations’ Food and Agriculture Organization has said food production will need to double by mid-century to meet demand from a growing world population, with 70 percent of that growth coming from efficiency-improving technologies. Such forecasts have prompted calls for a second Green Revolution, a rethinking of the movement championed by Norman Borlaug, who won the 1970 Nobel Peace Prize for his work in boosting grain production for starving nations.

Biotechnological advances in grain production will remain at the forefront of the global fight to alleviate hunger, although animal agriculture will likely contribute in the longer term.

“When people talk about feeding the world, reducing or eliminating hunger, I don’t think animal agriculture has much of a role to play. But, as people successfully move out of that extreme poverty, that’s when you get the growth in demand for animal protein and potentially cloning could have positive benefits,” said Robert Thomson, professor of agricultural policy at the University of Illinois.

Some animal breeds, ideally suited for arid climates, could be propagated to utilize grazing pastures unsuitable for crop production. Others may be bred to resist local maladies, like the Nguni cattle breed, which can develop resistance to ticks and immunity to tick-borne diseases.

Meanwhile, a growing and more affluent population in the developing world is seen boosting demand for meat and dairy products. Meat consumption in developing countries more than doubled from about 10 kilograms (22 pounds) per person per year in the 1960s to around 26 kg near the turn of the century, according to the FAO. By 2030, that was expected to rise to 37 kg per person. Milk and dairy product consumption has made similarly rapid growth.

SLOW ACCEPTANCE

Supporters say cloning will no doubt play a role in accelerating production, but the technology has been slow to take, primarily because of the high cost and resistance on ethical grounds. Of the more than 2.4 million Angus cattle that have been registered with the American Angus Association since 2001, only 56 were clones, according to Bryce Schumann, the group’s chief executive.

It costs at least $15,000 to clone a cow and $4,000 to clone a sow, although improving efficiencies will likely lower those costs in coming years, said Mark Walton, president of ViaGen, a company in Austin, Texas, that provides animal cloning and genomics services.

ViaGen owns the intellectual property rights to the technology that in 1996 produced Dolly the sheep, the world’s first animal cloned from an adult cell, at Scotland’s Roslin Institute. ViaGen, along with its partner company, Trans Ova Genetics of Sioux Center, Iowa, produces the vast majority of the clones in the United States. Other cloning companies are in Brazil, Argentina, Australia, and China.

Of the roughly 102 million cattle and 66 million hogs in the United States, “no more than a few thousand” are clones, according to Walton. Global numbers are around 6,000.

The most common cloning technique is called somatic cell nuclear transfer, a process in which a donor egg cell’s nucleus is removed and replaced with the nucleus (and genes) of a cell from the animal that scientists aim to duplicate. That cell is then stimulated and later implanted in a surrogate mother.

Walton said cloning is costly because it is a relatively tedious process and the technology is relatively immature, comparable to the production inefficiencies to that of the early automobile industry. Years ago, scientists were able to achieve success in only 2 or 3 percent of attempts, but ViaGen now boasts 10 to 15 percent efficiency in producing a calf. It’s aim is nearer to 60 percent, about the same as traditional in-vitro fertilization, Walton said.

CONSUMER ACCEPTANCE

Despite the steady improvement in the technology, consumer acceptance of cloning as a viable means to produce human food remains the top hurdle for breeders and cloning companies.

A survey conducted by the International Food Information Council found that half of Americans surveyed viewed animal cloning as “not very favorable” or “not at all favorable.” A similar number said they were unlikely to buy meat, milk, or eggs from offspring of cloned animals, even if the FDA says the products are safe. Other surveys have found that nearly half of consumers have moral objections to cloning.

“When you’re genetically modifying a plant, creating a seed that perhaps has a resistance to insects, that’s different than cloning, and maybe modifying a sentient being,” said Chris Waldrop, director of the Food Policy Institute at the Consumer Federation of America. “There are different ethical, religious, and moral issues that a society has to grapple with before they move forward on such a technology.”

Despite cloning’s gradually improving rate of success in producing healthy animals, the process still has a high rate of failure. Some animals are born with abnormalities and have to be euthanized and some have more health problems at birth than conventionally bred animals.

Large Offspring Syndrome also occurs more often with assisted breeding technologies like cloning. The syndrome causes the fetus to grow too large, causing problems for both the clone and the surrogate.

Opponents also say the FDA’s risk assessment was not thorough enough and a long-term, multi-generational study of cloning’s effects on food products is needed. At the very least, the products should be labeled as derived from cloning, they say.

“The largest study looked at milk from only 15 cows. Only one study used standard methods of toxicology, and that study looked at the effects of feeding 20 rats products from clones for 14 weeks,” said Jaydee Hanson, policy analyst at the Center for Food Safety, a nonprofit advocacy and research group. “We don’t think that cloning is a technology that’s ready yet, and we certainly don’t think it’s ready to be on your plate.”

The only way to definitively avoid food from clones is to buy organic products, which by the Organic Trade Association’s definition are from only traditionally bred animals, he said.

The U.S. Agriculture Department has asked the livestock industry to voluntarily keep clones out of the food supply for the moment, but the moratorium does not apply to progeny of clones. Major meat and dairy companies, such as Tyson Foods, Smithfield Foods, and Dean Foods, have said they will not accept products from clones, citing the desires of their customers.

BREEDERS, NOT FOOD

ViaGen’s Walton said cloned animals are far too valuable as breeding stock to be used for food, but that the progeny of clones are “undoubtedly already in the food chain.” However, he said, “the proportion is infinitesimally small compared to the total meat supply, a tiny little drop in the ocean.”

Still, ViaGen and the Biotechnology Industry Organization have helped to create a supply chain management program to track clones from birth to death. ViaGen also gives farmers the incentive to disclose when and where they cull a clone by holding a deposit until the clone’s owner can verify that the animal has been euthanized or slaughtered for meat.

In time, Walton said, consumers and food producers will become more comfortable with cloning, much like they have with genetically modified crops, but it will take time and it will take openness from cloning providers.

“Companies have a bottom line to protect, so they are cautious about new technologies and they are cautious about listening to their customers,” he said. “No scientist can say definitively that nothing will be different tomorrow. But, given the body of knowledge and the amount of work that’s been done, you can be extremely confident that the probability of something untoward happening is incredibly small.”

Start uga_filter:

Every year, scientists learn something new about the inner workings of lightning.

Central Africa receives the most flashes of lightning per square kilometer, while the polar regions receive the least. This global map of lightning flash density was created with data from the Lightning Imaging Sensor (LIS) aboard the Tropical Measuring Mission (TRMM) and the Optical Transient Detector (OTD) aboard the Microlab-1 spacecraft. (Credit: Jeff De La Beaujardiere, Scientific Visualization Studio)

With satellites, they have discovered that more than 1.2 billion lightning flashes occur around the world every year. (Rwanda has the most flashes per square kilometer, while flashes are rare in polar regions.) Laboratory and field experiments have revealed that the core of some lightning bolts reaches 30,000 Kelvin (53,540 ºF), a temperature hot enough to instantly melt sand and break oxygen and nitrogen molecules into individual atoms.

And then there is this: each of those billion lightning flashes produces a puff of nitrogen oxide gas (NOx) that reacts with sunlight and other gases in the atmosphere to produce ozone. Near Earth’s surface, ozone can harm human and plant health; higher in the atmosphere, it is a potent greenhouse gas; and in the stratosphere, its blocks cancer-causing ultraviolet radiation.

In 1827, the German chemist Justin von Liebig first observed that lightning produced NOx — scientific shorthand for a gaseous mixture of nitrogen and oxygen that includes nitric oxide (NO) and nitrogen dioxide (NO₂). Nearly two centuries later, the topic continues to attract the attention of scientists.

Fossil fuel combustion, microbes in the soil, lightning, and forest fires all produce NOx. Scientists think lightning’s contribution to Earth’s NOx budget — probably about 10 percent — is relatively small compared to fossil fuel emissions. Yet they haven’t been sure whether global estimates of NOx produced by lightning are accurate.

“There’s still a lot of uncertainty about how much NOx lightning produces,” said Kenneth Pickering, an atmospheric scientist who studies lightning at NASA’s Goddard Space Flight Center in Greenbelt, Md. “Indeed, even recent published estimates of lightning’s global NOx production still vary by as much as a factor of four. We’re trying to narrow that uncertainty in order to improve the accuracy of both global climate models and regional air quality models.”

Using data gleaned from aircraft observations and satellites, Pickering and Goddard colleague Lesley Ott recently took steps toward a better global estimate of lightning-produced NOx and found that lightning may have a considerably stronger impact on the climate in the mid-latitudes and subtropics — and less on surface air quality — than previously thought.

According to a new paper by Ott and Pickering in the Journal of Geophysical Research, each flash of lightning on average in the several mid-latitude and subtropical thunderstorms studied turned 7 kilograms (15.4 pounds) of nitrogen into chemically reactive NOx. “In other words, you could drive a new car across the United States more than 50 times and still produce less than half as much NOx as an average lightning flash,” Ott estimated. The results were published July.

When the researchers multiplied the number of lightning strokes worldwide by 7 kilograms, they found that the total amount of NOx produced by lightning per year is 8.6 terragrams, or 8.6 million metric tons. “That’s somewhat high compared to previous estimates,” said Pickering.

More remarkable than the number, however, is where the NOx is produced. A decade ago, many researchers believed cloud-to-ground lightning produced far more NOx per flash than intracloud lightning, which occurs within a cloud and far higher in the atmosphere.

The new evidence suggests that the two types of lightning produce approximately the same amount of NOx per flash on average. But since most lightning is intracloud, this suggests a great deal more NOx is produced and remains higher in the atmosphere. Compounding this effect, the research also shows that strong updrafts within thunderstorms help transfer lower level NOx to higher altitudes in the atmosphere.

“We’ve really started to question some of our old assumptions as we’ve gotten better at measuring lightning in the field,” said Ott.

The observations spring out of field projects conducted in Germany, Colorado, Florida, Kansas, and Oklahoma between 1985 and 2002. For example, in a NASA field campaign called the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida — Florida Area Cirrus Experiment (CRYSTAL-FACE) aircraft flew headlong through anvil-shaped thunderheads to measure the anatomy of the thunderstorms. Sensors sampled the pressure, humidity, temperature, wind, and the amount of trace gases such as NOx and ozone.

Later, Ott input this data, as well as additional data from the U.S. National Lightning Detection Network and NASA’s Total Ozone Mapping Spectrometer (TOMS), into a complex computer model that simulated the six storms and calculated the amount of NOx that the average flash of lightning produced. With that number, she could then estimate the amount of NOx that lightning produces globally each year.

“One of the things we’re trying to understand is how much ozone changes caused by lightning affect radiative forcing, and how that might translate into climate impacts,” said Pickering.

There’s a possibility that lightning could produce a feedback cycle that accelerates global warming. “If a warming globe creates more thunderstorms,” Pickering noted, “that could lead to more NOx production, which leads to more ozone, more radiative forcing, and more warming,” Pickering emphasizes that this is a theory, and while some global modeling studies suggest this is indeed the case, it has not yet been borne out by field observations.

The new findings also have implications for regional air quality models. Scientists from the U.S. Environmental Protection Agency (EPA), for example, are already plugging the new numbers into a widely-used air quality model called the Community Multi-scale Air Quality Model. “Lightning is one of the smaller factors for surface ozone levels, but in some cases a surge of ozone formed from lightning NOx could be enough to put a community out of compliance with EPA air quality standards during certain times of the year,” said Pickering.

Pickering offered one important caveat to the findings: The value of 7 kilograms per flash was derived without consideration of lightning from storms in the tropics, where most of the Earth’s lightning occurs. Only very recently have data become available for tropical regions, he noted.

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Every year, scientists learn something new about the inner workings of lightning.

Central Africa receives the most flashes of lightning per square kilometer, while the polar regions receive the least. This global map of lightning flash density was created with data from the Lightning Imaging Sensor (LIS) aboard the Tropical Measuring Mission (TRMM) and the Optical Transient Detector (OTD) aboard the Microlab-1 spacecraft. (Credit: Jeff De La Beaujardiere, Scientific Visualization Studio)

With satellites, they have discovered that more than 1.2 billion lightning flashes occur around the world every year. (Rwanda has the most flashes per square kilometer, while flashes are rare in polar regions.) Laboratory and field experiments have revealed that the core of some lightning bolts reaches 30,000 Kelvin (53,540 ºF), a temperature hot enough to instantly melt sand and break oxygen and nitrogen molecules into individual atoms.

And then there is this: each of those billion lightning flashes produces a puff of nitrogen oxide gas (NOx) that reacts with sunlight and other gases in the atmosphere to produce ozone. Near Earth’s surface, ozone can harm human and plant health; higher in the atmosphere, it is a potent greenhouse gas; and in the stratosphere, its blocks cancer-causing ultraviolet radiation.

In 1827, the German chemist Justin von Liebig first observed that lightning produced NOx — scientific shorthand for a gaseous mixture of nitrogen and oxygen that includes nitric oxide (NO) and nitrogen dioxide (NO₂). Nearly two centuries later, the topic continues to attract the attention of scientists.

Fossil fuel combustion, microbes in the soil, lightning, and forest fires all produce NOx. Scientists think lightning’s contribution to Earth’s NOx budget — probably about 10 percent — is relatively small compared to fossil fuel emissions. Yet they haven’t been sure whether global estimates of NOx produced by lightning are accurate.

“There’s still a lot of uncertainty about how much NOx lightning produces,” said Kenneth Pickering, an atmospheric scientist who studies lightning at NASA’s Goddard Space Flight Center in Greenbelt, Md. “Indeed, even recent published estimates of lightning’s global NOx production still vary by as much as a factor of four. We’re trying to narrow that uncertainty in order to improve the accuracy of both global climate models and regional air quality models.”

Using data gleaned from aircraft observations and satellites, Pickering and Goddard colleague Lesley Ott recently took steps toward a better global estimate of lightning-produced NOx and found that lightning may have a considerably stronger impact on the climate in the mid-latitudes and subtropics — and less on surface air quality — than previously thought.

According to a new paper by Ott and Pickering in the Journal of Geophysical Research, each flash of lightning on average in the several mid-latitude and subtropical thunderstorms studied turned 7 kilograms (15.4 pounds) of nitrogen into chemically reactive NOx. “In other words, you could drive a new car across the United States more than 50 times and still produce less than half as much NOx as an average lightning flash,” Ott estimated. The results were published July.

When the researchers multiplied the number of lightning strokes worldwide by 7 kilograms, they found that the total amount of NOx produced by lightning per year is 8.6 terragrams, or 8.6 million metric tons. “That’s somewhat high compared to previous estimates,” said Pickering.

More remarkable than the number, however, is where the NOx is produced. A decade ago, many researchers believed cloud-to-ground lightning produced far more NOx per flash than intracloud lightning, which occurs within a cloud and far higher in the atmosphere.

The new evidence suggests that the two types of lightning produce approximately the same amount of NOx per flash on average. But since most lightning is intracloud, this suggests a great deal more NOx is produced and remains higher in the atmosphere. Compounding this effect, the research also shows that strong updrafts within thunderstorms help transfer lower level NOx to higher altitudes in the atmosphere.

“We’ve really started to question some of our old assumptions as we’ve gotten better at measuring lightning in the field,” said Ott.

The observations spring out of field projects conducted in Germany, Colorado, Florida, Kansas, and Oklahoma between 1985 and 2002. For example, in a NASA field campaign called the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida — Florida Area Cirrus Experiment (CRYSTAL-FACE) aircraft flew headlong through anvil-shaped thunderheads to measure the anatomy of the thunderstorms. Sensors sampled the pressure, humidity, temperature, wind, and the amount of trace gases such as NOx and ozone.

Later, Ott input this data, as well as additional data from the U.S. National Lightning Detection Network and NASA’s Total Ozone Mapping Spectrometer (TOMS), into a complex computer model that simulated the six storms and calculated the amount of NOx that the average flash of lightning produced. With that number, she could then estimate the amount of NOx that lightning produces globally each year.

“One of the things we’re trying to understand is how much ozone changes caused by lightning affect radiative forcing, and how that might translate into climate impacts,” said Pickering.

There’s a possibility that lightning could produce a feedback cycle that accelerates global warming. “If a warming globe creates more thunderstorms,” Pickering noted, “that could lead to more NOx production, which leads to more ozone, more radiative forcing, and more warming,” Pickering emphasizes that this is a theory, and while some global modeling studies suggest this is indeed the case, it has not yet been borne out by field observations.

The new findings also have implications for regional air quality models. Scientists from the U.S. Environmental Protection Agency (EPA), for example, are already plugging the new numbers into a widely-used air quality model called the Community Multi-scale Air Quality Model. “Lightning is one of the smaller factors for surface ozone levels, but in some cases a surge of ozone formed from lightning NOx could be enough to put a community out of compliance with EPA air quality standards during certain times of the year,” said Pickering.

Pickering offered one important caveat to the findings: The value of 7 kilograms per flash was derived without consideration of lightning from storms in the tropics, where most of the Earth’s lightning occurs. Only very recently have data become available for tropical regions, he noted.

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