Big Ecosystem Shifts from Climate Change

Big Ecosystem Shifts from Climate Change

  12:47:00 AM    Science Lover

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By 2100, global climate change will modify plant communities covering almost half of Earth's land surface and will drive the conversion of nearly 40 percent of land-based ecosystems from one major ecological community type -- such as forest, grassland or tundra -- toward another, according to a new NASA and university computer modeling study.

Predicted percentage of ecological landscape
being driven toward changes in plant species
as a result of projected human-induced climate
change by 2100. (Credit: NASA/JPL-Caltech)

Researchers from NASA's Jet Propulsion Laboratory and the California Institute of Technology in Pasadena, Calif., investigated how Earth's plant life is likely to react over the next three centuries as Earth's climate changes in response to rising levels of human-produced greenhouse gases. Study results are published in the journal Climatic Change.

The model projections paint a portrait of increasing ecological change and stress in Earth's biosphere, with many plant and animal species facing increasing competition for survival, as well as significant species turnover, as some species invade areas occupied by other species. Most of Earth's land that is not covered by ice or desert is projected to undergo at least a 30 percent change in plant cover -- changes that will require humans and animals to adapt and often relocate.

In addition to altering plant communities, the study predicts climate change will disrupt the ecological balance between interdependent and often endangered plant and animal species, reduce biodiversity and adversely affect Earth's water, energy, carbon and other element cycles.

"For more than 25 years, scientists have warned of the dangers of human-induced climate change," said Jon Bergengren, a scientist who led the study while a postdoctoral scholar at Caltech. "Our study introduces a new view of climate change, exploring the ecological implications of a few degrees of global warming. While warnings of melting glaciers, rising sea levels and other environmental changes are illustrative and important, ultimately, it's the ecological consequences that matter most."

When faced with climate change, plant species often must "migrate" over multiple generations, as they can only survive, compete and reproduce within the range of climates to which they are evolutionarily and physiologically adapted. While Earth's plants and animals have evolved to migrate in response to seasonal environmental changes and to even larger transitions, such as the end of the last ice age, they often are not equipped to keep up with the rapidity of modern climate changes that are currently taking place. Human activities, such as agriculture and urbanization, are increasingly destroying Earth's natural habitats, and frequently block plants and animals from successfully migrating.

To study the sensitivity of Earth's ecological systems to climate change, the scientists used a computer model that predicts the type of plant community that is uniquely adapted to any climate on Earth. This model was used to simulate the future state of Earth's natural vegetation in harmony with climate projections from 10 different global climate simulations. These simulations are based on the intermediate greenhouse gas scenario in the United Nations' Intergovernmental Panel on Climate Change Fourth Assessment Report. That scenario assumes greenhouse gas levels will double by 2100 and then level off. The U.N. report's climate simulations predict a warmer and wetter Earth, with global temperature increases of 3.6 to 7.2 degrees Fahrenheit (2 to 4 degrees Celsius) by 2100, about the same warming that occurred following the Last Glacial Maximum almost 20,000 years ago, except about 100 times faster. Under the scenario, some regions become wetter because of enhanced evaporation, while others become drier due to changes in atmospheric circulation.

The researchers found a shift of biomes, or major ecological community types, toward Earth's poles -- most dramatically in temperate grasslands and boreal forests -- and toward higher elevations. Ecologically sensitive "hotspots" -- areas projected to undergo the greatest degree of species turnover -- that were identified by the study include regions in the Himalayas and the Tibetan Plateau, eastern equatorial Africa, Madagascar, the Mediterranean region, southern South America, and North America's Great Lakes and Great Plains areas. The largest areas of ecological sensitivity and biome changes predicted for this century are, not surprisingly, found in areas with the most dramatic climate change: in the Northern Hemisphere high latitudes, particularly along the northern and southern boundaries of boreal forests.

"Our study developed a simple, consistent and quantitative way to characterize the impacts of climate change on ecosystems, while assessing and comparing the implications of climate model projections," said JPL co-author Duane Waliser. "This new tool enables scientists to explore and understand interrelationships between Earth's ecosystems and climate and to identify regions projected to have the greatest degree of ecological sensitivity."

"In this study, we have developed and applied two new ecological sensitivity metrics -- analogs of climate sensitivity -- to investigate the potential degree of plant community changes over the next three centuries," said Bergengren. "The surprising degree of ecological sensitivity of Earth's ecosystems predicted by our research highlights the global imperative to accelerate progress toward preserving biodiversity by stabilizing Earth's climate."

JPL is managed for NASA by the California Institute of Technology in Pasadena.

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City Lights Could Reveal E.T. Civilization

City Lights Could Reveal E.T. Civilization

  10:51:00 PM    Science Lover

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In the search for extraterrestrial intelligence, astronomers have hunted for radio signals and ultra-short laser pulses. In a new paper, Avi Loeb (Harvard-Smithsonian Center for Astrophysics) and Edwin Turner (Princeton University) suggest a new technique for finding aliens: look for their city lights. "Looking for alien cities would be a long shot, but wouldn't require extra resources. And if we succeed, it would change our perception of our place in the universe," said Loeb.

If an alien civilization builds brightly-lit cities like those shown in this artist's conception, future generations of telescopes might allow us to detect them. This would offer a new method of searching for extraterrestrial intelligence elsewhere in our Galaxy. (Credit: David A. Aguilar (CfA))

As with other SETI methods, they rely on the assumption that aliens would use Earth-like technologies. This is reasonable because any intelligent life that evolved in the light from its nearest star is likely to have artificial illumination that switches on during the hours of darkness.

How easy would it be to spot a city on a distant planet? Clearly, this light will have to be distinguished from the glare from the parent star. Loeb and Turner suggest looking at the change in light from an exoplanet as it moves around its star.

As the planet orbits, it goes through phases similar to those of the Moon. When it's in a dark phase, more artificial light from the night side would be visible from Earth than reflected light from the day side. So the total flux from a planet with city lighting will vary in a way that is measurably different from a planet that has no artificial lights.

Spotting this tiny signal would require future generations of telescopes. However, the technique could be tested closer to home, using objects at the edge of our solar system.

Loeb and Turner calculate that today's best telescopes ought to be able to see the light generated by a Tokyo-sized metropolis at the distance of the Kuiper Belt -- the region occupied by Pluto, Eris, and thousands of smaller icy bodies. So if there are any cities out there, we ought to be able to see them now. By looking, astronomers can hone the technique and be ready to apply it when the first Earth-sized worlds are found around distant stars in our galaxy.

"It's very unlikely that there are alien cities on the edge of our solar system, but the principle of science is to find a method to check," Turner said. "Before Galileo, it was conventional wisdom that heavier objects fall faster than light objects, but he tested the belief and found they actually fall at the same rate."

As our technology has moved from radio and TV broadcasts to cable and fiber optics, we have become less detectable to aliens. If the same is true of extraterrestrial civilizations, then artificial lights might be the best way to spot them from afar.

Loeb and Turner's work has been submitted to the journal Astrobiology.

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Global Warming Is Real, New Analysis Confirms

Global Warming Is Real, New Analysis Confirms

  9:38:00 PM    Science Lover

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Global warming is real, according to a major study released Oct. 20. Despite issues raised by climate change skeptics, the Berkeley Earth Surface Temperature study finds reliable evidence of a rise in the average world land temperature of approximately 1°C since the mid-1950s.

Comparison of data showing decadal land-surface average world temperature changes from 15 different sources, some going back as far as 1800. (Credit: Image courtesy of Berkeley Earth Surface Temperature)

Analyzing temperature data from 15 sources, in some cases going as far back as 1800, the Berkeley Earth study directly addressed scientific concerns raised by skeptics, including the urban heat island effect, poor station quality, and the risk of data selection bias.

On the basis of its analysis, according to Berkeley Earth's founder and scientific director, Professor Richard A. Muller, the group concluded that earlier studies based on more limited data by teams in the United States and Britain had accurately estimated the extent of land surface warming.

"Our biggest surprise was that the new results agreed so closely with the warming values published previously by other teams in the U.S. and the U.K.," Muller said. "This confirms that these studies were done carefully and that potential biases identified by climate change skeptics did not seriously affect their conclusions."

Previous studies, carried out by NOAA, NASA, and the Hadley Center, also found that land warming was approximately 1°C since the mid-1950s, and that the urban heat island effect and poor station quality did not bias the results. But their findings were criticized by skeptics who worried that they relied on ad-hoc techniques that meant that the findings could not be duplicated. Robert Rohde, lead scientist for Berkeley Earth, noted that "the Berkeley Earth analysis is the first study to address the issue of data selection bias, by using nearly all of the available data, which includes about 5 times as many station locations as were reviewed by prior groups."

Elizabeth Muller, co-founder and Executive Director of Berkeley Earth, said she hopes the Berkeley Earth findings will help "cool the debate over global warming by addressing many of the valid concerns of the skeptics in a clear and rigorous way." This will be especially important in the run-up to the COP 17 meeting in Durban, South Africa, later this year, where participants will discuss targets for reducing Greenhouse Gas (GHG) emissions for the next commitment period as well as issues such as financing, technology transfer and cooperative action.

The Berkeley Earth team includes physicists, climatologists, and statisticians from California, Oregon, and Georgia. Rohde led the development of a new statistical approach and what Richard Muller called "the Herculean labor" of merging the data sets. One member of the group, Saul Perlmutter, was recently announced as a winner of the 2011 Nobel Prize in Physics (for his work in cosmology).



The Berkeley Earth study did not assess temperature changes in the oceans, which according to the Intergovernmental Panel on Climate Change (IPCC) have not warmed as much as land. When averaged in, they reduce the global surface temperature rise over the past 50 years -- the period during which the human effect on temperatures is discernable -- to about two thirds of one degree Centigrade.

Specifically, the Berkeley Earth study concludes that:

• The urban heat island effect is locally large and real, but does not contribute significantly to the average land temperature rise. That's because the urban regions of Earth amount to less than 1% of the land area.
• About 1/3 of temperature sites around the world reported global cooling over the past 70 years (including much of the United States and northern Europe). But 2/3 of the sites show warming. Individual temperature histories reported from a single location are frequently noisy and/or unreliable, and it is always necessary to compare and combine many records to understand the true pattern of global warming.
• The large number of sites reporting cooling might help explain some of the skepticism of global warming," Rohde commented. "Global warming is too slow for humans to feel directly, and if your local weather man tells you that temperatures are the same or cooler than they were a hundred years ago it is easy to believe him." In fact, it is very hard to measure weather consistently over decades and centuries, and the presence of sites reporting cooling is a symptom of the noise and local variations that can creep in. A good determination of the rise in global land temperatures can't be done with just a few stations: it takes hundreds -- or better, thousands -- of stations to detect and measure the average warming. Only when many nearby thermometers reproduce the same patterns can we know that the measurements were reliably made.
• Stations ranked as "poor" in a survey by Anthony Watts and his team of the most important temperature recording stations in the U.S., (known as the USHCN -- the US Historical Climatology Network), showed the same pattern of global warming as stations ranked "OK." Absolute temperatures of poor stations may be higher and less accurate, but the overall global warming trend is the same, and the Berkeley Earth analysis concludes that there is not any undue bias from including poor stations in the survey.

Four scientific papers setting out these conclusions have been submitted for peer review and will form part of the literature for the next IPCC report on Climate Change. They can be accessed on: www.BerkeleyEarth.org. A video animation graphically shows global warming around the world since 1800.

Berkeley Earth is making its preliminary results public, together with its programs and dataset, in order to invite additional scrutiny. Elizabeth Muller said that "one of our goals is to make the science behind global warming readily accessible to the public." Most of the data were previously available on public websites, but in so many different locations and different formats that most people could access only a small subset of the data. The merged database, which combines 1.6 billion records, is now accessible from the Berkeley Earth website: www.BerkeleyEarth.org .

What Berkeley Earth has not done is make an independent assessment of how much of the observed warming is due to human actions, Richard Muller acknowledged. As a next step, Berkeley Earth plans to address the total warming of the oceans, with a view to obtaining a more accurate figure for the total amount of global warming observable.

More information about Berkeley Earth is available at www.BerkeleyEarth.org.

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Measuring Global Photosynthesis Rate: Earth's Plant Life 'Recycles' Carbon Dioxide Faster Than Previously Estimated

Measuring Global Photosynthesis Rate: Earth's Plant Life 'Recycles' Carbon Dioxide Faster Than Previously Estimated

  8:58:00 AM    Science Lover

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A Scripps Institution of Oceanography at UC San Diego-led research team followed the path of oxygen atoms on carbon dioxide molecules during photosynthesis to create a new way of measuring the efficiency of the world's plant life.

Researchers followed the path of oxygen atoms on carbon
dioxide molecules during photosynthesis to create a new
way of measuring the efficiency of Earth's plant life.
(Credit: © Dmitrijs Dmitrijevs / Fotolia)

A team led by postdoctoral researcher Lisa Welp considered the oxygen atoms contained in the carbon dioxide taken up by plants during photosynthesis. The ratio of two oxygen isotopes in carbon dioxide told researchers how long the CO2 had been in the atmosphere and how fast it had passed through plants. From this, they estimated that the global rate of photosynthesis is about 25 percent faster than thought.

"It's really hard to measure rates of photosynthesis for forests, let alone the entire globe. For a single leaf it's not so hard, you just put it in an instrument chamber and measure the CO2 decreasing in the chamber air," said Welp. "But you can't do that for an entire forest. What we have done is to use a naturally occurring marker in atmospheric CO2 that let us track how often it ended up inside a plant leaf, and from that we estimated the mean global rate of photosynthesis over the last few decades."

The authors of the study, published in the journal Nature, said the new estimate of the rate of global photosynthesis enabled by their method will in turn help guide other estimates of plant activity such as the capacity of forests and crops to grow. Understanding such variables is becoming increasingly important to scientists and policymakers attempting to understand the potential changes to ecosystems that can be expected from global warming.

"It speaks to the question, how alive is the Earth? We answer that it is a little more alive than previously believed," said study co-author and director of the Scripps CO2 Research Group, Ralph Keeling.

The key to this new approach was establishing a means of linking the changes in oxygen isotopes to El Niño, the global climate phenomenon that is associated with a variety of unusual weather patterns including low amounts rainfall in tropical regions of Asia and South America. The naturally occurring forms of oxygen known as 18O and 16O are present in different proportions to each other in water inside leaves during dry periods in the tropics. This signal in leaf waters is passed along to CO2 when CO2 mingles with the water inside leaves. This exchange of oxygen between CO2 and plant water also occurs in regions outside of the tropics that aren't as affected by El Niño and eventually returns this 18O/16O ratio to its norm. Welp's team used the time it took for this return to normal to infer the speed at which photosynthesis is taking place. They discovered that the ratio returned to normal faster than previously expected.




From this, the team revised the rate of global photosynthesis upward. The rate is expressed in terms of how much carbon is processed by plants in a year. From the previous estimate of 120 petagrams of carbon a year, the team set the annual rate between 150 and 175 petagrams. One petagram equals one trillion kilograms.

Keeling added that part of the value of the study is its validation of the importance of long-term measurement series and of making multiple independent measurements of the same phenomena. The researchers conducted isotope analyses of air that has been collected by the Scripps CO2 group at several locations around the world since 1977. It was only after decades of measurements that the researchers saw that the several bumps in the isotope record matched the timing of El Niño events. They compared their data to samples collected by Australia's Commonwealth Science and Industrial Research Organization (CSIRO). The redundancy was needed to make sure the data from Scripps' own samples weren't the result of measurement errors, said Keeling, whose research group maintains the famous record of atmospheric carbon dioxide concentration known as the Keeling Curve. Keeling's father, Charles David Keeling, established the CO2 measurements in 1958.

"Supporting long-term measurements is not easy through the normal funding mechanisms, which expect to see results on time scales of typically four years or less," said Keeling. "Few science agencies are happy to commit to measuring variables over longer periods but the value of tracking changes in the atmosphere doesn't stop after four years. Decades of measurements were required to unravel the features highlighted in this paper."

Other co-authors of the report were Harro A.J. Meijer from the University of Groningen in the Netherlands; Roger Francey and Colin Allison from CSIRO; and Alane Bollenbacher, Stephen Piper, and Martin Wahlen from Scripps and Kei Yoshimura of University of Tokyo. The National Science Foundation and the federal Department of Energy have provided long-term support for collection of the data used in the study.

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Invisible World Discovered: Planet Alternately Runs Late and Early in Its Orbit, Tugged by Second Hidden World

Invisible World Discovered: Planet Alternately Runs Late and Early in Its Orbit, Tugged by Second Hidden World

  7:20:00 PM    Science Lover

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Usually, running five minutes late is a bad thing since you might lose your dinner reservation or miss out on tickets to the latest show. But when a planet runs five minutes late, astronomers get excited because it suggests that another world is nearby.

The "invisible" world Kepler-19c, seen in the foreground of this artist's conception, was discovered solely through its gravitational influence on the companion world Kepler-19b - the dot crossing the star's face. Kepler-19b is slightly more than twice the diameter of Earth, and is probably a "mini-Neptune." Nothing is known about Kepler-19c, other than that it exists. (Credit: David A. Aguilar (CfA))

NASA's Kepler spacecraft has spotted a planet that alternately runs late and early in its orbit because a second, "invisible" world is tugging on it. This is the first definite detection of a previously unknown planet using this method. No other technique could have found the unseen companion.

"This invisible planet makes itself known by its influence on the planet we can see," said astronomer Sarah Ballard of the Harvard-Smithsonian Center for Astrophysics (CfA). Ballard is lead author on the study, which has been accepted for publication in The Astrophysical Journal.

"It's like having someone play a prank on you by ringing your doorbell and running away. You know someone was there, even if you don't see them when you get outside," she added.

Both the seen and unseen worlds orbit the Sun-like star Kepler-19, which is located 650 light-years from Earth in the constellation Lyra. The 12th-magnitude star is well placed for viewing by backyard telescopes on September evenings.

Kepler locates planets by looking for a star that dims slightly as a planet transits the star, passing across the star's face from our point of view. Transits give one crucial piece of information -- the planet's physical size. The greater the dip in light, the larger the planet relative to its star. However, the planet and star must line up exactly for us to see a transit.



The first planet, Kepler-19b, transits its star every 9 days and 7 hours. It orbits the star at a distance of 8.4 million miles, where it is heated to a temperature of about 900 degrees Fahrenheit. Kepler-19b has a diameter of 18,000 miles, making it slightly more than twice the size of Earth. It may resemble a "mini-Neptune," however its mass and composition remain unknown.

If Kepler-19b were alone, each transit would follow the next like clockwork. Instead, the transits come up to five minutes early or five minutes late. Such transit timing variations show that another world's gravity is pulling on Kepler-19b, alternately speeding it up or slowing it down.

Historically, the planet Neptune was discovered similarly. Astronomers tracking Uranus noticed that its orbit didn't match predictions. They realized that a more distant planet might be nudging Uranus and calculated the expected location of the unseen world. Telescopes soon observed Neptune near its predicted position.

"This method holds great promise for finding planets that can't be found otherwise," stated Harvard astronomer and co-author David Charbonneau.

So far, astronomers don't know anything about the invisible world Kepler-19c, other than that it exists. It weighs too little to gravitationally tug the star enough for them to measure its mass. And Kepler hasn't detected it transiting the star, suggesting that its orbit is tilted relative to Kepler-19b.

"Kepler-19c has multiple personalities consistent with our data. For instance, it could be a rocky planet on a circular 5-day orbit, or a gas-giant planet on an oblong 100-day orbit," said co-author Daniel Fabrycky of the University of California, Santa Cruz (UCSC).

The Kepler spacecraft will continue to monitor Kepler-19 throughout its mission. Those additional data will help nail down the orbit of Kepler-19c. Future ground-based instruments like HARPS-North will attempt to measure the mass of Kepler-19c. Only then will we have a clue to the nature of this invisible world.

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New Force Driving Earth's Tectonic Plates

New Force Driving Earth's Tectonic Plates

  7:54:00 PM    Science Lover

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Bringing fresh insight into long-standing debates about how powerful geological forces shape the planet, from earthquake ruptures to mountain formations, scientists at Scripps Institution of Oceanography at UC San Diego have identified a new mechanism driving Earth's massive tectonic plates.

Reconstruction of the Indo-Atlantic Ocean at 63 million years, during the time of the superfast motion of India which Scripps scientists attribute to the force of the Reunion plume head. The arrows show the relative convergence rate of Africa (black arrows) and India (dark blue) relative to Eurasia before, during and after (from left to right) the period of maximum plume head force. The jagged red and brown lines northeast of India show two possible positions of the trench (the subduction zone) between India and Eurasia depending on whether the India-Eurasia collision occurred at 52 million years or 43 million years. (Credit: Scripps Institution of Oceanography, UC San Diego)

Scientists who study tectonic motions have known for decades that the ongoing "pull" and "push" movements of the plates are responsible for sculpting continental features around the planet. Volcanoes, for example, are generally located at areas where plates are moving apart or coming together. Scripps scientists Steve Cande and Dave Stegman have now discovered a new force that drives plate tectonics: Plumes of hot magma pushing up from Earth's deep interior. Their research is published in the July 7 issue of the journal Nature.

Using analytical methods to track plate motions through Earth's history, Cande and Stegman's research provides evidence that such mantle plume "hot spots," which can last for tens of millions of years and are active today at locations such as Hawaii, Iceland and the Galapagos, may work as an additional tectonic driver, along with push-pull forces.

Their new results describe a clear connection between the arrival of a powerful mantle plume head around 70 million years ago and the rapid motion of the Indian plate that was pushed as a consequence of overlying the plume's location. The arrival of the plume also created immense formations of volcanic rock now called the "Deccan flood basalts" in western India, which erupted just prior to the mass extinction of dinosaurs. The Indian continent has since drifted north and collided with Asia, but the original location of the plume's arrival has remained volcanically active to this day, most recently having formed Réunion island near Madagascar.

The team also recognized that this "plume-push" force acted on other tectonic plates, and pushed on Africa as well but in the opposite direction.



"Prior to the plume's arrival, the African plate was slowly drifting but then stops altogether, at the same time the Indian speeds up," explains Stegman, an assistant professor of geophysics in Scripps' Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics. "It became clear the motion of the Indian and African plates were synchronized and the Réunion hotspot was the common link."

After the force of the plume had waned, the African plate's motion gradually returned to its previous speed while India slowed down.

"There is a dramatic slow down in the northwards motion of the Indian plate around 50 million years ago that has long been attributed to the initial collision of India with the Eurasian plate," said Cande, a professor of marine geophysics in the Geosciences Research Division at Scripps. "An implication of our study is that the slow down might just reflect the waning of the mantle plume-the actual collision might have occurred a little later."

Funding for the research was provided by the National Science Foundation.

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Solar wind samples give insight into birth of solar system

Solar wind samples give insight into birth of solar system

  9:33:00 AM    Science Lover

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Two papers in this week's issue of Science report the first oxygen and nitrogen isotopic measurements of the Sun, demonstrating that they are verydifferent from the same elements on Earth. These results were the top two priorities of NASA's Genesis mission, which was the first spacecraft to return from beyond the Moon, crashing in the Utah desert in 2004 after its parachute failed to deploy during re-entry.

The Solar Wind Concentrator is a special instrument built
by a team at Los Alamos National Laboratory to enhance
the flow of solar wind onto a small target to make possible
oxygen and nitrogen measurements. Shown here, the target
section of the concentrator, which produced essential
samples of nitrogen and oxygen.

Most of the Genesis payload consisted of fragile solar-wind collectors, which had been exposed to the solar particles over a period of two years. Nearly all of these collectors were decimated during the crash. But the capsule also contained a special instrument built by a team at Los Alamos National Laboratory to enhance the flow of solar wind onto a small target to make possible oxygen and nitrogen measurements. The targets of this Solar Wind Concentrator survived the crash and eventually yielded today's solar secrets.

"Genesis is the biggest comeback mission since Apollo 13," said Roger Wiens, a Los Alamos National Laboratory physicist and Genesis flight payload lead. "Everyone who saw the crash thought it was a terrible disaster, but instead the project has been fully successful, and the results are absolutely fascinating."

The results provide new clues to how the solar system was formed. Oxygen and nitrogen samples collected from various meteorites, as well as nitrogen sampled in lunar soil and in the Jupiter atmosphere by the Galileo probe, vary significantly from that on Earth by cosmochemical standards: 38 percent for nitrogen and up to 7 percent for oxygen. With the first solar wind samples in hand, showing the early Sun's composition, scientists can begin the game of determining where Earth's different O and N came from.



"For nitrogen, Jupiter and the Sun look the same," said Wiens. "It tells us that the original gaseous component of the inner and outer solar system was homogeneous for nitrogen, at least. So where did Earth gets its heavier nitrogen from? Maybe it came here in the material comets are made of. Perhaps it was bonded with organic materials."

For oxygen, the evidence points toward a different astrophysical mechanism called photochemical self-shielding, which the authors believe modified the composition of space dust before it coalesced to form the planets, including Earth. According to the article, the Sun shows an enrichment of pure 16O relative to Earth instead of differences in 16O, 17O, and 18O that are proportional to their atomic weight or some other mixture that doesn't show exclusive enrichment of a single isotope. This unique arrangement strongly favors the self-shielding theory, in which solar UV radiation was responsible for uniformly enhancing the two rarer isotopes, 17O and 18O, in the terrestrial planets.

The Science papers are titled "A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples" and "The oxygen isotopic composition of the Sun inferred from captured solar wind." Wiens is among several collaborating authors on both papers, which together are cover stories for this issue. Other LANL coauthors, Beth Nordholt and Ron Moses, along with former LANL scientist Dan Reisenfeld, were all part of the team to develop and fly the Solar Wind Concentrator that provided the samples for the studies reported in Science.

And now that some of the particles flowing past Earth from the sun are in hand, "It's going to make a mission to a comet all the more interesting," Wiens said.

Provided by Los Alamos National Laboratory

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Global Warming Happening Faster Than Ever?

Global Warming Happening Faster Than Ever?

  8:33:00 PM    Science Lover

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Current Carbon Dioxide Emission Higher Than It Was Just Before Ancient Episode of Severe Global Warming

The present rate of greenhouse carbon dioxide emissions through fossil fuel burning is higher than that associated with an ancient episode of severe global warming, according to new research. The findings are published online this week by the journal Nature Geoscience.

Core shed in Spitsbergen. (Credit: Image courtesy of 
National Oceanography Centre, Southampton (UK))

Around 55.9 million years ago, Earth experienced a period of intense global warming known as the Palaeocene-Eocene Thermal Maximum (PETM), which lasted for around 170,000 years. During its main phase, average annual temperatures rose by around 5°C.

Scientists believe that the warming may have been initially triggered by an event such as the baking of organic-rich sediments by igneous activity that released the potent greenhouse gas, methane. This initial temperature increase warmed ocean bottom waters which allowed the break down of gas hydrates (clathrates), which are found under deep ocean sediments: this would have greatly amplified the initial warming by releasing even more vast volumes of methane. As the methane diffused from the seawater into the atmosphere it would have been oxidised to form carbon dioxide, another potent and longer-lived greenhouse gas.

Adam Charles and his PhD supervisor, Dr Ian Harding, both palaeoceanographers at the University of Southampton's School of Ocean and Earth Science (SOES) based at the National Oceanography Centre, Southampton, co-authored the report. Dr Harding said: "The PETM has been seen by many as a natural test bed for understanding modern human-made global warming, despite it not being a perfect analogy. However, the total amount of carbon released during this climatic perturbation and its rate of release have been unclear."

To help fill this gap in knowledge, the researchers measured carbon isotope ratios of marine organic matter preserved in sediments collected in Spitsbergen. The sedimentary section is important because it records the entirety of the PETM, from its initiation to through the recovery period, and as such is the most complete record of the warming event so far known in high northern latitudes.

Based on their carbon isotope measurements and computer simulations of Earth system, the researchers estimated that the rate of carbon emissions during the PETM peaked at between 300 million and 1,700 million metric tonnes per year, which is much slower than the present carbon emission rate.



"Our findings suggest that humankind may be causing atmospheric carbon dioxide to increase at rates never previously seen on Earth, which would suggest that current temperatures will potentially rise much faster than they did during the PETM," concluded Dr Harding.

This research was supported by The Worldwide Universities Network, Pennsylvania State University, and the US National Science Foundation.

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How the Japan Earthquake Shortened Days on Earth

How the Japan Earthquake Shortened Days on Earth

  10:14:00 AM    Science Lover

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The massive earthquake that struck northeast Japan Friday (March 11) has shortened the length Earth's day by a fraction and shifted how the planet's mass is distributed.

A new analysis of the 8.9-magnitude earthquake in Japan has found that the intense temblor has accelerated Earth's spin, shortening the length of the 24-hour day by 1.8 microseconds, according to geophysicist Richard Gross at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

On March 11, 2011, at 2:46 p.m. local time (05:46 UTC), 
a magnitude 8.9 earthquake struck off the east coast of 
Japan. The epicenter was 80 miles (130 kilometers) east 
of Sendai, and 231 miles (373 km) northeast of Tokyo.If 
initial measurements are confirmed, it will be the world’s 

fifthlargest earthquake since 1900 and the worst in 

Japan's history.This image of Japan from 1999 was taken 

as part of SeaWiFS, the Sea-viewing Wide Field-of-view 

Sensor Project. CREDIT: NASA/Goddard Space 
Flight Center,SeaWiFSProject and ORBIMAGE

Gross refined his estimates of the Japan quake's impact – which previously suggested a 1.6-microsecond shortening of the day – based on new data on how much the fault that triggered the earthquake slipped to redistribute the planet's mass. A microsecond is a millionth of a second.

"By changing the distribution of the Earth's mass, the Japanese earthquake should have caused the Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds," Gross told SPACE.com in an e-mail. More refinements are possible as new information on the earthquake comes to light, he added.

The scenario is similar to that of a figure skater drawing her arms inward during a spin to turn faster on the ice. The closer the mass shift during an earthquake is to the equator, the more it will speed up the spinning Earth.

One Earth day is about 24 hours, or 86,400 seconds, long. Over the course of a year, its length varies by about one millisecond, or 1,000 microseconds, due to seasonal variations in the planet's mass distribution such as the seasonal shift of the jet stream.

The initial data suggests Friday's earthquake moved Japan's main island about 8 feet, according to Kenneth Hudnut of the U.S. Geological Survey. The earthquake also shifted Earth's figure axis by about 6 1/2 inches (17 centimeters), Gross added.

The Earth's figure axis is not the same as its north-south axis in space, which it spins around once every day at a speed of about 1,000 mph (1,604 kph). The figure axis is the axis around which the Earth's mass is balanced and the north-south axis by about 33 feet (10 meters).

"This shift in the position of the figure axis will cause the Earth to wobble a bit differently as it rotates, but will not cause a shift of the Earth's axis in space – only external forces like the gravitational attraction of the sun, moon, and planets can do that," Gross said.

This isn't the first time a massive earthquake has changed the length of Earth's day. Major temblors have shortened day length in the past.

The 8.8-magnitude earthquake in Chile last year also sped up the planet's rotation and shortened the day by 1.26 microseconds. The 9.1 Sumatra earthquake in 2004 shortened the day by 6.8 microseconds.

And the impact from Japan's 8.9-magnitude temblor may not be completely over.The weaker aftershocks may contribute tiny changes to day length as well.

The March 11 quake was the largest ever recorded in Japan and is the world's fifth largest earthquake to strike since 1900, according to the USGS. It struck offshore about 231 miles (373 kilometers) northeast of Tokyo and 80 miles (130 km) east of the city of Sendai, and created a massive tsunami that has devastated Japan's northeastern coastal areas. At least 20 aftershocks registering a 6.0 magnitude or higher have followed the main temblor.

"In theory, anything that redistributes the Earth's mass will change the Earth's rotation," Gross said. "So in principle the smaller aftershocks will also have an effect on the Earth's rotation. But since the aftershocks are smaller their effect will also be smaller."

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Carbon Dioxide Controls Earth's Temperature, New Modeling Study Shows

Carbon Dioxide Controls Earth's Temperature, New Modeling Study Shows

  10:35:00 AM    Science Lover

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Water vapor and clouds are the major contributors to Earth's greenhouse effect, but a new atmosphere-ocean climate modeling study shows that the planet's temperature ultimately depends on the atmospheric level of carbon dioxide.

Various atmospheric components differ in their contributions 
to the greenhouse effect, some through feedbacks and some 
through forcings. Without carbon dioxide and other non-
condensing greenhouse gases, water vapor and clouds would 
be unable to provide the feedback mechanisms that
amplify the greenhouse effect. (Credit: NASA GISS)

The study, conducted by Andrew Lacis and colleagues at NASA's Goddard Institute for Space Studies (GISS) in New York, examined the nature of Earth's greenhouse effect and clarified the role that greenhouse gases and clouds play in absorbing outgoing infrared radiation. Notably, the team identified non-condensing greenhouse gases -- such as carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons -- as providing the core support for the terrestrial greenhouse effect.

Without non-condensing greenhouse gases, water vapor and clouds would be unable to provide the feedback mechanisms that amplify the greenhouse effect. The study's results are published Oct. 15 in Science.

A companion study led by GISS co-author Gavin Schmidt that has been accepted for publication in the Journal of Geophysical Research shows that carbon dioxide accounts for about 20 percent of the greenhouse effect, water vapor and clouds together account for 75 percent, and minor gases and aerosols make up the remaining five percent. However, it is the 25 percent non-condensing greenhouse gas component, which includes carbon dioxide, that is the key factor in sustaining Earth's greenhouse effect. By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth's greenhouse effect.

The climate forcing experiment described in Science was simple in design and concept -- all of the non-condensing greenhouse gases and aerosols were zeroed out, and the global climate model was run forward in time to see what would happen to the greenhouse effect.

Without the sustaining support by the non-condensing greenhouse gases, Earth's greenhouse effect collapsed as water vapor quickly precipitated from the atmosphere, plunging the model Earth into an icebound state -- a clear demonstration that water vapor, although contributing 50 percent of the total greenhouse warming, acts as a feedback process, and as such, cannot by itself uphold the Earth's greenhouse effect.

"Our climate modeling simulation should be viewed as an experiment in atmospheric physics, illustrating a cause and effect problem which allowed us to gain a better understanding of the working mechanics of Earth's greenhouse effect, and enabled us to demonstrate the direct relationship that exists between rising atmospheric carbon dioxide and rising global temperature," Lacis said.

The study ties in to the geologic record in which carbon dioxide levels have oscillated between approximately 180 parts per million during ice ages, and about 280 parts per million during warmer interglacial periods. To provide perspective to the nearly 1 C (1.8 F) increase in global temperature over the past century, it is estimated that the global mean temperature difference between the extremes of the ice age and interglacial periods is only about 5 C (9 F).

"When carbon dioxide increases, more water vapor returns to the atmosphere. This is what helped to melt the glaciers that once covered New York City," said co-author David Rind, of NASA's Goddard Institute for Space Studies. "Today we are in uncharted territory as carbon dioxide approaches 390 parts per million in what has been referred to as the 'superinterglacial.'"

"The bottom line is that atmospheric carbon dioxide acts as a thermostat in regulating the temperature of Earth," Lacis said. "The Intergovernmental Panel on Climate Change has fully documented the fact that industrial activity is responsible for the rapidly increasing levels of atmospheric carbon dioxide and other greenhouse gases. It is not surprising then that global warming can be linked directly to the observed increase in atmospheric carbon dioxide and to human industrial activity in general."

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Too Much of a Good Thing: Human Activities Overload Ecosystems With Nitrogen

Too Much of a Good Thing: Human Activities Overload Ecosystems With Nitrogen

  12:57:00 AM    Science Lover

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Humans are overloading ecosystems with nitrogen through the burning of fossil fuels and an increase in nitrogen-producing industrial and agricultural activities, according to a new study. While nitrogen is an element that is essential to life, it is an environmental scourge at high levels.

At Lake Atitlan in Guatemala, excess nitrogen promotes algae growth, which leads to eutrophication. Over-nourished by excess nutrients including nitrogen, which drains from nearby farms, swirls of blue-free algae form. The eventual decay of the algae robs the water of oxygen, and thereby creates a dead zone where other plants and animals cannot survive. (Credit: NASA Earth Observatory image by Jesse Allen, based on data from the NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team)

According to the study, excess nitrogen that is contributed by human activities pollutes fresh waters and coastal zones, and may contribute to climate change. Nevertheless, such ecological damage could be reduced by the adoption of time-honored sustainable practices.

Appearing in the October 8, 2010 edition of Science and conducted by an international team of researchers, the study was partially funded by the National Science Foundation.

The Nitrogen Cycle

The nitrogen cycle--which has existed for billions of years--transforms non-biologically useful forms of nitrogen found in the atmosphere into various biologically useful forms of nitrogen that are needed by living things to create proteins, DNA and RNA, and by plants to grow and photosynthesize. The transformation of biologically useful forms of nitrogen to useful forms of nitrogen is known as nitrogen fixation.

Mostly mediated by bacteria that live in legume plant roots and soils, nitrogen fixation and other components of the nitrogen cycle weave and wind through the atmosphere, plants, subsurface plant roots, and soils; the nitrogen cycle involves many natural feedback relationships between plants and microorganisms.

According to the Science paper, since pre-biotic times, the nitrogen cycle has gone through several major phases. The cycle was initially controlled by slow volcanic processes and lightning and then by anaerobic organisms as biological activity started. By about 2.5 billion years ago, as molecular oxygen appeared on Earth, a linked suite of microbial processes evolved to form the modern nitrogen cycle.

Human Impacts on the Nitrogen Cycle

But the start of the 20th century, human contributions to the nitrogen cycle began skyrocketing. "In fact, no phenomenon has probably impacted the nitrogen cycle more than human inputs of nitrogen into the cycle in the last 2.5 billion years," says Paul Falkowski of Rutgers University, a member of the research team.

"Altogether, human activities currently contribute twice as much terrestrial nitrogen fixation as natural sources, and provide around 45 percent of the total biological useful nitrogen produced annually on Earth," says Falkowski. Much of the human contributions of nitrogen into ecosystems come from an 800 percent increase in the use of nitrogen fertilizers from 1960 to 2000.

Another problem: Much of nitrogen fertilizer that is used worldwide is applied inefficiently. As a result, about 60 percent of the nitrogen contained in applied fertilizer is never incorporated into plants and so is free to wash out of root zones, and then pollute rivers, lakes, aquifers and coastal areas through eutrophication. (Eutrophication is a process caused by excess nutrients that depletes oxygen in water bodies and ultimately leads to the death of animal life.)

In addition, some reactions involving nitrogen release nitrogen oxide into the atmosphere. Nitrogen oxide is a greenhouse gas that has 300 times (per molecule) the warming potential of carbon dioxide. In addition, nitrogen oxide destroys stratospheric ozone, which protects the earth from harmful ultraviolet (UV-B) radiation.

Methods to Reduce Nitrogen Overloading

"Natural feedbacks driven by microorganisms will likely produce a new steady-state over time scales of many decades," says Falkowski. "Through this steady state, excess nitrogen added from human sources will be removed at rates equivalent to rates of addition, without accumulating."

But meanwhile, the Earth's population is approaching 7 billion people, and so ongoing pressures for food production are continuing to increase. "There is no way to feed people without fixing huge amounts of nitrogen from the atmosphere, and that nitrogen is presently applied to crop plants very ineffectively." says Falkowski.

So unless promising interventions are taken, the damage done by humans to the Earth's nitrogen cycle will persist for decades or centuries. These promising interventions, which would be designed to reduce the need to use fertilizers that add nitrogen to ecological systems, could include:

* Using systematic crop rotations that would supply nitrogen that would otherwise be provided by fertilizers;

* Optimizing the timing and amounts of fertilizer applications, adopting selected breeding techniques or developing genetically engineered varieties of plants that would increase the efficiency of nitrogen use;

* Using traditional breeding techniques to boost the ability of economically important varieties of wheat, barley and rye to interact favorably with the microbial communities associated with plant root systems and do so in ways that enhance the efficiency of nitrogen use.

"While the processes of eutrophication have been recognized for many years, only recently have scientists been able to begin placing the anthropogenic processes in the context of an understanding of the broader biogeochemical cycles of the planet," says Robert Burnap, an NSF program director. This is an important article because it concisely develops this understanding and also provides reasonable predictions regarding the economic and policy dimensions of the problem."

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Einstein's Relativity at a Personal ScalePair of Aluminum Atomic Clocks Reveal Einstein's Relativity at a Personal Scale

Einstein's Relativity at a Personal ScalePair of Aluminum Atomic Clocks Reveal Einstein's Relativity at a Personal Scale

  10:12:00 AM    Science Lover

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Scientists have known for decades that time passes faster at higher elevations -- a curious aspect of Einstein's theories of relativity that previously has been measured by comparing clocks on the earth's surface and a high-flying rocket.

Now, physicists at the National Institute of Standards and Technology (NIST) have measured this effect at a more down-to-earth scale of 33 centimeters, or about 1 foot, demonstrating, for instance, that you age faster when you stand a couple of steps higher on a staircase.

NIST physicists compared a pair of the world's best atomic clocks to demonstrate that you age faster when you stand just a couple of steps higher on a staircase. (Credit: Loel Barr for NIST)

Described in the Sept. 24 issue of Science, the difference is much too small for humans to perceive directly -- adding up to approximately 90 billionths of a second over a 79-year lifetime -- but may provide practical applications in geophysics and other fields.

Similarly, the NIST researchers observed another aspect of relativity -- that time passes more slowly when you move faster -- at speeds comparable to a car travelling about 20 miles per hour, a more comprehensible scale than previous measurements made using jet aircraft.

NIST scientists performed the new "time dilation" experiments by comparing operations of a pair of the world's best experimental atomic clocks. The nearly identical clocks are each based on the "ticking" of a single aluminum ion (electrically charged atom) as it vibrates between two energy levels over a million billion times per second. One clock keeps time to within 1 second in about 3.7 billion years and the other is close behind in performance. The two clocks are located in different laboratories at NIST and connected by a 75-meter-long optical fiber.

NIST's aluminum clocks -- also called "quantum logic clocks" because they borrow logical decision-making techniques from experimental quantum computing -- are precise and stable enough to reveal slight differences that could not be seen until now. The clocks operate by shining laser light on the ions at optical frequencies, which are higher than the microwave frequencies used in today's standard atomic clocks based on the cesium atom.

Optical clocks could someday lead to time standards 100 times more accurate than today's standard clocks.

The aluminum clocks can detect small relativity-based effects because of their extreme precision and high "Q factor" -- a quantity that reflects how reliably the ion absorbs and retains optical energy in changing from one energy level to another -- says NIST postdoctoral researcher James Chin-Wen Chou, first author of the paper.

"We have observed the highest Q factor in atomic physics," Chou says. "You can think about it as how long a tuning fork would vibrate before it loses the energy stored in the resonating structure. We have the ion oscillating in sync with the laser frequency for about 400 thousand billion cycles."

The NIST experiments focused on two scenarios predicted by Einstein's theories of relativity. First, when two clocks are subjected to unequal gravitational forces due to their different elevations above the surface of the Earth, the higher clock -- experiencing a smaller gravitational force -- runs faster. Second, when an observer is moving, a stationary clock's tick appears to last longer, so the clock appears to run slow. Scientists refer to this as the "twin paradox," in which a twin sibling who travels on a fast-moving rocket ship would return home younger than the other twin. The crucial factor is the acceleration (speeding up and slowing down) of the travelling twin in making the round-trip journey.

NIST scientists observed these effects by making specific changes in one of the two aluminum clocks and measuring the resulting differences in the two ions' relative ticking rates, or frequencies.

In one set of experiments, scientists raised one of the clocks by jacking up the laser table to a height one-third of a meter (about a foot) above the second clock. Sure enough, the higher clock ran at a slightly faster rate than the lower clock, exactly as predicted.

The second set of experiments examined the effects of altering the physical motion of the ion in one clock. (The ions are almost completely motionless during normal clock operations.) NIST scientists tweaked the one ion so that it gyrated back and forth at speeds equivalent to several meters per second. That clock ticked at a slightly slower rate than the second clock, as predicted by relativity. The moving ion acts like the traveling twin in the twin paradox.

Such comparisons of super-precise clocks eventually may be useful in geodesy, the science of measuring the Earth and its gravitational field, with applications in geophysics and hydrology, and possibly in space-based tests of fundamental physics theories, suggests physicist Till Rosenband, leader of NIST's aluminum ion clock team.

NIST scientists hope to improve the precision of the aluminum clocks even further, as much as 10-fold, through changes in ion trap geometry and better control of ion motion and environmental interference. The aim is to measure differences in timekeeping well enough to measure heights to an accuracy of 1 centimeter, a performance level suitable for making geodetic measurements. The paper suggests that optical clocks could be linked to form a network of "inland tidal gauges" to measure the distance from the earth's surface to the geoid (the surface of the earth's gravity field that matches the global mean sea level). Such a network could be updated far more frequently than current techniques.

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