Archive for the ‘Science’ Category

Australia Carbon Tax

Tuesday, June 19th, 2012

On July 1, 2012 Australia will impose a price on carbon emissions.

A price on carbon is the most environmentally effective and economically efficient way to reduce pollution. This means our economy can continue to prosper – without our pollution continuing to grow. The Government’s plan for a clean energy future includes four key components. Firstly, the establishment of a carbon price. Secondly, support for renewable energy. Thirdly, to support improvements in energy efficiency. And fourthly, to store carbon through changed land-use practices. So, they’re the four key foundations, if you like, of our plan for a clean energy future. A carbon price has got a very important role to play because it puts a price tag on pollution. For the first time in our economy, the largest polluters will have to pay a price for every tonne of pollution that they put into the atmosphere, and that creates the incentive to cut pollution and it also creates the pressure to innovate, the pressure to invest in cleaner energy sources. And that’ll be very important for the future of our country and our economy and our living standards, because it’s the countries in the 21st century that have innovated and that have got clean energy as a key part of their economic future that will be the most competitive, and that’s very important for our future as well.

More on Carbon Taxes, Cap and Trade and Emissions Trading
More on Global Warming and Climate Change

Questions Answered

Q. Where will the money raised from the carbon price go?

A.

More than half of the money raised will be used to assist households. The majority of households will receive tax cuts, increased assistance payments  or both. With the rest of the money, the Government will be supporting jobs in the most affected industries and investing in our clean energy future. Find more questions about: Carbon Price , Household / Family

Q. Will I have to pay the carbon price?

A.

No, it’s not a tax on households or small businesses - Australia’s biggest polluters will be required to pay for their pollution under the carbon pricing mechanism. They account for around 60 per cent of our carbon pollution. For more information on Australia’s biggest polluters. Find more questions about: Carbon Price , Household / Family

An environmental problem with an economic solution

Putting a price on carbon is the most environmentally effective and cheapest way to cut pollution. This is a fact that is well recognized by economists from around the world, and respected institutions such as the OECD and the Productivity Commission. Currently, releasing carbon pollution is free despite the fact that it is harming our environment. A carbon price changes this. It puts a price on the carbon pollution that Australia’s largest polluters produce. This creates a powerful incentive for all businesses to cut their pollution, by investing in clean technology or finding more efficient ways of operating. It encourages businesses across all industries to find the cheapest and most effective way of reducing carbon pollution, rather than relying on more costly approaches such as government regulation and direct action.

A carbon price means a strong and growing economy

The economy will continue to grow as Australia embraces a clean energy future. Treasury modelling estimates that under a carbon price:

  • Average incomes grow strongly under a carbon price. Average incomes are expected to increase by about 16 per cent from current levels by 2020, an increase of around $9000 in today’s dollars. By 2050, the increase is expected to be more than $30,000.
  • National employment is projected to increase by 1.6 million jobs by 2020.


Breaking the link between emissions and economic growth

The carbon price is the first element of the Government’s plan for a clean energy future: it will trigger a broad transformation of the economy. Our economy has successfully handled comparable structural changes over its history. In fact, transformative changes – new products and technologies, and the integration of our economy into the global economy set in train by the reforms of the 1980s and 1990s – have underpinned rising prosperity and sustainable growth in Australia. Treasury modelling shows that, under a carbon price, the economy continues to grow.

Figure 1: Gross National Income with and without the carbon price

Breaking the link between emissions and economic growth For more information see: Chapter 3 – Putting a price on carbon pollution. For further details about a carbon price see:

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Voyager Golden Record

Friday, June 15th, 2012

The Voyager Golden Records are phonograph records which were included aboard both Voyager spacecraft, which were launched in 1977. They contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form, or for future humans, who may find them.

“This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings.” – Jimmy Carter

Golden Record
(Click on the image for a larger view)

Golden Record
(Click on the image for a larger view)

“In the upper left-hand corner is an easily recognized drawing of the phonograph record and the stylus carried with it. The stylus is in the correct position to play the record from the beginning. Written around it in binary arithmetic is the correct time of one rotation of the record, 3.6 seconds, expressed in time units of 0,70 billionths of a second, the time period associated with a fundamental transition of the hydrogen atom. The drawing indicates that the record should be played from the outside in. Below this drawing is a side view of the record and stylus, with a binary number giving the time to play one side of the record – about an hour.

“The information in the upper right-hand portion of the cover is designed to show how pictures are to be constructed from the recorded signals. The top drawing shows the typical signal that occurs at the start of a picture. The picture is made from this signal, which traces the picture as a series of vertical lines, similar to
ordinary television (in which the picture is a series of horizontal lines). Picture lines 1, 2 and 3 are noted in binary numbers, and the duration of one of the “picture lines,” about 8 milliseconds, is noted. The drawing immediately below shows how these lines are to be drawn vertically, with staggered “interlace” to give the correct picture rendition. Immediately below this is a drawing of an entire picture raster, showing that there are 512 vertical lines in a complete picture. Immediately below this is a replica of the first picture on the record to permit the recipients to verify that they are decoding the signals correctly. A circle was used in this picture to insure that the recipients use the correct ratio of horizontal to vertical height in picture reconstruction.

“The drawing in the lower left-hand corner of the cover is the pulsar map previously sent as part of the plaques on Pioneers 10 and 11. It shows the location of the solar system with respect to 14 pulsars, whose precise periods are given. The drawing containing two circles in the lower right-hand corner is a drawing of the hydrogen atom in its two lowest states, with a connecting line and digit 1 to indicate that the time interval associated with the transition from one state to the other is to be used as the fundamental time scale, both for
the time given on the cover and in the decoded pictures.

“Electroplated onto the record’s cover is an ultra-pure source of uranium-238 with a radioactivity of about 0.00026 microcuries. The steady decay of the uranium source into its daughter isotopes makes it a kind of radioactive clock. Half of the uranium-238 will decay in 4.51 billion years. Thus, by examining this two-centimeter diameter area on the record plate and measuring the amount of daughter elements to the remaining uranium-238, an extraterrestrial recipient of the Voyager spacecraft could calculate the time elapsed since a spot of uranium was placed aboard the spacecraft. This should be a check on the epoch of launch, which is also described by the pulsar map on the record cover.”

Photosynthetic Puzzle

Wednesday, June 13th, 2012

Quantum physics and plant biology seem like two branches of science that could not be more different, but surprisingly they may in fact be intimately tied.

Quantum physics and plant
biology seem like two branches
of science that could not be
more different, but surprisingly
they may in fact be intimately
tied.

Quantum physics and plant biology seem like two branches of science that could not be more different, but surprisingly they may in fact be intimately tied.

Researchers at DOE’s Argonne National Laboratory and the Notre Dame Radiation Laboratory at the University of Notre Dame used ultrafast spectroscopy to see what happens at the subatomic level during the very first stage of photosynthesis. “If you think of photosynthesis as a marathon, we’re getting a snapshot of what a runner looks like just as he leaves the blocks,” said Argonne biochemist David Tiede. “We’re seeing the potential for a much more fundamental interaction than a lot of people previously considered.”

The quantum effects observed in the course of the experiment hint that the natural light-harvesting processes involved in photosynthesis may be more efficient than previously indicated by classical biophysics, said chemist Gary Wiederrecht of Argonne’s Center for Nanoscale Materials. “It leaves us wondering: how did Mother Nature create this incredibly elegant solution?” he said.

R.I.P. Ray Bradbury

Wednesday, June 6th, 2012

Ray Bradbury, infamous sci-fi writer has died at age 91. His best known science fiction works include “The Martian Chronicles,” “Fahrenheit 451,” “Dandelion Wine” and “Something Wicked This Way Comes”, as well as, more than 600 short stories.

“I’m not a science fiction writer,” he was frequently quoted as saying. “I’ve written only one book of science fiction [“Fahrenheit 451”]. All the others are fantasy. Fantasies are things that can’t happen, and science fiction is about things that can happen.”

Space X Launches Historic Mission

Tuesday, May 22nd, 2012
Space X Rocket Launch

Space X Rocket Launch

Hawthorne, CA – Today, Space Exploration Technologies (SpaceX) successfully launched its Falcon 9 rocket carrying a Dragon spacecraft to orbit in an exciting start to the mission that will make SpaceX the first commercial company in history to attempt to send a spacecraft to the International Space Station — something only a handful of governments have ever accomplished.

At 3:44 a.m. Eastern, the Falcon 9 carrying Dragon launched from SpaceX’s launch pad at the Cape Canaveral Air Force Station. Now, the Dragon heads toward the International Space Station. On that journey, it will be subjected to a series of tests to determine if the vehicle is ready to berth with the station.

Broadcast quality videos, including video inside of the SpaceX factory, may be downloaded at vimeo.com/spacexlaunch and high-resolution photos are posted at spacexlaunch.zenfolio.com.

At a press conference held after the launch, SpaceX CEO and Chief Designer Elon Musk began, “I would like to start off by saying what a tremendous honor it has been to work with NASA. And to acknowledge the fact that we could not have started SpaceX, nor could we have reached this point without the help of NASA… It’s really been an honor to work with such great people.”

The vehicle’s first stage performed nominally before separating from the second stage. The second stage successfully delivered the Dragon spacecraft into its intended orbit. This marks the third consecutive successful Falcon 9 launch and the fifth straight launch success for SpaceX.

“We obviously have to go through a number of steps to berth with the Space Station, but everything is looking really good and I think I would count today as a success no matter what happens with the rest of the mission,” Musk said.

He continued by expressing his gratitude to the more than 1,800 SpaceX employees. “People have really given it their all.” Describing the scene inside of SpaceX headquarters in Hawthorne, California, he said, “We had most of the company gathered around SpaceX Mission Control. They are seeing the fruits of their labor and wondering if it is going to work. There is so much hope riding on that rocket. When it worked, and Dragon worked, and the solar arrays deployed, people saw their handiwork in space operating as it should. There was tremendous elation. For us it is like winning the Super Bowl.”

Explaining the significance of the day, Musk stated, “This mission heralds the dawn of a new era of space exploration, one in which there is a significant commercial space element. It is like the advent of the Internet in the mid-1990s when commercial companies entered what was originally a government endeavor. That move dramatically accelerated the pace of advancement and made the Internet accessible to the mass market. I think we’re at a similar inflection point for space. I hope and I believe that this mission will be historic in marking that turning point towards a rapid advancement in space transportation technology.”

This is SpaceX’s second demonstration flight under a 2006 Commercial Orbital Transportation Services (COTS) agreement with NASA to develop the capability to carry cargo to and from the International Space Station. Demonstration launches are conducted to determine potential issues so that they might be addressed; by their very nature, they carry a significant risk. If any aspect of the mission is not successful, SpaceX will learn from the experience and try again.

Mission Highlights: During the mission, Dragon must perform a series of complex tasks, each presenting significant technical challenges (dates subject to change):

  • May 22/Launch Day: SpaceX’s Falcon 9 rocket launches a Dragon spacecraft into orbit from the Cape Canaveral Air Force Station.
  • May 23: Dragon orbits Earth as it travels toward the International Space Station.
  • May 24: Dragon’s sensors and flight systems are subjected to a series of complicated tests to determine if the vehicle is ready to berth with the space station; these tests include maneuvers and systems checks in which the vehicle comes within 1.5 miles of the station.
  • May 25: NASA decides if Dragon is allowed to attempt berthing with the station. If so, Dragon approaches. It is captured by station’s robotic arm and attached to the station, a feat that requires extreme precision.
  • May 25 – 31: Astronauts open Dragon’s hatch, unload supplies and fill Dragon with return cargo.
  • May 31: After approximately two weeks, Dragon is detached from the station and returns to Earth, landing in the Pacific, hundreds of miles west of Southern California.

About SpaceX

SpaceX designs, manufactures and launches the world’s most advanced rockets and spacecraft. With a diverse manifest of 40 launches to deliver commercial and government satellites to orbit, SpaceX is the world’s fastest growing launch services provider. In 2010, SpaceX became the first commercial company in history to put a spacecraft into orbit and return it safely to Earth. With the retirement of the space shuttle, the SpaceX Falcon 9 rocket and Dragon spacecraft will soon carry cargo, and one day astronauts, to and from the Space Station for NASA. Founded in 2002 by Elon Musk, SpaceX is a private company owned by management and employees, with minority investments from Founders Fund, Draper Fisher Jurvetson, and Valor Equity Partners. The company has over 1,800 employees in California, Texas, Washington, D.C., and Florida. For more information, visit www.SpaceX.com.

Cause Of Bee Colony Collapse

Wednesday, May 2nd, 2012

Use of Common Pesticide Linked to Bee Colony Collapse

Boston, MA – The likely culprit in sharp worldwide declines in honeybee colonies (colony collapse disorder) since 2006 is imidacloprid, one of the most widely used pesticides, according to a new study from Harvard School of Public Health. Pinpointing the cause of the problem is crucial because bees — beyond producing honey — are prime pollinators of roughly one-third of the crop species in the U.S. and livestock feed. Massive loss of honeybees could result in billions of dollars in agricultural losses, experts estimate.

The authors, led by Chensheng (Alex) Lu, associate professor of environmental exposure biology in the Department of Environmental Health, write that the new research provides “convincing evidence” of the link between imidacloprid and the phenomenon known as Colony Collapse Disorder (CCD), in which adult bees abandon their hives.

The study will appear in the June issue of the Bulletin of Insectology.

“The significance of bees to agriculture cannot be underestimated,” says Lu. “And it apparently doesn’t take much of the pesticide to affect the bees. Our experiment included pesticide amounts below what is normally present in the environment.”

Pinpointing the cause of the problem is crucial because bees—beyond producing honey—are prime pollinators of roughly one-third of the crop species in the U.S., including fruits, vegetables, nuts, and livestock feed such as alfalfa and clover. Massive loss of honeybees could result in billions of dollars in agricultural losses, experts estimate.

Lu and his co-authors hypothesized that the uptick in CCD resulted from the presence of imidacloprid, a neonicotinoid introduced in the early 1990s. Bees can be exposed in two ways: through nectar from plants or through high-fructose corn syrup beekeepers use to feed their bees. (Since most U.S.-grown corn has been treated with imidacloprid since 2005, it’s also found in corn syrup.)

In the summer of 2010, the researchers conducted an in situ study in Worcester County, Mass. aimed at replicating how imidacloprid may have caused the CCD outbreak. Over a 23-week period, they monitored bees in four different bee yards; each yard had four hives treated with different levels of imidacloprid and one control hive. After 12 weeks of imidacloprid dosing, all the bees were alive. But after 23 weeks, 15 out of 16 of the imidacloprid-treated hives—94%—had died. Those exposed to the highest levels of the pesticide died first.

The characteristics of the dead hives were consistent with CCD, said Lu; the hives were empty except for food stores, some pollen, and young bees, with few dead bees nearby. When other conditions cause hive collapse—such as disease or pests—many dead bees are typically found inside and outside the affected hives.

Strikingly, said Lu, it took only low levels of imidacloprid to cause hive collapse—less than what is typically used in crops or in areas where bees forage.

Scientists, policymakers, farmers, and beekeepers, alarmed at the sudden losses of between 30% and 90% of honeybee colonies since 2006, have posed numerous theories as to the cause of the collapse, such as pests, disease, pesticides, migratory beekeeping, or some combination of these factors.

This study was supported by a grant funded by Harvard University Center for the Environment.

“In Situ Replication of Honey Bee Colony Collapse Disorder,” Chensheng Lu, Kenneth M. Warchol, Richard A. Callahan, Bulletin of Insectology, June 2012

For more information:

Todd Datz
tdatz@hsph.harvard.edu
617.432.8413

Global Warming Refuge

Monday, April 30th, 2012

Ocean currents may mitigate warming near handful of equatorial islands

Photo of a coral reef near the island nation of Kiribati.
Coral reefs near the island nation of Kiribati may be somewhat protected from global warming.
Credit and Larger Version

Scientists predict ocean temperatures will rise in the equatorial Pacific by the end of the century, wreaking havoc on coral reef ecosystems.

But a new study shows that climate change could cause ocean currents to operate in a way that mitigates warming near a handful of islands right on the equator.

Those islands include some of the 33 coral atolls that form the nation of Kiribati. This low-lying country is at risk from sea-level rise caused by global warming.

Surprisingly, these Pacific islands within two degrees north and south of the equator may become isolated climate change refuges for corals and fish.

“The finding that there may be refuges in the tropics where local circulation features buffer the trend of rising sea surface temperature has important implications for the survival of coral reef systems,” said David Garrison, program director in the National Science Foundation’s (NSF) Division of Ocean Sciences, which funded the research.

Here’s how it could happen, according to the study by Woods Hole Oceanographic Institution (WHOI) scientists Kristopher Karnauskas and Anne Cohen, published today in the journal Nature Climate Change.

At the equator, trade winds push a surface current from east to west.

About 100 to 200 meters below, a swift countercurrent develops, flowing in the opposite direction.

This, the Equatorial Undercurrent (EUC), is cooler and rich in nutrients. When it hits an island, like a rock in a river, water is deflected upward on an island’s western flank.

This upwelling process brings cooler water and nutrients to the sunlit surface, creating localized areas where tiny marine plants and corals flourish.

On color-enhanced satellite maps showing measurements of global ocean chlorophyll levels, these productive patches of ocean stand out as bright green or red spots–for example, around the Galapagos Islands in the Eastern Pacific.

But as you gaze west, chlorophyll levels fade like a comet tail, giving scientists little reason to look closely at scattered low-lying coral atolls in that direction.

These islands are easy to overlook because they are tiny, remote, and lie at the far left edge of standard global satellite maps that place continents in the center.

Karnauskas, a climate scientist, was working with coral scientist Cohen to explore how climate change would affect central equatorial Pacific reefs.

When he changed the map view on his screen in order to view the entire tropical Pacific at once, he saw that chlorophyll concentrations jumped up again exactly at the Gilbert Islands on the equator.

Satellite maps also showed cooler sea surface temperatures on the west sides of these islands, part of Kiribati.

“I’ve been studying the tropical Pacific Ocean for most of my career, and I had never noticed that,” he said. “It jumped out at me immediately, and I thought, ‘there’s probably a story there.’”

So Karnauskas and Cohen began to investigate how the EUC would affect the equatorial islands’ reef ecosystems, starting with global climate models that simulate effects in a warming world.

Global-scale climate models predict that ocean temperatures will rise nearly 3 degrees Celsius (5.4 degrees Fahrenheit) in the central tropical Pacific.

Warmer waters often cause corals to bleach, a process in which they lose the tiny symbiotic algae that live in them and provide vital nutrition.

Bleaching has been a major cause of coral mortality and loss of coral reef area during the last 30 years.

Even the best global models, with their planet-scale views and lower resolution, cannot predict conditions in areas as small as these small islands, Karnauskas said.

So the scientists combined global models with a fine-scale regional model to focus on much smaller areas around minuscule islands scattered along the equator.

To accommodate the trillions of calculations needed for such small-area resolution, they used the new high-performance computer cluster at WHOI called “Scylla.”

“Global models predict significant temperature increases in the central tropical Pacific over the next few decades, but in truth conditions can be highly variable across and around a coral reef island,” Cohen said.

“To predict what the coral reef will experience in global climate change, we have to use high-resolution models, not global models.”

The model predicts that as air temperatures rise and equatorial trade winds weaken, the Pacific surface current will also weaken by 15 percent by the end of the century.

The then-weaker surface current will impose less friction and drag on the EUC, so this deeper current will strengthen by 14 percent.

“Our model suggests that the amount of upwelling will actually increase by about 50 percent around these islands and reduce the rate of warming waters around them by about 0.7 C (1.25 F) per century,” Karnauskas said.

A handful of coral atolls on the equator, some as small as 4 square kilometers (1.54 square miles) in area, may not seem like much.

But Karnauskas’ and Cohen’s results say that waters on the western sides of the islands will warm more slowly than at islands 2 degrees, or 138 miles, north and south of the equator that are not in the path of the EUC.

That gives the Gilbert Islands a significant advantage over neighboring reef systems.

“While the mitigating effect of a strengthened Equatorial Undercurrent will not spare corals the perhaps-inevitable warming expected for this region, the warming rate will be slower around these equatorial islands,” Karnauskas said.

“This may allow corals and their symbiotic algae a better chance to adapt and survive.”

If the model holds true, even if neighboring reefs are hard-hit, equatorial island coral reefs may survive to produce larvae of corals and other reef species.

Like a seed bank for the future, they might be a source of new corals and other species that could re-colonize damaged reefs.

“The globe is warming, but there are things going on underfoot that will slow that warming for certain parts of certain coral reef islands,” said Cohen.

“These little islands in the middle of the ocean can counteract global trends and have a big effect on their own future,” Karnauskas said, “which I think is a beautiful concept.”

-NSF-

Fires In Nepal

Saturday, April 28th, 2012

EARTH –

Numerous forest fires were burning throughout Nepal when the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Aqua satellite captured this image of the Siwalik Hills on April 24, 2012.

Nepalese officials say they have counted at least 225 fires burning; the largest has destroyed more than 600 hectares (1,480) acres of forest. Officials say the fires have been caused by a long dry spell, windy weather, and discarded cigarettes. There were 1,857 active fires last year, a relatively small number compared to the 4,217 that occurred in 2009, an exceptionally dry year.

“This might be the peak time for fire incidents for this season. However, the rise in the mercury might give rise to more devastating forest fires across the country,” Sundar Prasad Sharma, the coordinator at the UN International Strategy for Disaster Reduction-South Asia Wildland Fire Network, told the Kathmandu Post.

Nepalese officials are currently testing a pilot version of a new wildfire monitoring system based on data from MODIS. Interactive maps showing fire locations are available here.

NASA image by Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Adam Voiland.

Instrument:
Aqua – MODIS
Fires in Nepal

acquired April 24, 2012 download large image (429 KB, JPEG, 2000×1600)

More Information On Global Warming

Asteroids Impact On Earth

Thursday, April 26th, 2012

WASHINGTON — Research by NASA and international scientists concludes giant asteroids, similar or larger than the one believed to have killed the dinosaurs, hit Earth billions of years ago with more frequency than previously thought.

To cause the dinosaur extinction, the killer asteroid that impacted Earth 65 million years ago would have been almost 6 miles (10 kilometers) in diameter. By studying ancient rocks in Australia and using computer models, researchers estimate that approximately 70 asteroids the same size or larger impacted Earth 1.8 to 3.8 billion years ago. During the same period, approximately four similarly-sized objects hit the moon.

“This work demonstrates the power of combining sophisticated computer models with physical evidence from the past, further opening an important window to Earth’s history,” said Yvonne Pendleton, director of NASA’s Lunar Science Institute (NLSI) at NASA’s Ames Research Center at Moffett Field, Calif.

Evidence for these impacts on Earth comes from thin rock layers that contain debris of nearly spherical, sand-sized droplets called spherules. These millimeter-scale clues were formerly molten droplets ejected into space within the huge plumes created by mega-impacts on Earth. The hardened droplets then fell back to Earth, creating thin but widespread sedimentary layers known as spherule beds.
The new findings are published today in the journal Nature.

“The beds speak to an intense period of bombardment of Earth,” said William Bottke principal investigator of the impact study team at the Southwest Research Institute (SwRI) in Boulder, Colo. “Their source long has been a mystery.”

The team’s findings support the theory Jupiter, Saturn, Uranus and Neptune formed in different orbits nearly 4.5 billion years ago, migrating to their current orbits about 4 billion years ago from the interplay of gravitational forces in the young solar system. This event triggered a solar system-wide bombardment of comets and asteroids called the “Late Heavy Bombardment.” In the paper, the team created a model of the ancient main asteroid belt and tracked what would have happened when the orbits of the giant planets changed. They discovered the innermost portion of the belt became destabilized and could have delivered numerous big impacts to Earth and the moon over long time periods.

At least 12 mega-impacts produced spherule beds during the so-called Archean period 2.5 to 3.7 billion years ago, a formative time for life on Earth. Ancient spherule beds are rare finds, rarer than rocks of any other age. Most of the beds have been preserved amid mud deposited on the sea floor below the reach of waves.

The impact believed to have killed the dinosaurs was the only known collision over the past half-billion years that made a spherule layer as deep as those of the Archean period. The relative abundance of the beds supports the hypothesis for many giant asteroid impacts during Earth’s early history.

The frequency of the impacts indicated in the computer models matches the number of spherule beds found in terrains with ages that are well understood. The data also hint at the possibility that the last impacts of the Late Heavy Bombardment on Earth made South Africa’s Vredefort crater and Canada’s Sudbury crater, both of which formed about 2 billion years ago.

“The Archean beds contain enough extraterrestrial material to rule out alternative sources for the spherules, such as volcanoes,” said Bruce Simonson, a geologist from Oberlin College in Oberlin, Ohio.

The research was funded by NLSI and conducted by members or associates of NLSI’s Center of Lunar Origin and Evolution, based at SwRI.

The impact study team also includes scientists from Purdue University in West Lafayette, Ind.; Charles University in Prague, Czech Republic; Observatorie de la Cote d’Azur in Nice, France; and Academia Sinica in Taipei, Taiwan.

To learn about the NLSI, visit:

http://lunarscience.arc.nasa.gov

Antarctica Ice Loss

Thursday, April 26th, 2012

Warm Ocean Currents Cause Majority of Ice Loss from Antarctica

WASHINGTON, DC (USA) — Warm ocean currents attacking the underside of ice shelves are the dominant cause of recent ice loss from Antarctica, a new study using measurements from NASA’s Ice, Cloud, and land Elevation Satellite (ICESat) revealed.

An international team of scientists used a combination of satellite measurements and models to differentiate between the two known causes of melting ice shelves: warm ocean currents thawing the underbelly of the floating extensions of ice sheets and warm air melting them from above. The finding, published today in the journal Nature, brings scientists a step closer to providing reliable projections of future sea level rise.

The researchers concluded 20 of the 54 ice shelves studied are being melted by warm ocean currents. Most of these are in West Antarctica, where inland glaciers flowing down to the coast and feeding into these thinning ice shelves have accelerated, draining more ice into the sea and contributing to sea-level rise. This ocean-driven thinning is responsible for the most widespread and rapid ice losses in West Antarctica and the majority of Antarctic ice sheet loss during the period studied.

“We can lose an awful lot of ice to the sea without ever having summers warm enough to make the snow on top of the glaciers melt,” said the study’s lead author Hamish Pritchard of the British Antarctic Survey in Cambridge, United Kingdom. “The oceans can do all the work from below.”

To map the changing thickness of almost all the floating ice shelves around Antarctica, the team used a time series of 4.5 million surface height measurements taken by a laser instrument mounted on ICESat from October 2003 to October 2008. They measured how the ice shelf height changed over time and ran computer models to discard changes in ice thickness because of natural snow accumulation and compaction. The researchers also used a tide model that eliminated height changes caused by tides raising and lowering the ice shelves.

“This study demonstrates the power of space-based, laser altimetry for understanding Earth processes,” said Tom Wagner, cryosphere program scientist at NASA Headquarters in Washington.” Coupled with NASA’s portfolio of other ice sheet research using data from our GRACE mission, satellite radars and aircraft, we get a comprehensive view of ice sheet change that improves estimates of sea level rise.”

Previous studies used satellite radar data to measure the evolution of ice shelves and glaciers, but laser measurements are more precise in detecting changes in ice shelf thickness through time. This is especially true in coastal areas. Steeper slopes at the grounding line, where floating ice shelves connect with the landmass, cause problems for lower-resolution radar altimeters.

ICESat was the first satellite specifically designed to use laser altimetry to study the Earth’s polar regions. It operated from 2003 to 2009. Its successor, ICESat-2, is scheduled for launch in 2016.

“This study demonstrates the urgent need for ICESat-2 to get into space,” said Jay Zwally, ICESat project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “We have limited information on the changes in polar regions caused by climate change. Nothing can look at these changes like satellite measurements do.”

The new research also links the observed increase in melting that occurs on the underside of a glacier or ice shelf, called basal melt, and glacier acceleration with changes in wind patterns.

“Studies have shown Antarctic winds have changed because of changes in climate,” Pritchard said. “This has affected the strength and direction of ocean currents. As a result warm water is funnelled beneath the floating ice. These studies and our new results suggest Antarctica’s glaciers are responding rapidly to a changing climate.”

A different picture is seen on the Antarctic Peninsula, the long stretch of land pointing towards South America. The study found thinning of the largest ice shelf on the peninsula can be explained by warm summer winds directly melting the snow on the ice shelf surfaces. The patterns of widespread ocean-driven melting and summer melting on the Antarctic Peninsula can be attributed to changing wind patterns.

The study was carried out by an international team from the British Antarctic Survey, Utrecht University in Utrecht, Netherlands, the University of California in San Diego and the non-profit research institute Earth and Space Research in Corvallis, Ore.

For more information, a visualization and related imagery, visit:

http://www.nasa.gov/topics/earth/features/currents-ice-loss.html

For more information about ICESat and ICESat-2, visit:

http://icesat.gsfc.nasa.gov



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