Is Earth Undergoing a 6th Mass Extinction? --"99.9% of all Past Species Extinct"

Of all species that have existed on Earth, 99.9 percent are now extinct. Many of them perished in five cataclysmic events. The classical "Big Five" mass extinctions identified by Raup and Sepkoski are widely agreed upon as some of the most significant: End Ordovician, Late Devonian, End Permian, End Triassic, and End Cretaceous. According to a recent poll, seven out of ten biologists think we are currently in the throes of a sixth mass extinction. Some say it could wipe out as many as 90 percent of all species living today. Other scientists dispute such dire projections.

“If you look at the fossil record, it is just littered with dead bodies from past catastrophes,” observes University of Washington paleontologist Peter Ward. Ward says that only one extinction in Earth’s past was caused by an asteroid impact – the event 65 million years ago that ended the age of the dinosaurs. All the rest, he claims, were caused by global warming.

Ward's study, Under a Green Sky, explores extinctions in Earth’s past and predicts extinctions to come in the future. Ward demonstrates that the ancient past is not just of academic concern. Everyone has heard about how an asteroid did in the dinosaurs, and NASA and other agencies now track Near Earth objects.

Unfortunately, we may not be protecting ourselves against the likeliest cause of our species' demise. Ward explains how those extinctions happened, and then applies those chilling lessons to the modern day: expect drought, superstorms, poison–belching oceans, mass extinction of much life, and sickly green skies.

The significant points Ward stresses are geologically rapid climate change has been the underlying cause of most great "extinction" events. Those events have been, observed Harvard evolutionary biologist Stephen Gould, major drivers of evolution.

Drastic climate change has not always been gradual; there is solid empirical evidence of catastrophic warming events taking place in centuries, perhaps even decades. The impact of atmospheric warming is most potent in its modification of ocean chemistry and of circulating currents; warming inevitably leads to non-mixing anoxic dead seas.

We are already in the middle, not the beginning, of an anthropogenic global warming, caused by agriculture and deforestation, which began some 10,000 years ago but which is now accelerating exponentially; though the earliest wave of anthropogenic warming has been stabilizing and beneficial to human development, it appears to have the potential for catastrophic effects within a lifetime or two.

Looking at the ancient evidence, Ward notes that ice caps began to shrink. "Melting all the ice caps causes a 75-meter increase in sea level will remove every coastal city on our planet." It will also cover earth's most productive farmland, the author warns, adding, "It will happen if we do not somehow control CO2 rise in the atmosphere."

An analysis of the geological record of the Earth's sea level, carried out by scientists at Princeton and Harvard universities supports Ward using a novel statistical approach that reveals the planet's polar ice sheets are vulnerable to large-scale melting even under moderate global warming scenarios. Such melting would lead to a large and relatively rapid rise in global sea level.

According to the analysis, an additional 2 degrees of global warming could commit the planet to 6 to 9 meters (20 to 30 feet) of long-term sea level rise. This rise would inundate low-lying coastal areas where hundreds of millions of people now reside. It would permanently submerge New Orleans and other parts of southern Louisiana, much of southern Florida and other parts of the U.S. East Coast, much of Bangladesh, and most of the Netherlands, unless unprecedented and expensive coastal protection were undertaken. And while the researchers' findings indicate that such a rise would likely take centuries to complete, if emissions of greenhouse gases are not abated, the planet could be committed during this century to a level of warming sufficient to trigger this outcome.

The last interglacial stage provides a historical analog for futures with a fairly moderate amount of warming; the high sea levels during the stage suggest that significant chunks of major ice sheets could disappear over a period of centuries in such futures.

Previous geological studies of sea level benchmarks such as coral reefs and beaches had shown that, at many localities, local sea levels during the last interglacial stage were higher than today. But local sea levels differ from those in this earlier stage; one major contributing factor is that the changing masses of the ice sheets alter the planet's gravitational field and deform the solid Earth.

As a consequence, inferring global sea level from local geological sea level markers requires a geographically broad data set, a model of the physics of sea level, and a means to integrate the two. The study's authors provide all three, integrating the data and the physics with a statistical approach that allows them to assess the probability distribution of past global sea level and its rate of change.

The findings indicate that sea level during the last interglacial stage rose for centuries at least two to three times faster than the recent rate, and that both the Greenland and West Antarctic ice sheet likely shrank significantly and made important contributions to sea level rise. However, the relative timing of temperature change and sea level change during the last interglacial stage is fairly uncertain, so it is not possible to infer from the analysis how long an exposure to peak temperatures during this stage was needed to commit the planet to peak sea levels.

A similar study by a team of scientists from Bristol, Cardiff and Texas A&M universities braved the lions and hyenas of a small East African village to extract microfossils from rocks which have revealed the level of CO2 in the Earth’s atmosphere at the time of the formation of the ice-cap. New carbon dioxide data confirm that formation of the Antarctic ice-cap some 33.5 million years ago was due to declining carbon dioxide in the atmosphere.

Professor Paul Pearson from Cardiff University’s School of Earth and Ocean Sciences, who led the mission to the remote East Africa village of Stakishari said: “About 34 million years ago the Earth experienced a mysterious cooling trend. Glaciers and small ice sheets developed in Antarctica, sea levels fell and temperate forests began to displace tropical-type vegetation in many areas.

“The period culminated in the rapid development of a continental-scale ice sheet on Antarctica, which has been there ever since. We therefore set out to establish whether there was a substantial decline in atmospheric carbon dioxide levels as the Antarctic ice sheet began to grow.”

Co-author Dr Bridget Wade from Texas A&M University Department of Geology and Geophysics added: “This was the biggest climate switch since the extinction of the dinosaurs 65 million years ago. Our study is the first to provide a direct link between the establishment of an ice sheet on Antarctica and atmospheric carbon dioxide levels and therefore confirms the relationship between carbon dioxide levels in the atmosphere and global climate.”

Geologists have long speculated that the formation of the Antarctic ice-cap was caused by a gradually diminishing natural greenhouse effect. The study’s findings, published in Nature online, confirm that atmospheric CO2 started to decline about 34 million years ago, during the period known to geologists as the Eocene - Oligocene climate transition, and that the ice sheet began to form about 33.5 million years ago when CO2 in the atmosphere reached a tipping point of around 760 parts per million.

The team mapped large expanses of bush and wilderness and pieced together the underlying local rock formations using occasional outcrops of rocks and stream beds. Eventually they discovered sediments of the right age near a traditional African village called Stakishari. By assembling a drilling rig and extracting hundreds of meters of samples from under the ground they were able to obtain exactly the piece of Earth's history they had been searching for.

Ward is encouraged that we are beginning to make changes in their daily lives and demanding action from their leaders -"that we are on a planet that has violent convulsions, and that we humans are playing with nature in such a way that we could recreate what were some really awful times in earth's history, that we really tinker with the earth's atmosphere at our peril."

The image at the top of the page shows a a very well-preserved example of a Paleoniscoid fish thought related to Rhabdolepis. The paleoniscoids were the first ray-finned fish, a feature readily seen here. Some 40 or more families appeared during the Carboniferous and Permian Periods. This taxon went extinct during the Lower Permian.

Source: 

www.dailygalaxy.com

Radiation ring around Earth mysteriously appears, then dissipates

RING AROUND THE WORLD In September, a third ring appeared between the two known Van Allen radiation belts that girdle the Earth thousands of miles above. Johns Hopkins Univ. Applied Physics Laboratory/Univ. of Colorado Boulder Laboratory for Atmospheric and Space Physics

High above Earth’s surface float two rings of energetic charged particles, and for about four weeks in September, they were joined by a third. The temporary ring may have formed in response to a solar shock wave that passed by Earth, researchers report online February 28 in Science.

The discovery could force scientists to revisit decades of ideas about the structure of the Van Allen belts, donut-shaped rings of radiation trapped in orbit by the planet’s magnetic field. Those revisions could improve predictions of space weather and scientists’ understanding of the space environment near Earth, resulting in better protection for manned and unmanned spacecraft that navigate those areas.

“It's a very important discovery,” says Yuri Shprits of the University of California, Los Angeles, who wasn’t involved in the study. “Over half a century after the discovery of the radiation belts, this most important region of space where most of the satellites operate presents us with new puzzles.”

Until the discovery, researchers thought the Van Allen belts always contained two zones of high-energy particles: an inner zone made mostly of protons and some electrons, and an outer zone dominated by electrons. A sparsely populated area separates the zones. The belts run from the top of the atmosphere, some 1,000 kilometers above Earth’s surface, to as far as five or six Earth radii from the planet’s surface.

NASA’s early Explorer and Pioneer spacecraft discovered and mapped the belts in 1958. Scientists have since learned that the radiation reservoirs can fluctuate dramatically, especially in the outer zone. Disturbances such as solar storms that disrupt Earth’s magnetic field can cause the outer zone to change shape or to gain or lose particles.

On August 30, NASA launched twin space probes to study the fine details of such disruptions and take a closer look at the belts’ composition. The probes repeatedly pass through the belts, completing an orbit about every nine hours. Just days after the probes launched, researchers led by Daniel Baker of the University of Colorado Boulder watched a third ring grow between the two existing belts, and the outer ring to expand. After a month, it disappeared, as did the outer zone, temporarily leaving only one ring. In the following months, the normal two-ring structure gradually returned.

“I'm delighted that observations so early in the program could reveal such new things,” Baker says.

A sun-produced shock wave that passed Earth in early September may have created the third ring, the researchers propose. Another shock wave came through in early October and may have obliterated the outer two rings.

Researchers don’t know how often a third ring forms. “I would be amazed if in the past 4.5 billion years this hasn't happened before,” Baker says. The probes could provide answers about the third ring’s frequency.

No reports have emerged of satellite damage from the third ring’s brief existence, though operators often do not reveal that information, says Joe Kunches of the National Weather Service’s Space Weather Prediction Center.

Scientists will continue to comb through data from the probes to refine theoretical and observational knowledge of the belts. The probes’ findings could also help engineers design spacecraft better protected against the belts’ harmful radiation. And forecasters could use real-time data feeds from the probes to give satellite operators better warnings and predictions about the belts’ activity. “That's what we're really excited about,” Kunches says.

Source:

http://www.sciencenews.org/view/generic/id/348664/title/Radiation_ring_around_Earth_mysteriously_appears_then_dissipates

NASA's Aquarius Sees Salty Shifts

NASA has released the first full year of validated ocean surface salinity data from the agency's Aquarius instrument aboard the Aquarius/SAC-D spacecraft. The data cover the period from Dec. 2011 through Dec. 2012. Red colors represent areas of high salinity, while blue shades represent areas of low salinity. Among the prominent salinity features visible in this view are the large area of highly saline water across the North Atlantic. This area, the saltiest anywhere in the open ocean, is analogous to deserts on land, where little rainfall and much evaporation occur. Aquarius is a focused effort to measure ocean surface salinity and will provide the global view of salinity variability needed for climate studies. The mission is a collaboration between NASA and the Space Agency of Argentina (Comision Nacional de Actividades Espaciales). Image credit: NASA/GSFC/JPL-Caltech

The colorful images chronicle the seasonal stirrings of our salty world: Pulses of freshwater gush from the Amazon River's mouth; an invisible seam divides the salty Arabian Sea from the fresher waters of the Bay of Bengal; a large patch of freshwater appears in the eastern tropical Pacific in the winter. These and other changes in ocean salinity patterns are revealed by the first full year of surface salinity data captured by NASA's Aquarius instrument. 

"With a bit more than a year of data, we are seeing some surprising patterns, especially in the tropics," said Aquarius Principal Investigator Gary Lagerloef, of Earth & Space Research in Seattle. "We see features evolve rapidly over time." 

Launched June 10, 2011, aboard the Argentine spacecraft Aquarius/Satelite de Aplicaciones Cientificas (SAC)-D, Aquarius is NASA's first satellite instrument specifically built to study the salt content of ocean surface waters. Salinity variations, one of the main drivers of ocean circulation, are closely connected with the cycling of freshwater around the planet and provide scientists with valuable information on how the changing global climate is altering global rainfall patterns. 

The salinity sensor detects the microwave emissivity of the top approximately 1 inch (1 to 2 centimeters) of ocean water - a physical property that varies depending on temperature and saltiness. The instrument collects data in 240-mile-wide (386 kilometers) swaths in an orbit designed to obtain a complete survey of global salinity of ice-free oceans every seven days. 

The Changing Ocean 

The animated version of Aquarius' first year of data unveils a world of varying salinity patterns. The Arabian Sea, nestled up against the dry Middle East, appears much saltier than the neighboring Bay of Bengal, which gets showered by intense monsoon rains and receives freshwater discharges from the Ganges and other large rivers. Another mighty river, the Amazon, releases a large freshwater plume that heads east toward Africa or bends up north to the Caribbean, depending on the prevailing seasonal currents. Pools of freshwater carried by ocean currents from the central Pacific Ocean's regions of heavy rainfall pile up next to Panama's coast, while the Mediterranean Sea sticks out in the Aquarius maps as a very salty sea. 

One of the features that stand out most clearly is a large patch of highly saline water across the North Atlantic. This area, the saltiest anywhere in the open ocean, is analogous to deserts on land, where little rainfall and a lot of evaporation occur. A NASA-funded expedition, the Salinity Processes in the Upper Ocean Regional Study (SPURS), traveled to the North Atlantic's saltiest spot last fall to analyze the causes behind this high salt concentration and to validate Aquarius measurements. 

"My conclusion after five weeks out at sea and analyzing five weekly maps of salinity from Aquarius while we were there was that indeed, the patterns of salinity variation seen from Aquarius and by the ship were similar," said Eric Lindstrom, NASA's physical oceanography program scientist, NASA Headquarters, Washington, and a participant of the SPURS research cruise. 

Future Goals 

"The Aquarius prime mission is scheduled to run for three years but there is no reason to think that the instrument could not be able to provide valuable data for much longer than that," said Gene Carl Feldman, Aquarius project manager at NASA's Goddard Space Flight Center in Greenbelt, Md. "The instrument has been performing flawlessly and our colleagues in Argentina are doing a fantastic job running the spacecraft, providing us a nice, stable ride." 

In future years, one of the main goals of the Aquarius team is to figure out ways to fine-tune the readings and retrieve data closer to the coasts and the poles. Land and ice emit very bright microwave emissions that swamp the signal read by the satellite. At the poles, there's the added complication that cold polar waters require very large changes in their salt concentration to modify their microwave signal. 

Still, the Aquarius team was surprised by how close to the coast the instrument is already able to collect salinity measurements. 

"The fact that we're getting areas, particularly around islands in the Pacific, that are not obviously badly contaminated is pretty remarkable. It says that our ability to screen out land contamination seems to be working quite well," Feldman said. 

Another factor that affects salinity readings is intense rainfall. Heavy rain can affect salinity readings by attenuating the microwave signal Aquarius reads off the ocean surface as it travels through the soaked atmosphere. Rainfall can also create roughness and shallow pools of freshwater on the ocean surface. In the future, the Aquarius team wants to use another instrument aboard Aquarius/SAC-D, the Argentine-built Microwave Radiometer, to gauge the presence of intense rain simultaneously to salinity readings, so that scientists can flag data collected during heavy rainfall. 

An ultimate goal is combining the Aquarius measurements with those of its European counterpart, the Soil Moisture and Ocean Salinity satellite (SMOS) to produce more accurate and finer maps of ocean salinity. In addition, the Aquarius team, in collaboration with researchers at the U.S. Department of Agriculture, is about to release its first global soil moisture dataset, which will complement SMOS' soil moisture measurements. 

"The first year of the Aquarius mission has mostly been about understanding how the instruments and algorithms are performing," Feldman said. "Now that we have overcome the major hurdles, we can really begin to focus on understanding what the data are telling us about how the ocean works, how it affects weather and climate, and what new insights we can gain by having these remarkable salinity measurements." 

Aquarius was built by NASA's Jet Propulsion Laboratory, Pasadena, Calif.; and NASA Goddard. JPL managed Aquarius through its commissioning phase and is archiving mission data. Goddard now manages Aquarius mission operations and processes science data. Argentina's space agency, Comision Nacional de Actividades Espaciales (CONAE), provided the SAC-D spacecraft, optical camera, thermal camera with Canada, microwave radiometer, sensors from various Argentine institutions and the mission operations center. France and Italy also contributed instruments. For more information about NASA's Aquarius mission, visit: http://www.nasa.gov/aquarius . 

For a narrated global tour of Aquarius ocean surface salinity measurements, see: http://www.youtube.com/watch?v=5xQP_B18vMw . A visualization showing changes in global ocean surface salinity as measured by Aquarius from Dec. 2011 through Dec. 2012 can be seen at: http://www.youtube.com/watch?v=RJVnZnZUUYc . - See more at: http://www.jpl.nasa.gov/news/news.php?release=2013-074&cid=release_2013-074#sthash.B43H9PQd.dpuf

Source:

http://www.jpl.nasa.gov/news/news.php?release=2013-074&cid=release_2013-074

Cities Affect Temperatures for Thousands of Miles

This composite image shows a global view of Earth at night, compiled from over 400 satellite images. New research shows that major cities, which generally correspond with the nighttime lights in this image, can have a far-reaching impact on temperatures. (Credit: Image courtesy NASA and NOAA)

Even if you live more than 1,000 miles from the nearest large city, it could be affecting your weather.

In a new study that shows the extent to which human activities are influencing the atmosphere, scientists have concluded that the heat generated by everyday activities in metropolitan areas alters the character of the jet stream and other major atmospheric systems. This affects temperatures across thousands of miles, significantly warming some areas and cooling others, according to the study this week in Nature Climate Change.

The extra "waste heat" generated from buildings, cars, and other sources in major Northern Hemisphere urban areas causes winter warming across large areas of northern North America and northern Asia. Temperatures in some remote areas increase by as much as 1 degree Celsius (1.8 degrees Fahrenheit), according to the research by scientists at the Scripps Institution of Oceanography; University of California, San Diego; Florida State University; and the National Center for Atmospheric Research.

At the same time, the changes to atmospheric circulation caused by the waste heat cool areas of Europe by as much as 1 degree C (1.8 degrees F), with much of the temperature decrease occurring in the fall.

The net effect on global mean temperatures is nearly negligible -- an average increase worldwide of just 0.01 degrees C (about 0.02 degrees F). This is because the total human-produced waste heat is only about 0.3 percent of the heat transported across higher latitudes by atmospheric and oceanic circulations.

However, the noticeable impact on regional temperatures may explain why some regions are experiencing more winter warming than projected by climate computer models, the researchers conclude. They suggest that models be adjusted to take the influence of waste heat into account.

"The burning of fossil fuel not only emits greenhouse gases but also directly affects temperatures because of heat that escapes from sources like buildings and cars," says NCAR scientist Aixue Hu, a co-author of the study. "Although much of this waste heat is concentrated in large cities, it can change atmospheric patterns in a way that raises or lowers temperatures across considerable distances."

Distinct from urban heat island effect

The researchers stressed that the effect of waste heat is distinct from the so-called urban heat island effect. Such islands are mainly a function of the heat collected and re-radiated by pavement, buildings, and other urban features, whereas the new study examines the heat produced directly through transportation, heating and cooling units, and other activities.

The study, "Energy consumption and the unexplained winter warming over northern Asia and North America," appeared online January 27. It was funded by the National Science Foundation, NCAR's sponsor, as well as the Department of Energy and the National Oceanic and Atmospheric Administration.

Hu, along with lead author Guang Zhang of Scripps and Ming Cai of Florida State University, analyzed the energy consumption -- from heating buildings to powering vehicles -- that generates waste heat release. The world's total energy consumption in 2006 was equivalent to a constant-use rate of 16 terawatts (1 terawatt, or TW, equals 1 trillion watts). Of that, an average rate of 6.7 TW was consumed in 86 metropolitan areas in the Northern Hemisphere.

Using a computer model of the atmosphere, the authors found that the influence of this waste heat can widen the jet stream.

"What we found is that energy use from multiple urban areas collectively can warm the atmosphere remotely, thousands of miles away from the energy consumption regions," Zhang says. "This is accomplished through atmospheric circulation change."

The release of waste heat is different from energy that is naturally distributed in the atmosphere, the researchers noted. The largest source of heat, solar energy, warms Earth's surface and atmospheric circulations redistribute that energy from one region to another. Human energy consumption distributes energy that had lain dormant and sequestered for millions of years, mostly in the form of oil or coal.

Though the amount of human-generated energy is a small portion of that transported by nature, it is highly concentrated in urban areas. In the Northern Hemisphere, many of those urban areas lie directly under major atmospheric troughs and jet streams.

"The world's most populated and energy-intensive metropolitan areas are along the east and west coasts of the North American and Eurasian continents, underneath the most prominent atmospheric circulation troughs and ridges," Cai says. "The release of this concentrated waste energy causes the noticeable interruption to the normal atmospheric circulation systems above, leading to remote surface temperature changes far away from the regions where waste heat is generated."

Source: http://www.sciencedaily.com/releases/2013/01/130127134210.htm

Prehistoric Beaches Hold Key to Understanding Climate Change

As many people in the Northeast continue a long and painful recovery in the wake of Hurricane Sandy, scientists are working hard to determine how high and how fast global sea levels are rising. In order to do this, they are looking not only to the future—in the form of computer-generated forecasts—but also to the past. Due to rising levels of carbon dioxide produced by human emissions of greenhouse gases, the Earth is expected to warm at a faster rate over the coming century, a situation that is roughly comparable to the climate change that happened some 3 million years ago, during the mid-Pliocene Epoch. In an effort to find out how high global sea levels rose during the mid-Pliocene, scientists traveled to South Africa to study beach deposits dating to that time, some of which can now be found more than 100 feet above modern sea level.

As reported in the New York Times this week, a team of scientists headed by Dr. Maureen E. Raymo of Columbia University traveled to the southern and western coasts of South Africa last summer to find prehistoric beaches that could contain invaluable records of past climate change. Through often-risky exploration of various sites, including old quarries and diamond mines, the team managed to find 38 suspected beaches dating to the Pliocene Epoch. The beach deposits ranged from 38 feet to 111 feet above modern sea level, indicating how high seas may have risen during that period in Earth’s history.

Past climate research has shown that when the earth’s temperature rises by only a couple of degrees Fahrenheit, polar ice melting causes the global sea level to rise some 25 to 30 feet. The Earth is expected to warm at a faster rate over the coming century, possibly by as much as four or five degrees. Rising sea levels due to melting polar ice have almost certainly contributed to the coastal flooding caused by Hurricane Sandy and other massive storms. The research group Climate Central estimates that an ocean rise of only five feet—within current scientific estimates for the coming century—will produce storm tides on the scale of Sandy’s about every 15 years in New York City.

Many scientists who study climate history, known as paleoclimatologists, have settled on the mid-Pliocene Epoch (roughly 3 million years ago) as a model for what might happen to global sea levels in the coming century. The mid-Pliocene was the first era in earth’s history where temperatures were consistently warmer than what we see today, and roughly comparable to what scientists expect them to be by the end of the 21st century.

One factor complicating the project is that rising sea levels are not the only cause of the variation in height among the Pleistocene beaches found in South Africa and elsewhere. The land itself has undoubtedly also moved over the last several million years, which likely shifted the height of existing beach deposits. Scientists now know that this movement can happen anywhere in the world, even far from known geologic hotspots with long histories of active volcanism, and must take this movement into account in their interpretation of past sea levels.

In the next several years, Raymo and her team plan to gather measurements from ancient beaches on different continents—including North America—in the hopes of determining the maximum global sea level rise that occurred during the mid-Pliocene. Previous estimates of that number, though not based on solid evidence, have ranged from 15 feet to 130 feet above today’s ocean, with 80 feet as the most commonly cited figure. If their research confirms such a drastic rise, it could suggest that the world’s largest ice sheet, which covers eastern Antarctica, is vulnerable to melting, contradicting computer forecasts predicting its stability even as global temperatures rise.

Source: http://www.history.com/news/prehistoric-beaches-hold-key-to-understanding-climate-change