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Posts Tagged ‘extinction’

Global Dimming and Death of Our Sun

Posted by jase on July 10, 2009

by Brian Cox

The Sun is Dying

Sol, our sun, will not live forever. It has enough fuel left, if our current understanding is correct, for another 5 billion years, at which point it will die. But could it be possible for the Sun to die much sooner, within the next 100 years even? From a scientific perspective, it should be said that this is very unlikely. But, it is also true that there is a lot about the universe that we do not understand.

Over the last few years astronomers have observed that there is extra “stuff” in the universe that we can see only by its gravitational influence on stars and galaxies. This stuff goes by the name of Dark Matter, and there is five times as much Dark Matter in the universe as there is normal matter, the stuff that makes up you, me, and the stars and planets we can see with our telescopes. What is this mysterious stuff? It’s possible, some scientists would say likely even, that this stuff is made of particles known as supersymmetric particles, a new and exotic form of matter that is high on the list of potential discoveries at CERN’s giant Large Hadron Collider, a 27km in circumference machine which begins operations this year after almost a decade of construction.

Theoretical physicists have spent many years calculating the properties of these supersymmetric particles, and we have a reasonable theoretical understanding of how they might behave. One possibility is that they could clump together into giant balls known as Q-balls. If this is true, then these heavy and exotic objects could have been made billionths of a second after our Universe began, and still be roaming the Universe today. It is speculated that, if a Q-ball drifts into the heart of a super-dense object such as a neutron star, it could begin to eat away at it’s core like a cancer, until the star is no longer massive enough to maintain itself and explodes in a violent explosion. Such explosions, known as gamma ray bursts, are seen in the Universe, although their cause is as yet unknown.

Could such a dangerous, exotic object drift into the Sun’s core and cause it to stop shining? It is likely that the Sun is many times too diffuse to stop a Q-ball – it would power right through. But maybe, just maybe, some strange exotic form of matter from the earliest times in the universe could settle deep within the Sun’s core, and disrupt its function enough to cause the catastrophic scenario seen in Sunshine. It’s far-fetched, but we have a saying in physics that anything that isn’t explicitly ruled out is therefore possible, so in the final analysis, you never quite know.

Global Dimming 

It is now suspected that pollution in the Earth’s atmosphere, caused by industrialization and natural phenomena such as volcanic eruptions, may have significantly reduced that amount of sunlight reaching the Earth’s surface. It is estimated that this could have led to a cooling effect of over 1 degree overt he last 40 years, which would go some way to offsetting the effect of global warming. Global warming is caused primarily by increasing carbon dioxide levels in the atmosphere that prevent heat being radiated back out into space from the Earth’s surface.

The phenomenon of global dimming may therefore have saved us, so far, from the worst affects of climate change, although it has been noticed that as pollution levels have been reduced, particularly in Western Europe, the affects of global dimming seem to be reducing, leading to an accelerating temperature rise once again. We may therefore be in the paradoxical situation that reducing pollution might INCREASE the effects of global warming, leading us ever more quickly towards catastrophe.

This discovery isn’t all bad, however, because it may suggest a short term solution to climate change. Why not intentionally put pollutants, which may be designed to be benign in other respects, into the atmosphere to accelerate global dimming, and therefore slow the climate change caused by carbon dioxide emissions. Several suggestions along these lines have been made, including adding small particles to airplane fuel, and therefore using one of the main contributors to climate change, aircraft, to slow its effects. It’s an intriguing possibility, and one that is the focus of significant research, although it should be said that we cannot at present predict the effects of such fine-tuning of the climate, so global dimming shouldn’t be seen as a means to allow us to continue to increase carbon dioxide emissions.

Posted in Astronomy, Climate, Earth, extinction, Global Warming, Science, Solar Energy, Space | Tagged: , , , , , , , , , , , | Leave a Comment »

350 Year Old Photo Uncovered of Dodo Before It was Extinct

Posted by jase on July 7, 2009

A previously undiscovered 17th century picture of a dodo, drawn before the bird became extinct, is to be sold at auction by Christie’s.

The drawing, which dates from the late 1600s, offers a rare insight into the appearance of the flightless bird that was the first recorded casualty of human interference in the habitat of other creatures.

Dodos were the main predators on Mauritius until settlers introduced bigger animals to Indian Ocean island, including pigs. Many were shipped to Europe as curiosities or had their nesting areas destroyed and the species was extinct by 1700.

The 350-year-old drawing, described by Christie’s as “vibrant”, is one of a small number of images of the unfortunate bird whose demise was largely unnoticed until a dodo featured in Lewis Carroll’s popular 1865 book Alice’s Adventures in Wonderland.

Painted by an unknown artist of the 17th century Dutch school in about 1650, the unframed 10×8 inch picture is expected to fetch up to £6,000 when it is sold by Christie’s in London on July 9.

The auction house believes it differs from existing images, many of which were drawn from a small number of dodos that were put on display in Europe, some of which were later stuffed.

Little is known about the origin of the picture, which has never before been published.

The inscription above the bird, ‘Dronte’, was the Dutch 17th-century name for the dodo, although at this period it was also used in a number of other languages including French, German and Italian.

Julian Hume, a dodo expert and a palaeontologist at the Natural History Museum, said the image was “very interesting but rather odd”.

“The lack of tail is anatomically correct – the ostrich-like plumes normally depicted are exaggerations – but this may be a fault by the artist,” he said. “The angle of the dodo is also novel, showing a 3D pose rather than the usual side view.”

He added that it was likely to have been copied from earlier drawings. “The image is somewhat based on Roelandt Savery’s 1626 image of the dodo standing by a rock. We know so little about the number of transported live dodo specimens, and coupled with repeated plagiarism of images, factual determination is almost impossible to obtain.”

Another dodo expert, Anthony Cheke, said: “There is always a lot of interest in artefacts like these because the dodo is such a curiosity. This is certainly an unusual image although the drawing is, frankly, not very good even by contemporary standards.”

Posted in Animals, extinction | Tagged: , , , , , , , | 1 Comment »

Earth Will Become Planet Without Ice Caps

Posted by jase on June 28, 2009

Rising sea levels will not extinguish humanity, but they will transform life on planet Earth as we know it according to Peter Ward professor of biology and earth sciences at the University of Washington. Here are his predictions in a new book, The Flooded Earth, which will be published this July.

By 2050: Sea levels will rise 0.5 to 1 meter. Well established coastal cities will battle the rising waters with dikes and levees; other cities will see their underground infrastructure impaired and face building collapse.

By 2300: The seas will rise 20 meters reshaping the world’s geography, forming new rivers and lakes as Antarctica’s ice melts. Massive icebergs will form in the southern hemisphere interrupting historic shipping lanes.

2500-3000: the sea will reach its maximum levels completely wiping out coastal cities and forcing massive human and animal migration. Greenland and Antarctica will be transformed into prime farmlands. Southern regions will face the spread of tropical diseases and the possibility of mass extinctions.

Image above: Red represents areas where temperatures have increased the most during the last 50 years, particularly in West Antarctica, while dark blue represents areas with a lesser degree of warming. Temperature changes are measured in degrees Celsius. Credit: NASA/GSFC Scientific Visualization Studio.

Further reading:

Is Global Warming Part of Earth’s Natural Cycle: MIT Team Says “Yes” -A Galaxy Insight

Global-Warming Tipping Point: 9 Degrees Temperature Increase Would Devastate Earth’s Population

Source: http://www.nasa.gov/topics/earth/features/warming_antarctica.html

Posted in Antarctica, Earth, Global Warming, Historic Events, Southern Hemisphere | Tagged: , , , , | Leave a Comment »

Hawking Says Asteroids Biggest Threats to Intelligent Life

Posted by jase on June 28, 2009

Stephen Hawking believes that one of the major factors in the possible scarcity of intelligent life in our galaxy is the high probability of an asteroid or comet colliding with inhabited planets. We have observed, Hawking points out in Life in the Universe, the collision of a comet, Schumacher-Levi, with Jupiter (below), which produced a series of enormous fireballs, plumes many thousands of kilometers high, hot “bubbles” of gas in the atmosphere, and large dark “scars” on the atmosphere which had lifetimes on the order of weeks. 

 

It is thought the collision of a rather smaller body with the Earth, about 70 million years ago, was responsible for the extinction of the dinosaurs. A few small early mammals survived, but anything as large as a human, would have almost certainly been wiped out.

Through Earth’s history such collisions occur, on the average every one million year. If this figure is correct, it would mean that intelligent life on Earth has developed only because of the lucky chance that there have been no major collisions in the last 70 million years. Other planets in the galaxy, Hawking believes, on which life has developed, may not have had a long enough collision free period to evolve intelligent beings.

“The threat of the Earth being hit by an asteroid is increasingly being accepted as the single greatest natural disaster hazard faced by humanity,” according to Nick Bailey of the University of Southampton’s School of Engineering Sciences team, who has developed a threat identifying program.[ Image: Comet Shoemaker-Levy 9 collision with Jupiter]

The team used raw data from multiple impact simulations to rank each country based on the number of times and how severely they would be affected by each impact. The software, called NEOimpactor (from NASA’s “NEO” or Near Earth Object program), has been specifically developed for measuring the impact of ‘small’ asteroids under one kilometer in diameter.

Early results indicate that in terms of population lost, China, Indonesia, India, Japan and the United States face the greatest overall threat; while the United States, China, Sweden, Canada and Japan face the most severe economic effects due to the infrastructure destroyed.

The top ten countries most at risk are China, Indonesia, India, Japan, the United States, the Philippines, Italy, the United Kingdom, Brazil and Nigeria.

“The consequences for human populations and infrastructure as a result of an impact are enormous,” says Bailey. “Nearly one hundred years ago a remote region near the Tunguska River witnessed the largest asteroid impact event in living memory when a relatively small object (approximately 50 meters in diameter) exploded in mid-air. While it only flattened unpopulated forest, had it exploded over London it could have devastated everything within the M25. Our results highlight those countries that face the greatest risk from this most global of natural hazards and thus indicate which nations need to be involved in mitigating the threat.”

What would happen to the human species and life on Earth in general if an asteroid the size of the one that created the famous K/T Event of 65 million years ago at the end of the Mesozoic Era that resulted in the extinction of the dinosaurs impacted our planet.

As Stephen Hawking says, the general consensus is that any comet or asteroid greater than 20 kilometers in diameter that strikes the Earth will result in the complete annihilation of complex life – animals and higher plants. (The asteroid Vesta, for example, one of the destinations of the Dawn Mission, is the size of Arizona).

How many times in our galaxy alone has life finally evolved to the equivalent of our planets and animals on some far distant planet, only to be utterly destroyed by an impact? Galactic history suggests it might be a common occurrence.

The first this to understand about the KT event is that is was absolutely enormous: an asteroid (or comet) six to 10 miles in diameter streaked through the Earth’s atmosphere at 25,000 miles an hour and struck the Yucatan region of Mexico with the force of 100 megatons -the equivalent of one Hiroshima bomb for every person alive on Earth today. Not a pretty scenario!

Recent calculations show that our planet would go into another “Snowball Earth” event like the one that occurred 600 million years ago, when it is believed the oceans froze over (although some scientists dispute this hypothesis -see link below).

While microbial bacteria might readily survive such calamitous impacts, our new understanding from the record of the Earth’s mass extinctions clearly shows that plants and animals are very susceptible to extinction in the wake of an impact.

Impact rates depend on how many comets and asteroids exist in a particular planetary system. In general there is one major impact every million years -a mere blink of the eye in geological time. It also depends on how often those objects are perturbed from safe orbits that parallel the Earth’s orbit to new, Earth-crossing orbits that might, sooner or later, result in a catastrophic K/T or Permian-type mass extinction.

The asteroid that hit Vredefort located in the Free State Province of South Africa is one of the largest to ever impact Earth, estimated at over 10 km (6 miles) wide, although it is believed by many that the original size of the impact structure could have been 250 km in diameter, or possibly larger(though the Wilkes Land crater in Antarctica, if confirmed to have been the result of an impact event, is even larger at 500 kilometers across). The town of Vredefort is situated in the crater (image).

Dating back 2,023 million years, it is the oldest astrobleme found on earth so far, with a radius of 190km, it is also the most deeply eroded. Vredefort Dome Vredefort bears witness to the world’s greatest known single energy release event, which caused devastating global change, including, according to many scientists, major evolutionary changes.

What has kept the Earth “safe” at least the past 65 million years, other than blind luck is the massive gravitational field of Jupiter, our cosmic guardian, with its stable circular orbit far from the sun, which assures a low number of impacts resulting in mass extinctions by sweeping up and scatters away most of the dangerous Earth-orbit-crossing comets and asteroids

Posted by Casey Kazan with Rebecca Sato

Note: This post was adapted from a news release issued by University of Southampton.

Source: http://www.rationalvedanta.net/node/131

Source: http://www.dailygalaxy.com

Posted in Earth, Extraterrestrial Life, Moon, NASA, Science, Space | Tagged: , , , , , , , , , , | 3 Comments »

Mammoth Fossils Discovered with Meteorite Scars

Posted by jase on June 21, 2009

“Mammoth hit by meteorite!” might sound like fantastical black-and-white puppet-fest filmed in glorious Moving-Picture-O-Vision, just before a gripping two-hour feature on why mixing ants and radioactive waste is, in fact, a bad idea – but it’s real.  Arizona geophysicist Allen West discovered burn marks consistent with micrometeorite impacts in a number of mammoth and bison bones. The resulting study, performed in association with Dr Firestone of the Lawrence Berkeley National Laboratory, found numerous impact scars over thirty thousand years old.

One of the leading theories to explain repeated large animal extinctions in Earth’s history is meteor impact – because megatons of rock slamming into the planet after a few billion meter run-up is a pretty convincing way to kill anything.  West hopes that these fossilized records will prove that a meteorite shower is responsible for the decline in some large mammal populations around 34,000 years ago, as well as providing a method to apply to other historical extinctions.

West urges museums and universities to re-examine their own fossil collections for signs of damage from beyond the sky, but that seems rather optimistic.  There are only a finite number of ways you can look at a fossil and the odds of people having missed a minor thing like “damage where rocks from space hit it” is pretty low. True, these meteor fragments aren’t anything to deploy Bruce Willis over (those discovered so far are 5 millimeters at most) but they punch a hole, they burn the material, and if that isn’t noticeable enough for you they turn the site magnetic – all things that skeletons generally aren’t and won’t be until the fabled time of the Robo-Swiss-Cheese-Burning Dinosaurs comes to end us all. 

Besides, the full-time job of anything in a museum is “be looked at”.  It’s unlikely that a curator will get off the phone, look over at the fossils again and suddenly realize “My god!  There’s a crater punched by the universe itself in that thing!

– Luke McKinney @ The Daily Galaxy

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