Saturday, June 23, 2012

The NRA’s silent motive

The NRA’s silent motive
What better way for the NRA to resupply the gun users pool than to strip the nation’s laws of obstacles to gun purchase, use fear of crime to motivate potential gun buyers, and to desensitize the nation’s majority of non-gun owners to the sight of civilians packing heat?

Friday, June 22, 2012

Not with a Bang, but a Whimper?

If we could somehow disassociate ourselves from ourselves and all we are, and stand well back away from this planet earth, and hit the rewind button on our remote, taking the planet back through time (whatever that is) to its inception, and then fast forward to the present, we'd be struck by what a dynamic planet the earth is, changing constantly in fits and starts, or more accurately, eruptions, explosions, and earthquakes, in fire and in ice.

In earlier posts I've written about the earth's five mass extinction events, and the hypothesis of many scientists today that we are in the midst of a sixth mass extinction event. In examining this hypothesis, scientists have to ask themselves, what caused the first five extinctions? And then, are we seeing similar conditions now? As you might have guessed, there are no easy answers.

It's important to understand what a "mass extinction" means, and how an "event" is defined. Because we ordinary humans have no understanding of time in a geologic sense (unlike rocks), we need to know that an event in paleo terms can occur over millions of years -- there's no agreement on how many millions of years.

A mass extinction is a loss of biodiversity -- plants and animals -- that exceeds what is considered "normal," that is, things becoming extinct as an expected result of evolution, otherwise known as "background" extinction. Thus, an extinction event is a dramatic loss of plant and animal life that occurs rapidly in geologic terms.
There have been a variety of singular events hypothesized as the cause of one or another mass extinction event. Perhaps the best known extinction event and its hypothesized cause is the so-called K-T extinction, named for the timing of the event, the boundary between the end of the Mesozoic -- the Cretaceous era -- and the beginning of the Tertiary period, 65 million years ago. This boundary event marked the end of the dinosaurs, and since most of us at one time or another have been fascinated by these gigantic, strange and fearsome looking creatures, it's no wonder this particular extinction event has generated so much popular interest.
But not just dinosaurs died off in the K-T extinction. Almost all the large vertebrates on Earth, on land, at sea, and in the air became extinct by the end of the Cretaceous Period, and most plankton and many tropical invertebrates, especially reef-dwellers, became extinct. Many land plants were severely affected. Thus, the earth in all its manifestations was a very different place after K-T. Why? What happened?

Many scientists -- paleontologists, biologists, geologists, etc. -- came to believe that a large asteroid impacted the earth at that time, causing widespread devastation and triggering catastrophic global climate change. In fact, a crater has been discovered; an egg-shaped geological structure called Chicxulub, deeply buried under the sediments of the  of Mexico (North America looked like this  65 million years ago). Some scientists insist the asteroid creating the crater impacted earth exactly 65 million years ago.

Other scientists argue the Chicxulub impact predated the K-T boundary by some 300,000 years, and propose that volcanism actually caused the mass extinction. The volcanism theory centers on the so-called Deccan Traps, flood basalts similar to the Columbia River basalts of the northwestern United States. This is one of the largest volcanic provinces in the world. It consists of more than 2,000 meters of flat-lying basalt lava flows and covers an area of nearly 500,000 square km (roughly the size of the states of Washington and Oregon combined) in west-central India. Estimates of the original area covered by the lava flows are as high as 1.5 million square km. The volume of basalt is estimated to be 512,000 cubic km (the 1980 eruption of Mount St. Helens produced just 1 km3 of volcanic material).

More recently, some scientists have come to the conclusion that it was a combination of meteor strikes and massive volcanic activity that brought about the K-T mass extinction event. What seems more likely to me at least, is that over several million years, the world, rife with erupting volcanoes, became less and less hospitable for its terrestrial and marine guests. Vast amounts of dust, carbon dioxide, and sulfur dioxide poured into the atmosphere, resulting in heavy acid rain (akin to battery acid), acidic oceans, and global temperatures that initially turned frigid (possibly lasting for years) due to dust and debris, and then intolerably hot, due to the longer-term green house effects of carbon dioxide. Violent tornadoes and hurricanes ravaged the earth, the seas fell and then rose, inundating coastal areas, normal food supplies dwindled and what was left was gobbled up by the more adaptable life forms that managed to survive the initial onslaught, such as the plankton species Guembelitria cretacea, a disaster opportunist that flourished in devastated environments when few other species survived.

Chicxulub may have looked like this. This is
actually 951 Gaspra, a much larger asteroid.
And then Chicxulub made its abrupt and violent (100 million megatons equivalent) arrival on the Yucatán peninsula creating a tipping point for the vulnerable planet and spelling an end to life as it existed 65 million years ago.

Friday, June 15, 2012

Asteroid 2012 LZ1

What if it hit the earth?

An asteroid the size of a city block flew by Earth today, June 13, 2012, “Flag Day.” The near-Earth asteroid named 2012 LZ1, which astronomers think is about 500 meters wide, will come within 5,381,600 kilometers (14 lunar distances) of Earth this evening; far enough away not to worry. We left the flag out and enjoyed a balmy evening.
Asteroids have collided with the earth in the past. Some scientists believe it was an asteroid impacting the earth that led to the last mass extinction event; the one 65 million years ago (the K-T extinction event) that wiped out the dinosaurs, along with most other land and marine life. That asteroid was estimated to be 15 kilometers wide; 30 times larger than 2012 LZ1. It slammed into the earth with a force one billion times more powerful than the atomic bomb that leveled Hiroshima. Proportionally, if an asteroid the size of 2012 LZ1 did hit the earth, it would only hit with a force about 16 or 17 million times that of the Hiroshima atomic bomb.

A relatively large meteorite (40 meters in diameter) hit the earth in what is now Arizona about 50,000 years ago during the late Pleistocene era. It is estimated that the meteorite had the density of iron (7870 kg/m3), weighed about 300,000 tons, and was traveling with a velocity of 12 to 20 km/s (27,000 to 45,000 mph).
















The Arizona landscape was cooler and wetter than it is today. The plain around it was covered with a forest, where mammoths, mastodons and giant ground sloths grazed. The force of the impact would have leveled the forest for miles around, hurling the mammoths across the plain and killing or severely injuring any animals nearby. Global effects were negligible.

I calculated the potential effects of the much larger 2012 LZ1 asteroid impacting the earth by using Purdue University’s  Impact Earth on-line tool. I used the following parameters:
  • Diameter: 502.3 m
  • Density: 3000kg/m3 (dense rock)
  • Angle of impact: 60 deg
  • Velocity: 17 km/s (38,000 mph)
  • Target: Sedimentary Rock
  • Distance: 65 km (40 miles)
S. Nelson, Tulane U., 11/16/11
I have the projectile impacting in an area between and approximately equidistant (40 miles) from Richland, Ellensburg, and Moses Lake, Washington. According to the Impact Earth calculations and my parameters, 2012 LZ1 strikes the earth with an impact equivalent to 6,700 megatons of TNT. It creates a crater 5.25 miles in diameter and 1850 ft deep. In Richland, Ellensburg, and Moses Lake, thermal radiation from the blast will arrive in mere milliseconds after impact. The fireball will be visible for almost 4 miles and appear 20 times larger than the sun. Thermal exposure is equivalent to thousands of degrees Fahrenheit.


People in this zone will suffer third degree burns over much of their body. The ejecta from the impact will arrive in less than 2 minutes, the blast wave in 3.25 minutes. Wind velocity will reach 237 mph. The sound intensity will be 95 dB. Multistory wall-bearing buildings will collapse. Wood frame buildings will be destroyed. Glass windows will shatter. Up to 90% of trees will be burned and/or blown down and the remainder will be stripped of leaves and branches. In Seattle and Portland, some 400 miles away, the impact will feel like a 7.2 magnitude earthquake. A fine dusting of particles and some larger fragments will fall on the cities.

The impact would put large quantities of dust into the atmosphere, blocking incoming solar radiation. Wildfires would be widespread, putting more dust, as well as smoke into the air. The dust could take months to settle back to the surface.  Meanwhile, the region would be overcast and dark, and temperatures would drop. This would result in a drop in temperatures.

Blockage of solar radiation would also diminish the ability of plants to photosynthesize, seriously disrupting agriculture, which might take years to recover. If the asteroid impacted in the Columbia River, the consequences would be even more catastrophic (for the purposes of this essay, I am not addressing the remote possibility of the asteroid impacting in the Hanford Nuclear Reservation, the consequences of which would be dire, but essentially unknowable).
On a global scale, the earth would not be strongly disturbed by the impact and would lose negligible mass. The impact would not make a noticeable change in the tilt of earth’s axis, nor would it shift the earth’s orbit noticeably. Climate consequences would most likely be regional or continental, rather than global.

Wednesday, June 13, 2012

The Current Mass Extinction


“Once there were brook trout in the streams in the mountains. You could see them standing in the amber current where the white edges of their fins wimpled softly in the flow. They smelled of moss in your hand. Polished and muscular and torsional. On their backs were vermiculate patterns that were maps of the world in its becoming. Maps and mazes. Of a thing which could not be put back. Not be made right again. In the deep glens where they lived all things were older than man and they hummed of mystery.”
(Cormack McCarthy, The Road)

I have described in an earlier post a rapid (in geologic terms) loss of species and a deteriorating environment, but the possibility that we, the human race, a "weedy" species, like dandelions in our lawns, may survive. And after many generations, our progeny may have no memory, no notion, of how much is missing from the impoverished world we have bequeathed them.

But there is another possibility. One in which things happen too fast for us to adapt, and along with the vast majority of other life on earth, we follow the Passenger Pigeon into extinction.

Climate scientists today are concerned about the so-called "tipping point," the moment at which a dynamical system, such as the earth, that has been changing slowly and predictably will suddenly "flip" to a state inimical to life as we know it. With respect to the climate, this can happen as a result of certain changes inducing other changes, which in turn, induce others and reinforce the original forcing function. This is a case of positive feedback not being a good thing.

Consider sea ice, for example, an implacable force of nature that covers an area on earth about two and one half times the size of Canada. Sea ice has a very significant impact on climate change. The ice has a bright surface that reflects sunlight back into space, so areas covered by sea ice don't absorb much solar energy, and temperatures in the polar regions remain relatively cool.
As warming temperatures melt sea ice, as they are doing now, fewer bright surfaces are available to reflect sunlight back into space, more solar energy is absorbed at the surface, and temperatures rise. As sea ice melts further, more solar energy is absorbed, and more sea ice melts.This chain of events starts a cycle of warming and melting, leading to greater and greater warming and continued loss of sea ice, with predictable results; the dynamics of sea ice freezing and melting reaches a tipping point where freezing can’t keep up with melting and the sea ice disappears, removing a vital component in the earth’s homeostasis -- its ability to maintain an equilibrium.

There’s another type of “melting” that’s taking place as a result of rising global temperatures, and that’s the thawing of the permafrost covering the earth’s tundra. Tundra is located at the top of the northern hemisphere in Europe, Asia and North America. It covers 20% of the earth's surface just below the polar cap. Permafrost trapped carbon buried since the Pleistocene era. When permafrost melts, that carbon comes bubbling to the surface of lakes, and dissipating into the atmosphere as methane, a greenhouse gas 23 times more potent than carbon dioxide. And the permafrost is melting -- at five times the rate previously thought.

The rapid release of methane will accelerate the greenhouse gas trapping effect that's currently warming the earth, and that will in turn, increase the rate at which sea ice is disappearing. And that takes us back to the role of sea ice in reflecting solar energy back into the atmosphere, instead of absorbing it in the ocean. You get the drift.

Another type of tipping point occurs when a particular ecosystem sustains so much damage that it can no longer sustain itself. This is what's happening in the Amazon Rainforest.

The dense forests of the Amazon soak up more than one-quarter of the world's atmospheric carbon, making it a critically important buffer against global warming. But a warming climate combined with unchecked slash and burn clearing is bringing the rainforest to the brink of disaster.
Billions of trees died in the record drought that struck the Amazon in 2010, and agriculture, and urban development along with the road building that accompanies it are destroy billions of additional trees and the essential and fragile ground cover that makes the rainforest possible.

The Amazon is but one of ten threatened forests on the earth. If forests lose their ability to act effectively as carbon sinks, additional green house gases will contribute to accelerating global warming, which will subject the earth to further extreme droughts, loss of additional trees, and runaway climate change.
Biologists who believe the earth is experiencing its sixth mass extinction identify five primary direct drivers in addition to climate change, all are the result of human behavior: habitat loss, invasive species, pollution, over-exploitation of resources, and the factor that magnifies all the others—human overpopulation.

According to studies, at least half of all plant and animal species are likely to disappear in the wild within the next 30-40 years, including many of the most familiar and beloved large mammals: elephants, polar bears, chimpanzees, gorillas and all the great apes, all the big cats, and many, many others.

Bird species are similarly imperiled, songbird populations have declined by 50% in the last 40 years. One out of every eight species of plant life worldwide and almost one third of the plant species within the United States already face extinction.

Populations of large ocean fish have declined by 90% since the 1950s. All around the world, birds, reptiles, mammals, amphibians, fish, and invertebrates, as well as trees, flowering plants, and other flora, are all in steep decline.

As disturbing as this rapid decline of species and its attendant support for a sixth extinction event is, there's an even more disturbing, even terrifying prospect -- sudden destabilization of the earth system with imminent death and destruction across all species, including most especially, human. Is this even remotely possible? You're damn right it is.

 I'll discuss this in a future post.

Saturday, June 9, 2012

Extinction



The coral reefs are dying. These largest of all earth’s living structures, intricate and brightly colored, home to a vast panoply of colorful fish, mollusks, marine life of all kinds -- the superstructure of biologically diverse ecosystems -- are bleaching white, breaking up, and withering away.
It won’t be the first time that the reefs have died away. In each of the five previous mass extinctions, coral reefs have been severely impacted, taking many millions of years to recover. In this respect, reefs are like the canary in the coal mine. They are a sentinel, whose current calamitous condition foretells the sixth mass extinction, an event many paleontologists believe the earth has already entered.
The cause or causes of earth’s previous mass extinctions have been a matter of intense scrutiny. Hypotheses have ranged from massive volcanism to asteroid strikes. 
The Permian-Triassic extinction of 250 million years ago (Mya), wiped out over 90% of the planet’s marine species. On land, over 70% of reptile, amphibian, insect, and plant species went extinct. It was the most catastrophic of all earth’s extinctions, and may have been triggered by the eruption of the super volcano known as the Siberian Traps, the most massive eruption and lava flow in earth’s history.

The Siberian Traps eruption, which lasted for a million years, added huge amounts of heat, carbon dioxide, and sulfur dioxide to Earth's surface and atmosphere, and the resulting greenhouse effect generated a long warming trend. The climate change triggered by the warming dramatically shifted weather patterns across the globe.
Carbon dioxide has left its fingerprints on all the massive die-offs experienced during earth’s often violent history. J.E.N. Vernon (2008) has pointed out in his article in the journal Coral Reefs, that recent palaeophysiological studies have clearly implicated CO2 in the destruction of most life on earth during the Permian-Triassic extinction.
There is also evidence of a sudden and massive release of methane, perhaps triggered by increased warming. This would have been an example of positive feedback, that is, CO2 causing warming, melting frozen tundra, and thereby releasing methane, which is considered a much more potent greenhouse gas than CO2.
As it happens, Russia’s Siberian tundra is currently melting. Russia has the largest extent of permafrost in the world. Scientists estimate that permafrost covers more than 10 million square kilometers of Russia. The warming planet is melting permafrost in Siberia, and the melting permafrost is releasing methane in much greater quantities than previously thought. Methane is considered 20 times more damaging as a greenhouse gas than carbon dioxide, which means that Siberia is now actively contributing to  warming. Russian scientists believe the melting of Siberian permafrost is irreversible, as the release of green house gases will perpetuate the warming climate.

Experts say Siberian tundra leaking methane in record amounts
And this brings us to the Sixth Mass Extinction -- the one happening now. We’ll address that in a coming blog post.

Tuesday, June 5, 2012

There's Rare and then there's Rare

Last night, June 5, 2012, we saw the planet Venus transit our Sun. This event is considered rare, because it happened last in 1882 and will not happen again until 2117. But “rare” is relative, in this case relative to the life span of most humans. But we are in the midst of another far, far rarer event, a mass extinction; the sixth in the history of the earth.
The last mass extinction occurred 65 million years ago (Mya), and obliterated more than half the world’s terrestrial and marine life, including those spellbinding behemoths of prehistory, the dinosaurs -- a species that had dominated earth for 135 million years. Global temperature was up to 40°F warmer than present, and seas over 900 feet higher than today swept over the land and in a flood of truly biblical extent covered 40% of the continents.
There have been five mass extinction events in the earth’s history; at the end of the Ordovician period, 434 Mya; late in the Devonian, 354 Mya: the end of the Permian, 251 Mya, when a staggering 80-90 percent of all marine species went extinct; and the end of the Triassic, when half of all marine invertebrates, and 80% of all land quadrupeds went extinct.
What caused these mass extinctions? The first modern human species appeared only some 2.2 Mya, so we stand blameless for these first five extinctions. That is not the case for the sixth. In coming posts we’ll examine what paleontologists and other scientists tell us about the causes of these events, and why these same scientists tell us we are in the midst of another mass extinction.
Stay tuned. We’ll get to this before Venus next transits the sun.