Could we blow up the world with nuclear weapons?

chixu impactorEver since the latest ruler of North Korea began testing missiles; the threat of detonation of nuclear devices is more often on the minds of the public. Simply stated, as long as these weapons of annihilation exist, so too will the temptation to use them. Although military experts speak of the survivability of what they characterize as a limited exchange, they are talking of survivability for the short-term. If one nation launches nuclear weapons, it is likely that others who possess such weapons will also use them. The likely result will be a full nuclear exchange, rather than the limited engagement politicians so calmly reference. That being said, the opinions rampant on Face Book, that such a war would “shatter the earth” is complete hokum. Still, a full nuclear exchange would alter the world we live in drastic ways.

While many films and books have tried to demonstrate the death and destruction that would result from the initial blast and resulting fallout of a full nuclear exchange, few have studied the likely effects on the ecosystem of our planet. Scientists who focus on the climatic changes throughout Earth’s history describe how a change of just a few degrees can have devastating, planet-wide effects. Some suggest that a nuclear exchange would prompt a “nuclear winter.” Dr. Carl Sagan and others introduced this idea in 1983, in the journal Science. In this theory, after the explosions of a nuclear exchange have stopped, the real devastation will be just beginning.

The spread of ash and smoke in the atmosphere from fires will partially obstruct sunlight, leading to a drop in global-wide temperatures by as much as 5-10 degrees centigrade within a few months. Conservative models suggest that a change in the temperature of even two degrees Centigrade could unbalance the ecosystem, leading to issues of survival for some species. Such a change would drastically alter the established weather patterns, bringing drought to some areas, and monsoon conditions to others. The migration of species would be disrupted, and some would die off as a result of these climatic changes.

The result of major climatic upheaval due to the smoke and ash in our atmosphere is more than an idle guess, instead based on the results of events that have occurred on our planet every 60-80 million years, the last one, around 66 million years ago.

In 1979, Dr. Walter Alvarez, distinguished professor of Earth and Planetary Science at University of California, was sifting through sediments from Italy that contained significant amounts of a rare radioactive element known as iridium. Iridium is rare on Earth but found in large quantities in meteorites. Alvarez was finding it in sediments dating to the boundary layer between the Cretaceous and Tertiary periods known by archeologists as the K-T boundary. Alvarez’s discovery and ongoing research lent support to the impact theory of the periodic extinctions that have occurred every so often.

Recently, two researchers have uncovered new evidence that supports the link between cyclical comets or asteroid showers and mass extinctions, including the one that they believe killed the remaining dinosaurs some 66 million years ago. Michael Rampino, a geologist at New York University, and Ken Caldeira, an atmospheric scientist at the Carnegie Institution for Science, reviewed the mass extinctions from the geological record, and found that approximately every 26 million years or so, there were huge impacts of space debris, accompanied by major extinctions.

Although we don’t feel it, our planet is in constant movement. Not only are we revolving at nearly 1,000 miles per hour, but orbiting the Sun at nearly 19 miles every second. Our solar system itself is in constant motion, traveling at over 138 miles per second (along with the stars closest to Earth) that lie in a minor spiral arm of the Milky Way Galaxy called the Orion Spur. Our galaxy is so large that even at these speeds, it takes 230 million years for us to make one orbit of our galaxy. And it doesn’t stop there. The Milky Way itself is also moving, being drawn gravitationally toward the Andromeda Galaxy at nearly 3,000 miles every second; however, because the two galaxies are nearly 2.5 million light-years apart, even at 3,000 miles per second the trip will take about 4 billion years.

As our solar system slowly moves around our galaxy (slow being a relative term), we are brought into contact with other space debris, including comets, asteroids, and other objects, both large and small. The result is that we are continually peppered with debris from space, although most of it is dust-sized. About 40-60,000 objects over 10KG fall on the Earth every year, most falling in the ocean. Now and then, larger objects fall to Earth. In 2013, Ukrainian astronomers located an object they named 2013TV135, which passed very near the Earth. The space rock was about a ¼ mile in diameter. Google announced that, had the object struck, it would have “Blown up the earth.” Like much on Google, the facts are very different. Had the object struck, it would most certainly have caused a great deal of devastation.

A collision with object 2013TV135 would have released an energy equivalent to 3,300 megatons of TNT, or about the same energy release as about half of all the world’s remaining nuclear weapons detonated at the same time, in the same place. The result of the impact of 2103TV135 would be a crater about 12 miles across, and perhaps a ¼ mile deep. The energy released at the instant of impact would vaporize about a hundred million cubic meters of rock, resulting in a significant earthquake. If the collision occurred in water, we could add a tsunami to the above description. Nasty, but certainly not enough to cause a mass extinction of life on the Earth(let alone “shatter the planet” i.e. Face Book claims).

The piece of rock and iron that struck Arizona about 50,000 years ago was only about 40 feet across, yet it left a crater a mile wide, and nearly 600 feet deep, and vaporized nearly 175 million tons of rock. Although significantly rare, large space objects do collide with the Earth. There have been ten known impacts, each causing a massive loss of species. These are known as Extinction Level Events or ELE.

The Earth has experienced at least ten major ELEs caused by impacts from debris from space. The largest impact crater so far discovered resulted in the Vredefort Crater, caused by an asteroid nearly 9 miles in diameter, which left a crater with a radius of 118 miles some 2 billion years ago. Diminishing in size, the Sudbury Basin Crater in what is today Northern Ontario is 81 miles in diameter and was formed 1.8 billion years ago by the impact of a large comet. The 56-mile Acraman Crater was formed about 580 million years ago when an asteroid struck what is today Australia. About 215 Million years ago, the region that is today Quebec suffered a major impact, resulting in a crater 62 miles wide. The most well known of these ancient impacts, the Chicxulub Crater is over 150 miles wide, caused by the impact 66 million years ago by a chunk of rock and iron 6 miles wide that helped sound the death knell for all large life forms, including the dinosaurs. While there have been at least 10 of these impacts, the one that ended the reign of the dinosaurs is the most famous.

Before the impact that led to their extinction, the dinosaurs, which had dominated Earth for more than 150 million years had been the dominant species (at least on land). The few mammal species of the time were mouse-sized, nocturnal and secretive. They spent most of their time and energy evading the much larger dinosaurs. With the Chicxulub impact, almost all animals larger than about 50 pounds became extinct. Not all at once, and not overnight.

The conditions after the Chicxulub impact were extremely hostile to life. The sun was blocked by the ash and debris thrown into the atmosphere. After six months or so, the skies cleared somewhat, and acid rain fell. Most plants withered and died, and the Earth’s climate rapidly cooled. By the time the skies cleared, the enormous amounts of ice and snow that blanketed the earth melted, putting a great deal of water vapor into the atmosphere, creating a greenhouse that rapidly heated the planet. The Cretaceous–Paleogene extinction event is used to mark the K-T boundary. From the Chicxulub impact, the climate disruption helped bring about the extinction of an estimated 75% of all species, including almost all of the dinosaurs.

Amazingly, some species not only survived, they thrived. The mammals who were at first small and timid, would move into the niches now empty of larger animals, becoming the genetic ancestors of the mammals alive today, including us.

The oceans also experienced a significant loss of species, including the top predators like Mosasaur. These enormous animals were lizards not dinosaurs, and some were enormous, rivaling even the largest whales of today. All life in the ocean depends on a food chain that begins with plankton. Plankton requires sunlight. If sunlight is diminished for very long, plankton dies, and the food chain collapses. The collapse of the ocean food chain signaled the extinction of a vast number of species, including large fish, most sharks (although a few smaller species survived), several species of mollusks, and most species of plankton.

While almost all of the dinosaurs became extinct, one small group of bird-like dinosaurs of the genus Maniraptora survived. It is thought that their beaks allowed them to feed on seeds, thus staying fed even though the plants had died. Seeds survive conditions that kill off the plants, and any animal that can break open the seeds can find nutrients. This handful of species gave rise to the birds we have today. A few species of crocodiles survived as well. Crocodiles are the only known land animal over 50 pounds that managed to survive the die off. The crocodiles of today look very much like their fossilized ancestors from 80 million years ago.

Once the skies cleared and the planet warmed again, the survivors, most notably the mammals, were able to diversify and fill-in the niches left by the demise of larger animals. From a handful of small, mouse-sized species evolved new forms including horses, and pigs, to bats and whales, to primates including Homo sapiens.

Currently, the nations of the world have a stockpile of nuclear weapons. Although exact figures are secret, the Federation of American Scientists estimates there are around 20,000 nuclear warheads, nearly all of which are Russian and American. While the explosive power of these weapons varies, the total of all weapons currently is thought to be about 10,000 Megatons (the bombs dropped on Hiroshima and Nagasaki were about 0.015 megatons); the energy generated from the Chicxulub impact was the equivalent to 100 Teratons or TNT, or about 2 million of the largest nuclear weapons of today. So obviously, even if humanity became so self-destructive as to detonate all of its nuclear weapons, the world would keep on turning. About that….

And much of humanity would go on living, at least for a while. Beyond the ejected debris sent into the atmosphere by so many detonations, the aerosolization of small particles would rapidly reduce the amount of heat reaching the earth from the Sun, producing the nuclear winter physicists warn about, accompanied by massive environmental damage. Such an all-out nuclear exchange would unleash a pulse of electromagnetic energy that would destroy virtually every modern device; national power grids and microchips alike would be useless. Assuming that all weapons will detonate on the surface, spaced out across the globe, 100 square kilometers of land will be obliterated, and nearly one quarter million square kilometers of infrastructure will have been leveled or incinerated.

The subsequent ionizing radiation in the atmosphere will rain down on the survivors of the original blasts, contaminating those who manage to survive, causing radiation sickness. Those survivors in shored-up bunkers, or in far-flung remote locations who escaped the blasts and radiation poisoning will have to prepare for darkness. The soot produced by the detonations and resulting fires of man-made structures will further pollute and darken the skies, plunging the world into darkness, and halting photosynthesis. The total collapse of the ecosystem would follow soon after.

Any alien beings, if there are any close enough to visit, would hear a deafening silence a few months (or a few years) after our demise (radio and television signals travel at the speed of light into the cosmos), and perhaps some advanced beings might investigate why after nearly 100 years of noise (we really can’t expect alien life to understand the CBS Evening News, or the Lucy Show) everything had fallen silent?

If they were to grow curious and visit, they would be able to detect the radiation from orbit, and know that a civilization that arrogantly believed itself to be enlightened, the very pinnacle of creation, rather than put aside petty grievances, had chosen instead to self-destruct.

 

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