18 Miles: The Epic Drama of Our Atmosphere and Its Weather
272
18 Miles: The Epic Drama of Our Atmosphere and Its Weather
272eBook
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Overview
“With wit and a humbling sense of wonder, this is a book that can be shared and appreciated by a wide audience who now religiously check their phones for daily forecasts.” — Publishers Weekly Starred Review
“This terrific, accessible, and exciting read helps us to better understand the aspects of weather and the atmosphere all around us.” —Library Journal Starred Review
We live at the bottom of an ocean of air — 5,200 million million tons, to be exact. It sounds like a lot, but Earth’s atmosphere is smeared onto its surface in an alarmingly thin layer — 99 percent contained within 18 miles. Yet, within this fragile margin lies a magnificent realm — at once gorgeous, terrifying, capricious, and elusive. With his keen eye for identifying and uniting seemingly unrelated events, Chris Dewdney reveals to us the invisible rivers in the sky that affect how our weather works and the structure of clouds and storms and seasons, the rollercoaster of climate. Dewdney details the history of weather forecasting and introduces us to the eccentric and determined pioneers of science and observation whose efforts gave us the understanding of weather we have today.
18 Miles is a kaleidoscopic and fact-filled journey that uncovers our obsession with the atmosphere and weather — as both evocative metaphor and physical reality. From the roaring winds of Katrina to the frozen oceans of Snowball Earth, Dewdney entertains as he gives readers a long overdue look at the very air we breathe.
Product Details
| ISBN-13: | 9781773052236 |
|---|---|
| Publisher: | ECW Press |
| Publication date: | 10/23/2018 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 272 |
| File size: | 2 MB |
About the Author
Christopher Dewdney is the award-winning, bestselling author of four books of nonfiction and eleven books of poetry. A four-time nominee for the Governor General’s Award, he won the CBC Literary Competition for poetry and has been awarded the Harbourfront Festival Prize. Christopher lives in Toronto, where he teaches writing at York University.
Read an Excerpt
CHAPTER 1
Stormy with a Chance of Life
The Improbable Birth of Our Atmosphere
The fortuitous creation of Earth took place about 4.5 billion years ago. A billion years is a long while. To get an idea of the immensity of such a span, imagine time could be condensed into a substance and that each year deposited a gram — the weight of a ballpoint pen cap or a dollar bill. If you added each year to the next, a decade would weigh 10 grams and a normal human life span would be 80 to 90 grams, about the weight of a chocolate bar.
Suppose we kept going — every year backward adding another gram to the lump — then 2,000 years, back to the time of the Roman Empire, it would weigh an easily hefted two kilograms, or as much as a small sack of potatoes. Spool back 200,000 years to the first anatomically modern humans, and you're getting close to the limit of what an Olympic weightlifter can clean and jerk, around 200 kilograms.
Go further back to the dinosaurs, 60 million years ago, and your gram-a-year interest account cashes out at 53 tons, about the weight of a small diesel locomotive. Five hundred million years ago, at the beginning of what paleontologists call the Ordovician period, when our oceans were populated with trilobites and crinoids, the yearly deposits would weigh in at about 50,000 tons, or the approximate weight of three Ohio-class nuclear submarines. Four and a half billion years ago, when our planet first coalesced from primordial dust, your gram-a-year investment would weigh as much as an asteroid, one big enough to wipe out life on an entire continent.
Back then, our planet collided with impactors the size of our time-deposit asteroid every few hundred million years or so. Despite this constant pummeling, our molten planet had enough time to let gravity sort its constituent parts into layers — iron at the core and lighter minerals and elements arrayed above. The lightest of these, the gases, formed the top layer. At the time, these were hydrogen and helium, and they formed Earth's first atmosphere. Think of the Hindenburg disaster: just one match and the whole works would've exploded. But you could strike a thousand matches 4.5 billion years ago without producing a single spark. There was no oxygen. Anyway, why would you bother? You'd be asphyxiating. And with all that helium around your squeaky last words would be comically high pitched, in a macabre sort of way.
But helium is a fickle gas, and it didn't stick around long. Less than a hundred million years after Earth's formation, most of it had escaped Earth's gravity and fled into space. Unbonded gaseous hydrogen followed helium shortly afterward, leaving behind an atmosphere that had transformed into a pungent mixture of nitrogen, water vapor, carbon dioxide and hydrogen sulfide. Eau de rotten eggs. Beneath this odiferous miasma was a watery planet studded with a few transient islands of rock. It took another 300 million years for the Earth's crust to stabilize into a thin layer of congealed lava over the primeval magma, yet even then whatever proto-continents had managed to poke their landmass above the oceans were pelted by meteors and asteroids. In fact, every few hundred million years, when a particularly large asteroid struck, the oceans evaporated in the subsequent planetary inferno. For thousands of years afterward, the seas bided their time as atmospheric steam and only reformed when the surface of the planet had cooled to the point where rain no longer vaporized instantly on the red-hot surface but began to accumulate in puddles, lakes and finally oceans.
In the midst of these hydrogen tempests, meteor bombardments and constant volcanic eruptions, the most extraordinary development on Earth took place — self-reproducing organisms with rudimentary DNA appeared. And, as it turned out, these diminutive creatures packed quite an atmospheric punch.
The Primordial Soup
Is there a hyperbole or superlative that can begin to capture how unlikely was the appearance of life? I think not. Life's emergence rivals, perhaps even surpasses, the sudden materialization of the universe itself, conjured ex nihilo over 10 billion years ago. But what is life? How can we characterize this special case of matter taking on such extraordinary abilities? Maybe I make too much of it. Perhaps life is, as a character drolly referred to it in Thomas Mann's The Magic Mountain, merely "an infectious disease of matter." But how did it start? How did inanimate molecules begin to copy themselves and persevere?
That's a question we have no detailed answer to. But we have a very informed general idea, and it goes something like this — life came from bad weather. It didn't begin on a calm planet with tranquil seas and light breezes; it started on a planet that had terrific storms, howling winds and waves hundreds of feet tall. Self-assembling molecules began to arrange themselves in the midst of volcanic eruptions and meteorite bombardments. They flourished in an agitated saline broth constantly electrified by lightning, scalded with lava and cooked by a young sun wielding dangerously high UV levels.
Alexander Oparin was the first scientist to envisage this alchemical, Frankensteinian jump-start to life. In his 1924 "primordial soup" theory, he speculated that ultraviolet light acting on elemental gases, liquids and solids in an oxygen-free environment created organic proteins, the basic constituents of life. Almost 30 years later, in 1953, Oparin's theory was vindicated by an ingenious and now famous laboratory experiment by Nobel laureate Harold Urey and his graduate student Stanley Miller. At the University of Chicago, they filled a series of beakers, glass tubing and electrical circuits with hydrogen, water and methane, seeking to reproduce the conditions on our planet as they were four billion years ago. For days, they zapped their broth with electricity to simulate the storms that raged across the ancient seas, and after only a week, 15 percent of the carbon in this shocked concoction had formed no less than 23 amino acids, the building blocks of complex life. They had proven that organic molecules could indeed have formed spontaneously from inorganic constituents.
There have been many critics of the theory since then, particularly creationists, of which one was my family's plumber, Gordon Lane. I remember watching him melt solder with a blowtorch to join two copper pipes under our bathroom sink when I was eight years old. Often he would stay for supper. He was a Jehovah's Witness with a Mensa IQ and, like my father, had a penchant for puns. He loved nothing better than to take on our agnostic family in fundamental arguments. He was particularly dismissive of the primordial soup explanation for the beginning of life. He knew the odds against assembling a simple cell were catastrophically immense, and he was right. A simple protein like collagen, for example, is a molecule with 1,055 sequences that have to be in exactly the right order to function. And that's just one of several hundred thousand proteins. He used a wonderful metaphor to underscore his argument against random mutations creating life-forms. "If I stood outside an auto wrecker's yard and threw rocks into the yard over the fence," he used to say, "I could stand there and throw rocks for a million years, and I'd never hear the sound of a car starting up on the other side of the fence."
Yet despite its critics, Oparin's theory still stands, mainly because there are so many naturally occurring amino acid proteins. It would appear that given enough time, in this case hundreds of millions of years, proteins could indeed have combined and gradually become more complex. Recently, the Miller-Urey experiment has been successfully revisited. Other researchers have added volcanic gases to the Miller-Urey mixture and they too have brewed amino acids as a result. Not only that, it appears that we have been importing some of our complex proteins, including amino acids, from outer space. A large meteorite that fell in Murchison, Australia, in 1969 was found to contain 20 types of amino acid with no terrestrial source. So if you add the infall of amino acids from meteorites and comets to the stew of proteins already brewing in the early oceans, then you have quite a broth of life-builders in the primordial soup.
But self-replicating proteins had to be reinvented many times over millions of years before one of them, again by chance, developed a membrane that gave it protection from the elements. It was the extraordinary good fortune of these proteins to emerge on a watery planet that orbited the sun at just the right distance — the Goldilocks Zone, as atmospheric scientists refer to it. Too close to the sun, like Venus, and water boils away; too far from the sun, like Mars, water freezes. And water, as it turns out, has a particular quality that jump- started intracellular transport and cell membranes.
Water is bipolar, not in the manic depressive sense, but in the electrical sense. One side of a water molecule has a positive charge, the other a negative charge. Like little magnets, they attract each other with just enough strength to stay grouped together but not so much as to turn into a solid. This makes water an excellent transport medium for dissolved minerals and chemicals. It's also why it has a meniscus, that layer of surface tension at the top of water you can see in an aquarium. Water molecules attract each other in all directions in deeper water, but at the surface they can only be attracted across the surface and downward, which aligns them into a temporary membrane. The first self-encapsulated proteins mimicked this property. Their membranes had water-loving molecules on the outside and water-repelling molecules on the inside. These joined in a circle to form a membrane that protected the delicate, nanomachinery of their interior.
Self-encapsulated proteins flourished and grew more complex, eventually crossing the line by which we define life a little more than four billion years ago, less than 500 million years after the birth of the planet. These first simple, single- cell creatures were called prokaryotes and used sulfates as a source of energy. They were anaerobic, meaning they flourished in the absence of free oxygen. Prokaryotes dominated the oceans for hundreds of millions of years. During their reign, unicellular life established itself and achieved planetary distribution, though a time traveler standing on the shore of that ancient ocean would see no evidence of life. Only a microscope would reveal the ubiquity of unicellular organisms. Anyway, you wouldn't have much time to collect samples because three billion years ago, when prokaryotic life had become firmly established, the environment was anything but temperate.
A Typical Weather Report Three Billion Years Ago
First of all, the days were shorter. The Earth was spinning three times faster than it is now. A full day-night cycle was eight hours long, with a little more than four hours of darkness and four hours of pale sunlight because, even though UV levels were high, the young sun was fainter than today. You'd definitely have needed an oxygen mask — the atmosphere was almost entirely composed of carbon dioxide. And when the moon rose, you'd have known it. It was much closer to Earth and would have appeared 12 times larger than it does now. Today, the moon looks to be the same size as a dime held at arm's length. Three billion years ago, it would have looked the size of a cantaloupe. And you could hardly have called it moonrise. It would leap above the horizon and careen into the heavens, wheeling dizzily through the sky. Shadows cast by the moon, or the sun for that matter, would stretch and slide visibly as you watched them, like a time-lapse film.
Certainly, moonrise over the primeval ocean would have been a wondrous sight, but you wouldn't want to have been anywhere close to the water. In fact, the only safe vantage on the ocean would have been from the summit of a mountain somewhat inland. The tides were 1,000 feet high and arrived as quickly as a tsunami. Those prokaryotes living in the primeval oceans mustn't have had much rest.
Evolution was a slow-acting force at this time, but after many hundreds of millions of years, a momentous change finally did occur, a chance mutation that led to a new single-celled life-form, one that had a terrific edge over its anaerobic predecessors. Cyanobacteria. This newcomer took advantage of the relative abundance of carbon dioxide in the atmosphere as well as the sunshine. Cyanobacteria combined carbon dioxide and sunlight with water to produce carbohydrates for food. In essence, they survived exactly as plants do today. They were green, and, like plants, their unique metabolic process had a simple waste product — oxygen. Free oxygen, that formerly minor player in Earth's oceans and atmosphere, became a major one somewhere between 2.8 and 2.5 billion years ago.
Tiny Terraformers
If humans eventually colonize other planets, they will rely on giant factories to process alien atmospheres into something breathable in a process called terraforming. Plans are already being drawn for the eventual terraforming of Mars. These mega-engineering projects will easily surpass any earthly achievements — the Pyramids, the Panama Canal, the Great Wall of China — but we have yet to build them.
Fortunately for us, Earth has already been terraformed. But huge machines didn't process our atmosphere; cyanobacteria did. Slightly less than three billion years ago, the dominant type of cyanobacteria lived in coral-like colonies called stromatolites. They formed knobby reefs in the oceans where they quietly bubbled away, releasing oxygen into the water. If you could stroll along the beach of a primeval ocean, you'd likely come upon wide, submerged ledges of these low reefs sitting just offshore, stretching alongside the ancient seaside as far as the eye could see. The air would be warm, but you'd still need an oxygen mask. The stromatolites and their allies had to pump out oxygen for hundreds of millions of years before the overflow leaked into the atmosphere.
Surprisingly, stromatolites have survived. They are the kings of living fossils. Nothing — not the tuatara lizard of New Zealand, unchanged for 100 million years, or even the coelacanth, the missing-link fish from Madagascar that looks today as it did 350 million years ago, or the sponges, with their billion-year heritage — holds a candle to the stromatolites, unchanged for 2.8 billion years. There is a thriving colony of them in Shark Bay on the west coast of Australia and another at Exuma Cays in the Bahamas. These unprepossessing, gray, blob-like rocks smeared with a thin layer of cyanobacterial cells — so small that one billion are contained in a square foot — were the dominant life-form on our planet for almost two billion years. It was almost as if life had stopped evolving.
The Oxygen Catastrophe
But while cyanobacteria were transforming the oceans, they were also killing off their predecessors. Oxygen was lethal for the pioneers of life on Earth — the prokaryotes and extremophiles that had flourished for a billion years. In a mere 300 million years, cyanobacteria had saturated the oceans with so much oxygen that 99 percent of the prokaryotic organisms died out in one of the greatest extinction events the Earth has known. Only a few survived at the bottom of oceans near thermal vents or buried under mud where oxygen could not find them. As a result, the Great Oxygenation Event is also called the Great Oxygenation Extinction Event or, more briefly, the Oxygen Catastrophe. Even so, the prokaryotes had a good run, dominating the planet for almost 400 million years. Their descendants still subsist today, buried deeply in rock or mud.
But those little bubbles of oxygen that cyanobacteria released not only exterminated most of the prokaryotes, they also initiated a vast, irreversible geochemical reaction. Underwater iron deposits began to rust for the first time in Earth's history. The oceans must have been tinged orange for millions of years during this great undersea rust bloom. The oxidizing iron left telltale bands in sedimentary rock that was laid down at the bottom of these newly oxygenated oceans. Today, geologists commonly find three-billion-year-old rocks with red band formations that contain layers of rust-dyed sediment, evidence of the first free oxygen on our planet.
Mars on Earth
For 300 million years, the cyanobacteria's steady output of oxygen was absorbed by iron and buried in ocean sediments. When all the available iron had bonded with oxygen, around 2.5 billion years ago, there was nowhere for the excess oxygen to go, so it bubbled out of the water and into the atmosphere. Oxygen levels in the atmosphere began to rise precipitously, triggering another oxidation event — all the exposed iron on dry land started to rust. Just like the banded marine sediments in ancient seafloor strata, these land-based layers can be plainly seen in rocks dating from this period.
(Continues…)
Excerpted from "18 Miles"
by .
Copyright © 2018 Christopher Dewdney.
Excerpted by permission of ECW PRESS.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Table of Contents
Introduction
1. Stormy with a Chance of Life: The Improbable Birth of Our Atmosphere
2. The Wild Blue Yonder: The Layers of the Atmosphere
3. Cloud Nine: Inside the Misty Giants above Our Heads
4. The Poem of Earth: Rain
5. The Secret Life of Storms
6. Katrina: The Life Story of a Hurricane
7. Palace of the Winds
8. Which Way the Wind Blows: The Story of Weather Forecasting
9. Apollo’s Chariot: The Seasons
10. A Cold Place: Winter and the Ice Ages
11. Climate Change Past and Present
12. Weather That Changed History
Postscriot: Fire, Water, Earth, Air
Appendix: Measurement Conversions
Selected Bibliography
Acknowledgments
Index