Sunday Book Excerpt from "Threshold: The Crisis of Western Culture"

The Iroquois Confederacy had a “law” that every decision had to be made in the context of its impact on the seventh subsequent generation...

First edition of Threshold: The Crisis of Western Culture

Imagine if scientists succeeded at genetically modifying a bacteria that’s found on the roots of almost all plants on Earth — and it was modified in a way that caused it to kill those plants. At the most extreme, if it got loose it could wipe out most plant life on Earth — and that almost happened just a few decades ago!

At their core, all these crises and near-misses are really cultural as much as technological problems. That assertion runs through this book, Threshold: The Crisis of Western Culture.

Chapter 1

The Environment

Too many people don’t know that when they harm the earth they harm themselves, nor do they realize when they harm themselves, they harm the earth

—Rolling Thunder (Cherokee, died 1997)

Land and Water

It seemed like an ordinary day and an ordinary science project. Little did Dr. Elaine Ingham and her Ph.D. student Michael Holmes know that the simple project they were doing could have prevented the end of most complex life on earth. But it may well have.

A tree is a living organism—it’s a complex entity that requires continual interaction with billions of other entities to survive. Trees can bring nutrients in only through their roots; bacterial and fungal colonies on those roots predigest the minerals in the soil and then make available to the tree the resulting nutrient soup. Some of these colonies are so complex in their interaction with the soil that there is as much growing under the ground—separate from the tree but necessary for its life—as there is above the ground.

Your body contains trillions of bacteria, fungi, and viruses, most benign, many absolutely necessary for life (we know best of the intestinal bacteria), as does the body of every other mammal. We’re mind-bogglingly complex, with more than a trillion cellular interactions happening in our bodies every second of every day.

And, of course, we depend on the food we eat, which all begins in the soil (even the animals we eat have to eat plants, which are grown in the soil).

As Dr. Ingham noted in a paper she wrote about hers and Holmes’s experiment, “Agricultural soil should have 600 million bacteria in a teaspoon. There should be approximately three miles of fungal hyphae in a teaspoon of soil. There should be 10,000 protozoa and 20 to 30 beneficial nematodes in a teaspoon of soil.”

Soil is complex stuff. And one of the bacteria found in soil all over the planet, and on the roots of most plants all over the planet, is a common and ubiquitous little organism named Klebsiella planticola. It’s everywhere—every plant ever tested for it, anywhere on earth, has been found to carry Klebsiella on its roots.

Thus, a small company based out of Europe had come to Oregon—where there are not the strict laws Europe has in place regarding the dispersal of genetically modified organisms in to the environment—with a really neat idea. The world has a lot of plant waste. Sugarcane and wheat stalks, for example, are often burned after the sugar and wheat berries, respectively, have been removed. This burning throws carbon, soot, and all sorts of pollutants into the air.

But what if all that cellulose, those leftover canes and stalks, could be converted into alcohol? If it could be done cheaply and easily, it would take care of a waste problem and provide a great new fuel source.

So this company came to Oregon and purified a common local strand of Klebsiella bacteria they found in the soil. Using the tools of genetic engineering, they modified the DNA of this Klebsiella to produce alcohol, inserting into its DNA the gene fragment in yeast that causes it to “ferment” things. Because Klebsiella grows on cellulose (unlike fermenting yeast, which grows on sugars), it could be tossed straight into a vat with a few tons of plant waste and, poof, within a few days you’d have hundreds of gallons of alcohol.

The company’s founders had visions of dollars in their eyes, and were preparing to field-test their newly modified organism within a matter of months (since at that time the George H. W. Bush administration was actively working against any sort of regulation of genetically modified organisms through Vice President Dan Quayle’s ”Competitiveness Council.”

Dr. Ingham’s student needed a project to work on as part of his doctoral thesis, so he decided to test the toxicity of this newly minted Klebsiella bacteria. In an article she wrote in 1999, Dr. Ingham described what happened next:

One of the experiments that Michael Holmes did for his Ph.D. work was to bring typical agricultural soil into the lab, sieve it so it was nice and uniform, and place it in small containers. We tested it to make sure it had not lost any of the typical soil organisms, and indeed, we found a very typical soil food web present in the soil. We divided up the soil into pint-size Mason jars, added a sterile wheat seedling in every jar, and made certain that each jar was the same as all the jars.

Into a third of the jars we just added water. Into another third of the jars, the not-engineered Klebsiella-planticola, the parent organism, was added. Into a final third of the jars, the genetically engineered microorganism was added.

The wheat plants grew quite well in the Mason jars in the laboratory incubator, until about a week after we started the experiment. We came into the laboratory one morning, opened up the incubator and went, “Oh my God, some of the plants are dead. What’s gone wrong? What did we do wrong?”

We started removing the Mason jars from the incubator. When we were done splitting up the Mason jars, we found that every one of the genetically engineered plants in the Mason jars was dead. Wheat with the parent bacterium, the normal bacterium, was alive and growing well. Wheat plants in the water-only treatment were alive and growing well.

It turns out that the beneficial contribution Klebsiella makes to plants’ roots is similar to that of intestinal bacteria in humans—it produces a slime layer that protects the roots while also helping the bacteria adhere to the roots and move nutrients into the root systems.

But when the Klebsiella on the wheat in the lab began producing alcohol (as it had been genetically modified to do), Dr. Ingram and Mr. Holmes found it was doing so at a level of around seventeen parts per million—almost twenty times more alcohol than a plant could withstand on its roots without dying.

As Dr. Ingham wrote, “The engineered bacterium makes the plants drunk, and kills them.”

Needless to say, when these results were communicated to the company, it pulled the experiment. But consider the possible outcome if they’d gone ahead and created a fermentation vat, fermented a bunch of agricultural waste, and then tossed the sludge out as fertilizer for a field (as is normally done with yeast fermentation to produce alcohol).

“Think about a wine barrel or beer barrel after the wine or beer has been produced,” Dr. Ingham wrote.

There is a good thick layer of sludge left at the bottom. After Klebsiella-planticola has decomposed plant material, the sludge left at the bottom would be high in nitrogen and phosphorus and sulfur and magnesium and calcium-all of those materials that make a perfectly wonderful fertilizer. This material could be spread as a fertilizer then, and there wouldn’t be a waste product in this system at all. A win-win-win situation.

But my colleagues and I asked the question: What is the effect of the sludge when put on fields? Would it contain live Klebsiella planticola engineered to produce alcohol? Yes, it would. Once the sludge was spread onto fields in the form of fertilizer, would the Klebsiella-planticola get into root systems? Would it have an effect on ecological balance; on the biological integrity of the ecosystem; or on the agricultural soil that the fertilizer would be spread on?

As her experiment demonstrated, it would and it did. And if that organism, or one like it, had gotten out into the wild, and if it turned out to be (or mutated into) a highly “contagious” bacterium, in the most extreme (albeit unlikely) possibility, it could have infected and then killed every root-based life form on the planet.

As Dr. Ingham wrote, using more scientific jargon: “From that experiment, we might suspect that there’s a problem with this genetically engineered microorganism. The logical extrapolation from this experiment is to suggest that it is possible to make a genetically engineered microorganism that would kill all terrestrial plants. Since Klebsiella planticola is in the root system of all terrestrial plants, presumably all terrestrial plants would be at risk.”

The Earth Is a Single Organism

Just as a tree or a person is a seemingly independent and single organism but is made up of a complex web of interacting living parts, so, too, is our planet. Earth’s atmosphere is a thin layer that’s mostly just five miles high, a distance that if laid flat you could walk from one end of to the other in a bit more than an hour. The surface of the land masses that aren’t raw mountainous rock, sand desert, or covered by glaciers or permafrost, is mostly topsoil.

While changes in our atmosphere (from violent weather to evaporating glaciers to spreading deserts) may well, in and of themselves, make much of the planet hostile to human life, at the same time we are destroying the primary source of our food: soil. It can take up to a thousand years for natural erosion and the action of plant roots (primarily trees) to break rock down to form a single inch of topsoil. When Europeans first arrived in North America the average depth of the topsoil was twenty-one inches, and it was rich in the types of symbiotic microorganisms necessary for plant roots to absorb minerals from the soil.

Today North America averages around six inches of topsoil, and most of it is exhausted of nutrients and much is devoid of life. We add four compounds (potassium, calcium, nitrogen, and phosphates) back in as “fertilizer,” because they are the absolute minimum necessary for plants to grow, but the whole spectrum of “trace minerals” and associated nutrients is now largely lost from our soil, and thus from our food.

Consider iron, which our body needs—mostly to make hemoglobin, the red stuff in our red blood cells that allows them to transport oxygen around the body. Without enough iron (a problem particularly for menstruating women), anemia sets in—people become lethargic, don’t sleep well, become depressed and tired, often gain weight, and are vulnerable to a wide variety of diseases. Spinach is a plant especially adept at absorbing iron from the soil, and thus has historically been considered a good source of iron for humans (remember Popeye?). Back in 1948, the U.S. government measured iron in spinach from around the country and found the average amount contained was 158 milligrams in 100 grams (a bit less than a quarter pound) of spinach. By 1965, the U.S. national average level of iron in spinach was 28 milligrams per 100 grams. And the last time there was an official survey, in 1973, the figure had dropped to 2.2 milligrams per 100 grams.

Cobalt is a trace mineral the body needs to process vitamin B12, the vitamin that keeps the blood vessels that carry the red blood cells strong and intact. A deficiency of B12 is called pernicious anemia, and the diagnosis (and use of B12 shots) is increasing every year in the United States. That could be because many vegetables now tested for cobalt show no trace—zero—of the mineral that once was an ordinary part of most of our food, albeit in very minute amounts. [1]

When Lewis and Clark reached the Willamette, the river on which I now live in Oregon, William Clark wrote in his journal on October 17, 1805, “The number of dead Salmon on the Shores & floating in the river is incredible to say,” as a result of an Indian tribe in the midst of a fishing expedition. “And they have only to collect the fish, Split them open, and dry them on their Scaffolds on which they have great numbers. … I saw great numbers of Salmon on the Shores and floating in the water. …The water of this river is clear, and a Salmon may be seen at the depth of 15 or 20 feet.”

Here in the Pacific Northwest, where I live, salmon, like the topsoil, are vanishing. In 2008, the three Pacific states declared a salmon emergency, and forbade salmon fishing along most of the coast because the numbers had fallen so badly.

But it’s not just the salmon and not just the Pacific Northwest. In 2006, the prestigious peer-reviewed journal Science published an article by Dr. Boris Worm, titled “Impacts of Biodiversity Loss on Ocean Ecosystem Services,”[i] which detailed the collapse of fisheries all over the world. Worm and his co-authors defined “collapse” as being when a part of the ocean where a particular fish species is plentiful and fished from has hit about 10 percent of its natural/original population. Once any species in any part of the world collapses below that 10 percent threshold, the chances of its recovering become slim and the species is often on the way to extinction.

Recently, my wife, Louise, and I had lunch with some friends at Corbett Fish House, a popular fish restaurant in Portland. On the table, among the sugar and sweetener packets, was a sugar packet–size three-page directory published by the Monterey Bay Aquarium that listed the commercial fish species around the world that were endangered (Chilean sea bass, Atlantic cod, queen conch, gulf corvina, king crab, Atlantic flounder/sole, grenadier, grouper, haddock, white hake, halibut, striped marlin, monkfish), and thus not carried by that particular restaurant. It’s a good start—publicizing the problem at the consumer level—but nothing close to a solution. The reality is that this is not just a problem of our running out of popular commercial fish species to consume; it’s a problem of biodiversity.

As species vanish, the web of life becomes less rich. In a rather simplified simile, it’s like losing organs from your body. The salmon goes, a kidney is gone. Whales vanish, a lung is gone. Because—like the organs of our body—each fish is part of the larger whole of the ocean; its loss reduces the living viability of the ocean.

A species may eat a particular bacterium phytoplankton, smaller fish, or plant in an area. Lacking a predator, those items/populations will overgrow and alter the area’s biology, overwhelming and driving to extinction dozens or hundreds or thousands of other local species. Or, like the salmon being eaten by bears and thus moving ocean nutrients into the forests in the form of bear poop, a species may recycle into its local environment essential nutrients; without that species, those nutrients will now be lacking.

In Science, Dr. Boris Worm and eleven other scientists from Canada, the United States, Panama, and Sweden, reported on all sixty-four large marine ecosystems worldwide, which collectively have produced 83 percent of global fisheries yields over the past fifty years. They found fisheries all over the world in or on the verge of collapse.

As Dr. Worm told New York Times writer Cornelia Dean,[ii] “We looked at absolutely everything—all the fish, shellfish, invertebrates, everything that people consume that comes from the ocean, all of it, globally.” Almost a third, 29 percent, of all species were at or beyond the point of collapse, and all others were moving in that direction.

As Dean reported:

What he saw, he said, was “just a smooth line going down.” And when he extrapolated the data into the future “to see where it ends at 100 percent collapse, you arrive at 2048.”

“The hair stood up on the back of my neck and I said, ‘This cannot be true,’” he recalled. He said he ran the data through his computer again, then did the calculations by hand. The results were the same.

“I don’t have a crystal ball and I don’t know what the future will bring, but this is a clear trend,” he said. “There is an end in sight, and it is within our lifetimes.”

Jonathan Lash, president of the World Resources Institute, summed up the crisis neatly in a 2006 speech to the John Hopkins School of Advanced International Studies: “Our technology has become so advanced that we have been able to track fish in places we did not know they existed, harvest them to exhaustion, and then move on to new areas and new species.” The result of this, Lash noted, is that, “In a single generation, we have essentially exhausted the wealth of the seas. Our fisheries are no longer sustainable, they are in constant decline.”[iii]

With a human population pushing seven billion and the number of humans who eat a meat/fish-rich diet (versus mostly a plant-rich diet) moving from under a billion to more than three billion (each consuming between ten and thirty times the basic plant protein necessary to feed the livestock, and each producing between ten and thirty times the waste upstream as the result of factory and fish farming), the capacity of the planet to carry this huge burden of human flesh is rapidly becoming exhausted.

As with wild fish, wild areas are vanishing, along with their incredibly species-rich habitats, leading to the loss of more than a hundred species a day worldwide. Rain forests—the richest source of biodiversity on land, the source of 20 percent of the planet’s oxygen, and a major regulator of the world’s weather—once covered 14 percent of the planet’s land surface; they now cover a mere 6 percent and, without major interventions, may be entirely gone (or thinned to the point of practical uselessness) within thirty to forty years.

So rich in species are our rain forests that such a loss will wipe out nearly half of all the estimated thirty million species of plants, animals, and microorganisms on the Earth (so far we’ve cataloged only around two million species). There goes another lung, another kidney, and the planet’s liver. And with them go potential pharmaceuticals for humans—while over a quarter of all our pharmaceutical drugs are derived from plants or organisms that originated in rain forests, we’ve examined for pharmaceutical usefulness fewer than 1 percent of the known tropical species.

As the rain forests go, so go the few humans who learned, over tens of thousands of years of trial-and-error experience, to coexist with the rain forests. In the Amazonian rain forest alone, it’s estimated that at the time Europeans first landed on South and North America, around five centuries ago, there were around ten million humans living an aboriginal existence. Today that human population—mostly because of loss of habitat (rain forest)—has shrunk to fewer than two hundred thousand. As more than nine million humans, representing thousands of tribes, cultures, and languages, have vanished from that rain forest, lost along with them, their language, and their culture is their knowledge of what plants, animals, and other things in the rain forest may help or heal humans. We’re cutting out our heart and part of our brain.

The Atmosphere

On February 24, 2007, an expedition across the polar north funded in part by the National Geographic Society and Sir Richard Branson set out on a seventy-eight-day journey.[iv] Guided by local Inuit hunters and trackers, they found that the environment there was changing—warming—at about twice the rate of the more temperate and equatorial regions of the world. The result was multifold.

Landmarks—usually giant mountains of ice that had been known by the Inuit people (and even named and the subject of folklore) for tens of thousands of years—are moving, changing, and in many cases vanishing altogether. The open sea (which absorbs about 70 percent of the solar radiation that hits it) is quickly replacing polar ice (which reflects back out into space about 70 percent of the solar radiation that hits it). Animals never before seen in the region—finches, dolphins, and robins, for example—are moving farther north as their migratory patterns are pushed by global climate change, while animals that have lived in the region for tens of thousands of years (most notably the polar bear) are facing extinction, as there is no place “farther north” for them to go to find the environment to which millions of years of evolution have adapted them.

Meanwhile, on the other end of the planet, the collapse of two massive ice sheets, the Larkin A and B shelves, on the edge of the Antarctic continent, have provided National Geographic Society and other scientists a glimpse of previously unknown species.[v] For millennia the Larsen A and B shelves provided a ceiling to a unique undersea environment, and the loss of these two shelves, totaling more than 3,900 square miles of polar ice, has exposed this world to man for the first time. Marine biologists found a poisonous sea anemone that attaches itself to the back of a snail, protecting it from predators; meanwhile the snail provides the movement necessary for the anemone to find food. They found a giant barnacle, and a shrimp-like crustacean.

It remains to be seen if the changes in the temperatures and levels of light reaching the area will now also cause the extinction of these and other newly discovered species.

How Much Power Is a Watt?

When I was thirteen years old, I got my novice and then my general amateur radio operator’s license from the Federal Communications Commission. It required passing what was, in 1964, a pretty hefty test on electronics, and one of the formulas I remember from the test is that one ampere (a measure of the “volume” of electricity) passing through a wire at one volt (a measure of the “pressure” of electricity) can do the amount of “work” (e.g., heat a wire, turn a motor, light a bulb) of one watt. The math is pretty simple: W = EI, where W is watts, E is volts, and I is amperes.

One watt of “work,” or “heat,” may not seem like a lot. After all, a typical electric room heater runs between 1,000 and 1,500 watts (the maximum capacity of a typical American household electrical outlet is 110 volts at 20 amperes, or 2,200 watts). A toaster may run as much as 1,800 watts. And a 60-watt light bulb, while it can throw enough light to illuminate a room, as well as getting hot enough to burn your hand, doesn’t seem like it’s going to melt the seas or change the face of the Earth.

Yet in June of 2005, the top climate scientist for NASA’s Goddard Institute for Space Studies, James Hansen, along with fourteen other scientists representing the Jet Propulsion Laboratory, the Lawrence Berkeley National Laboratory, Columbia University’s Department of Earth and Environmental Sciences and its Earth Institute, and SGT Incorporated published such a startling research paper[vi] in the peer-reviewed journal Science that the scientific community of the entire world was shaken.

They were looking at how much more “power”—expressed in watts per square meter (W/m2)—the Earth was absorbing from the Sun versus the amount it lost to radiation into outer space. Historically, the two numbers have been in balance, leaving the Earth at a relatively even temperature over millions of years. Their concern was that if the Earth began absorbing significantly more energy than in times past, this extra heat would drive a “climate forcing” that could produce radical changes in the world in which we live—changes that could even render it unfit for human habitation over a period as short as a few decades or centuries.

Looking at measurements of gasses in the atmosphere, and thousands of temperature-measurement points, from 1880 to today, they found that during this time the “thermal inertia”—the movement toward global warming—is now about 1.8 W/m2 over the entire surface of the Earth. This means that every square meter—roughly the surface size of the desk I’m working on right now—of the planet is absorbing 1.8 W/m2 more energy than it was in 1880.

A quarter-acre house lot (a pretty good-size lot these days) represents 1,012 square meters of planet surface. At 1.8 watts per square meter, that’s roughly 1,800 watts of energy—about the same as produced by the electric room heater referenced earlier. For every quarter acre of the planet.

As Hansen et al. point out in their Science article, up until recently (the past 150 years) the Earth had largely been stable in the amount of heat it absorbed. The increase wasn’t 1.8 W/m2 over a 128-year period, but zero W/m2 over at least a 10,000-year period. If the last 10,000 years had simply been 1 W/m2 higher (not the 1.8 W/m2 we’re seeing today), the surface temperature of the world’s oceans today would not be roughly 59 degrees Fahrenheit, but 271 degrees Fahrenheit. Water boils at 212 degrees Fahrenheit, which means that much of our oceans would simply have boiled off into the atmosphere, increasing heat-trapping atmospheric moisture, thus increasing the temperature even more. Our planet would not be even remotely habitable by humans—or most life forms alive today.

Since 1880, we’ve been throwing greenhouse gasses—particularly carbon dioxide and methane—into the atmosphere at rates the planet hasn’t seen since the early, heavily volcanic days prior to the dinosaurs. Thus the sea ice is melting, corals are dying/bleaching, sea life is dying/moving, and the ocean’s currents are changing (which alters our weather—seen a good-size tornado, cyclone, or hurricane recently?). And eventually—and maybe soon—that energy will begin to spill out of what Hansen refers to as the storage “pipeline” of the oceans, and the killing of life on land—the expanding deserts, vanishing glaciers, drying rivers and lakes—will speed up to astonishing and human-life-threatening levels.

Back in 2005—before the massive ice sheet breakups and the open water of the Arctic were visible, Hansen suggested we look for these as signs that the added wattage the planet was absorbing might be tipping us into a forward-crash of spiraling temperatures that would be impossible to stop. In the cold language of science, he and his colleagues wrote in that Science article:

The destabilizing effect of comparable ocean and ice sheet response times is apparent. Assume that initial stages of ice sheet disintegration are detected. Before action to counter this trend could be effective, it would be necessary to eliminate the positive planetary energy imbalance, now 0.85 W/m2, which exists as a result of the ocean’s thermal inertia. Given energy infrastructure inertia and trends in energy use, that task could require on the order of a century to complete. If the time for a substantial ice response is as short as a century, the positive ice-climate feedbacks imply the possibility of a system out of our control.

Three years later, on April 7, 2008, in a statement that went way beyond anything even Al Gore was predicting in his 2005 book and movie An Inconvenient Truth, Hansen and a group of scientists submitted a new article to Science. While Gore was largely concerned with rising oceans and spreading deserts, Hansen et al. were looking at the possibility of the extinction of most complex life forms on the planet if we don’t quickly get our atmospheric CO2 levels down below where they were twenty-five years ago. Their article, “Target Atmospheric CO2: Where Should Humanity Aim?”, though written in dense scientific jargon, included two frighteningly important sentences, in language any average non-scientist could understand:

If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm [parts per million] to at most 350 ppm. …If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects.

We are, Hansen et al. suggest, near the point where our use of carbon-based fossil fuels could throw the planet so out of balance that eventually the oceans will heat up to the point that they’re uninhabitable for current complex life forms, and much of the complex life as we know it will vanish. If this drastic worst-case scenario event were to happen, it could take billions of years of evolution for the deep-sea and single-cell organisms that survived to evolve back into anything resembling the complex life forms we’re familiar with (including ourselves).

The paper concludes:

Present policies, with continued construction of coal-fired power plants without CO2 capture, suggest that decision-makers do not appreciate the gravity of the situation. We must begin to move now toward the era beyond fossil fuels. Continued growth of greenhouse gas emissions, for just another decade, practically eliminates the possibility of near-term return of atmospheric composition beneath the tipping level for catastrophic effects.

The most difficult task, phase-out over the next 20–25 years of coal use that does not capture CO2, is herculean, yet feasible when compared with the efforts that went into World War II. The stakes, for all life on the planet, surpass those of any previous crisis. The greatest danger is continued ignorance and denial, which could make tragic consequences unavoidable.

In 2000, according to the Intergovernmental Panel on Climate Change (IPCC), 6.4 billion tons of CO2 were poured into our atmosphere by human activity, with about 5.5 billion tons coming from burning fossil fuels and 1.7 billion tons from the destruction of forests and rain forests worldwide. Just five years later, 2005, that 6.4 billion tons had jumped to 7.2 billion tons. All along, the oceans and land seem to be able to “sink out” or absorb only about 3.9 billion tons combined, leaving a net increase in CO2 in 2005 of around 3.3 billion tons.

As Hansen, et al. point out in their 2008 Science submission, unless we can reverse these numbers—turn them negative—long enough to go back down below 350 ppm, the human race (and most other mammals) may crash into a dead-end wall.

Other Greenhouse Gasses

And that’s just carbon dioxide. A methane molecule, like carbon dioxide, contains a single atom of carbon, but instead of attaching to it two atoms of oxygen (as with CO2), it attaches to it four atoms of hydrogen (CH4). The molecule is somewhat unstable: it will oxidize rapidly (burn) when exposed to high temperatures, and oxidize slowly (decompose into CO2 and H2O) in the atmosphere at a rate of about half of the total methane every seven years. (That’s the good news: methane will eventually wring itself out if we stop pushing it into the atmosphere.)

Natural gas is about 78 percent methane. But the biggest sources of it are decomposing vegetation and, literally, animal flatulence (farts). And we have a lot of very flatulent animals that we grow for human food.

For example, while there are more than six billion humans, there are more than twenty billion livestock mammals (pigs, cows, goats, sheep) and about sixteen billion chickens in the world, over 99 percent of them grown by humans as food for humans. The Food and Agriculture Organization of the United Nations (FAO) in a 2007 report[vii] noted that 37 percent of the world’s total methane production (and 9 percent of all CO2 and 65 percent of all nitrous oxide emissions) comes from our livestock. Because nitrous oxide is 296 times stronger than CO2 at global warming, and methane is about 23 times as potent as CO2, the combined greenhouse effect of our livestock worldwide is greater than the sum total of all our cars, trains, buses, trucks, ships, airplanes, and jets.