The Future: six drivers of global change Part 12

The neonicotinoids, which are neurotoxins similar in their makeup to nicotine, are widely used on corn seed, and the chemicals are then pulled from the seed into the corn plants as they grow. Commercial beekeepers, in turn, have long fed corn syrup to their bees. According to the U.S. Department of Agriculture's Agricultural Research Service, "Bee pollination is responsible for $15 billion in added crop value, particularly for specialty crops such as almonds and other nuts, berries, fruits, and vegetables. About one mouthful in three in the diet directly or indirectly benefits from honey bee pollination."

Bees, of course, play no role in the pollination of GM crops, because the engineered seeds must be purchased annually by farmers, and the bees' pesky habit of pollinating plants can introduce genes that do not fit into the seed company's design. According to The Wall Street Journal, the growers of a modified seedless mandarin threatened to sue beekeepers working with neighboring farms for allowing their bees to "trespa.s.s" into the orchards where the seedless mandarins were growing, out of worry that the seedless mandarins would be cross-pollinated with pollen from citrus varieties that have seeds. Understandably, the beekeepers protested that they couldn't control where their bees fly.

The global spread of industrial agriculture techniques has resulted in the increased reliance on monoculture, which has, in turn, accelerated the spread of resistance to herbicides and pesticides in weeds, insects, and plant diseases. In many countries, including the United States, all of the major commodity crops-corn, soybeans, cotton, and wheat-are grown from a small handful of genetic varieties. As a result, in most fields, virtually all of the plants are genetically identical. Some experts have long expressed concern that the reliance on monocultures makes agriculture highly vulnerable to pests and plant diseases that have too many opportunities to develop mutations that enable them to become more efficient at attacking the particular genetic variety that is planted in such abundance.

MUTATING PLANT DISEASES.

In any case, new versions of plant diseases are causing problems for farmers all over the world. In 1999, a new mutated variety of an old fungal disease known as stem rust began attacking wheat fields in Uganda. Spores from the African fields were carried on the wind first to neighboring Kenya, then across the Red Sea to Yemen and the Arabian Peninsula, and from there to Iran. Plant scientists are concerned that it will continue spreading in Africa, Asia, and perhaps beyond. Two scientific experts on the disease, Peter Njao and Ruth Wanyera, expressed concern in 2012 that it could potentially destroy 80 percent of all known wheat varieties. Although this wheat rust was believed to be reduced to a minor threat a half century ago, the new mutation has made it deadlier than ever.

Similarly, ca.s.sava (also known as tapioca, manioc, and yucca), the third-largest plant-based source of calories for people (after rice and wheat), is consumed mostly in Africa, South America, and Asia. It developed a new mutation in East Africa in 2005, and since then, according to Claude Fauquet, who is the director of ca.s.sava research at the Donald Danforth Plant Science Center in St. Louis, "There has been explosive, pandemic-style spread.... The speed is just unprecedented, and the farmers are really desperate." Some experts have compared this outbreak to the potato blight in Ireland in the 1840s, which was linked in part to Ireland's heavy reliance on a monocultured potato strain from the Andes.

Sixty percent of the U.S. corn crop was destroyed in 1970 by a new variety of Southern corn leaf blight, demonstrating clearly, in the words of the Union of Concerned Scientists, "that a genetically uniform crop base is a disaster waiting to happen." The UCS notes that "U.S. agriculture rests on a narrow genetic base. At the beginning of the 1990s, only six varieties of corn accounted for 46 percent of the crop, nine varieties of wheat made up half of the wheat crop, and two types of peas made up 96 percent of the pea crop. Reflecting the global success of fast food in the age of Earth Inc., more than half the world's potato acreage is now planted with one variety of potato: the Russet Burbank favored by McDonald's."

Although most of the debate over genetically modified plants has focused on crops for food and animal feed, there has been surprisingly little discussion about the robust global work under way to genetically modify trees, including poplar and eucalyptus. Some scientists have expressed concern that the greater height of trees means that the genetically modified varieties will send their pollen into a much wider surrounding area than plants like soybeans, corn, and cotton.

China is already growing an estimated thousands of hectares of poplar trees genetically modified to make the Bt toxin in its leaves in order to protect them against insect infestations. Biotech companies are trying to introduce modified eucalyptus trees in the U.S. and Brazil. Scientists argue that in addition to pest resistance, modifications might be useful in enabling trees to survive droughts and could modify the nature of the wood in ways that will facilitate the production of biofuel.

In addition to plants and trees, genetically modified animals intended for the production of food for humans have also generated considerable controversy. Since the discovery in 1981 of a new technique that allows the transfer of genes from one species into the genome of another species, scientists have genetically engineered several forms of livestock, including cattle, pigs, chickens, sheep, goats, and rabbits. Although earlier experiments that reduced susceptibility to disease in mice generated a great deal of optimism, so far only one of the efforts to reduce livestock susceptibility has succeeded.

However, the ongoing efforts to produce GM animals have already produced, among other results, spider silk from goats (described above) and the production of a synthetic growth hormone in dairy cattle that increases their milk production. Recombinant bovine growth hormone (rBGH), which is injected into dairy cows, has been extremely controversial. Critics do not typically argue that rBGH is directly harmful to human health, but rather, that evidence suggests it causes the increase of a second hormone known as insulin-like growth factor (IGF), which is found in milk from cows treated with bovine growth hormone at levels up to ten times what is found in other milk.

Studies have shown a connection between elevated levels of IGF and a significantly higher risk of prostate cancer and some forms of breast cancer. Although other factors obviously are involved in the development of these cancers, and even though IGF is a natural substance in the human body, the concerns of opponents have been translated into a successful consumer campaign for the labeling of milk with bovine growth hormone, which has significantly decreased its use.

Chinese geneticists have introduced human genes a.s.sociated with human milk proteins into the embryos of dairy cows, then implanted the embryos into surrogate cows that gave birth to the calves. When these animals began producing milk, it contained many proteins and antibodies that are found in human milk but not in milk from normal cows. Moreover, the genetically engineered animals are capable of reproducing themselves with the introduced genetic traits pa.s.sed on. At present, there is a herd of 300 such animals at the State Key Laboratory of Agrobiotechnology of the China Agricultural University, producing milk that is much closer to human breast milk than cow milk. Scientists in Argentina, at the National Inst.i.tute of Agribusiness Technology in Buenos Aires, claim to have improved on this process.

Scientists in the U.S. applied for regulatory approval in 2012 to introduce the first genetically engineered animal intended for direct consumption by human beings-a salmon modified with an extra growth hormone gene and a genetic switch that triggers the making of growth hormone even when the water temperature is colder than the threshold for normal production of growth hormone, resulting in a growth rate twice as fast as a normal salmon, which means it will reach market size in only sixteen months, compared to the normal thirty months.

Opponents of the "super salmon" have expressed concern about the possibility of increased levels of insulin-like growth factor-the same issue they have with milk produced from cattle injected with bovine growth hormone. And they expressed concern about these modified salmon escaping from their pens to breed with wild salmon, changing the species in an unintended way-much as the opponents of GM crops have expressed concern about the crosspollination of non-GM crops. Moreover, as noted in Chapter 4, farmed fish are fed fishmeal made from ocean fish in a pattern that typically requires three pounds of wild fish for each pound of farmed fish.

Scientists in Canada at the University of Guelph attempted to market genetically engineered pigs with a segment of mouse DNA introduced into their genome in order to reduce the amount of phosphorus in their feces. They called their creation Enviropigs because phosphorus is a source of algae blooms when dumped into rivers and creates dead zones where the rivers flow into the sea. They later abandoned their project and euthanized the pigs, in part because of opposition to what some critics have taken to calling "Frankenfood"-that is, food from genetically modified animals-but also because scientists elsewhere engineered an enzyme, phytase, which, when added to pig feed, accomplishes the same result hoped for with the ill-fated Enviropig.

In addition to the efforts to modify livestock and fish, there have also been initiatives over the last fifteen years to genetically engineer insects, including bollworms and mosquitoes. Most recently, a British biotechnology company, Oxford Insect Technologies (or Oxitec), has launched a project to modify the princ.i.p.al (though not the only) species of mosquito that carries dengue fever, in order to create mutant male mosquitoes engineered to produce offspring that require the antibiotic tetracycline in order to survive.

The larvae, having no access to tetracycline, die before they can take flight. The idea is that the male mosquitoes, which, unlike females, do not bite, will monopolize the females and impregnate them with doomed embryos, thereby sharply reducing the overall population. Although field trials in the Cayman Islands, Malaysia, and Juazeiro, Brazil, produced impressive results, there was vigorous public opposition when Oxitec proposed the release of large numbers of their mosquitoes in Key West, Florida, after an outbreak of dengue fever there in 2010.

Opponents of this project have expressed concern that the transgenic mosquitoes may have unpredictable and potentially disruptive effects on the ecosystem into which they are released. They argue that since laboratory tests have already shown that a small number of the offspring do in fact survive, there is an obvious potential for those that survive in the wild to spread their adaptation to the rest of the mosquito population over time.

Further studies may show that this project is a useful and worthwhile strategy for limiting the spread of dengue fever, but the focus on genetically modifying the princ.i.p.al mosquito that carries the disease poses a sharp contrast to the complete lack of focus on the princ.i.p.al cause of the rapid spread of dengue. The disruption of the Earth's climate balance and the consequent increase in average global temperatures is making areas of the world that used to be inhospitable to the mosquitoes carrying dengue part of their expanding range.

According to a 2012 Texas Tech University research study of dengue's spread, "Shifts in temperature and precipitation patterns caused by global climate change may have profound impacts on the ecology of certain infectious diseases." Noting that dengue is one of those diseases, the researchers projected that even though Mexico has been the main location of dengue fever in North America, with only occasional small outbreaks in South Texas and South Florida, it is spreading northward because of global warming.

Dengue, which now afflicts up to 100 million people each year and causes thousands of fatalities, is also known as "breakbone fever" because of the extreme joint pain that is one of its worst symptoms. Simultaneous outbreaks emerged in Asia, the Americas, and Africa in the eighteenth century but the disease was largely contained until World War II; scientists believe it was inadvertently spread by people during and after the war to other continents. In 2012, there were an estimated 37 million cases in India alone.

After it was spread by humans to the Americas, dengue's range was still limited to tropical and subtropical regions. But now, as its habitat expands, researchers predict that dengue is likely to spread throughout the Southern United States and that even northern areas of the U.S. are likely to experience outbreaks during summer months.

THIS CHAPTER BEGAN with a discussion of how we are, for the first time, changing the "being" in human being. We are also changing the other beings to which we are ecologically connected. When we disrupt the ecological system in which we have evolved and radically change the climate and environmental balance to which our civilization has been carefully configured, we should expect biological consequences larger than what we can fix with technologies like genetic engineering.

After all, human encroachment into wild areas is responsible for 40 percent of the new emerging infectious diseases that endanger humans, including HIV/AIDS, the bird flu, and the Ebola virus, all of which originated in wild animals forced out of their natural habitat by human encroachment, or brought into close proximity with livestock when farming expanded into previously wild regions. Veterinary epidemiologist Jonathan Epstein said recently, "When you disrupt the balance, you are precipitating the spillover of pathogens from wildlife to livestock to humans." Overall, 60 percent of the new infectious diseases endangering humans came originally from animals.

THE MICROBIOME.

We also risk disrupting the ecological system within our bodies. New research shows the key role played by microbial communities within (and on) every person. Indeed, all of us have a microbiome of bacteria (and a much smaller number of viruses, yeasts, and amoebas) that outnumber the cells of our bodies by a ratio of ten to one. In other words, every individual shares his or her body with approximately 100 trillion microbes that carry 3 million nonhuman genes. They live and work synergistically with our bodies in an adaptive community of which we are part.

Early in 2012, 200 scientists who make up the Human Microbiome Project published the genetic sequencing of this community of bacteria and found that there are three basic enterotypes-much like blood types-that exist in all races and ethnicities, and are distributed in all populations without any link to gender, age, body ma.s.s, or any other discernible markers. All told, the team identified eight million protein-coding genes in the organisms, and said that half of them have a function that the scientists still do not understand.

One of the functions performed by this microbiome is the "tutoring" of the acquired immune system, particularly during infancy and childhood. According to Gary Huffnagle, of the University of Michigan, "The microbial gut flora is an arm of the immune system." Many scientists have long suspected that the repeated heavy use of antibiotics interferes with this tutoring process and may do damage to the process by which the adaptive immune system learns precision in discriminating between invaders and healthy cells. What all autoimmune diseases have in common is the inappropriate attack of healthy cells by the immune system, which needs to learn to distinguish invaders from cells of the body itself. "Autoimmune" means immunity against oneself.

There is mounting evidence that inappropriate and repeated use of antibiotics in young children may be impairing the development and "learning" of their immune systems-thereby contributing to the apparent rapid rise of numerous diseases of the immune system, such as type 1 diabetes, multiple sclerosis, Crohn's disease, and ulcerative colitis.

The human immune system is not fully developed at birth. Like the human brain, it develops and matures after pa.s.sage through the birth ca.n.a.l. (Humans have the longest period of infancy and helplessness of any animal, allowing for rapid growth and development of the brain following birth-with the majority of the development and learning taking place in interaction with the environment.) The immune system has an innate ability at birth to activate white blood cells to destroy invading viruses or bacteria, but it also has an acquired-or adaptive-immune system that learns to remember invaders in order to fight them more effectively if they return. This acquired immune system produces antibodies that attach themselves to the invaders so that specific kinds of white blood cells can recognize the invaders and destroy them.

The essence of the problem is that antibiotics themselves do not discriminate between harmful bacteria and beneficial bacteria. By using antibiotics to wage war on disease, we are inadvertently destroying bacteria that we need in order to remain in a healthy balance. "I would like to lose the language of warfare. It does a disservice to all the bacteria that have co-evolved with us and are maintaining the health of our bodies," said Julie Segre, a senior investigator at the National Human Genome Research Inst.i.tute.

One important bacterium in the human microbiome, Helicobacter pylori (or H. pylori), affects the regulation of two key hormones in the human stomach that are involved in energy balance and appet.i.te. According to genetic studies, H. pylori has lived inside us in large numbers for 58,000 years. Up to 100 years ago, it was the single most common microbe in the stomachs of most human beings. As reported in an important 2011 essay in Nature by Martin Blaser, professor of microbiology and chairman of the Department of Medicine at NYU School of Medicine, however, studies have found that "fewer than 6 percent of children in the United States, Sweden and Germany were carrying the organism. Other factors may be at play in this disappearance, but antibiotics may be a culprit. A single course of amoxicillin or a macrolide antibiotic, most commonly used to treat middle-ear or respiratory infections in children, may also eradicate H. pylori in 2050% of cases."

It is important to note that H. pylori has been found to play a role in both gastritis and ulcers; the Australian biologist who won the 2005 n.o.bel Prize in Medicine for discovering H. pylori, Dr. Barry Marshall, noted, "People have been killed who didn't get antibiotics to get rid of it." Still, several studies have found strong evidence that people who lack H. pylori "are more likely to develop asthma, hay fever or skin allergies in childhood." Its absence is also a.s.sociated with increased acid reflux and esophageal cancer. Scientists in Germany and Switzerland have found that the introduction of H. pylori into the guts of mice serves to protect them against asthma. Among people, for reasons that are not yet fully understood, asthma has increased by approximately 160 percent throughout the world in the last two decades.

One of the hormones regulated by H. pylori, ghrelin, is one of the keys to appet.i.te. Normally, the levels of ghrelin fall significantly after someone eats a meal, thus signaling to the brain that it's time to stop eating. However, in people missing H. pylori in their guts, the ghrelin levels do not fall after a meal-so the signal to stop eating is not sent. In the laboratory run by Martin Blaser, mice given antibiotics sufficient to kill the H. pylori gained significant body fat on an unchanged diet. Interestingly, while scientists have long said that they cannot explain the reason why subtherapeutic doses of antibiotics in livestock feed increase the animals' weight gain, there is now new evidence that it may be due to changes in their microbiome.

The replacement of beneficial bacteria wiped out by antibiotics has been shown to be an effective treatment for some diseases and conditions caused by harmful microbes normally kept in check by beneficial microbes. Probiotics, as they are called, are not new, but some doctors are now treating patients infected with a harmful bacterium known as Clostridium difficile by administering a suppository to accomplish a "fecal transplant."

Although the very idea triggers a feeling of repugnance in many, the procedure has been found to be both safe and extremely effective. Scientists at the University of Alberta, after reviewing 124 fecal transplants, found that 83 percent of patients experienced immediate improvement when the balance of their internal microbiome was restored. Other scientists are now hard at work developing probiotic remedies designed to restore specific beneficial bacteria when it is missing from a patient's microbiome.

Just as we are connected to and depend upon the 100 trillion microbes that live in and on each one of us from birth to death, we are also connected to and depend upon the life-forms all around us that live on and in the Earth itself. They provide life-giving services to us just as the microbes in and on our bodies do. Just as the artificial disruption of the microbial communities inside us can create an imbalance in the ecology of the microbiome that directly harms our health, the disruption of the Earth's ecological system-which we live inside-can also create an imbalance that threatens us.

The consequences for human beings of the large-scale disruption of the Earth's ecological system-and what we can do to prevent it-is the subject of the next chapter.

* Olaf Sp.o.r.ns, a professor of computational cognitive neuroscience at Indiana University, was the first to coin the word "connectome." The National Inst.i.tutes of Health now have a Human Connectome Project.

The first effective polio vaccine was developed by Jonas Salk in 1952 and licensed for the public in 1955. A team led by Albert Sabin developed the first oral polio vaccine, which was licensed for the public in 1962.

Historians date the introduction of Hammurabi's Code to around 1780 BC.

Other scientists have mimicked the molecular design of spider silk by synthesizing their own from a commercially available substance (polyurethane elastomer) treated with clay platelets only one nanometer (a billionth of a meter) thick and only 25 nanometers across, then carefully processing the mixture. This work has been funded by the Inst.i.tute for Soldier Nanotechnologies at MIT because the military applications are considered of such high importance.

For a larger version of the following image, click here.

6.

THE EDGE.

THE EMERGENT POWER AND ACCELERATING MOMENTUM OF EARTH Inc., the rapid growth of destructive resource-consumption patterns, the absence of global leadership, and the dysfunctional governance in the community of nations have all combined to produce flows of pollution that are seriously damaging the integrity of the planetary climate balance that is essential to the survival of civilization.

We have been slow to recognize the extreme danger we are creating, in part because of the suddenness with which the underlying relationship between humankind and the ecological system of the Earth has been radically transformed by the relatively recent confluence of three basic factors. First, our numbers have quadrupled in less than a century and are still increasing; second, our way of thinking-both individually and collectively-is dominated by short-term horizons and distorted by habits of thought inherited from our prehistoric ancestors, who had to survive threats very different from the ones we face today; and third, the technologies now in common use are far more powerful than those available even a few generations ago.

In particular, our continued burning of carbon-rich fossil fuels for 85 percent of the energy that powers Earth Inc. spews 90 million extra tons of heat-trapping global warming pollution every twenty-four hours into the extraordinarily thin sh.e.l.l of atmosphere surrounding our planet, as if it is an open sewer. That means we are adding the equivalent by weight of more than 5,000 Deepwater Horizon Gulf oil spills every day to the dangerous concentrations that started acc.u.mulating with the Industrial Revolution at a rate that picked up speed dramatically throughout the last half century and is still accelerating.

As a result, human civilization is colliding with the natural world and causing grave harm to important natural systems on which our continued thriving as a species depends. There are multiple manifestations of this collision: the prospective extinction of 20 to 50 percent of all the living species on Earth within this century; the a.s.sault on the largest and most important forests in the world; the acidification of the oceans, depletion of important fish species, and imminent loss of coral reefs; the buildup of long-lived toxic chemical wastes that pose a persistent threat to people and other forms of life; the depletion of topsoil and groundwater resources at unsustainable rates; and more.

But the single most important and threatening manifestation of this collision is the climate crisis. Because the atmosphere surrounding our planet is so thin, it is highly vulnerable to the drastic change in its chemical composition brought about when we recklessly and constantly pollute it with such prodigious volumes of gaseous chemical waste. This growing blanket of pollution is smothering the atmosphere's ability to mediate the radiative balance between the Earth and the sun, trapping more extra heat energy each day in the lower atmosphere than would be released by 400,000 Hiroshima atomic bombs. In the process, we are profoundly altering the water cycle of the Earth, destroying crucial ecological balances, and compounding all of the other injuries we are inflicting on nature, including the plants and animals upon which we depend.

The good news is that we do have the capacity to begin solving the climate crisis-if we awaken to the reality of our circ.u.mstances and decide that saving the future of human civilization is a priority. That means recognizing not only the danger but also the opportunity inherent in this crisis. It means abandoning the illusion that there may be some clever technological quick fix for a planetary emergency that requires a multip.r.o.nged global strategy to convert our energy systems-particularly electricity generation-manufacturing, agriculture, forestry, building technologies, transportation, mining, and other sectors of the world's economy to a low-carbon, highly efficient pattern.

And yes, when you lay out the complexity and magnitude of the response needed, it can sound daunting. But there have been recent stunning improvements in the technologies enabling us to succeed. They're increasing in efficiency and being deployed much faster than predicted. The scale of renewable energy markets has led to much sharper cost reductions than anyone predicted. The price of electricity from solar and wind has dropped so rapidly that in some areas of the world, both are already compet.i.tive with the average grid price for electricity. Globally, renewables will be the second-largest source of power generation by 2015.

REAL ALTERNATIVES.

The more energy we produce from solar and wind, the cheaper it gets; the more energy we get from oil and coal, the more expensive it gets. And of course, the "fuel" for solar and wind is effectively limitless. For example, more potentially usable energy is received by the Earth from sunlight each and every hour than would be needed for all of the world's energy consumption in a full year. The potential for wind energy also exceeds the world's total energy demand several times over.

In the summer of 2012, there were periods when Germany received more than half its electricity from renewable energy sources. Some skilled investment experts are now projecting that on a global basis, even a conservative estimate of continued cost reductions for photovoltaic (PV) electricity will lead to a meteoric rise in its market share for new generating capacity over the next few years-to the point where almost half of the entire world's additional electricity generation will come from PV by midway through the next decade.

In 2010, for the first time in history, global investments in renewable energy exceeded those in fossil fuels ($187 billion, compared to $157 billion). The same year, solar photovoltaic installations in the United States rose 102 percent over those installed just one year earlier. Also, during the previous decade, 166 proposed new U.S. coal-fired generating plants were canceled, in large part due to public opposition.

Architects and builders are incorporating new designs and technologies that reduce energy consumption and the operating cost of buildings. This is particularly important because approximately 30 percent of all CO2 emissions come from buildings, and of all buildings needed by 2050, two thirds have yet to be built. According to an EPA report, "On average, 30 percent of the energy consumed in commercial buildings is wasted. Energy efficiency is the single largest way to eliminate this waste, reduce emissions, and save money."

Hundreds of millions of people have already made changes in their purchasing decisions in order to seek out lower-carbon goods and services. In response, many businesses and industries have demonstrated leadership in accelerating carbon reductions and shifting to profitable strategies based on sustainability and a switch to renewable energy. Energy efficiency improvements are being implemented on a large scale. In the aggregate, however, greenhouse gas emissions will continue their steep rise until and unless government policies are enacted that accelerate the transition to a low-carbon world.

In order to move forward with this transition much faster, at a pace that is necessary to begin solving the climate crisis, we must first build a global political consensus-starting with a consensus in the United States-strong enough to support the policy changes that will solve the crisis: we have to put an adequate market price on the emissions of global warming pollution with a carbon tax, a steadily declining limit on emissions, and market mechanisms that promote maximum efficiency in the allocation of expenditures to achieve overall reductions.

Leaders in civic society must also place a political and social price on the dishonest distribution of false information about this existential crisis by cynical global warming deniers, many of whom know better but are trying to preserve destructive yet highly profitable business models by sowing confusion, false doubt, and political discord to delay the recognition of reality and prevent the congealing of a consensus.

Ultimately, here is the choice we face: we can either make the solution to the climate crisis the central organizing principle of global civilization-or the hostile conditions we are creating will grow rapidly worse, thickening the smothering blanket of global warming pollution surrounding our planet and destroy the viability of civilization as we know it.

For all of recorded history, we have configured the patterns of our lives and the design of our civilization to fit precisely into a relatively narrow envelope of familiar variations in temperatures, winds and rains, sh.o.r.elines, river flows, frost lines, and snowfalls. We have built our communities in the places we call home-near reliable sources of the water we drink and the productive fields that give us food-in a world whose natural contours have varied little for more than 300 generations.

Since the glaciers retreated at the end of the last Ice Age, not long before the first cities were built and the invention of writing preserved the memory of man, we have taken for granted the enduring and relatively stable pattern of jet streams and ocean currents, warm spells and cold snaps, rainy seasons and dry seasons, spring planting and fall harvesting, tadpoles and b.u.t.terflies, and the other enduring natural phenomena that have characterized our world for almost ten millennia. Just as the proverbial fish doesn't know it is in water-because it knows nothing but water-we have never known anything other than the planetary conditions that have given rise to the flourishing of humankind.

All of those who preceded us added their contributions to the elaborate legacy of the human enterprise bequeathed to us in our time. And each generation in turn has been sustained by gifts from nature itself: the pollination of crops and wild plants by insects and other animals, the natural purification of water by soils, and numerous other ecological benefits that modern economists call "ecosystem services."

All of this and more we take for granted. All of this and more we are putting at risk. Very large human-caused changes in the long predictable climate pattern we have always known could so radically reorder the nature of nature that it is difficult for us to imagine the challenges our species would confront. When a fish is taken out of the water, it cannot survive. By the same token, if we completely disrupt the conditions on which our civilization is based-not just for a few years, but for many thousands of years-it too would be unlikely to survive in anything resembling its current form.

SECURITY AND STABILITY.

One of the many consequences of huge disruptions in the climate pattern we have always known would be a much higher risk of political instability. In fact, this risk is one of the princ.i.p.al reasons why military and national security experts in the United States have long expressed more concern about global warming than most elected officials. In many regions of the world, governance is already under tremendous stress with several failed states-Somalia, Yemen, and Zimbabwe, for example-creating difficult challenges for their regional neighbors. The increased stress that would accompany large alterations in climate patterns could push many other countries to the breaking point.

After a war game run by the National Defense University in the U.S. to simulate the geopolitical consequences of a ma.s.s migration of climate refugees from low-lying areas of Bangladesh, the head of the Bangladesh Inst.i.tute of Peace and Security Studies, Major General A. N. M. Muniruzzaman, said, "By 2050, millions of displaced people will overwhelm not just our limited land and resources but our government, our inst.i.tutions and our borders."

The few exceptions to the relative climate stability we have always enjoyed prove the rule. A recent study by David Zhang and others of the relationship between relatively small climate fluctuations in the past and civil conflict, published in the Proceedings of the National Academy of Sciences, reported, "Climate-driven economic downturn was the direct cause of large-scale human crises in pre-industrial Europe and the northern hemisphere." Indeed, our histories record the disruptive effects of comparatively small variations in the prevailing conditions in which we have thrived: * The medieval warm period was connected to the disappearance of the Mayan civilization in Central America and the temporary colonization of southern Greenland by farmers from Scandinavia; * During the Little Ice Age, Eskimos wrapped in fur paddled their kayaks to Scotland; farther south, millions died in a European famine centered in France; * The huge downpours in fourteenth-century China triggered a chain of events leading to the Black Death that wiped out one quarter of the population of Europe; * The unusually large eruption of the Tambora volcano in Indonesia in 1815 filled the Earth's atmosphere with particulates and led to the "year without a summer" in 1816 that caused widespread crop failures around the world, a wave of revolutions in Europe, and ma.s.s migrations in many regions by people searching for food and warmth.

All of these events were rare extremes that nevertheless fell within the natural boundaries of variations consistent with the same overarching climate pattern we have always known. And as terrible as the resulting catastrophes were, they were mostly temporary and relatively short-lived. By contrast, the much larger climate disruptions we are now causing threaten to create a planetary emergency lasting for time periods beyond the scope of human imagination. An estimated 25 percent of the CO2 we put into the atmosphere this year will still be contributing to higher temperatures at least 10,000 years from now. If we force the melting of giant ice sheets in Antarctica and Greenland, they are not likely to return on a timescale that has any relevance whatsoever to our species.

Nine of the ten hottest years ever recorded since accurate measurements began in the 1880s have occurred in the last ten years. And the extra heat energy is already disrupting millions of lives. Extreme and destructive weather events that used to occur infrequently are becoming both more common and more destructive. Sometimes described as "once in a thousand year events," many bring with them enormous economic and human losses. And they are predicted to get much more common and much, much worse.

Among the recent examples: the epic flooding in Pakistan that displaced 20 million people, further destabilizing a nuclear-armed country; unprecedented heat waves in Europe in 2003 that killed 70,000 people, and in Russia in 2010 that led to 55,000 deaths, ma.s.sive fires, and crop damage that pushed global food prices to record levels; the flooding of northeastern Australia in 2011 covering an area the size of France and Germany combined; the huge droughts in southern China and southwestern North America in 2011; the even deeper drought in over half of the U.S. in 2012; Superstorm Sandy in 2012, which devastated portions of New Jersey and New York City; multiple historic windstorms and downpours in many regions of the world.

The global water cycle-in which evaporation from the oceans falls as precipitation on the land and flows back to the oceans through streams that become rivers-is being radically intensified and accelerated by global warming. The warmer oceans allow significantly more water vapor to evaporate into the sky. More important still is the fact that warmer air holds more water vapor. If you take a cold shower, the mirror above your sink won't steam up, but if you take a hot shower it may. With so much more water in the atmosphere, there is also more energy fueling the size and destructive power of the storms.

Scientists have already measured an extra 4 percent of water vapor in the atmosphere above the oceans, and even though 4 percent doesn't sound like much, it has a large effect on the hydrological cycle. Because storms often reach out up to 2,000 kilometers, they gather water vapor from a large area of the sky and funnel it inward into the regions where storm conditions trigger a downpour.

By a.n.a.logy, if you pull the drain in a bathtub filled with water, the water rushing down the drain does not come just from the part of the tub directly over the drain, it comes from the whole tub. In the same way, the great basins of water vapor in the sky are funneled to the "drains" opened above the land by rainstorms and snowstorms. When these basins are filled with much more water vapor than in the past, the downpours are more intense. The bigger downpours lead to bigger floods. The floods rush across the land, eroding the soil. And less of the water seeps down through the soil to recharge the underground aquifers.

Climate change is also driving desertification by altering atmospheric circulation patterns and drying out the land and vegetation. The same extra heat that evaporates more water vapor from the oceans also speeds up the evaporation of soil moisture-leading to longer, deeper, and more widespread droughts. Since the refilling of the atmospheric "basins" of moisture still takes a lot of time, many areas of the world are experiencing longer periods without rain in between the intense downpours. These longer periods of hotter temperatures in between precipitation events lead to more widespread and even deeper droughts. Once it is devoid of vegetation, the surface begins to absorb more heat. When the soil moisture is gone, the ground is baked, local temperatures rise higher still, and the topsoil becomes more vulnerable to wind erosion.

The parching and desiccation of the most highly productive agricultural breadbaskets of the world portend a food crisis in the future that could have humanitarian and political consequences too horrific to imagine. A top official with the International Maize and Wheat Improvement Center in Mexico, Marianne Banziger, said, "There's just such a tremendous disconnect, with people not understanding the highly dangerous situation we are in."

The consequences for food production and water availability are already extremely harsh. In 2012, largely because of climate-related events that reduced crop yields, the world experienced a record one-month price increase for food, with additional record price hikes predicted for 2013. More than 65 percent of the U.S. suffered from drought conditions in 2012. In addition to the impacts on industrial agriculture in North America, Russia, Ukraine, Australia, and Argentina, subsistence agriculture has been hit hard in many tropical and subtropical countries by large alterations in the timing, duration, and magnitude of precipitation patterns due to global warming's disruption of the hydrological cycle. As a rice farmer in northeastern India, Ram Khatri Yadav, told Justin Gillis of The New York Times, "It will not rain in the rainy season, but it will rain in the non-rainy season. The cold season is also shrinking."

Along with the impacts discussed in Chapter 4-including the depletion of topsoil and groundwater and the compet.i.tion that farmers face for land and water from fast-growing cities, industry, and biofuels production-the rising temperatures threaten many food crops with catastrophic yield reductions from heat stress alone. Stanford researcher David Lobell, who recently completed a study of the impact of temperature increases on crop yields with Columbia researcher Wolfram Schlenker, said recently, "I think there's been an under-recognition of just how sensitive crops are to heat, and how fast heat exposure is increasing."

In the last three years, new scientific research has overturned the long-held view by agricultural experts that, in the absence of drought, food crops would be relatively unharmed by rising temperatures. Many had thought that the higher CO2 levels might fertilize plant growth by enough to counterbalance any yield decreases due to heat stress. But unfortunately, intensive research designed to confirm that hypothesis now shows that food crop yields are likely to decline much more rapidly with higher temperatures than previously believed, and that the CO2 fertilization effect is much smaller than predicted. Moreover, weeds appear to benefit from extra CO2 much more than food crops.

As temperatures continue to increase, corn (maize)-the most widely grown crop in the world-appears to be the most vulnerable to heat stress. Corn yields start to decrease at a range of temperatures the Earth is already experiencing regularly in summer months. Every day during the growing season (roughly from the beginning of March to the end of August) that temperatures climb above a threshold of 84 degrees F (29 degrees C), corn yields drop by 0.7 percent.

As temperatures grow hotter than 84 degrees F, the yield declines plummet further with every degree added. If temperatures in the United States are allowed to rise as much as is now projected as a result of global warming, by the end of this century corn yields could fall by as much as a third from heat stress alone, with the impact of worsening droughts and the disruption of precipitation patterns taking a larger toll still. Soybeans have a higher threshold for heat stress than corn (86 F/30 degrees C), but the same accelerated drops in yields begin when temperatures reach and exceed that level.

The warm season is longer; spring is arriving about a week earlier (and fall about a week later) in both the northern and southern hemispheres. Moreover, the decreasing size of mountain snowpacks and glaciers is adding to the worsening shortages of water for agriculture in several important regions, bringing bigger spring floods earlier in the year and depriving these regions of water during the hot summer months when it is most needed. And while the focus is normally on daytime high temperatures, nighttime temperatures are at least as important. Both the computer models and consistent observations confirm that global warming increases nighttime temperatures more than daytime temperatures.

According to some studies, each degree increase in nighttime temperatures corresponds with a linear decrease in wheat yields. A large global review of the impact of climate change on crop yields between 1980 and 2010 showed that worldwide wheat production fell due to climate-related factors by 5.5 percent. A researcher at the International Rice Inst.i.tute in the Philippines, Shaobing Peng, published findings in the Proceedings of the National Academy of Sciences showing that yields of rice declined by 10 percent with each one degree Celsius increase in nighttime temperatures during the dry part of the growing season, even though there were no significant drops in yield a.s.sociated with increasing maximum temperatures during the daytime.

Crop diseases and pests are also increasing with global warming. Higher temperatures are leading to a dramatic expansion in the range of insects harmful to food crops, sending them farther north in the northern hemisphere and farther south in the southern hemisphere, and into higher alt.i.tudes. A team of crop scientists publishing in Environmental Research Letters wrote, "These range expansions could have substantial economic impacts through increased seed and insecticide costs, decreased yields, and the downstream effects of changes in crop yield variability."

Other scientists have determined that higher levels of CO2 also stimulate insect populations. Evan DeLucia, a plant biologist working with a team of entomologists at the University of Illinois, tested the impact of higher carbon dioxide levels on soybeans and found that aphids and j.a.panese beetles flocked to the soybeans grown in higher CO2 environments, ate more of the plants, lived longer, and produced more eggs. "That means crop losses may go up in the future," DeLucia said.

Other scientists on DeLucia's team found that higher carbon dioxide levels caused soybeans to deactivate genes that are crucial to the production of chemicals that help to defend them against insects by blocking enzymes in the stomachs of beetles that digest soybean plants, and by deactivating other genes used by soybeans to lure the natural enemies of the beetles. As a result, according to team member Clare Casteel, the soybeans grown in higher levels of CO2 "appear to be helpless against herbivores."

Higher temperatures are having the same effect in boosting pest populations in most areas of the world. One of the leaders of an Asian international agricultural research group, Pramod K. Agrawal, said, "Warmer conditions and longer dry seasons linked to climate change could prove to be the perfect catalyst for outbreaks of pests and diseases. They are already formidable enemies affecting food crops." A team of Indian scientists noted that, because insects are cold-blooded, "Temperature is probably the single most important environmental factor influencing insect behavior, distribution, development, survival, and reproduction.... It has been estimated that with a 2 degree C temperature increase, insects might experience one to five additional lifecycles per season."

Scientists at the International Center for Tropical Agriculture, for example, found that the ca.s.sava crop in Southeast Asia-worth an estimated $1.5 billion each year-is seriously threatened by pests and plant diseases that expand with warmer temperatures. According to ca.s.sava entomologist Tony Bellotti, "The ca.s.sava pest situation in Asia is pretty serious as it is. But according to our studies, rising temperatures could make things a whole lot worse." Bellotti adds, "One outbreak of an invasive species is bad enough, but our results show that climate change could trigger multiple, combined outbreaks across Southeast Asia, Southern China and the ca.s.sava-growing areas of Southern India."

Microbes that cause human diseases-and the species that carry them-are also expanding their range. In the highly populated temperate zones of the world, the prevailing climate conditions in which civilization developed were unfavorable to the survival of many disease-causing organisms. But now that warmer climate bands are moving poleward, some of these pathogens are moving with them.