The town of Bellingham, Washington, is one of those smaller American cities that routinely makes the various “most livable” lists. And why not? It has a good state university, ensuring an influx of culture and scholarly lectures unavailable in most cities of its modest size. It also sits amid stunning green hills rising out of the cold, clear waters of Puget Sound. The gigantic volcano Mount Baker looms over it in regal fashion, and the rainy but cool climate ensures year-round verdure. Most of its trees are scrubby, deciduous maples and alder, with the numerous garden transplants such as rhododendrons, camellias, and magnolias adding spring color. But as recently as a century ago, the vegetation had a radically different look. In place of the now dominant flowering, broad-leafed trees there rose gigantic Douglas fir and western red cedar in old-growth splendor. Needles, not leaves, reached skyward for photons, and so dense was this forest that its floor was in perpetual gloom, to the depressive chagrin of the still-settling inhabitants. Soon enough they felled these trees and saw the sky.
This grand forest was a bristly blanket that stretched several thousand miles along the Pacific Coast, gradually changing species composition northward toward Alaska, and south into the Northern California coast. And it is ancient, not just in the short measures of human history but also in the more robust and virtually unimaginable scale of millions of years. While buffeted by the ice ages, advancing with the warmer intervals only to again retreat back into small pockets during the height of the ice sheets, the western North American coastal forest stretches far back into the nebulous geological past. It is old—but it sits on a rock cover that is older yet, holding evidence of a very different West Coast than we know now.
Chuckanut Drive is a beautiful, windy road leading southward from Bellingham along a steep rocky coast. It is often closed by seasonal rock falls, for the road was carved into steeply dipping sedimentary strata, dating back some 60 million years, a time when vast mountains to the immediate east were rising upward, and in so doing rapidly eroding and dumping vast volumes of gravel, sand, and mud into the rivers, streams, and accompanying ponds, swamps, and lakes in the forelands. The grains of these sedimentary rocks give away the provenance of their origin, telling of mountains made of granite and high-grade metamorphic rock. But more interesting than these clues to their rocky origin are other clues to a past 60 million years old. Most of the precipitous outcrops along Chuckanut Drive bear bedding planes smeared with fossil leaves. In some places the rock seems to be nothing but bedded leaves, as if some ancient gardener willed an autumn leaf compost pile into rock.
Broad-leaf fossils in a place now that should harbor nothing but pine needles? And not just any broad-leaf species—the fossils show the exotic and exuberant leaf shapes that today are found only in the humid tropical jungle of our world. And if any doubt remained about the heated time that these Chuckanut formation fossils come from, they are immediately erased at every larger bedding plane, for imprinted over the smaller tropical leaves are gigantic, spectacular palm fronds. Washington State, meet Florida.
Vertebrate paleontologists have also prowled these beds, finding numerous turtle shells and crocodile fossils. And just as the Douglas fir old-growth forests should today extend vast distances along the coast, so too did this ancient, 60-million-year-old forest from the time interval formally known as the Eocene epoch cloak huge areas of North America. The Eocene palms and crocodile fossils can be found as far north as the Arctic Circle. There is only one possible explanation for this distribution. In the Eocene epoch, the world had to be far warmer than it is today. Warm enough to allow tropical flora and fauna to thrive in what is now the land of permafrost and ice.
What would it be like to live in such a world? What if all of human civilization was suddenly transported to the Eocene world? Our coastal cities would be in for a nasty, wet surprise, for they would be instantly drowned. The Eocene epoch was so hot that there were no polar ice caps, and thus sea level was about 150 feet higher than it is today. There would be no snow angels or autumn leaves or sledding for any American. There would be no seasons at all, other than endless summer. Today, even Los Angeles and Miami detect some passing of the seasons. Not so in this Eocene world. Where should we go now to see such a world?
A long jet-plane hour east of Australia lays the island of New Caledonia. Beautiful place, this Calédonie (as the locals call it). It is a huge island somewhat parallel to, if south of, the Great Barrier Reef off Australia. It is not your run-of-the-mill Pacific atoll chain, typified by a low topography made up of crushed white limestone gripping a coconut palm community in equatorial heat, but a real hunk of continental land, high mountains being the backbone of 300 miles of 75-mile-wide real estate, one of the biggest islands in the world, with two really different and sensational kinds of rocks raising it from ocean depths. There is lots of limestone, of course, for the entire length of the island is skirted by a wide and fabulous barrier reef of diverse Indo-Pacific coral, while the 10-mile-wide lagoon made by the outer barrier reef is a veritable carbonate factory. But that is just veneer, for this island is both old and something peculiar on Earth’s surface: It was torn from the ancient, Permian–Triassic supercontinent of 250 million years ago, ripped from its Gondwanaland heritage by the titanic tectonic forces that created the Atlantic Ocean and at the same time sent all the continents scurrying to new places about the globe. New Caledonia was but one small sliver, but in the tearing, it scooped out rocks from far deeper in Earth than is the norm, rocks from Earth’s mantle region itself, that deep place on which the peripatetic crustal plates float. The rocks of this region are far denser than their silicate-rich cousins on the surface, with a far higher metal content. New Caledonia became a slice of metal ore, eroding to deepest red in color when eroded to soil. It was rapidly colonized by European powers once its mineral wealth became known, and it is still a colony of France to this day, one of the last. It is featured here because it gives us a glimpse of what the future world may look like. Even though, as we saw in Chapter 6, “The Driver of Extinction,” our oncoming carbon dioxide levels are more akin to those of the Cretaceous period than the Eocene epoch, the similarity in flora and fauna of this latter time interval makes for a more accurate comparison.
At first glance, that future seems like a pretty good deal, especially for those who live in colder climes. New Caledonia is not on the equator—far from it. It straddles the Tropic of Capricorn, latitude 25 degrees south, and because of this its water is cooler than many places of lower latitude, yet still warm enough to support coral reefs and many varieties of palm trees. It has a huge barrier reef that encloses many smaller reefs gathered in the wide lagoon, and around and within these smaller reefs lives a rich molluscan fauna. Among many varieties of the more prosaic bivalves there is a high diversity of snails spectacular in their extravagant color and morphology. Cones, conchs, turrets, whelks, turbans, and more—even the rare chambered nautilus—can be found off the deeper reefs. Yet even among these many beauties there is one family of snails that stands out in terms of pleasing color and shape: cowries, those colorful snails living only in warm water.
Thus with its palms and snails, New Caledonia can serve as a vision of what much of the globe might be like, at least for a geologically short time in the future as our planet warms, and its animals and plants are already familiar to those paleontologists and paleobotanists studying the 60-million-year-old Eocene epoch. Their fossils are common in the numerous and rich Eocene-age deposits found in many places around the world, including those where even during the Eocene the animals of the time were living at high latitude, places quite cold in our world but warm enough for the New Caledonia kinds of animals in the past.
The Eocene epoch, a time of warmth. It is this ancient Eocene that many of the experts looking at and projecting Earth’s future climate now study, for the Eocene was the last time the world was totally globally warmed to worldwide tropical conditions with palms and crocodiles and cone shells and nautiloid cephalopods spanning the globe, a time when there was absolutely no ice at the poles and snow was something limited to the highest mountains only, a world where once again palm trees, tropical mollusks, and basking crocodilians will be able to make a living in places like Canada or northern Europe, as the world once again becomes a tropical paradise.
Will we be going forward into the past? In this final chapter let us look at what the Eocene epoch was like, in order to prepare us for what a world with carbone dioxide levels of 1,000 parts per million will be like.
THERE IS A TRUISM NOT KNOWN TO MANY WHO LIVE THEIR LIVES IN the temperate realms of the world. Even those in places such as Florida think that they live in heat, and that they do during the summer months. But the occasional frost still menaces the Florida citrus crops; there are many cool and comfortable days in winter. And besides, the summer of Florida and every other hot but industrialized place of human habitation keeps the heat at bay with the vast air-conditioning enterprises that eat up so much of our planet’s energy output each year. These places do not qualify as really hot places. The really hot places are united by a very different human activity than turning up the air conditioner: Because human life is so miserable in humid, unrelenting equatorial heat, everyone uses drugs, drugs to help escape the heat, the misery, to make time go by. We who live in the more comfortable climes seem to think that just because the human tribes who have long inhabited the equatorial zone have evolved through many generations living in constant heat, night and day, that somehow these people no longer feel the heat and humidity, that unlike us, they are not made uncomfortable by the horrible climate. Not so. Hence the many varieties of “little helpers” to get through the day.
They are not called drugs, of course, nor are they illegal. But an interesting variety of pharmacological substances can be traced around the world in the world’s hot zones, and the habit of using these various drugs goes back through history in each place that they are found. Starting in Fiji, and heading east through the Western Pacific Islands, the drug of choice is kava root. In every market stall or place of work outside or in, the Fijians invariably have a coconut or other kind of bowl with the milky white liquid within. Drinking goes on all day, and the effect is to make time pass more quickly. To get through the day, in other words.
Moving east to Vanuatu, the old New Hebrides Islands, the kava gets immeasurably stronger. Instead of the Fijian variety that provides a pleasant buzz to the point that one forgets the heat, the Vanuatuans are nearly knocked over by their potent brew, which has an awful taste, but one sure isn’t bothered by the temperature of 98 degrees Fahrenheit and the 99 percent humidity. In Micronesia, the drug changes. Here, and up into the old Indochina peninsula, the drug of choice is betel nut. This nasty stuff also yields a potent buzz. It is ingested by chewing the tough little nuts wrapped in a small bit of palm leaf with some white coral grit enclosed as well. The calcium carbonate reacts with the alkenes in the nut to form a red intoxicant that is not swallowed but swished around the mouth and then spit out in a highly staining red expectorant. Sidewalks, roads, market stalls—all are stained red because of the habit, as are the gums of the chewer. A more significant change occurs as well: The prolonged chewing of the coral grit grinds down the teeth, often to sharp points, and a smile from a red-mouthed, sharp-fanged Micronesian, spitting out gobs of red goo, puts to shame the special effects of any Hollywood vampire. The effect of the betel nut buzz is heightened by smoking island marijuana, a shrub now found growing wild throughout the widespread islands of the many archipelagos stretching from the Philippines through the vast regions of Indonesia.
As one moves into India, the drug of choice again changes, to khat, an intoxicant widely available. As in the other tropical areas, its use is something that goes on all day and cuts through most social classes. Again, it provides a pleasant buzz, and while the heat of the day remains, the day is conquered and the unpleasantness of the heat is put aside. Khat is widespread in Asia Minor and is found as well in the Sahara regions. The more vegetated parts of Africa at equatorial latitudes have khat but many other kinds of drugs as well, as befits a place where the diversity of plants and people is so high.
Finally, swinging around the world again, now to South America, we find the widespread chewing of coca leaves as a way to beat the heat. Hours on end, spitting out the used leaves and chewing new ones, the day goes by unnoticed, energy levels are increased in the enervating heat, the day’s duties are accomplished.
We humans evolved near the equator, it seems, but this brain of ours does not do well when heated for long periods of time. British neurobiologist Martin Wells, the grandson of H.G., once observed that human thinking is best done at “sweater” temperatures—in other words, if it is cool enough to require a sweater, as is the case in older British households, characterized by a lack of central heating. There may be something to this; the sum total of great intellectual insights and contributions coming from the extreme tropics is scant indeed, as are the products of prodigious human industry in such places. No brand of cars comes from any country with year-round heat; no computers, no airplanes. Southern India, which has long hot seasons interspersed with monsoons, is becoming the sole exception to this, but its factory work and thinking take place in air-conditioning, not outside in the heat. Singapore is also an exception, an equatorial powerhouse that exists as such only because of the most extensive use of air-conditioning to be found on the planet, at huge cost in energy.
There is another characteristic of the equatorial regions: malaria. While AIDS remains the most visible killer in the hot zones, far more people die of malaria, and the infection rate throughout most of the really tropical areas is staggering. For example, in the Solomon Islands (a very hot island chain in the western Pacific), the infection rate is more than 90 percent. The Anopheles mosquito is the vector of this protozoan-caused malady, and fortunately for humanity this mosquito requires great heat to live. One can only imagine what humanity would be like if the many species of mosquitoes in temperate and Arctic regions also carried and caused malaria. Heroic efforts are underway to reduce the misery of malaria, but all efforts at a vaccine have so far failed, and the current prophylactic measures involve ingesting poisons toxic enough to kill the protozoa in the human bloodstream but not quite toxic enough to kill the human. This is a very poor solution, and sooner or later most visitors to the tropics will contract this killer.
TWO QUESTIONS NOW ARISE: WILL THERE BE ANOTHER GREENHOUSE extinction similar in any way to the events of the deep past profiled in this book? If one is in our future, when might it occur? For the moment let us accept an affirmative answer for the first and see what (if any) consensus there already is regarding the second.
The latter question was examined in a landmark paper published in Nature in 2005. That study estimated that climate changes brought about by global warming will lead to the extinction of more than a million species by the year 2050. Since there are only 1.6 million species now identified (although many more are yet to be described), such numbers result in an extinction rate of more than 60 percent. To compare this with the past, this number would place the next greenhouse extinction second only to the Permian extinction. And the first million species, if the Nature study is correct, would just be the start of things. As we shall see below, a shift to a new kind of oceanic conveyer current system would create an anoxic ocean, eventually changing into a Canfield ocean. The shift from mixed to anoxic ocean would likely kill off the majority of marine species, just as it has in each of the ancient greenhouse extinctions.
With this in mind, let us return to the first question posed above. Can such an event be already happening—are we in the first stages of a greenhouse extinction? For this latter question, our knowledge coming from the past extinctions is of little use. The rock record is excellent at tracking million-year or even hundred-thousand-year events. But here we are looking at events happening on decadal scales. There is no ice-core equivalent in the rock record that resolves such short-term events in the past. Yet we can gain insight into this question by looking at the state of the world’s climate in the present.
Books take time to write and time to be put into print. Any book is a multiyear effort. In 2006, as I write words that will not appear in print until 2007, we can try to summarize the state of Earth’s climate in 2006. (By state we might mean the picture produced by the values of temperature and greenhouse gases and the nature of the conveyer belt, among many others.) Hopefully the state of the climate will be about the same in 2007 as it was in early 2006. There will be more carbon dioxide and methane in the atmosphere, of course, and more of the ice caps will have melted, freshening the sea, most dangerously in the North Atlantic. But perhaps the rate of change is faster than one can hope, fast enough, perhaps, to have taken our world past the combined climate tipping point. Of all of the irreversible changes that might be triggered by the tipping point, two are paramount—the oceanic conveyer, obviously, given the importance it has been awarded throughout this book, but also the great ice sheets now resting atop Antarctic bedrock or Arctic land and sea. Ice sheets on Greenland and Antarctica hold 20 percent of all of the fresh water on our planet, water locked up in its solid phase. But what happens if all of that ice melts?
Let us look at this and additional environmental changes that could lead to the next greenhouse extinction, including sea-level rise, ocean acidification, global warming (oceanic as well as terrestrial), and coral reef “bleaching.”
THERE WAS PLENTY OF HEATED CONTROVERSY IN 2006 ABOUT WHETHER the high-latitude ice bodies are already on an irreversible slide toward melting. It turns out that the early phases of the irreversible slide will be masked by natural process and because of this, proceed very slowly. With a warming atmosphere, the edges of ice sheets melt and glaciers recede. But the melting does not all go into the ocean. Local climate change and the warming itself can increase rainfall over the ice caps, and if this precipitation reaches the cold central regions of any ice body or begins to fall anytime in the still-frigid high-latitude winters, it falls as snow, which rapidly is converted back into the freshwater ice that this water originally came from. The edges melt, the center accumulates new ice, and the system only slowly moves toward something much more dramatic. At some point the warming ocean, the source of all this change, increases in temperature enough to cause disintegration of the ice sheets. Faster and faster they melt, first calving off armadas of icebergs and later simply converting to water, which finds its way into the ocean. The ocean freshens, but more ominously, the volume of new liquid water entering the world ocean is so great that the very level of the oceans themselves, known as sea level, begins to rise.
The rise in sea level that has occurred to date is still very low, on the order of a centimeter over the last century. But if either part of the Antarctic (western part) or all of the Greenland ice sheet melts, which would occur (according to climate models) with a global rise in temperature of between 2 degrees and 3 degrees Celsius, the rise in sea level would be 6 meters, or about 20 feet! If both melt, the rise is more than 60 meters, or 200 feet. Good-bye, all coast cities, and good-bye, a good proportion of the planetary agricultural yield, since a very significant quantity of human food is grown in the large deltas such as those found at the ends of the rivers Nile, Mississippi, and Ganges. All of the deltas and their rich soil would be pretty well inundated with even a 1- to 2-meter rise in sea level. The eventual rise of 25 meters would bring back the old coastlines of the Eocene epoch.
Melting of the ice sheets would produce a radically different climate than what we have now. Radically different. As stressed here, what we call climate is made of many individual and largely interconnected systems, and the past evidence of change suggests that these thresholds are both sensitive and can have dramatic consequences, once a critical level is passed. A good way to analogize this is by thinking about the action of an electric light switch. Slowly increasing pressure on the button does nothing until the threshold is reached, and once that point arrives the switch jumps forcefully and quickly into a new position. Pushed past a threshold, most climate systems can jump quickly from one stable operating mode to a completely different one.
A rising sea level would be the most dramatic effect of ice-cap melting. But in all probability, no less important would be the consequence of all of that freshwater entering the oceanic conveyer belt system. As we saw in Chapter 5, “A New Paradigm for Mass Extinction,” the conveyer is powered by the density and temperature difference of its seawater at different geographic areas and depths. Freshwater entering the system in the North Atlantic would be particularly significant. South of Greenland is the area where previously warm Atlantic Ocean seawater, which had made its way from the tropics off the Caribbean, finally cools enough to sink into deep water. Warm water has more salt ions, and once it cools, its density is higher than surrounding water. But the injection of fresh water, with a much lower density because of its lack of salt ions, would effectively stop the conveyer or perhaps shift where it starts and stops on the surface. A rising sea level would drown cities, but a conveyer belt shift would kill people, lots of them, because of the great effect it would necessarily have on climate in European agricultural areas. It can be surmised that a suddenly cooled, cropless European subcontinent with its large population would by necessity look toward still-arable lands to make up food loss. Here’s hoping under this scenario that the Europeans have enough cash in reserve to buy an awfully large volume of food for centuries to come.
The rise in sea level displaces not only crops but people as well. This is an aspect so obvious that it is usually lost in any discussion of the effects of rising sea level. However, as any urban geographer can attest, a large proportion of humanity currently resides in coastal or low-elevation riverside locales. All such localities would be affected by even a small rise in sea level, and when we start looking at 25-foot increases (a common estimate for an ice-free world following melting of the Greenland and Antarctic ice sheets), we see a reality in which vast populations of humans will have to move to higher ground. Perhaps nowhere is this more evident than in the low-lying country of Bangladesh, which currently has one of the densest populations of humans on Earth and whose population is estimated to double over the next century. Let us look in detail at what a 25-foot rise in sea level would do to that country.
While it seems at first glance easy to map a future coastline following a known rise in sea level, simply by making the new coast at the appropriate topographic level on a detailed map of the region, in reality such mapping is more complex than that. Coastal areas are prone to subsidence—sinking as the wet soil beneath them compacts—while the flooding of deltas, lagoons, estuaries, and especially the river mouths of large continental rivers can produce startlingly different topography. One group that has attempted to make maps taking these factors into account is the future-mapping group at the University of Arizona. The mapper in chief, geographer T. Overbeck, has put online a number of such maps, and these are reproduced here with his kind permission.
FIGURE 9.1
The impact of a 1.5-meter rise in sea level on Bangladesh
In Figure 9.1, Overbeck shows the current geography and population centers of Bangladesh. Currently, Bangladesh is home to 112,000,000 people on 134,000 square acres of land. What happens to these people and the land area with a rise in sea level? The bottom part of Figure 9.1 shows the estimated new shoreline positions after a rise in sea level. In this case, however, the map is based not on the catastrophic maximum rise in sea level of 25 feet but on only a 5-foot (1.5-meter) rise, which all scientists agree is inevitable, largely because of the expansion of the oceans from their warming but also because of the initial volume increase from the ice that has melted to date. That rise in sea level would displace 17 million people (15 percent of the population) and inundate 22,000 square acres—16 percent of all land area.
So what happens with a rise in sea level of more than 25 feet? Because Bangladesh is so low-lying, this kind of rise would almost wipe out the entire country. Only a small strip abutting the Indian subcontinent would remain subaerial. Virtually the entire population of Bangladesh, one of the poorest countries in the world, would have to migrate. But who would take the perhaps 200 million people who would need land, food, water, and energy on an unprecedented scale?
The Bangladesh case brings home the urgency of confronting this problem. With global help, countries like Bangladesh could probably cope with the 1.5-meter rise in sea level. And there are plenty of other countries in similar straits. Indonesia, for instance, has great areas of its habitable land surface of such low elevation that it would be largely flooded by the higher of these two rises in sea level.
Let us look at another case—the United States. Again, we can map the areas that are within 1.5 meters of sea level, as shown in Figure 9.2.
From the areas in black, it is clear that large parts of Louisiana, Florida, and estuaries along the Atlantic coast, especially Delaware Bay, would be covered by a 1.5-meter rise, and far more by a 3-meter rise. South Florida, the population center of the region, would be especially hard hit. The higher rise in sea level, not shown in Figure 9.2, would of course prove far more catastrophic.
All in all, it is safe to say that between one-quarter and one-half of all people on Earth would be displaced by the 25-foot rise in sea level. Words cannot begin to suggest the human suffering and mass extinction of humans that would occur. Our world cannot let the ice caps melt. But have we already passed the tipping point, at least for Greenland?
FIGURE
9.2
The effect of a rise in sea level on the United States
Let us look at new and ominous data on glacial movement in Greenland that point toward a more rapid reduction in ice cover than previously considered.
WHILE RELATIVELY SMALL COMPARED WITH THE AMOUNT AND THICKNESS of ice found on the Antarctic continent, the Northern Hemisphere ice caps, and especially the ice cover on the subcontinent of Greenland, hold a formidable volume of water as ice. Since the ice-cap ice floats, its melting has no effect on sea level. Not so for Greenland, however, where the ice sits on rock, not seawater. As we have seen, if all of the Greenland ice cap were to melt, the sea level would rise 6 to 7 meters, or about 20 feet. Because Greenland is closer to the equator than Antarctica is, the temperatures there are higher, so the ice is more likely to melt. And not only is air temperature higher around Greenland than above the Antarctic continent but the temperature of seawater around Greenland is also higher than that of seawater around Antarctica. The crucial observation that needs to be made is whether the ice on Greenland is melting, and if it is, how fast.
This is where the alarming new data come in. In early 2006 a study determined the average rate of movement of the glaciers on Greenland (most ice there is tied up in glaciers, which are slow-moving rivers of ice). While melting of an ice cap conjures up pictures of an ice cube disappearing on a Phoenix street corner in July, the reality is that melting also involves the rate at which the glaciers, most terminating at the coastline, dump ice into the sea. Much of the now water-borne ice floats off as icebergs. The study showed that the speed of the glaciers had increased by a factor of eight compared with a decade earlier. This more rapid speed could only be caused by lubrication at the base of the ice—and this lubrication is water, whose source is indeed the melting of ice in the traditional manner. If the glaciers can replace the ice they lose to the sea at the same rate, there is no net loss. But the opposite is happening. The glaciers are not being replaced at a higher rate. In fact, some are not being replaced at all. Every indication is that Greenland is poised to see its ice cover disappear with increasing speed. The north Arctic region has undergone a regional temperature increase that is 20 times that of the whole world. That is what is driving the disappearance of the Northern Hemisphere, and especially Northern Hemisphere, high-latitude ice—such as that of Greenland.
How long till all is gone? Not in the twenty-first century, perhaps, even at the rapid rate just measured. But enough will disappear to certainly have an affect on sea level. Perhaps the 2-foot rise predicted is woefully underestimated. And as we have already seen, even that slight rise will negatively affect crops and people, especially in the highly productive deltas of the world.
Antarctica holds the world’s main ice cover, with about 90 percent of the world’s ice (and 70 percent of its fresh water). Antarctica is covered with ice an average of 2,133 meters thick. So what would happen if we lost all ice caps? If all of the Antarctic ice melted, sea levels around the world would rise about 61 meters—about 200 feet. That is where I think we will be by the year 3000.
THERE IS ALREADY SIGNIFICANT HUMAN MORTALITY FROM THE CURRENT greenhouse-induced global warming of Earth. A 2004 study by scientists at the World Health Organization and the London School of Hygiene and Tropical Medicine determined that 160,000 people die every year from the effects of global warming, from malaria to malnutrition, children in developing nations seemingly the most vulnerable. These numbers could almost double by the year 2020.
A second cause of human mortality comes from storm-related deaths. Any suggestion that better technology for forecasting could reduce the danger of oncoming storms through earlier evacuations was certainly exposed as myth by the tragedy of Hurricane Katrina and its flooding of New Orleans as well as vast tracts of coastal Louisiana by oceanic storm surge. As Earth’s tropical regions become warmer, its systems of redistributing that heat become more energetic. Thus, the warmer this planet gets, the warmer the Atlantic Ocean gets, bringing warmer and more moist ocean air, the fuel of hurricanes. This is why scientists and insurers fear climate change will worsen hurricanes. The number of the deadliest hurricanes—that is, category 4 and 5 hurricanes—has, between 1990 and 2004, almost doubled since the period of 1970 through 1985. Globally, between 1990 and 2004, there has been an increase from an annual average of 10 such hurricanes to an annual average of 18. The increase in intensity of hurricanes is the direct result of an increase in water temperature of 0.5 degree to 1 degree Fahrenheit. While some argue that a natural, 30-year cycle in hurricane number may be part of this cause, it is also true that this 30-year periodicity may itself have been affected not just by the last few decades of global warming but also in fact by two centuries of rising carbon dioxide levels.
Another danger to human life is heat waves. Heat waves in August 2003 caused 35,000 deaths in Europe, 15,000 of them in France alone. The U.S. Environmental Protection Agency points to one study that projects in New York City the probability of warming of 1 degree Fahrenheit, which could more than double heat-related deaths during a typical summer, from about 300 in 2006 to more than 700. The lead author of this study, Thomas Karl, director of the National Climatic Data Center, noted in his summary of the situation:
It now seems probable that warming will accompany changes in regional weather. For example, longer and more intense heat waves—a likely consequence of an increase in either the mean temperature or in the variability of daily temperatures—would result in public health threats and even unprecedented levels of mortality. High temperatures are likely to become more extreme, and because night temperatures will increase by at least as much as daytime temperatures, heat waves should become more serious.
Already we have seen killer heat waves that caused more than 500 heat-related deaths in Chicago in 1995 and more than 250 deaths in the eastern United States during a period of hot weather in the fall of 1999. And things are projected to get worse. The World Meteorological Organization projects that by the year 2020 there could be 3,000 to 4,000 deaths in the United States alone. These numbers will be dwarfed by human mortality in cities in other nations that are less energy rich. As fuel costs of cooling increase, the number of poor dying globally because of heating periods will skyrocket.
CLIMATE CHANGE IS ALREADY THREATENING THE PLANET WITH THE spread of infectious diseases, which will move farther northward and to higher elevations. The World Health Organization projects tens of millions more cases of malaria and other infectious diseases than exist now. While insects are proliferating, carrying these diseases, three-fourths of all bird species are on the decline. We are thus losing our first line of defense against the threat of disease-carrying insects, since insectivorous birds are the major insect predators. In addition, 26 percent of bat species are threatened with extinction. It is estimated that bat colonies in Texas alone eat 250 tons of insects each night. The loss of many species of birds and bats, while insects proliferate, could lead to an escalation of the use of pesticides, threatening yet more damage to the world’s animal species, including us.
The misery of living in a tropical climate as well as the ever-present threat of contracting malaria are the two aspects of climate change through heating that don’t get much press. Yet as the tropics begin to spread north and south from the low latitudes of Earth, scourges of the tropics will be coming too. We are returning to a planet with worldwide malaria foremost, but there’re more: Ebola, elephantiasis, schistosomiasis, leprosy, rampant intestinal parasites, poisonous spiders and centipedes, new and vicious kinds of ants—all will follow the heat once the barriers of coolness are overcome.
WHILE THE PROBLEMS FOR HUMANS LISTED ABOVE ARE SERIOUS ENOUGH, they are not the two most lethal dangers. The greatest threats posed by global warming are surely famine and war, two Horsemen of the Apocalypse going hand in hand.
Our world sits on a knife edge of global starvation already. We six billion humans, heading toward a far higher number at about the time that rising carbon dioxide levels should begin to stabilize a new pattern of climate, are able to be fed, all of us right now, through the miracle of that long-ago breakthrough of the human mind, agriculture. We need every bushel of grain, however. There cannot be even a single season without harvest in either hemisphere, and this is why there is extreme danger of rapid weather change if there is a Krakatoa-type volcanic explosion or impact of a 100-meter or larger asteroid. Both would put so much dust in the air that one hemisphere or the other (or perhaps both) would have a yearlong or longer winter and thus no crops.
Short-term climate change would be nearly as devastating, and in the long run, more devastating. Neurobiologist Bill Calvin, who has written extensively on the dangers and effects of sudden climate change, suggests that a 10- to 20-year event is far more difficult to deal with societally than is a sudden catastrophe.
Why would a warmed world be in danger of plummeting crop yields? It would seem that plants might flourish in the higher carbon dioxide levels, and with longer growing seasons, perhaps an additional crop could be counted in many areas. This will surely be true for some kinds of human food. Tropical fruits and starches will be available in abundance. But the staple of human sustenance, grains and cereals, the very first crops, in fact, from 10,000 years ago, would suffer. The grain belts rely on cool but not frigid winters, and summers with abundant moisture. Current projections are that the great breadbaskets of Earth, especially the greatest of them all, the American Midwest, would have climate changes that would reduce summer moisture. As droughts become more frequent, yields of wheat, corn, barley, and oat crops would decline.
In the new climate, new regions would become arable that currently are not. Two thousand years ago, northern Africa was the granary for the Roman Empire, but climate change since then caused an expansion of the Sahara Desert and dryness in the formerly fecund states of Morocco, Tunisia, Algeria, and Libya. Those regions would likely get more rain and could perhaps again begin producing bountiful harvests. But it is not likely that they could immediately take advantage of the more propitious climate. Efficient farming is highly mechanized and highly oil intensive. All of the African states listed above are Muslim countries with some of the highest population growth rates on the planet. They do not have a tradition of American-style megafarms, the institutions that create the current food surplus that are so important to help feed so much of the world. They do not have factories that can manufacture the complicated farm machinery necessary. The same goes for areas in Eastern Europe, and all of sub-Saharan Africa. South America could pick up some of the slack, but not all, should the American Midwest become a dust bowl of greater extent than during the Great Depression of the 1930s.
The second great problem is warfare. Nations are unlikely to sit around and watch their populations starve or their national treasuries deplete in order to buy enough food. It will become more and more tempting to simply take or blackmail other countries with nuclear weapons. The desert kingdoms and dictatorships of the Middle East, watching their deserts become even more arid, will become increasingly dangerous as many become armed with nuclear weapons.
The next two centuries will be an interesting time. Our ingenuity as a species could let us get through this. Our darker natures and impulses, however, in the face of sudden climate change, could result in the loss of half of all humans on Earth in a century or less.
AT WHAT LEVEL WILL GREENHOUSE GAS LEVELS PLATEAU AND THEN DESCEND, and, more important, how much will the world warm? Our homework, then, is to ensure that the world warms no more than 2 degrees Celsius from its present state. Why is that goal important, and how realistic is it? A guest column by Malte Meinshausen, Reto Knutti, and Dave Frame in the best source for climate change—realclimate. org—on January 31, 2006, is a good discussion and summary of this problem (and offers a possible solution), and if I pirate the spirit of their article, it is (hopefully) for a good cause.
The three authors go through the math, showing that a stable carbon dioxide level of 400 parts per million (to reiterate, we are at about 380 parts per million and rising as I write this in 2006) will yield an 80 percent chance that Earth will warm no more than 2 degrees Celsius. For instance, the rise from carbon dioxide levels of 280 parts per million at the start of the Industrial Revolution to the present level of 380 parts per million has brought about a global temperature increase of 0.8 degrees Celsius, thus calibrating the climate models used to predict future temperature increases that are tied to greenhouse gas concentration increases. The good news is that one of the most troublesome of greenhouse gases now being produced by human activity, methane, has a short life in the atmosphere before it breaks down. Also, the oceans are an effective sink for atmospheric carbon. If human emissions can be sharply curtailed in the twenty-first century, concentrations of all greenhouse gases could begin to decline near the end of the century according to the best models now available. However, these are just that—models. This model even lets greenhouse gas levels peak to 475 parts per million for a short time, but we do not go past the 2-degree increase if we can then bring them back down to 400 parts per million before the end of the century.
So how does society do this? Drive less. Drive less-polluting cars. Buy hybrids or electric cars. And there is more. For instance, the authors state:
We need to start taking large amounts of carbon out of the air. One very good way to get this going with positive environmental effects if managed properly is to grow biomass then char it and use the elemental carbon to mix in large quantities deep into soil as “terra preta” or Amazonian dark earths. This has major soil conditioning properties (i.e., reducing conventional fertilizer need by 50 percent).
In other words, use the enhancing carbon dioxide levels to grow lots of new plant material, turn that biomass into charcoal, and bury it into tropical soils.
WITHOUT HOPE THERE WILL BE NO ACTION. AS FAR AS CAN BE SEEN IN the present, we have not yet reached the point of no return, or the tipping point. We as a worldwide society can keep carbon dioxide levels below 450 parts per million. If we do not, we head irrevocably toward an ice-free world, which will lead to a change of the thermohaline conveyer belt currents, will lead to a new greenhouse extinction. The past tells us that this is so.