Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100 (40 page)

One of my acquaintances was the late Theodore Taylor, who had the rare distinction of designing some of the biggest and smallest nuclear warheads for the Pentagon. One of his designs was the Davy Crockett, weighing only fifty pounds, but capable of hurling a small atomic bomb at the enemy. Taylor was such a gung ho advocate of nuclear bombs that he worked on the Orion project, which was to use nuclear bombs to propel a spaceship to the nearby stars. He calculated that by successively dropping nuclear bombs out the end, the resulting shock wave would propel such a spacecraft to near the speed of light.

I once asked him why he got disillusioned with designing nuclear bombs and switched to working on solar energy. He confided to me that he had a recurring nightmare. His work on nuclear weapons, he felt, was leading to one thing: producing third-generation atomic warheads. (First-generation warheads of the 1950s were huge and difficult to carry to their targets. Second-generation warheads of the 1970s were small, compact, and ten of them could fit into the nose cone of a missile. But third-generation bombs are “designer bombs,” specifically tailored to work in various environments, such as the forest, the desert, even outer space.) One of these third-generation bombs is a miniature atomic bomb, so small that a terrorist could carry it in a suitcase and use it to destroy an entire city. The idea that his life’s work could one day be used by a terrorist haunted him for the rest of his life.

By midcentury, the full impact of a fossil fuel economy should be in full swing: global warming. It is now indisputable that the earth is heating up. Within the last century, the earth’s temperature rose 1.3° F, and the pace is accelerating. The signs are unmistakable everywhere we look:

• The thickness of Arctic ice has decreased by an astonishing 50 percent in just the past fifty years. Much of this Arctic ice is just below the freezing point, floating on water. Hence, it is acutely sensitive to small temperature variations of the oceans, acting as a canary in a mineshaft, an early warning system. Today, parts of the northern polar ice caps disappear during the summer months, and may disappear entirely during summer as early as 2015. The polar ice cap may vanish permanently by the end of the century, disrupting the world’s weather by altering the flow of ocean and air currents around the planet.

• Greenland’s ice shelves shrank by twenty-four square miles in 2007. This figure jumped to seventy-one square miles in 2008. (If all the Greenland ice were somehow to melt, sea levels would rise about twenty feet around the world.)

• Large chunks of Antarctica’s ice, which have been stable for tens of thousands of years, are gradually breaking off. In 2000, a piece the size of Connecticut broke off, containing 4,200 square miles of ice. In 2002, a piece of ice the size of Rhode Island broke off the Thwaites Glacier. (If all Antarctica’s ice were to melt, sea levels would rise about 180 feet around the world.)

• For every vertical foot that the ocean rises, the horizontal spread of the ocean is about 100 feet. Already, sea levels have risen 8 inches in the past century, mainly caused by the expansion of seawater as it heats up. According to the United Nations, sea levels could rise by 7 to 23 inches by 2100. Some scientists have said that the UN report was too cautious in interpreting the data. According to scientists at the University of Colorado’s Institute of Arctic and Alpine Research, by 2100 sea levels could rise by 3 to 6 feet. So gradually the map of the earth’s coastlines will change.

• Temperatures started to be reliably recorded in the late 1700s; 1995, 2005, and 2010 ranked among the hottest years ever recorded; 2000 to 2009 was the hottest decade. Likewise, levels of carbon dioxide are rising dramatically. They are at the highest levels in 100,000 years.

• As the earth heats up, tropical diseases are gradually migrating northward. The recent spread of the West Nile virus carried by mosquitoes may be a harbinger of things to come. UN officials are especially concerned about the spread of malaria northward. Usually, the eggs of many harmful insects die every winter when the soil freezes. But with the shortening of the winter season, it means the inexorable spread of dangerous insects northward.

CARBON DIOXIDE—GREENHOUSE GAS

According to the UN’s Intergovernmental Panel on Climate Change, scientists have concluded with 90 percent confidence that global warming is driven by human activity, especially the production of carbon dioxide via the burning of oil and coal. Sunlight easily passes through carbon dioxide. But as sunlight heats up the earth, it creates infrared radiation, which does not pass back through carbon dioxide so easily. The energy from sunlight cannot escape back into space and is trapped.

We also see a somewhat similar effect in greenhouses or cars. The sunlight warms the air, which is prevented from escaping by the glass.

Ominously, the amount of carbon dioxide generated has grown explosively, especially in the last century. Before the Industrial Revolution, the carbon dioxide content of the air was 270 parts per million (ppm). Today, it has soared to 387 ppm. (In 1900, the world consumed 150 million barrels of oil. In 2000, it jumped to 28 billion barrels, a 185-fold jump. In 2008, 9.4 billion tons of carbon dioxide were sent into the air from fossil fuel burning and also deforestation, but only 5 billion tons were recycled into the oceans, soil, and vegetation. The remainder will stay in the air for decades to come, heating up the earth.)

The rise in temperature is not a fluke, as we can see by analyzing ice cores. By drilling deep into the ancient ice of the Arctic, scientists have been able to extract air bubbles that are thousands of years old. By chemically analyzing the air in these bubbles, scientists can reconstruct the temperature and carbon dioxide content of the atmosphere going back more than 600,000 years. Soon, they will be able to determine the weather conditions going back a million years.

I had a chance to see this firsthand. I once gave a lecture in Reykjavik, the capital of Iceland, and had the privilege of visiting the University of Iceland, where ice cores are being analyzed. When your airplane lands in Reykjavik, at first all you see is snow and jagged rock, resembling the bleak landscape of the moon. Although barren and forbidding, the terrain makes the Arctic an ideal place to analyze the climate of the earth hundreds of thousands of years ago.

When I visited their laboratory, which is kept at freezing temperatures, I had to pass through thick refrigerator doors. Once inside, I could see racks and racks containing long metal tubes, each about an inch and a half in diameter and about ten feet long. Each hollow tube had been drilled deep into the ice of a glacier. As the tube penetrated the ice, it captured samples from snows that had fallen thousands of years ago. When the tubes were removed, I could carefully examine the icy contents of each. At first, all I could see was a long column of white ice. But upon closer examination, I could see that the ice had stripes made of tiny bands of different colors.

Scientists have to use a variety of techniques to date them. Some of the ice layers contain markers indicating important events, such as the soot emitted from a volcanic eruption. Since the dates of these eruptions are known to great accuracy, one can use them to determine how old that layer is.

These ice cores were then cut in various slices so they could be examined. When I peered into one slice under a microscope, I saw tiny, microscopic bubbles. I shuddered to realize that I was seeing air bubbles that were deposited tens of thousands of years ago, even before the rise of human civilization.

The carbon dioxide content within each air bubble is easily measured. But calculating the temperature of the air when the ice was first deposited is more difficult. (To do this, scientists analyze the water in the bubble. Water molecules can contain different isotopes. As the temperature falls, heavier water isotopes condense faster than ordinary water molecules. Hence, by measuring the amount of the heavier isotopes, one can calculate the temperature at which the water molecule condensed.)

Finally, after painfully analyzing the contents of thousands of ice cores, these scientists have come to some important conclusions. They found that temperature and carbon dioxide levels have oscillated in parallel, like two roller coasters moving together, in synchronization over many thousands of years. When one curve rises or falls, so does the other.

Most important, they found a sudden spike in temperature and carbon dioxide content happening just within the last century. This is highly unusual, since most fluctuations occur slowly over millennia. This unusual spike is not part of this natural heating process, scientists claim, but is a direct indicator of human activity.

There are other ways to show that this sudden spike is caused by human activity, and not natural cycles. Computer simulations are now so advanced that we can simulate the temperature of the earth with and without the presence of human activity. Without civilization producing carbon dioxide, we find a relatively flat temperature curve. But with the addition of human activity, we can show that there should be a sudden spike in both temperature and carbon dioxide. The predicted spike fits the actual spike perfectly.

Lastly, one can measure the amount of sunlight that lands on every square foot of the earth’s surface. Scientists can also calculate the amount of heat that is reflected into outer space from the earth. Normally, we expect these two amounts to be equal, with input equaling output. But in reality, we find the net amount of energy that is currently heating the earth. Then if we calculate the amount of energy being produced by human activity, we find a perfect match. Hence, human activity is causing the current heating of the earth.

Unfortunately, even if we were to suddenly stop producing any carbon dioxide, the gas that has already been released into the atmosphere is enough to continue global warming for decades to come.

As a result, by midcentury, the situation could be dire.

Scientists have created pictures of what our coastal cities will look like at midcentury and beyond if sea levels continue to rise. Coastal cities may disappear. Large parts of Manhattan may have to be evacuated, with Wall Street underwater. Governments will have to decide which of their great cities and capitals are worth saving and which are beyond hope. Some cities may be saved via a combination of sophisticated dikes and water gates. Other cities may be deemed hopeless and allowed to vanish under the ocean, creating mass migrations of people. Since most of the commercial and population centers of the world are next to the ocean, this could have a disastrous effect on the world economy.

Even if some cities can be salvaged, there is still the danger that large storms can send surges of water into a city, paralyzing its infrastructure. For example, in 1992 a huge storm surge flooded Manhattan, paralyzing the subway system and trains to New Jersey. With transportation flooded, the economy grinds to a halt.

A report by the Intergovernmental Panel on Climate Change isolated three hot spots for potential disaster: Bangladesh, the Mekong Delta of Vietnam, and the Nile Delta in Egypt.

The worst situation is that of Bangladesh, a country regularly flooded by storms even without global warming. Most of the country is flat and at sea level. Although it has made significant gains in the last few decades, it is still one of the poorest nations on earth, with one of the highest population densities. (It has a population of 161 million, comparable to that of Russia, but with 1/120 of the land area.) About 50 percent of the land area will be permanently flooded if sea levels rise by three feet. Natural calamities occur there almost every year, but in September 1998, the world witnessed in horror a preview of what may become commonplace. Massive flooding submerged two-thirds of the nation, leaving 30 million people homeless almost overnight; 1,000 were killed, and 6,000 miles of roads were destroyed. This was one of the worst natural disasters in modern history.

Another country that would be devastated by a rise in sea level is Vietnam, where the Mekong Delta is particularly vulnerable. By midcentury, this country of 87 million people could face a collapse of its main food-growing area. Half the rice in Vietnam is grown in the Mekong Delta, home to 17 million people, and much of it will be flooded permanently by rising sea levels. According to the World Bank, 11 percent of the entire population would be displaced if sea levels rise by three feet by midcentury. The Mekong Delta will also be flooded with salt water, permanently destroying the fertile soil of the area. If millions are flooded out of their homes in Vietnam, many will flock to Ho Chi Minh City seeking refuge. But one-fourth of the city will also be underwater.

In 2003 the Pentagon commissioned a study, done by the Global Business Network, that showed that, in a worst-case scenario, chaos could spread around the world due to global warming. As millions of refugees cross national borders, governments could lose all authority and collapse, so countries could descend into the nightmare of looting, rioting, and chaos. In this desperate situation, nations, when faced with the prospect of the influx of millions of desperate people, may resort to nuclear weapons.