Armageddon Science (13 page)

Looking back over time—this is possible thanks to analysis of bubbles trapped in ancient ice cores from Antarctica and Greenland, where the further down we drill, the further back we look in time—the carbon dioxide level was roughly stable for around eight hundred years before the start of the Industrial Revolution. Since then it has been rising, and even the rate at which it rises is on the increase—not only is the level of CO
₂
in the atmosphere growing; the growth is accelerating.

In preindustrial times, the amount of carbon dioxide in the atmosphere was around 280 ppm (parts per million). By 2005 it had reached 380 ppm, higher than it has been at any time in the last 420,000 years. It’s thought that the last time there was a consistent comparable level was 3.5 million years ago in the warm period in the middle of the Pliocene epoch, well before the emergence of Homo sapiens, and it’s likely that levels haven’t been much higher since the Eocene epoch, 50 million years ago. The Intergovernmental Panel on Climate Change predicts that if we don’t change the amount of CO
₂
we generate, levels could be as high as 650 to 1,000 ppm by the end of the century. The Goddard Institute for Space Studies (GISS) model, one of the best computer simulations of the Earth’s climate, which reflects the impact of these changes on water patterns, predicts that most of the continental United States will regularly suffer severe droughts well before then.

Current predictions are that by the end of the century, the tropics will live through droughts thirteen times as often as they do now. Drought is already on the increase. A 2005 report from the U.S. National Center for Atmospheric Research notes that the percentage of land areas undergoing serious drought had doubled since the 1970s. Southwestern Australia, for instance, is facing a steady reduction in rainfall, leading to both potential drought and increased chances of bushfires.

As drought conditions spread, availability of water becomes restricted. Significant decreases in water output from rivers and aquifers are likely in Australia, most of South America and Europe, India, Africa, and the Middle East. Across the world, drought will be dramatic. The 2007 report of the UN Intergovernmental Panel on Climate Change predicted that by the last quarter of the century between 1.1 billion and 3.2 billion people will be suffering from water-scarcity problems.

Most historical droughts have been relatively short-term. Caused by statistical blips in the climate rather than marked permanent change, they cause devastation and disaster, but can be recovered from. A long-term drought provides no way out. Where these have happened in the past, civilizations have simply disappeared. After three or four years, the inhabitants of the drought area are faced with a simple choice: evacuation or death. A couple of years later and you have an abandoned region, littered with ghost towns and dead villages. Drought is no minor inconvenience.

At first glance, the whole concept of running low on water is an insane one. Looked at from space, the defining feature of the Earth when compared with the other planets in our solar system is water. Our world is blue with the stuff. In round figures there are 1.4 billion cubic kilometers (a third of a billion cubic miles) of water on the Earth. This is such a huge amount, it’s difficult to get your head around. A single cubic mile (think of it, a cube of water, each side a mile long) is around 1 trillion gallons of water.

Divide the amount of water in the world by the number of people and we end up with nearly a tenth of a cubic mile of water each. More precisely, 56 billion gallons for everyone. With a reasonable consumption of 1.3 gallons per person per day, the water in the world would last for 116,219,178 years. And that assumes that we totally use up the water. In practice, much of the water we “consume” soon becomes available again for future use. So where’s the water shortage?

Things are, of course, more complicated than this simplified picture suggests. In practice, we don’t just get through our 1.3 gallons a day. The typical Western consumer uses between 1,500 and 3,000 gallons. In part this happens directly. Some is used in taking a bath, watering the lawn, flushing the toilet—but by far the biggest part of our consumption, vastly outweighing personal use, is the water taken up by manufacturing the goods and food that we consume. Just producing the meat for one hamburger can use 1,000 gallons, while amazingly, a one-pound can of coffee will eat up 2,500 gallons in its production.

However, even at 3,000 gallons a day, we still should have enough to last us over 57,000 years without even adding back in reusable water. So where is the crisis coming from? Although there is plenty of water, most of it is not easy to access. Some is locked up in ice or underground, but by far the greatest majority—around 97 percent of the water on the planet—is in the oceans.

For countries with a coastline, like the United States, this is not particularly difficult to get to, but it is costly to take seawater and make it drinkable. The fact that nations with coastlines are prepared to spend huge amounts of money on reservoirs to collect a relatively tiny proportion of fresh rainwater, rather than use the vast quantities of sea that border them, emphasizes just how expensive is the desalination process required to turn seawater into drinkable freshwater.

Water shortages, then, come down to a lack of cheap power. If we had unlimited extremely cheap power, there would not be a water shortage. More indirectly, the price of power also limits our access to food. Drought makes food harder to grow, since we must rely more on expensive irrigation; but with sufficient power, irrigation should not be an issue. On the world scale, as climate change bites, limits on power availability make it harder to provide irrigation and to transport food around the world to meet global need.

Even where there is not the immediate threat of drought, the rise in temperature can push previously lush areas into decline. Many areas that are currently tropical forests—the Amazon rain forest has to be the best known example—are predicted to change to savannah, grassland, or even desert as carbon dioxide levels rise and a combination of lack of water and wildfire destroy the woodland. The Amazon, long touted as the lungs of the world, has already become an overall source of carbon dioxide, pumping over 200 million tons of carbon from forest fires into the air—more than is absorbed by the growing forest. If things continue the way they are, the expectation is that the Amazon rain forest will be just a memory by the end of the century.

This change of the environment from carbon sink—a mechanism to eat up carbon dioxide from the air—to carbon source is a feature of not just tropical forests. In 2005, scientists in the United Kingdom reported that soil in England and Wales had switched from being a carbon sink to being a carbon emitter. As average temperatures rise, the bacteria in the soil become more active, giving off more CO
₂
. Remarkably, in 2005 this was already proving enough of a carbon source to cancel out all the benefits from reductions in emissions that the United Kingdom had made since 1990.

A combination of decrease in rainfall over areas like the Amazon rain forest with increase in temperature is expected to result in a massive die-off. There is a similar expectation that temperate and coniferous forests in Europe and parts of North America will be drastically reduced. The picture isn’t uniformly gloomy—there is some expectation of a northern expansion of forest in North America and Asia—but even so, the overall effect is that vegetation that has been soaking up carbon will, in our lifetimes, reverse to being an overall source of carbon, kicking the greenhouse effect into positive feedback. And positive feedback is the worst possible news about climate change.

The best-known example of positive feedback is the howl from a sound system when a microphone is brought too close to the speaker. Tiny ambient sounds are picked up by the microphone, come out of the speaker louder, are collected again by the microphone, and are reamplified, getting louder and louder until they become an ear-piercing screech. One of the most worrying aspects of climate change is that the global climate also features a number of positive-feedback systems, where a change reinforces the cause of the change, making the change happen faster, which reinforces the cause more, and so on.

Positive feedback has often been omitted from predictions. As
New Scientist
put it in February 2007, “The rising tide of concern among researchers about positive feedbacks in the climate system is not reflected in the [IPCC report] summary…. One clear need is to get to grips with the feared positive feedbacks.”

It’s not just the Amazon rain forest and the Australian bush that are tipping into positive feedback, adding to the greenhouse effect. Other forests around the world are being taken out of the carbon-sink equation as temperatures rise. For example, a combination of the increased temperature and the spread of pests is having a devastating effect on some Canadian forests. In one year, British Columbia lost nearly one hundred thousand square kilometers (forty thousand square miles) of pine trees (over half the land area of the state of Washington) to a combination of forest fires and disease. The local government estimates that 80 percent of the area’s pines will be gone by 2013.

Wildfires, destroying thousands of hectares of land and properties, are becoming increasingly common. In 1998 fires destroyed 485,000 acres in Florida and 2.2 million acres in Nicaragua. This is happening more and more frequently. More than 600,000 acres were destroyed on the Florida/Georgia border in 2007. Even in previously temperate areas like the United Kingdom, wildfires now pose a threat.

Agriculture will be forced to undergo major changes. Traditional crops of hot countries will take over in previously temperate regions, while areas already growing such high-temperature crops will find it increasingly hard to provide any food. The 2007 IPCC report that forecast huge water shortages also predicted that as the twenty-first century progresses, up to 600 million extra people will go hungry as a direct result of climate change.

If things get too drastic, perhaps our only hope will be a “Noah’s ark” of food—the vault being built by the Global Crop Diversity Trust in the permafrost of the Svalbard Archipelago near the North Pole, which will contain 3 million batches of seeds from all current known varieties of crops as a defense against the impact of global catastrophe.

There is an even more insidious effect of global warming that provides another, particularly dramatic, positive-feedback loop in the climate system—the melting of the Siberian permafrost.

In western Siberia lies a huge peat bog, around 900,000 square kilometers (350,000 square miles) in area—the size of Texas and Kansas put together. Peat, the partly decayed remains of ancient moss and vegetation, is a rich source of methane, a gas that contributes twenty-three times as much to the greenhouse effect weight for weight as does carbon dioxide. The methane from the bog is frozen in place by the permafrost—a solid mix of ice and peat that never melts. At least, that never melted until now. That permafrost is liquefying, discharging a huge quantity of methane into the atmosphere. By 2005 it was estimated that the bog was releasing 100,000 tons of methane a day. That has more warming effect than the entire man-made contribution of the United States. And thanks to positive feedback, the more the bog releases methane, the faster it warms up, releasing even more.

The impact of increasing temperatures is even worse for our city dwellers than for the rest of the population, thanks to the urban heat island effect. In a normal environment, summertime temperatures are kept under control by nighttime cooling. Without energy from the Sun hitting the dark side of the Earth, the planet can only lose heat, and where there are clear skies this can happen surprisingly quickly, providing the biting cold nights of the desert. But something goes wrong with this natural cooling process in a city. The sidewalks and canyonlike streets act as storage heaters, absorbing energy that will keep temperatures relatively high at night.

This is the reason that many of the casualties of the European heat wave of 2003 were in cities. It’s not a sudden, short snap of heat that is a large-scale killer; it’s sustained heat that goes on day after day, and particularly that carries on through the hours of darkness. In the 2003 heat wave, it never got cool enough at night for relief. On August 12, 2003, Paris suffered a nighttime temperature that never went below 25.5 degrees Celsius (78 degrees Fahrenheit), stifling for the majority of city-center households without air-conditioning. Thousands died from the impact of the relentless heat held in place by the city streets. The final European death toll was over thirty-five thousand from the heat and up to fifteen thousand more from the pollution that built up, particularly over cities, in the warm still air.

Europe isn’t alone in suffering the impact of sustained heat. Even though air-conditioning is much more widespread in the United States, hundreds died in Chicago in July 1995 when a heat wave of such sustained ferocity hit the city that on two successive nights the thermometer never dropped below 27 and 29 degrees Celsius (80 and 84 degrees Fahrenheit) respectively. To make matters still worse, warm air rises. The temperature difference between the ground floor and the top floor of a building can be enough to make the difference between comfort and trying to sleep in a virtual oven. Older high-rise buildings without air-conditioning but with relatively good air flows are particularly susceptible to roasting inhabitants on upper floors.

The urban heat island effect is real, and because it is factored out of climate change calculations to avoid confusing the impact from greenhouse gases, it means that cities are likely to fare significantly worse than the predictions of temperature rise given by the climate change models. It has been shown that urban heat islands don’t contribute particularly to the overall warming of the planet (this can be seen because there is no real difference in global temperature between still days in the city, when the effect arises, and windy days)—but that really doesn’t matter to the person in the city apartment. She will still suffer much more than the models predict.