Humans are the most successful species in the history of our planet. But our very success has encouraged us to increase numbers so much that our own survival is now at risk. The danger is of no more tiger economies but a lot more Gazas.
Scientists have long pondered how many people the planet can sustain. In 1679 a Dutchman called Antoni van Leeuwenhoek, an early microbiologist and friend of the painter Johannes Vermeer, calculated that the inhabited area of the planet was some thirteen thousand times larger than Holland, which then had a population of about a million people. So he reckoned the world could handle at least thirteen billion people. Current environmentalists have somewhat lower figures.
Paul Ehrlich figured that what he called the planet's "carrying capacity" might be about five billion. More recently, scientist have calculated that with 6.8 billion people on the planet, we were by 2008 consuming 30 percent more resources each year than the planet produces, so we are trashing the rainforests, emptying the oceans, eroding the soils, and filling the air with greenhouse gases. In the jargon, we are "drawing down" our natural capital. They suggest that the way we live now, the true long-term carrying capacity of the planet is about 5.2 billion people.
There are other, lower figures. Britain's leading organization campaigning for smaller populations, the Optimum Population Trust, which counts Ehrlich among its patrons, says we have to bring our numbers down to three billion or face "nature's brutal population policies . . . increasing the death rate by famines and disease." The scientist James Love lock, inventor of the Gaia hypothesis, says we are treating the planet so badly that we are likely to require a population crash to about one billion people before the world can again live within its ecological means.
It is easy to see why there is so much pessimism. We are wrecking many of the earth's life support systems. An inventory of the state of nature's bounty makes a sobering read. We have removed half the planet's forests. They once covered two-thirds of the planet's land surface but are now down to one-third. We have destroyed about a quarter of its topsoil through plowing and erosion. We have killed off most of its large animals and probably nine-tenths of its fish stocks. We are consuming about 40 percent of the plant matter grown on the planet and diverting about 60 percent of its river flows for irrigation, for cities and industry, or to hydroelectric reservoirs.
Every year we extract from underground, and then burn, the fossilized remains of plants that it took nature about a million years to produce. The resulting carbon dioxide emissions have so far warmed the atmosphere by one degree. As a result, we are melting the Arctic, raising sea levels, and intensifying droughts, floods, and storms. The warming will last so long that we are probably close to canceling the next ice age.
In addition, we have altered the chemistry of the atmosphere sufficiently to rip a hole in the protective ozone layer and to acidify the rain and even the oceans. We are now the dominant force in the nitrogen cycle. Fertilizers are flushing so much of the element into soils and water sources that forests die and giant dead zones form in rivers, lakes, and oceans. We have created (but thankfully have so far refrained from using) hydrogen bombs with the ability to wipe out most life on earth. This is a planetary crisis. And many people blame it on human numbers.
Our sheer numbers have clearly been crucial to what has happened, but they are only part of the story. In The Population Bomb, Paul Ehrlich pointed out that our environmental impact on the planet is a combination of three things: the number of individuals, the consumption of each individual, and the resources needed, or pollution created, in satisfying that consumption. He argued that population growth was the dominant factor in increasing our environmental impact in the 1960s. Perhaps for a while it was. But since then, the pace of population growth has slowed. And what growth continues is increasingly confined to the planet's poorest people, those who consume the least. So the impact of those extra people is surprisingly small. By late in the century, when some threats like climate change are expected to become most serious, our population may be falling.
If population was the only thing we had to worry about, we might be okay. The trouble is that, as population growth has slackened, Ehr-lich's second factor in humanity's impact on the planet has come to the fore. Rising consumption is now a much bigger threat to the planet. It is responsible for almost all our increased ecological footprint in the past thirty years, the period when analysts say we have overshot the planet's carrying capacity. Despite the rise of economies like China's, that increase in consumption is mainly in the rich world, among those already consuming the most.
The average citizen of the United States has an ecological footprint of 23.5 acres—that is, the amount of the planet's surface needed to provide him or her with food, clothing, and other consumables, and to soak up his or her pollution. Meanwhile, Australians and Canadians require 17 acres, Europeans and Japanese 10 to 12 acres, the Chinese 5 acres, and Indians and most Africans less than 2.5 acres. Of course, there are rich people in the poor world and vice versa. But if we look just at the richest billion people on the planet, their average consumption of resources and production of waste today is thirty-two times that of the average for the nearly six billion remaining people.
A separate calculation has been done on who is responsible for the greenhouse gas emissions behind climate change. It turns out that the poorest three billion or so people on the planet (roughly 45 percent of the total) are currently responsible for only 7 percent of emissions, while the richest 7 percent (about half a billion people) are responsible for 50 percent of emissions. A woman in rural Ethiopia can have ten children and her family will still do far less damage, and consume fewer resources, than the family of the average soccer mom in Minnesota or Manchester or Munich. In fact, in the unlikely event that her ten children live to adulthood and all have ten children of their own, the entire clan of more than a hundred will still be emitting only about as much carbon dioxide each year as you or I will.
So to suggest, as some do, that the real threat to the planet arises from too many children in Ethiopia, or rice-growing Bangladeshis on the Ganges delta, or Quechuan alpaca herders in the Andes, or cow-pea farmers on the edge of the Sahara, or chai wallahs in Mumbai, is both preposterous and dangerous. This is not to say that population is irrelevant. The quadrupling of global population during the twentieth century helped bring us to the edge of the abyss. But any analysis of the damage being caused today by rising population and rising consumption must conclude that consumption is the greater peril.
It is of course true that poor people with small ecological footprints may grow rich, or produce children who grow rich, eventually assuming ecological footprints as great as ours. If they do that, it is hard to see anything other than disaster ahead. If nothing else, climate change will create such chaos that the prospects of feeding five billion, let alone more, will be all but impossible. But there is good news. We can reduce our ecological footprints while keeping, if not every aspect of our lifestyles, then at any rate those parts of our lifestyles that make our lives truly worth living.
The wonder is that we rich-world consumers have come so far without already precipitating a major crisis of the kind envisaged by Mal-thus, Vogt, Ehrlich, and others. Our bacon has been saved by the third, and least discussed, element in Ehrlich's equation. As our technologies improve and become more efficient, so we are getting smarter at generating wealth. We are using fewer resources and creating less waste in making each dollar. Our power stations produce more power from the same amount of fuel, our industries take less power and make better use of metals, we replace scarce materials with more abundant ones, we recycle more things we used to landfill, and so on.
The gains are remarkable. The trouble is that they are masked by our rising consumption. The most obvious example is our cars. They are much more fuel efficient and much less polluting than vehicles of the same weight and performance even a few years ago. Unfortunately, we insist on taking advantage of that fact by driving bigger vehicles, like SUVs, and driving them longer distances. So the gains are lost. We are still using more resources.
The hope now must be that our growing concern for the planet's limits will drive us to cut the environmental impact of generating the good things in life and to be more green-minded in our sense of what the good things in life are. Chris Goodall, in his book How to Live a Low-carbon Life, concluded that most of us could reduce our carbon footprints by 75 percent at little inconvenience. So there is a way forward that requires neither culling large numbers of people nor sacrificing our quality of life. We just have to take it.
We have to trust that Ester Boserup, the Danish economist, was right when she said that crises, and our awareness of them, are what stimulate major innovation, both in technologies and in the way we organize things. I believe we can. We humans are good problem solvers, once we have figured out what the problem is.
My optimism won't necessarily be borne out by events. Humans don't always get things right. The planet is littered with the remains of past civilizations that crashed painfully, often as their natural environments gave out. And this time we have a global civilization that is impacting on the planet as a whole, especially through climate change. We have to get this one right. I can see why many reckon there is little chance of success and why, metaphorically at least, they are ready to head for the hills. But I am not.
There are plenty of practical examples to justify my optimism that Ehrlich's third factor can come to our rescue. The green revolution happened because we recognized a crisis over the planet's ability to feed a population expected to double in a generation. Faced with that crisis, we acted. Both Europe and North America have dramatically improved their domestic environments in the past half century—reducing smog, cleaning rivers, and reforesting. A handful of poor countries are now taking the same road, reversing the loss of tropical rainforests, for instance.
Take Costa Rica. As ranchers and loggers ransacked the country's forests, tree cover in this small Central American country fell from 80 percent in the 1950s to just 21 percent in 1987. It was, for a while, being deforested faster than any country on the planet. For years, environmentalists argued that this was the "inevitable consequence" of a population that at one point had doubled in seventeen years—another world record. The only thing wrong with that statement was the word "inevitable."
Since 1987, Costa Rica has been regrowing its forests. Today tree cover is back above 50 percent, even though the population has grown more in the two decades since 1987 than in the two decades before. The nation now pays farmers to protect the forests rather than to chop them down, and gets extra income from millions of tourist coming to see the jungle wildlife. "We discovered that it was government policies that were destroying the forest, not too many farmers. This is true across the world," says former Costa Rican environment minister Carlos Manuel Rodriguez. That is an important lesson, and one which environmental pessimists miss. There is another way.
The most global threat we face today is climate change. So what chance do we have of fixing that before it fixes us? The task looks daunting. Climate scientists say the world needs to cut greenhouse gas emissions by at least 80 percent by 2050 to curb dangerous climate change. That means transforming how we generate and use energy—in homes, factories, offices, public spaces, and transportation. It requires a combination of new energy technologies that do not release carbon dioxide into the atmosphere. And it requires redesigning our lives and living environments to reduce energy needs—for instance, building cities where local services can be reached on foot and the rest by mass transit systems rather than cars.
We need to spread the new ideas and technologies fast. And they need to arrive fastest in the countries currently developing their energy infrastructure most rapidly. The UN estimates that by 2030, $26 trillion will be invested in energy worldwide, and more than half of that will be in developing countries, where two billion people still lack electricity supplies. Those countries need to leapfrog to the new technologies without passing through the dirty and polluting phase that most industrializing countries have taken.
The good news is that we know most of the technologies that we require. Wind energy is well developed and not expensive. Solar power is fast emerging. There is growing interest today in concentrated solar power, which uses mirrors and lenses to focus solar energy to heat water that then runs conventional power turbines. Large areas of desert, from Nevada to Algeria to India, could be covered in mirrors catching the sun's energy. Other natural sources of energy that can be harvested include tidal and wave power and geothermal energy (hot rocks). We could keep burning fossil fuels if we found ways to capture carbon dioxide emissions and bury them out of harm's way. Nuclear power and hydroelectricity have their detractors but will live on.
Future vehicles are likely to be driven by electricity. If the electricity is generated without emitting carbon dioxide, that will be a huge gain. Biofuels have been justly criticized for taking land and water needed for growing food. But future biofuels, particularly those using algae or waste products from farming, may be a better bet. My guess is that their main use will be to power planes. Above all, there is huge potential, in almost every sphere of life, for much greater efficiency in the use of energy. From heavy industry to transportation, buildings, and consumer electronics, cost-effective modifications and redesign can cut energy use, typically by 30-50 percent. The world is switching to energy-efficient light bulbs right now. But almost every other use of energy could make a similar step change at similarly negligible cost.
There is no inevitability about more consumption requiring more energy, or about more energy resulting in more carbon emissions. The link can be, and sometimes is being, broken. An international comparison of how much wealth different countries currently create (in terms of gross domestic product) for every ton of carbon dioxide they emit is revealing. Both Russia and China produce only around $400 of GDP per ton of emissions. Five times better are the United States and Australia, which each produce around $2,000 of GDP per ton. Britain, Germany, and Italy do still better at around $3,500 per ton, while nuclear-powered France is above $5,000. Sweden manages $6,000 per ton, and two countries as different as Switzerland and Cambodia both manage to produce around $9,000 of GDP for every ton of carbon dioxide emitted. If the whole world did as well as those two countries, then the world's carbon dioxide emissions would be only a third what they are today. So cutting emissions by 80 percent by 2050 is not impossible. It is doable. Today.
We have the capability to tackle these great issues and to carve out a sustainable future. In the next chapter, I will look at whether we can continue to feed ourselves. But we have to persuade ourselves of the seriousness of the threats we face, so that we act. If necessity is the mother of invention, we have to recognize the necessity. We have to fear those
"limits to growth" in order to defeat them. Just as the green revolution staved off mass global hunger, so a new revolution to change the way we generate and use energy can stave off the worst of climate change—if we have the will to do it.
For me, environmentalists are at their best when they alert us to the dangers—and at their worst when they succumb to the belief that their worst predictions are destined to come true. The optimists are at their best when they convince us that anything is possible—and at their worst when they are convinced that we don't have to change in order to achieve it, that all we need to do is trust God or the markets.
There is a paradox here, of course. Half a century ago, Vogt, Huxley, Ehrlich, and the rest were wrong to predict mass hunger in the late twentieth century. But it was their dire predictions and the world's response to them that ensured it didn't happen. The appalling thought of billions of dead galvanized a generation. The challenge now is to prove the doomsayers wrong again. If we do it right, everyone can live a good life. As Mahatma Gandhi famously put it, "There is enough for everyone's need, but not for everyone's greed."
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Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.