Food: Will There Be Enough?
Human history is replete with dire warnings of mass famine, and, frequently, the real thing. And ever since Thomas Malthus observed that population growth tends to outstrip food production, debate has raged over whether an ever-growing human population will be able to feed itself. But the links between population growth and hunger are complex. Famine is never simply a function of too many people: for example, the food crisis of 2007-8 was largely rooted in a free-market economic model that has undermined food security around the globe. Still, humanity’s continued ability to feed itself is far from assured.
The recent food crisis was not caused by population growth. Consider the case of Mexico, where the price of tortillas rose 60% in 2007, causing widespread hunger and sparking food riots. The roots of the crisis can be traced back to the 1980s, when the heavily-indebted Mexican government turned to the World Bank and International Monetary Fund for loans. In exchange for those loans, Mexico was forced to enact free-trade “reforms,” including dismantling subsidies for small farmers. Those farmers took a bigger blow in 1994, when the North American Free Trade Agreement (Nafta) flooded the Mexican market with inexpensive, subsidized corn from the U.S. By 2007, Mexico—the land where corn was first domesticated—had become a net importer of corn. That left Mexicans extraordinarily vulnerable to price increases—as in 2007, when demand for ethanol drove up the price of corn—and tortillas.
Food production has increased. Despite persistent hunger, humanity has made dramatic progress towards food security in the last half-century. Production of the “big three” grains – wheat, rice and corn — has more than tripled since 1950, increasing from 630 million to 2 billion tons. These gains were achieved in two ways: by increasing the number of acres under cultivation (extensification) by clearing forests and grasslands, and by boosting the productivity of each acre (intensification) with irrigation, high-yield crops, new farming practices and synthetic fertilizer.
But will those increases continue? The prospects for continuing gains in extensification and intensification are limited. As a result, farmers will be hard-pressed to maintain current levels of production, much less make the increases necessary to accommodate a growing population. Already, growth in world grain production has slowed. The rate of increase in the yields of the big three crops fell below the growth in world population after 1984. And the number of hungry people in the world–which was greatly reduced from 1950 to 1984 and continued to decline until the late 1990s–has since turned upward.
The challenges are daunting: Today farmers contend with shrinking cropland, shortages of irrigation water, diminishing returns from fertilizers, climate change, rising fuel costs, and a dwindling backlog of yield-raising technologies. At the same time, they face fast-growing demand from the more than 70 million people added to the world’s population each year, the desire of billions to “move up the food chain” and consume more grain-based meat and dairy products, and now the millions of motorists turning to crop-based fuels.
Urban sprawl is claiming some of the world’s best farmland. Many major cities were established in regions of exceptional agricultural productivity. Today, half of humanity lives in urban areas, and the world’s urban population is expected to double in the next half century. Right now the most densely settled half of the planet’s population lives on two to three percent of all ice-free land. If cities double in area as well as population by 2050, urban areas could grow to occupy six percent of the world’s land. Withdrawing that amount from the 10 to 15 percent of land considered arable could significantly diminish agricultural production.
Fast Facts:
- Grain production is falling behind. World grain production has fallen short of consumption in six of the last nine years, drawing down world grain stocks.
- Hunger is growing. The U.N. Food and Agriculture Organization estimates that the number of undernourished people grew from 848 million to 963 million between 2004 and 2008, largely because of the food price crisis.
- Some 20% of the world’s cropland has been degraded by human activity – such as poor farming practices, pollution, and overgrazing. One quarter of humanity – 1.5 billion people – depends directly on land that is being degraded.
- Irrigation water sources are being used up faster than they can be replenished. In the United States, the massive Ogallala aquifer, which supplies about 30 percent of the ground water used for irrigation in the United States, is so heavily overdrawn that water levels have dropped by more than 100 feet in some areas.
- The Green Revolution has left a toxic legacy. Synthetic fertilizer has boosted agricultural productivity, but at great cost to the ecosystems we depend on. For example, fertilizer carried into bays and oceans creates oxygen-depleted “dead zones” that cannot support aquatic life. There are now 405 such zones worldwide, up from 49 in the 1960s. Dead zones decimate fisheries – another critical source of food for a growing human population.
- The grain required to fill an SUV’s 25-gallon tank with ethanol just once will feed one person for a whole year.
- How many people can the Earth support? It depends. If everyone on Earth ate like Americans – consuming roughly 800 kilograms of grain per person annually for food and animal feed, the two-billion-ton annual world harvest of grain would support only 2.5 billion people. At the 200 kilograms of grain consumed by the average Indian, it would support a population of 10 billion.
Population and Climate
Slowing population growth can make a significant contribution to climate change mitigation. Moreover, the means to slow population growth—family planning and reproductive health services, girls’ education, and poverty alleviation—can help societies adapt to climate change by bolstering resilience.
Slowing population growth is a piece of the mitigation “pie.” Slower population growth could make a substantial contribution to mitigating climate change. To put that contribution into perspective, consider the Socolow and Pacala “wedge” approach to reducing greenhouse gas emissions (see below). Socolow and Pacala compare the current emissions trajectory to one that would stabilize climate at a safer level. The gap between those trajectories is divided into pie-shaped “wedges,”—each representing an action begun today that would eliminate 1 billion tons of CO2 per year by 2050. Seven slices are needed to avert disastrous change. Socolow and Pacala estimate that stabilizing world population at 8 billion, rather than 9 billion or more, would provide one—or even two— “wedges” of emissions reductions.
Source: Pacala and Socolow, 2004, Stabilization wedges.
Stabilizing world population at 8 billion, rather than 9 billion or more, would provide one—or even two— “wedges” of emissions reductions.
Slowing population growth is not all we must do. A smaller human population is no guarantee of lower emissions; continued reliance on fossil fuels could easily outweigh the positive impact of slower growth. For example, in the emissions scenarios generated by the International Panel on Climate Change, the highest emissions of all were produced in the “A1 scenario,” which featured robust economic growth, greater use of fossil fuels – and slow population growth. Prudent climate policy encompasses a range of strategies: conservation, technological innovation, and slower population growth.
The greatest impact of slower growth will be felt later this century. Slower population growth is not a quick fix for climate change; its full impact would not be felt until the second half of this century. However, according to mitigation scenarios, that is also when the deepest reductions in emissions must be made. Those reductions are likely be the most expensive, because the cheapest reductions are typically made first and each additional ton reduced is more expensive than the last. Slower population growth could therefore have an even larger impact when viewed from the perspective of costs, by eliminating the need for the most expensive reductions.
Slowing population growth is also an adaptation strategy. Proven strategies to slow population growth, such as family planning and girls’ education, can help families and societies adapt to climate change. These programs have been shown to improve public health, economic well-being and women’s empowerment—crucial building blocks of resilience.
Fast Facts:
- Emissions are affected by other demographic changes, as well. Aging populations are associated with decreased emissions, while urbanization is associated with a rise in emissions.
- There are vast disparities in per-capita emissions. The average American produces nearly 20 metric tons of CO2 emissions every year, while each sub-Saharan African produces little more than a ton.
- In aggregate terms, the developing countries now emit more than the developed countries. The biggest emitters of carbon dioxide, in absolute terms, are the rapidly emerging economies of the global south. According to the Center for Global Development, rapidly rising emissions would put developing countries on track to produce their own climate crisis in just twenty years—even without emissions from the high-income countries.
- Countries with youthful age structures—which are associated with rapid population growth—tend to be least resilient to climate change impacts. The Vulnerability-Resilience Indicators Model (VRIM) index developed at the Joint Global Change Research Institute provides a framework to measure and rank country vulnerability and resilience, examining both sensitivity and adaptive capacity. Eighty-eight percent of the countries ranked lowest in resilience to climate change have very young age structures.
Population and the Environment
Population growth has a significant impact on the natural environment, but that impact is shaped by a wide range of mediating factors — including technology, consumption patterns, economic policies and political choices. Slower population growth alone will not solve today’s environmental challenges. But slower growth—together with reduced resource consumption in affluent countries–could help give us a fighting chance to meet those challenges, by reducing pressure on natural systems that are reeling from stress.
Some people have much greater environmental impact than others. We in the U.S. comprise only 5% of the world’s population, but account for 25% of all energy use.
Still, while there are great disparities in environmental impact among the world’s citizens, everyone has some impact. And the citizens of the developing world must increase their resource use—and environmental impact—so that the half of humanity that lives on $2 a day can escape from poverty.
Eight billion would be better than 10.5 billion—for people and the planet. If we take seriously the twin imperatives of sustainability and equity, it becomes clear that it would be easier to provide a good life – at less environmental cost – for eight billion rather than 10.5 billion people. And slower growth could help give families and nations a chance to make essential investments in education, health care and sustainable economic development.
Slowing population growth is not all we must do. Rapacious consumption in the affluent countries drives environmental destruction worldwide; changing our own systems of production and consumption must be the top priority if we are to preserve a habitable planet.
The Numbers: A New Demographic Landscape
Population growth has slowed, but it has not ended. Decisions made today will determine whether world population grows by one billion, two billion, or almost four billion by 2050. Most growth will take place in urban areas of the developing world.
World population is still growing. Most people assume the “population bomb” has been defused. But while the rate of growth has slowed in most parts of the world, rapid growth is hardly a thing of the past. Our numbers still increase by 75 million to 80 million every year, the equivalent of adding another U.S. to the world every four years or so. Virtually all population growth in the next 45 years is expected to take place in the developing countries.
Tomorrow’s population size will be determined today. A certain amount of future growth is inevitable, but choices made today will determine whether human numbers—now at 6.8 billion—climb to anywhere between 8 billion and 10.5 billion by mid-century.
Population projections to 2050
Source: United Nations Population Division
Much depends on access to reproductive health services. All of the population projections above (except the constant fertility variant) assume that fertility will continue to decline in developing countries. In the fifty least-developed countries, largely in sub-Saharan Africa and the Middle East, the medium variant assumes a sharp decline—from over 4.6 children per woman now to 2.5 children per woman in 2050. This in turn assumes that access to family planning will improve in these countries. But if this does not occur and fertility levels stay where they are now, world population would reach around 11 billion.
Fast facts:
- It took from the beginning of time until the early 19th century for human numbers to reach one billion; today, one billion people are added to the population in only 13 to 14 years. Subsequent billions are expected to arrive more slowly. Ultimately, population is expected to stabilize, as fertility falls into line with death rates worldwide.
- The rate of population growth peaked between 1965 and 1970 and is now declining in all regions.
- The less developed countries are expected to grow by just under 50% by 2050; the poorest countries will double in size over that period.
- By 2050, 9 out of 10 of the world’s young people will live in developing countries.
- Half the global increase in population will take place in just nine nations. In order of their expected contribution, they are: India, Pakistan, Nigeria, Democratic Republic of the Congo, Bangladesh, Uganda, the U.S., Ethiopia and China.
- If recent trends continue as projected to 2050, virtually all of the world’s population growth will be in urban areas. In effect, the poor countries will have to build the equivalent of a city to accommodate one million people every five days for the next 40 to 45 years.
- During the next half century, many richer nations will lose population. Falling fertility and increasing longevity worldwide will expand the proportion of potentially dependent elderly people.
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