Some time late in 2011—at least according to the people-crunchers at the U.N. Population Reference Bureau—humanity will reach a new demographic milestone with the birth of the 7th billion living person. (As a measure of just how fast global population is growing, the 6th billionth living person—Bosnian Adnan Nevic—is only 11.) You can expect the event to be marked by the usual Malthusian worries—can the planet Earth really support 7 billion people, especially with the population expected to top 9 billion by mid-century? With some 1.5 billion people already living on less than $1.25 a day, nearly 1 billion people hungry and the natural world already heavily damaged, are we on the path to destruction? 
 
 That’s the question the environment writer Robert Kunzig tackles in a cover story on population for National Geographic magazine. (I’ll excerpt a bit below, but it’s a great piece and worth reading in its entirety—in fact, consider picking up the issue, which tackles the 7 billion question with photos, articles and graphics.) Kunzig notes that global population has grown astoundingly fast during most of our lifetimes—while it took all of human history to around 1800 for the global population to reach 1 billion (a little Black Death here and there didn’t help), it will take a little more than 50 years for the world’s numbers to grow from 3 billion to 7 billion. A U.N. graph shows how fast population has grown, and where it might be headed: 
 
 That rapid increase is due to the demographic transition—and on the surface, it’s a sign of human progress. In the past, high fertility rates were the norm around the world, as women had to have large number of children to ensure that at least a few them would survive into adulthood. (That’s often still the case in extremely poor, heavily rural countries like Niger, where the average woman has seven children.) Eventually, though, child mortality declined thanks to advances in medicine and sanitation. As women adjusted to the new reality—and as families moved from farms to cities, where additional children were more of an economic burden than a boon—the fertility rate dropped, but that took a generation or so, and in the meantime population exploded. (Suddenly there were lots more surviving children who could then go and reproduce themselves.) The U.S., Europe and other rich countries have already gone through the transition—in most well-off countries fertility is around or even well below the replacement rate of 2.1 children per woman—and it’s begun to happen in all but the poorest developing countries as well. (China, thanks to the one-child policy, put itself through an accelerated demographic transition.) But the transition will take a while to play itself out, and global population will keep growing rapidly, albeit unevenly—for the next several decades, eventually reaching a level as high as nearly 11 billion or 8 billion by 2050, depending on how fertility rates change in the years ahead. 
 
 Either way that seems to be a lot of people—and most of them will be born in poor developing nations, to parents already struggling to support themselves. If you’ve ever visited the urban slums outside growing megacities like Bombay or Lagos you might wonder how they could take any more people—yet they’ll continue to proliferate like bacterial cultures. Those teeming slums seem to provoke a visceral disgust among the thinkers who worry most about population—like Paul Ehrlich, the author of The Population Bomb, whom Kunzig quotes: 
 
 I have understood the population explosion intellectually for a long time. I came to understand it emotionally one stinking hot night in Delhi a couple of years ago… The temperature was well over 100, and the air was a haze of dust and smoke. The streets seemed alive with people. People eating, people washing, people sleeping. People visiting, arguing, and screaming. People thrusting their hands through the taxi window, begging. People defecating and urinating. People clinging to buses. People herding animals. People, people, people, people. 
 
 As Kunzig notes, that was written in 1966, when India only had 500 million people—today it has 1.2 billion, and it is projected to have over 1.7 billion by mid-century, which would make it the most heavily populated nation on Earth. But the question isn’t whether we will literally have enough space for more people—Kunzig points out that if 9 billion people were spread out around the habitable parts of the planet, the entire Earth would still have only half the population density of France. The fear—from Malthus to Ehrlich—is that we won’t be able to support ourselves, that there won’t be enough food, water or energy to go around, as Kunzig wonders: 
 
 Many people are justifiably worried that Malthus will finally be proved right on a global scale—that the planet won’t be able to feed nine billion people. Lester Brown, founder of Worldwatch Institute and now head of the Earth Policy Institute in Washington, believes food shortages could cause a collapse of global civilization. Human beings are living off natural capital, Brown argues, eroding soil and depleting groundwater faster than they can be replenished. All of that will soon be cramping food production. Brown’s Plan B to save civilization would put the whole world on a wartime footing, like the U.S. after Pearl Harbor, to stabilize climate and repair the ecological damage. “Filling the family planning gap may be the most urgent item on the global agenda,” he writes, so if we don’t hold the world’s population to eight billion by reducing fertility, the death rate may increase instead. Eight billion corresponds to the UN’s lowest projection for 2050. In that optimistic scenario, Bangladesh has a fertility rate of 1.35 in 2050, but it still has 25 million more people than it does today. Rwanda’s fertility rate also falls below the replacement level, but its population still rises to well over twice what it was before the genocide. If that’s the optimistic scenario, one might argue, the future is indeed bleak. 
 
 I wrote earlier this week about the debate between Malthusians and Cornucopians—the economists who believe that human ingenuity, responding to human need, always prevails to find new resources to match rising populations. It’s an open question for the future, though so far the Cornucopians have been proven right. It’s worth noting that while we worry about the effects of overpopulation in the future, humanity was far worse off by every material standard in the centuries before the Industrial Revolution, when the global population was a fraction of what it is today. As Kunzig writes, the future of humanity—and of the planet we live on—will have less to do with absolute numbers that it will with how we choose to live: 
 
 For centuries population pessimists have hurled apocalyptic warnings at the congenital optimists, who believe in their bones that humanity will find ways to cope and even improve its lot. History, on the whole, has so far favored the optimists, but history is no certain guide to the future. Neither is science. It cannot predict the outcome of People v. Planet, because all the facts of the case—how many of us there will be and how we will live—depend on choices we have yet to make and ideas we have yet to have. We may, for example, says [population biologist Joel] Cohen, “see to it that all children are nourished well enough to learn in school and are educated well enough to solve the problems they will face as adults.” That would change the future significantly. 
 
 Indeed, growing populations won’t be the only demographic challenge the world faces in the decades to come. Remember how I said that population was growing globally but unevenly? Even as a country like India will likely need to cope with 500 million new people between now and mid-century, most rich nations—where the fertility rate is below replacement level and people live longer and longer—will need to cope with extreme aging. As the 2010 World Population fact sheet shows (download a PDF here), in Japan, Italy and Germany there are already only 3 working people to support every 1 pensioner. Compare that to sub-Saharan Africa and the Middle East, where the ratio is closer to 25 to 1. That disparity will only grow in the future, exacerbating budget headaches and skewing economies. In the U.S., for example, spending on Social Security and Medicare is expected to rise from 8.4% of GDP today to 14.5% by mid-century. 
 
 So here’s the planet we could have in 2050: an overpopulated, overstressed developing world and an aging, economically stagnant developed world, with inequality even larger than it is today. Is there any way to escape that fate? While development and education will be incredibly important (especially for women—literacy is one of the best ways to reduce fertility), the answer may end up being immigration. Think about it—in the future the developed world will lack young workers, and the developing world will have an excess of that resource. Immigration could be a way to balance demographics and economics—alleviating population pressure in the poorer parts of the world while jump starting aging developed nations. The U.S. already does this—immigration will provide most of American population growth. It would be a radical solution, given the political resistance to increased immigration in much of the rich world. (If you think it’s a hot topic in the U.S., try Japan, which steadfastly resists assimilating foreigners, despite the dire threat posed by an aging population.) But it might be the only way to save our overpopulated planet. 
 
 More from TIME on population: 
 
 What Condoms Have to Do With Climate Change 
 
 Population: The Numbers Game ||||| GLOBAL FOOD 
 
 WASTE NOT, WANT NOT 
 
 Feeding the 9 Billion: The tragedy of waste 
 
 By 2075, the United Nations’ mid-range projection for global population growth predicts that human numbers will peak at about 9.5 billion people. This means that there could be an extra three billion mouths to feed by the end of the century, a period in which substantial changes are anticipated in the wealth, calorific intake and dietary preferences of people in developing countries across the world. 
 
 Such a projection presents mankind with wide-ranging social, economic, environmental and political issues that need to be addressed today to ensure a sustainable future for all. One key issue is how to produce more food in a world of finite resources. 
 
 Today, we produce about four billion metric tonnes of food per annum. Yet due to poor practices in harvesting, storage and transportation, as well as market and consumer wastage, it is estimated that 30–50% (or 1.2–2 billion tonnes) of all food produced never reaches a human stomach. Furthermore, this figure does not reflect the fact that large amounts of land, energy, fertilisers and water have also been lost in the production of foodstuffs which simply end up as waste. This level of wastage is a tragedy that cannot continue if we are to succeed in the challenge of sustainably meeting our future food demands. 
 
 Read the Global Food report [PDF, 1MB] 
 
 Where Food Waste Happens 
 
 In 2010, the Institution of Mechanical Engineers identified three principal emerging population groups across the world, based on characteristics associated with their current and projected stage of economic development. 
 
 Fully developed, mature, post-industrial societies, such as those in Europe, characterised by stable or declining populations which are increasing in age. 
 
 Late-stage developing nations that are currently industrialising rapidly, for example China, which will experience decelerating rates of population growth, coupled with increasing affluence and age profile. 
 
 Newly developing countries that are beginning to industrialise, primarily in Africa, with high to very high population growth rates (typically doubling or tripling their populations by 2050), and characterised by a predominantly young age profile. 
 
 Each group over the coming decades will need to address different issues surrounding food production, storage and transportation, as well as consumer expectations, if we are to continue to feed all our people. 
 
 Third World and Developing Nations 
 
 In less-developed countries, such as those of sub-Saharan Africa and South-East Asia, wastage tends to occur primarily at the farmer-producer end of the supply chain. Inefficient harvesting, inadequate local transportation and poor infrastructure mean that produce is frequently handled inappropriately and stored under unsuitable farm site conditions. 
 
 Developed Nations 
 
 In mature, fully developed countries such as the UK, more-efficient farming practices and better transport, storage and processing facilities ensure that a larger proportion of the food produced reaches markets and consumers. However, characteristics associated with modern consumer culture mean produce is often wasted through retail and customer behaviour. 
 
 Major supermarkets, in meeting consumer expectations, will often reject entire crops of perfectly edible fruit and vegetables at the farm because they do not meet exacting marketing standards for their physical characteristics, such as size and appearance. For example, up to 30% of the UK’s vegetable crop is never harvested as a result of such practices. Globally, retailers generate 1.6 million tonnes of food waste annually in this way. 
 
 Of the produce that does appear in the supermarket, commonly used sales promotions frequently encourage customers to purchase excessive quantities which, in the case of perishable foodstuffs, inevitably generate wastage in the home. Overall between 30% and 50% of what has been bought in developed countries is thrown away by the purchaser. 
 
 Better use of our Finite Resources 
 
 Wasting food means losing not only life-supporting nutrition but also precious resources, including land, water and energy. As a global society therefore, tackling food waste will help contribute towards addressing a number of key resource issues: 
 
 Effective Land Usage 
 
 Over the last five decades, improved farming techniques and technologies have helped to significantly increase crop yields along with a 12% expansion of farmed land use. However, with global food production already utilising about 4.9Gha of the 10Gha usable land surface available, a further increase in farming area without impacting unfavourably on what remains of the world’s natural ecosystems appears unlikely. The challenge is that an increase in animal-based production will require greater land and resource requirement, as livestock farming demands extensive land use. One hectare of land can, for example, produce rice or potatoes for 19–22 people per annum. The same area will produce enough lamb or beef for only one or two people. Considerable tensions are likely to emerge, as the need for food competes with demands for ecosystem preservation and biomass production as a renewable energy source. 
 
 Water Usage 
 
 Over the past century, fresh water abstraction for human use has increased at more than double the rate of population growth. Currently about 3.8 trillion m3 of water is used by humans per annum. About 70% of this is consumed by the global agriculture sector, and the level of use will continue to rise over the coming decades. Indeed, depending on how food is produced and the validity of forecasts for demographic trends, the demand for water in food production could reach 10–13 trillion m3 annually by mid-century. This is 2.5 to 3.5 times greater than the total human use of fresh water today. 
 
 Better irrigation can dramatically improve crop yield and about 40% of the world’s food supply is currently derived from irrigated land. However, water used in irrigation is often sourced unsustainably, through boreholes sunk into poorly managed aquifers. In some cases government development programmes and international aid interventions exacerbate this problem. In addition, we continue to use wasteful systems, such as flood or overhead spray, which are difficult to control and lose much of the water to evaporation. Although the drip or trickle irrigation methods are more expensive to install, they can be as much as 33% more efficient in water use as well as being able to carry fertilisers directly to the root. 
 
 In processing of foods after the agricultural stage, there are large additional uses of water that need to be tackled in a world of growing demand. This is particularly crucial in the case of meat production, where beef uses about 50 times more water than vegetables. In the future, more- effective washing techniques, management procedures, and recycling and purification of water will be needed to reduce wastage. 
 
 Energy Usage 
 
 Energy is an essential resource across the entire food production cycle, with estimates showing an average of 7–10 calories of input being required in the production of one calorie of food. This varies dramatically depending on crop, from three calories for plant crops to 35 calories in the production of beef. Since much of this energy comes from the utilisation of fossil fuels, wastage of food potentially contributes to unnecessary global warming as well as inefficient resource utilisation. 
 
 In the modern industrialised agricultural process – which developing nations are moving towards in order to increase future yields – energy usage in the making and application of agrochemicals such as fertilisers and pesticides represents the single biggest component. Wheat production takes 50% of its energy input for these two items alone. Indeed, on a global scale, fertiliser manufacturing consumes about 3–5% of the world’s annual natural gas supply. With production anticipated to increase by 25% between now and 2030, sustainable energy sourcing will become an increasingly major issue. Energy to power machinery, both on the farm and in the storage and processing facilities, together with the direct use of fuel in field mechanisation and produce transportation, adds to the energy total, which currently represents about 3.1% of annual global energy consumption. 
 
 Recommendations 
 
 Rising population combined with improved nutrition standards and shifting dietary preferences will exert pressure for increases in global food supply. Engineers, scientists and agriculturalists have the knowledge, tools and systems that will assist in achieving productivity increases. However, pressure will grow on finite resources of land, energy and water. The potential to provide 60–100% more food by simply eliminating losses, while simultaneously freeing up land, energy and water resources for other uses, is an opportunity that should not be ignored. In order to begin tackling the challenge, the Institution recommends that: 
 
 1. The UN Food and Agriculture Organisation (FAO) works with the international engineering community to ensure governments of developed nations put in place programmes that transfer engineering knowledge, design know-how, and suitable technology to newly developing countries. This will help improve produce handling in the harvest, and immediate post-harvest stages of food production. 
 
 2. Governments of rapidly developing countries incorporate waste minimisation thinking into the transport infrastructure and storage facilities currently being planned, engineered and built. 
 
 3. Governments in developed nations devise and implement policy that changes consumer expectations. These should discourage retailers from wasteful practices that lead to the rejection of food on the basis of cosmetic characteristics, and losses in the home due to excessive purchasing by consumers. 
 
 Download the IMechE Global Food Report [PDF, 1MB] 
 
 Read the Press Release on the Global Food: Waste Not, Want Not 
 
 See all IMechE Reports
– Things to look forward to in 2011: all-natural Frito-Lay chips, a bunch of truly unnecessary movie sequels, and … the world’s 7 billionth living person. That lucky baby will arrive sometime next year, according to the UN Population Reference Bureau, writes Bryan Walsh for Time. The world’s 6 billionth living person was born just 11 years ago in Bosnia, and the population is expected to exceed 9 billion by the middle of the century. Can the planet really handle that? Robert Kunzig attempts to take on that question in a very lengthy National Geographic cover story (worth a read). Walsh picks out a few highlights: Kunzig calls out attention to the fact that it took nearly all of human history to get us to the 1 billion mark, but we're set to explode from 3 billion to 7 billion in about 50 years. By 2050, we'll be somewhere between 8 billion and 10.5 billion, according to the UN. Space isn't the issue. Kunzig notes that if 9 billion people were spread throughout Earth's habitable regions, the population density would be half of that in France. The potential problems: Not enough food, water, energy. And a lot of aging people. Writes Kunzig, "Fixating on population numbers is not the best way to confront the future. The number of people does matter, of course. But how people consume resources matters a lot more ... It’s too late to keep the new middle class of 2030 from being born; it’s not too late to change how they and the rest of us will produce and consume food and energy."