Today, one in nine of the world’s 7.3 billion people — more than 800 million men, women and children — don’t get enough to eat, despite the fact that more than enough food is produced daily to feed everyone on Earth (at least based on calories).

Most of the world’s hungry live in the developing regions of Asia and Sub-Saharan Africa, and many of them are children. Inadequate nutrition kills more than three million children under age 5 every year, and is responsible for 45% of all such global deaths. Worldwide, one in six kids (a total of about 100 million) is underweight.

And yet, according to the Chicago Council on Global Affairs’ “Healthy Food for a Healthy World” report, 1.9 billion people globally are overweight and 600 million are obese. Thanks in large part to growing consumption of so-called empty calories, many of these people are also among those with inadequate nutrition. “There are a billion hungry people, and more than two billion who are overweight or obese,” said Danielle Nierenberg, the president of the nonprofit Food Tank advisory group. “People can be overweight and also malnourished.”

Some progress is being made, however. The United Nations Food and Agriculture Organization (FAO) reports a drop of 42% in the number of chronically hungry people in the developing world since 1990, although China alone accounts for the vast majority of this progress (the reduction would have been just 7% without China’s contribution).

Making more progress on hunger means facing up to the following six challenges:

  1. Population Growth. The FAO notes that world population growth is slowing, but the U.N. still projects an additional 2.3 billion people by 2050, nearly all of them in the developing world. Sub-Saharan Africa’s population will grow by 114% in the period, and that of East and Southeast Asia by 13%. Accelerating urbanization means that 70% of the world’s population will be living in cities by 2050 (up from 49% in 2009).

Estimates of how much more food will be needed to feed this growing population range from 60% (according to the ActionAid report, “Rising to the Challenge: Changing Course to Feed the World in 2050”) to 100% (the estimate that Robert Fraley, chief technology officer at Monsanto, gave National Public Radio in a 2014 interview). The FAO projects that it will require “raising overall food production by some 70% between 2005-2007 and 2050.” According to the agency, “Production in the developing countries would need to almost double.” Specifically, “annual cereal production will need to rise to about three billion tons from 2.1 billion today and annual meat production will need to rise by over 200 million tons to reach 470 million tons.”

Today, one in nine of the world’s 7.3 billion people — more than 800 million men, women and children — don’t get enough to eat.

The need to increase food production so dramatically in just 35 years is daunting, but Nierenberg points out that such a scenario “is based on a lot of assumptions,” such as the conclusion that a growing middle class will demand more meat in their diets, and that educating girls and investing in family planning won’t reduce actual population numbers. “If nothing changes we’ll have to reach that 70% figure, but much can be done to change that scenario,” she said. “Just reducing post-harvest losses through better storage [cutting the tops off sweet potatoes before you store them, for example, or better silos and drying mats] could help reduce the 1.3 billion tons of food waste ever year.”

  1. Food Waste. Many experts say that enough food exists to feed 10 billion people today. Unfortunately, it’s not only inadequately distributed but also, to a large extent, wasted. “It’s terrible that farmers put so much labor and water into growing crops, but then can’t sell them because they rot before getting to market,” Food Tank’s Nierenberg said. “Food waste is the low-hanging fruit in the system.”

According to the World Resources Institute, “About 24% of all the calories produced for human consumption don’t actually end up reaching human mouths.” The group said that if that rate of loss could be cut in half, to 12%, the world would need about 1,314 trillion kilocalories (kcal) less food per year than in a business-as-usual scenario.

“Food is lost or wasted throughout the supply chain, from initial production down to final household consumption,” the FAO said. “The decrease may be accidental or intentional, but ultimately leads to less food available for all. This may be due to problems in harvesting, storage, packing, transport, infrastructure or market/price mechanisms, as well as institutional and legal frameworks.”

While more than half of all food waste (56%) occurs in the developed world, a 2014 report titled, “Feeding Cities: Food Security in a Rapidly Urbanizing World,” concludes that the most severe food losses occur in Asia, at five stages in the process — production, handling and storage, processing and packaging, distribution and market, and consumption. According to the authors, Eugénie L. Birch, co-director of the Penn Institute for Urban Research (IUR) and Alexander Keating, Penn IUR project director, more than 80% of all this waste occurs in just three stages — 24% in production, 24% in handling and storage and 35% in consumption. “In the west, it occurs on the plate,” Birch said in an interview. “In the developing world, the biggest problems are during production and the journey from the farm to the city. These are two different issues that have to be addressed.”

  1. Climate Change. “Trying to understand the overall effect of climate change on our food supply can be difficult,” wrote the U.S. Environmental Protection Agency (EPA) in a report titled, “Climate Impacts on Agriculture and Food Supply,” based in part on 2008 reporting from the U.S. Climate Change Science program and others. The EPA points out that, ironically, increases in carbon dioxide can be beneficial to “some crops in some places,” but only if necessary conditions of nutrient levels, soil moisture and water availability are met. “Changes in the frequency and severity of droughts and floods could pose challenges for farmers and ranchers…. Overall, climate change could make it more difficult to grow crops, raise animals and catch fish in the same ways and same places as we have done in the past.”

A 2014 paper by scientists at the Massachusetts Institute of Technology and Colorado State University, published in the journal Nature, concluded that climate change would reduce crop yields by more than 10% by 2050, “with a potential to substantially worsen global malnutrition in all scenarios considered.” The International Food Policy Research Institute (IFPRI) concluded in a 2009 report that an additional 25 million children would be malnourished by 2050 because of global warming’s negative effect on agriculture.

Rising temperatures are a key part of the problem. “It’s an unknown, but we do know that as temperatures rise, crop productivity declines,” said Alan M. Kelly, the Gilbert S. Kahn dean emeritus at the University of Pennsylvania School of Veterinary Medicine. A National Academies of Science report said that yields of corn, soybeans and cotton in the U.S. could drop dramatically because of many more days with temperatures above 86 degrees Fahrenheit. A further wild card is that both insects and crop diseases are likely to flourish with warmer temperatures.

Some 1.9 billion people globally are overweight and 600 million are obese. Thanks in large part to growing consumption of so-called empty calories, many of these people are also among those with inadequate nutrition.

Ozone levels are another part of the challenge posed by climate change. According to the Nature article, “Ozone trends either exacerbate or offset a substantial fraction of climate impacts depending on the scenario, suggesting the importance of air quality management in agricultural planning. Furthermore, we find that depending on the region, some crops are primarily sensitive to either ozone (for example, wheat) or heat (for example, maize) alone, providing a measure of relative benefits of climate adaptation versus ozone regulation for food security in different regions.”

All of these climate-induced changes will affect food prices, a critical consideration for the world’s poor. IFPRI agricultural economist Gerald Nelson told Scientific American, “Biological impacts on crop yields work through the economic system resulting in reduced production, higher crop and meat prices, and a reduction in cereal consumption. This reduction means reduced calorie intake and increased childhood malnutrition.” Without climate change, IFPRI reported that wheat prices could rise 39% by 2050 (from $113 to $158 per metric ton). Once global warming is factored in, the cost of wheat could rise at least 170%, to approximately $190 per metric ton.

“If climate change were to retard economic development beyond the direct effects on agriculture in the poorer regions, especially in Africa [as a result of human health impacts or other factors], then overall impacts could be sizeable,” noted the FAO study titled, “Global Climate Change and Agricultural Production: Direct and Indirect Effects.” Relative agricultural productivity will shift to favor developed countries, it said, with direct impact on already skewed resource allocation.

  1. What People Eat. The World Resources Institute projects livestock consumption in the U.S. and Canada could actually drop 2% between 2006 and 2050 (and climb just 7% in the European Union), but increase 46% in China and 94% in India.

Overall, the FAO report “World Livestock 2011” concludes that by 2050, average global consumption of meat protein will be 73% higher than in 2011. Dairy consumption is also on an upward trajectory, scheduled to grow 58% in the period.

A switch to meat-based diets, which are resource-intensive, has clear implications for agricultural productivity and feeding a growing world population. Much new meat production would come from the intensive systems common in the U.S., and FAO writes that such methods “are a concern because of potential environmental impacts, such as groundwater pollution and greenhouse gas emissions.” The study adds, “An urgent challenge is to make intensive production more environmentally benign.”

The primary driver of this increase in meat and dairy consumption is increasing wealth. FarmEcon LLC, an agricultural and food industry consulting firm, projects, “Production growth will be primarily driven by a near doubling of per capita GDP in constant dollar purchasing power. A more affluent world will, as it has in the past, want the variety and nutrition offered by more meat in the diet.”

But Food Tank’s Nierenberg suggests that this assumption is worth questioning. “The assumption is that the growing middle class in places such as China and India is going to eat more meat, but people could be convinced that industrially produced meat isn’t the best bet for their future.” Food Tank advocates for gradual steps, such as Meatless Mondays, and healthy steps such as increasing vegetables and fruit in the diet.

  1. Water Risk. “The water issue is more imminent than climate change,” says Lester Brown, author of the forthcoming book When the Wells Go Dry and founder of both the Worldwatch Institute and the Earth Policy Institute. “We’re overpumping our aquifers virtually everywhere in the world to support the current population,” he said. “The world is running up a vast water deficit.”

In the book, Brown writes that the number of rivers in China dropped from 50,000 in 1950 to 23,000 in 2013. In India, he said, “Water tables are falling in every state. And aquifer depletion can shrink harvests, something we’ve seen in the Middle East. The grain harvest in Texas and Oklahoma has been affected in that way, and that’s in part because those states are on the shallow, southern end of the Ogallala Aquifer.” Asian Pacific Economic Cooperation’s Human Resources Development Working Group reports that in the Texas High Plains, 10 times as much water is being pumped out of the aquifer than is being replaced by rainfall.

Climate change would reduce crop yields by more than 10% by 2050, “with a potential to substantially worsen global malnutrition in all scenarios considered.”

And National Geographic reported, “As drought worsens groundwater depletion, water supplies for people and farming shrink, and this scarcity can set the table for social unrest. Saudi Arabia, which a few decades ago began pumping deep underground aquifers to grow wheat in the desert, has since abandoned the plan, in order to conserve what groundwater supplies remain, relying instead on imported wheat to feed the people of this arid land.”

By 2025, 1.8 billion people are likely to be living in regions with absolute water scarcity, the United Nations reports — and Sub-Saharan Africa leads the world in the number of water-stressed countries in any region. By 2030, up to 250 million Africans will be living in areas of high water stress. Scarcity in arid and semi-arid places, mostly in the developing world, will affect — and displace — up to 700 million people.

According to the World Bank, a warmer world would leave about a billion people living in monsoon basins (and 500 million in deltas) “especially vulnerable” to water scarcity. The 2012 report, titled, “Turn Down the Heat,” concludes, “Poorer countries, which contributed least to the problem, will be the most affected.”

The Bank said that 70% of global water withdrawals are for agriculture, and that meeting the food needs of nine billion people by 2050 will require a 15% increase in those withdrawals.

  1. Global Conflict and Food Insecurity. Food insecurity is both a cause of civil conflict, and a result of it. According to “Food Insecurity and Global Conflict,” a 2011 report from the World Food Programme, “Rising food prices contribute to food insecurity, which is a clear and serious threat to human security.” In 2007 and 2008, food protests and riots occurred in 48 countries as a result of record high prices. In 2011, FAO reported a new peak for the food price index, with subsequent protests in North Africa and the Middle East (toppling two presidents).

The Global Food Report for 2014/2015 recounts the destroyed infrastructure in Gaza, Iraq, Nigeria, Syria, Yemen and other “conflicted-afflicted places” in 2014. And it concludes, “In addition to the humanitarian tragedies associated with these conflicts, the destruction of infrastructure, together with disruptions in access to markets, often renders goods and services prohibitively expensive or makes them unavailable altogether. Both investors and tourists often abandon conflict-affected areas, and clashes between conflicting parties force millions of refugees to flee either to safer places within the affected countries or across the border to neighboring countries. As a result, economies often contract, instability and insecurity spill over national borders, and food and nutrition insecurity rises.”

Ÿ Ÿ The world faces substantial challenges in meeting the food and water needs of 2050, when global population could be 9 billion or more. Initiatives to address our future needs are critical, and they will have to take into account the complicated interplay of a variety of stressors on the world agriculture system.