**Abstract**

The twenty-first century global food enterprise faces numerous challenges. The most critical is how to meet the food needs of the rapidly growing world's population that is expected to increase by 2 billion persons in the next 30 years. The food system is also under increasing threat from climate change. As a result, the resources required for increasing food production are becoming heavily constrained. Innovative approaches to mitigate these threats to the food system are needed. This paper's overall goal is to highlight challenges and opportunities to address the sustainability of the global food system. Various examples are drawn from the contemporary literature, including the author's research, to illustrate some of the steps needed to meet sustainability needs. Relevant issues are discussed for different food system segments from farm production to processing, distribution, storage, retail, and food preparation for consumption.

**Keywords:** sustainability, food system, climate change, food losses, food waste

## **1. Introduction**

The agricultural production system's capacity to meet the increasing population demands has been questioned in the past, notably by Malthus in 1798 in "An Essay on *the Principle of Population,*" where he theorized a specter of largescale deaths due to inadequate food production and increasing population [1]. Luckily, Malthusian prophecy did not materialize as technological advances in farming helped raise agricultural production to feed the growing population. Another alarm regarding the food system was raised by Sir William Crookes, a brilliant experimentalist known for discovering the element called thallium. Sir Crookes is also well known for his inaugural presidential speech, titled "The Wheat Problem," that he gave on September 10, 1898, to the British Association for the Advancement of Science [2]. In this talk, using data on wheat production and the increasing human population, he raised his concern about the food system's sustainability. He noted, "*we are drawing on the Earth's capital, and our drafts will not perpetually be honored. England and all… nations are in deadly peril of not having enough to eat.*" Sir Crooks' concern was based on a significant threat to the day's farming system, the potential depletion of fertilizer to grow wheat and other crops. In the late 1800s, 100% of the nitrogen used in farming was mined and shipped from Peru, Baja California, and Chile as guano. Guano is bird droppings that build up over a long period. But the mining fields were getting depleted of guano, and Sir Crookes could foresee that if the supply of guano is exhausted, then the farming will collapse, and millions will starve.

Being a chemist, he observed that the Earth's atmosphere has plenty of nitrogen. Sir Crookes challenged his fellow scientists to determine how to chemically fix nitrogen from the air to help to create what he called "chemical manure." One of the chemists, Fritz Haber, took him up on that challenge. Haber discovered the chemical reaction that allowed fixing nitrogen to make ammonia, and in 1918, he received a Nobel Prize. Working with Carl Bosch, he commercialized that research finding to create the Haber-Bosch process. The products of this process are used not only for agriculture but also for the manufacture of pharmaceuticals, plastics, textiles, and explosives.

In the 1900s, when Sir William Crookes was concerned about the food supply, the world population was less than 2 billion, now it is about 8 billion, and by the year 2050, it is predicted to increase to 10 billion. According to the current estimates, to meet the increasing population's needs and fill the food gap to 2050, an increase in agricultural production by almost 60% is required—a daunting task facing today's food and agricultural scientist [3]. Whereas the supply of guano was the main threat to the food production system in the late 1800s, today, multiple threats impact the food system. These include the increasing population, rapid urbanization rate, a dramatic ongoing depletion of natural resources, and the various impacts of climate change.

The United Nations has recognized the global scope of the problem by issuing a call for developing sustainable development goals [4]. These goals are intended to provide a blueprint to achieve a better and more sustainable future for everyone on the planet. A list of 17 sustainable development goals was identified. These goals underpin the future developmental projects supported by the United Nations. The global food system's sustainability has a significant role in several developmental goals such as zero hunger, good health, clean water, conserving marine resources, reversing land degradation, and climate action.

A simplified version of today's food system, from farm to fork, involves production to consumption, as seen in **Figure 1**. The output from agricultural production moves through processing, storage, and distribution sectors, before preparation and consumption either at home or out-of-home establishments. Primary inputs at various steps in the system include arable land, labor, energy, and water. There are food losses at each stage, and waste products, including wastewater, are generated, and greenhouse gas emissions are released into the atmosphere. Each step of the system will be next considered with a description of some of the threats it faces.

**Figure 1.** *A simplified version of a modern food system from farm to fork.*
