In 1798 Thomas Malthus incorrectly predicted that population growth would out-run food supply by the mid 19th century. In 1968, Paul R. Ehrlich reprised this argument in The Population Bomb, predicting famine in the 1970s and 1980s. The dire predictions of Ehrlich and other neo-Malthusians were vigorously challenged by a number of economists, notably Julian Lincoln Simon. Agricultural research already under way, such as the green revolution, led to dramatic improvements in crop yields. Food production has kept pace with population growth, but Malthusians point out the green revolution relies heavily on petroleum-based fertilizers, and that many crops have become so genetically uniform that a crop failure would be very widespread. Food prices in the early 21st century are rising sharply on a global scale, and causing serious malnutrition to spread widely.
From 1950 to 1984, as the Green Revolution transformed agriculture around the world, grain production increased by over 250%. The world population has grown by about four billion since the beginning of the Green Revolution and most believe that, without the Revolution, there would be greater famine and malnutrition than the UN presently documents (approximately 850 million people suffering from chronic malnutrition in 2005). The energy for the Green Revolution was provided by fossil fuels in the form of fertilizers (natural gas), pesticides (oil), and hydrocarbon-fueled irrigation.
The peaking of world oil production (Peak oil) may test Malthus and Ehrlich critics. As of May 2008, the price of grain has been pushed up by increased farming for use in bio fuels, world oil prices at over $140 per barrel ($880/m3), global population growth, climate change, loss of agricultural land to residential and industrial development, and growing consumer demand in China and India. Food riots have recently occurred in some countries across the world. However, oil prices have fallen sharply since then, and they have remained below $100/barrel since September 2008. Resource demands are expected to ease as population growth declines, but it is unclear whether rising living standards in developing countries will once again create resource shortages.
Growing populations, falling energy sources and food shortages will create the "perfect storm" by 2030, the
government chief scientist has warned. He said food reserves are at a fifty-year low but the world will require 50% more energy, food and water by 2030. The world will have to produce 70% more food by 2050 to feed a projected extra 2.3 billion people and as incomes rise, the United Nations' Food and Agriculture Organization (FAO) said. UK
The observed figures for 2007 show an actual increase in absolute numbers of undernourished people in the world, 923 million in 2007 versus 832 million in 1995; the more recent FAO estimates point out to an even more dramatic increase, to 1.02 billion in 2009.