Little more than a decade ago, Sir John Beddington, a professor of applied population biology, said that the world was facing “the perfect storm”.
He said increasing demand for food, energy and water could leave the planet facing acute shortages of all three by the year 2030, sparking conflict and unrest.
While the timetable for when the planet – and humanity – is likely to suffer such upheavals may have changed, the issues as a whole appear no less pressing today.
International Institute for Applied Systems Analysis, Austria
With the world’s population growing by about 80 million a year, the 7.7 billion people on Earth is likely to be closer to 10 billion by 2050, when demand for food could be 70 per cent higher than it was in 2014.
By 2100, the world’s population is expected to be about 11 billion, according to a UN report, although by then numbers will, according to forecasts, have plateaued.
Global temperatures, meanwhile, are rising by an average of 0.18 °C per decade, affecting crop yields at just the time when food needs are growing.
Global population increase: past, present and future
One study found that, for each 1°C increase in average temperatures, crop yields will fall between 3.1 per cent and 7.4 per cent.
Dr Raya Muttarak, programme director of the Population and Just Societies Programme at the International Institute for Applied Systems Analysis in Austria, says that agriculture in arid areas, and even parts of Europe, could be negatively affected. Some regions may benefit – although the overall effect is not likely to be positive.
“There are areas of the world that could benefit from a longer and warmer growing season due to climate change, such as the colder climate [areas] – northern Europe and some parts of Russia, such as Siberia,” she says.
Superimposed on the incremental effects of temperature increases are extreme events such as droughts, floods, fires and heatwaves, which are forecast to become more frequent as a result of climate change.
“We’re not just talking about lowering yields, we’re talking about a complete loss of one year’s productivity, which can be devastating for communities that don’t have other options,” says Prof Peter Smith, science director of Scotland’s Climate Change Centre of Expertise and a professor in plant and soil science at the University of Aberdeen.
The various factors at play will interact in unpredictable ways. Dr Muttarak is currently investigating how climate change will affect population dynamics through its effect on fertility, mortality and migration.
Global surface temperature change 1880-2020
“The impact of climate change on human health is already being felt, directly and indirectly,” she says. “The growing evidence does suggest climate change will affect our health and, to a certain extent, mortality.”
Migration will be affected, although climate change’s effects will not be straightforward. Dr Muttarak says it will increase movements of people under some circumstances – such as when they have the resources to move – while reducing it in others.
Against such a complex backdrop, it is no surprise that researchers take different views on how patterns of food scarcity will play out.
"[There are] those who are arguing that the population growth is what’s going to cause the demise of a lot of society because of food availability,” says Prof Terry Dawson, a professor of global environmental change at King’s College London.
“There’s another camp who says there’s plenty of food, it’s the inequality that is the problem.”
While models vary in their predictions, work by Prof Dawson, Prof Smith and colleagues indicates that in the decades to come, population growth may play a greater role than climate change in creating food shortages. Their analysis indicates that climate change may cause about 20 per cent of any increases in undernourishment.
They found that, if nothing is done, there will be “a considerable increase in the number of countries with a very high prevalence of undernourishment” by 2050.
There are, however, measures such as improvements to how food is produced, and the strengthening of trade and aid links, that could mitigate these effects.
Nowhere will these be more important than in Africa.
Number of undernourished worldwide, in Africa and its sub-regions 2000-2019 (million)
The population of sub-Saharan Africa is growing by 2.7 per cent a year, a rate more than twice that of South Asia and three times that of Latin America. The continent’s population of more than 1.2 billion is predicted by a UN report to reach about 2.5 billion by 2050.
The youthfulness of Africa’s population means that, even if birth rates fall, populations will continue to increase for decades.
As they are, less-developed sub-Saharan African countries will have “the least economic capacity and elasticity” to deal with the challenges posed by climate change and population growth, Prof Smith says.
“Some of the famines that we’ve seen over the last 20 or 30 years could become more frequent unless we address the inequalities rapidly,” he says. But Africa has great opportunities to improve its agricultural output to feed its growing numbers.
“Africa has a huge yield gap in the amount of crops produced per hectare compared with the rest of the world,” Prof Dawson says.
“If the technology was there, they could probably get a six-fold increase in the number of tonnes of food produced per hectare relative to Europe. It just shows there are funds needed to buy fertilisers, to support improved irrigation systems ... a lot of Africa is still rain-fed crop production.”
China is an example of how countries can increase their food production, with the country having achieved what has been described as an “agricultural miracle” in growing enough food for its 1.4 billion people.
Hunger and food security in China
Yet the world’s most populous nation also offers cautionary lessons, because high levels of pollution and greenhouse gas emissions have resulted from its heavy use of nitrogen fertilisers.
Economic development is seen as key if the poorest parts of Africa and other regions of the world are to cope with the looming challenges.
Nations, Prof Dawson says, have to become “plugged into the global economy”. As an example, he cites Kenya and its cut-flowers sector, which is the country’s second-largest exporter, employing more than 100,000 people.
"People would argue that’s not a good use of land for food but it creates an economy, which means they can afford to import staple foods,” Prof Dawson says.
Developed nations, through aid, can assist by, for example, promoting education, especially for women and girls, because this can contribute to fertility reduction and makes population growth more manageable.
"The best thing we can do in the developed world is to provide aid and support and capacity building to help them live where they are rather than to rely on others for their living and continued survival,” Prof Smith says.
Greenhouse gas emissions per kilogram of food product (kgCO2eq)
One concern is that as countries become wealthier, meat and dairy consumption goes up. Prof Smith says that consuming animal products requires 10 to 100 times as much land as eating plant-based foods does, and causes carbon emissions to increase by a similar factor.
This link between wealth and the consumption of animal products must, he says, be broken. This is something he says needs to “start with the industrialised countries”.
“We can comfortably feed 12 billion people with less pressure on the land if we significantly cut livestock and dairy consumption,” he says.
