Land & Food

06 Land & Food
06 Land & Food

Share of global emissions (IPCC)

Can nature be saved?

The global population explosion of the 20th century continues to have a profound effect on the Earth and its environment. The United Nations forecasts that the world population will reach 8 billion on November 15 2022, and will continue rising to peak at 10.4 billion in the 2080s.1 However, the rate of growth has slowed dramatically compared to the mid-20th century. The “demographic transition” — the shift from the high birth rates and high childhood death rates characteristic of premodern societies to a regime of low birth and death rates — is nearly complete. Only a few areas of the world, including parts of South Asia, some Middle Eastern countries and most of Africa south of the Sahara Desert, still exhibit high rates of population growth.

Global fertility rates, 2021

Rates are children per woman. Replacement fertility is approximately 2.1 children per woman, so large parts of the world are now below this level.

The people responsible for most of the historical emissions leading to climate change — and certainly for the bulk of the per capita emissions — are the 1 billion or so people who live in the wealthy, developed countries. The United States alone, with less than 5 percent of the world population, is responsible for 20 percent of historical emissions, more than any other country.2 Catching up fast on emissions are the residents of middle-income countries like China and India, where fossil-fuel use is booming as those countries climb out of poverty. India will shortly surpass China as the world’s most populous country, but it appears to have both the ability and willingness to bring fertility down over the next decade or so in the country’s remaining hotspots. Whether runaway global warming can be averted depends more on whether these countries can leapfrog to clean energy than it does on their population trajectories.

The population explosion has had its most profound influence on the course of climate change through the increase in the global demand for food. In the 19th and early 20th centuries, forests were chopped down across the Northern Hemisphere so that land could be converted to farming. This trend long ago ran its course as northern agriculture grew more intensive and efficient, and many of those northern forests are now regrowing, helping to soak up a significant fraction of humanity’s carbon emissions.

The cycle is now playing out in the tropics, where deforestation is an acute problem, as Figure 23 shows. Three basins account for most of the world’s tropical forests: the Amazon in Brazil and neighbouring countries, the Congo basin in Africa, and the islands of the Indonesian archipelago. Under previous governments, Brazil succeeded in cutting the deforestation rate in the Amazon, but the gains have been partially reversed under the far-right government of Jair Bolsonaro. Deforestation in Indonesia has been occurring at very high levels, with entire landscapes being denuded in order to plant palm-oil farms to supply the global market. Outside pressure has helped to bring it down somewhat. Much of the deforestation in the Congo basin was historically done by families gathering wood for subsistence cooking, but commercial deforestation there is rising. Among the coming stresses on the forest are new concessions for the production of oil and gas.3

Non-fire related loss can occur from mechanical clearing for agriculture and logging, as well as natural causes such as wind damage and river meandering. All figures are calculated with a 30 percent minimum tree cover canopy density.

Overall, global deforestation has been declining for the past several decades, with ups and downs.4 It needs to stop immediately, not only to permit continued uptake of greenhouse gases, but to salvage what is left of the biological richness of life on Earth. (See “The Sixth Extinction” below for further discussion.)

An RLI value of 1.0 equates to all species qualifying as Least Concern (i.e., not expected to become extinct in the near future). An RLI value of 0 equates to all species having gone extinct.

At the heart of the continuing deforestation is a broken promise on the part of the rich world’s governments. They know they ought to be willing to pay poor countries to preserve their forests, and indeed they have been promising to do so for decades. But they have never come up with a mechanism for raising money in the sums required: tens of billions of dollars per year.

The expansion of agriculture is a major reason forests are chopped down, but farming is a large contributor to climate change even when it occurs on land cleared long ago. It requires fossil fuels, it requires nitrogen fertiliser that can volatilise into a greenhouse gas, and methane emissions from activities like cattle-farming and rice-growing have an outsized effect on planetary warming in the near term.6

The reason the population explosion of the 20th century did not result in mass starvation was the spread around the world of high-yielding methods of cultivation, a historical development known as the Green Revolution. Varieties of wheat, rice and other crops were developed that could benefit from heavy applications of nitrogen fertiliser, producing immense increases in yields.7 Yet the Green Revolution had its downsides: excessive fertiliser use is a problem in many countries, including the United States and parts of Europe. It is most acute in China and India, where subsidised fertiliser is one of the legacies of the Green Revolution. These excessive quantities of fertiliser not only volatilise into a greenhouse gas; they also pollute streams and rivers. Hundreds of seasonal “dead zones” caused by fertiliser run-off now occur where rivers meet the sea.8 Meanwhile, even as fertiliser is overused in the global North, too little of it is available in the global South, greatly suppressing crop yields there.

Source: World Bank

A critical issue, one that governments have been reluctant to confront, is the rising worldwide demand for meat as more and more consumers move into the middle class. Meat consumption in rich regions like the United States and Europe is excessive, far beyond the protein levels required for adequate nutrition; if global consumption rises to such levels, the increase in emissions will be enormous. But it is not at all clear what public policies could hold back the rise in meat consumption in developing countries, or cut that consumption in the West, largely because governments have been so reluctant to experiment. A group of researchers at Oxford University has proposed a “meat tax” as one way to get at the problem.9 A handful of countries, and the European Union, have begun discussions on the idea or announced tentative plans to move forward with special taxes for meat or meat and dairy products, though it appears the initial policies will be modest. The bright spot in this picture is that many countries are seeing a change in consumer preferences, away from beef in favour of chicken, which is still environmentally costly, but much less so than cattle production.

Progress has been made developing plant-based meat substitutes that many consumers find appetizing, and this trend needs to continue. Over the horizon, it may become possible to grow actual meat tissue in bioreactors in an economical and environmentally benign way, creating a direct substitute for meat. However, little evidence has been published yet regarding such systems and how they would operate; it is unclear, in particular, what inputs would go into the bioreactors to be converted into proteins and fats in the meat cells. One scientific paper has warned that under certain circumstances, the production of meat in bioreactors could actually have worse environmental effects than farms growing beef cattle.10 This newborn industry must subject itself to outside scrutiny and environmental benchmarking if it is to win public trust.

Confronting the many problems associated with modern agriculture, many people dream of replacing it with something entirely new. But the reality is that entire countries depend on intensive, modern food production for their existence. While we are unlikely to move entirely away from conventional food systems — they are certain to continue growing with rising populations — we can take important steps towards making agriculture more sustainable. We need an intensive global focus on the overall environmental performance of the food system, using methods like regenerative agriculture and sustainable intensification to produce more food with less damage to the wild lands that are left. They are priceless treasures that must be preserved.

Among the most promising opportunities of coming decades is to turn nature into a greater ally in the fight against global overheating. Trees and other plants already absorb some 30 percent of humanity’s emissions of carbon dioxide.11 Planting more trees across degraded lands and on the margins of agricultural land could have enormous benefits, though doing it at scale will require large amounts of money. Other potential interventions include managing soils in a way that they accumulate carbon, turning the land surface into a giant carbon sponge. That can be done with methods like planting cover crops, but it costs farmers more money than they see in immediate economic benefits, so it will likely be necessary to pay the farmers to manage their land differently.

Such nature-based solutions are already being turned into projects that create carbon “offsets”, which are essentially certificates that are sold into a voluntary market of companies and people wanting to reduce their emissions. However, some of these offsetting programmes have received intensive scrutiny and criticism on the grounds that they promise more than they deliver, such as “saving” forests that would not have been cut down anyway.12 One of the great challenges of our time is finding ways to steer more private money into these kinds of projects, while at the same time setting strong rules to guarantee their environmental integrity.

One carbon credit represents one ton of carbon dioxide equivalent (CO₂e) avoided or sequestered.

  • 1. United Nations, World Population Prospects 2022, July 2022. https://www.un.org/development... Back to inline
  • 2. Evans, Simon: “Analysis: Which countries are historically responsible for climate change?”, Carbon Brief, October 5 2021. https://www.carbonbrief.org/an... Back to inline
  • 3. Maclean, Ruth and Dionne Searcey: “Congo to Auction Land to Oil Companies: ‘Our Priority Is Not to Save the Planet’”, The New York Times, July 24 2022. https://www.nytimes.com/2022/0... Back to inline
  • 4. For a detailed overview of forest loss and forest transitions, see Ritchie, Hannah and Max Roser: “Deforestation and Forest Loss”, Our World in Data, 2021. https://ourworldindata.org/def... Back to inline
  • 5. For a detailed analysis of the human factors causing the extinction crisis, see Kolbert, Elizabeth: “The Sixth Extinction: An Unnatural History”, Macmillan Publishers, 2015. https://us.macmillan.com/books... Back to inline
  • 6. Note that methane and carbon dioxide operate on far different time scales. The half-life of methane in the atmosphere is about a decade, whereas some of the carbon dioxide emitted today is likely to remain in the atmosphere, heating the climate, for many hundreds of years. The other major greenhouse gases have their own distinct atmospheric lifetimes, creating considerable difficulty in comparing them. See Mooney, Chris: “Why we’re still so incredibly confused about methane’s role in global warming”, The Washington Post, May 2 2016. https://www.washingtonpost.com... Back to inline
  • 7. For a capsule history of the Green Revolution, see Gillis, Justin: “Norman Borlaug, plant scientist who fought famine, dies at 95”, The New York Times, September 13 2009. https://www.nytimes.com/2009/0... Back to inline
  • 8. The use of nitrogen pulled from the air and converted in factories into a reactive form is essential to global food security, but its environmental implications are profound. For a summary of the issues, see Smil, Vaclav: “Global population and the nitrogen cycle”, Scientific American, July 1 1997. https://www.scientificamerican... Back to inline
  • 9. Funke, Franziska, et al: “Is meat too cheap? Towards optimal meat taxation”, forthcoming in Review of Environmental Economics and Policy; retrieved on September 3 2022 as Working Paper 2022-01 of the Institute for New Economic Thinking at the Oxford Martin School, University of Oxford. https://www.inet.ox.ac.uk/file...
    Back to inline
  • 10. Lynch, John and Raymond Pierrehumbert: “Climate impacts of cultured meat and beef cattle”, Frontiers in Sustainable Food Systems, February 19 2019. https://www.frontiersin.org/ar... Back to inline
  • 11. Friedlingstein, Pierre, et al: “Global carbon budget 2021“, Earth System Science Data, April 26 2022. Best estimates of all anthropogenic carbon fluxes are contained in Figure 2. https://essd.copernicus.org/ar... Back to inline
  • 12. For one example of such scrutiny, see Elgin, Ben: “These trees are not what they seem”, Bloomberg Green, December 9 2020. https://www.bloomberg.com/feat... Back to inline