In the context of climate change, the term “land use” is an exceptionally broad term which refers to how land is used (the purpose the land serves) as well as the actions taken in the process (how the land is managed, maintained, fertilized, irrigated etc). Examples of land use categories include: grazing, agriculture, forest, timber extraction, wildlife habitat, recreation, transport, residential, commercial, urban, and so on. There may be multiple land uses at any one place. 1 2
Land use has become a key buzzword in the literature of global warming, and has spawned a series of overlapping and confusing acronyms, such as LUC (“Land Use Change”), LULUCF (“Land Use, Land-Use Change, and Forestry”), FOLU (“Forestry and Other Land Use”) and AFOLU (“Agriculture, Forestry and Other Land Use”), all of which have been taken up by climate organizations like the UN Framework Convention on Climate Change (UNFCCC) and its scientific advisory body the Intergovernmental Panel on Climate Change (IPCC). Land management practices not only have a significant impact on the carbon cycle, as well as on natural resources like water, soil, nutrients, biodiversity and animal habitat, but also on Earth’s climate system, due to emissions of carbon dioxide, methane and nitrous oxide.
- What Is Land Cover?
- What Is Land Use Change?
- Why Is It So Important?
- How Does Land Use Change Cause Global Warming?
- Land Use Made Simple
- How Can Land Use Help To Reduce Climate Change?
- IPCC Special Report On Climate Change And Land (2019)
- How To Improve Land Use?
- How Improved Agricultural Practices Can Reduce Global Warming
- How To Feed A Growing Population Without Destroying The Planet?
What Is Land Cover?
The term “land cover” describes what covers the surface of the earth. It refers to the physical characteristics of the pedosphere – the actual terrain. Examples of different categories of land cover include: tree-covered areas (e.g. evergreen needleleaf forest (boreal, taiga), evergreen broadleaf (rainforest), herbaceous croplands (most agricultural crops), grassland, shrub-covered areas, wetlands, mangroves (tropical coastal wetlands), open shrubland (e.g. Australian outback), barren or sparsely vegetated (desert), permafrost, permanent snow covered areas (e.g. glaciers), and artificial surfaces (including urban and associated areas). 3 4
What Is Land Use Change?
Land-use change (LUC) refers to alterations in the use of land (e.g. such as converting forest to agricultural land) or its management (e.g. changes in crop type, fertilizer use, harvesting practices, expansion of irrigation system), which may lead to a change in land cover and a possible adverse effect on greenhouse gas levels. For this reason, the Kyoto Protocol climate treaty (1997) introduced mandatory reporting of any LUCs as part of its enhanced climate monitoring system.
Why Is It So Important?
Because the way we use land has a significant effect on greenhouse gas emissions (mostly CO2). 5 It’s worth noting that emissions of carbon dioxide resulting from land-use change was the predominant source of annual CO2 emissions until about 1950, when the use of fossil fuels surged ahead due to the post-war boom. 6
As of 2018, net CO2 emissions from deforestation and other land-use change accounted for roughly 12 percent of all emissions from human activity – that is, fossil fuel, industry and land use change. 7
According to the IPCC, land cover and land-use change affects the surface albedo, evapotranspiration, sources and sinks of greenhouse gases (GHGs), and other aspects of the planet’s climate system, leading to climate forcing and other effects on long term weather patterns both locally or globally.
How Does Land Use Change Cause Global Warming?
- Trees and plants absorb carbon dioxide from the atmosphere for the purpose of photosynthesis. If they are cut down or cleared, they stop removing CO2, which leads to higher concentrations of carbon dioxide in the atmosphere.
- When trees or plants are cut down and discarded, they stop absorbing CO2 and start emitting it. How much they emit remains a source of debate. 8 9 10
- Burning chopped trees and other vegetation leads directly to an increase in CO2 emissions. 11
- Increasing the area of land devoted to rice cultivation also leads directly to global warming. This is because water-logged rice paddies, allied to increasingly warm weather, leads to an increase in anaerobic plant decay, which in turn causes an increase in methane greenhouse gas emissions. Rice paddies now account for roughly 15 percent, or more, of anthropogenic methane emissions. 12 13 For more on this, see: Why Are Methane Levels rising?
Land Use Made Simple
In case you’re confused by any of this, here’s a very simple outline.
(1) Although there are many different ways of using land, three are more damaging from a climate viewpoint. These are: cattle farming, rice cultivation and intensive agriculture. Building houses and commercial units is also damaging, but according to data from GRUMP (Global Rural-Urban Mapping Project), towns and cities still occupy a relatively small percentage of land (roughly 3 percent).
(2) The more commercial the use, the more likely it is to involve the construction of roads, truck stops, bridges, and other associated infrastructure – all of which can damage the natural environment. Unfortunately, building environmentally friendly infrastructure is usually far too expensive for developing countries: one reason they need help.
(3) One crunch issue is likely to dominate the land use agenda: the battle between food and global warming. The world population is scheduled to grow from 7.7 billion (2020) to 11 billion by 2100. 14 Experts already say this is likely to cause a 50 percent increase in demand for food by 2050. 15 A demand which, some say, necessitates more forest clearance and more cattle. On the other hand, rising temperatures will make it progressively more difficult to maintain food production, because of extreme heat, drought, soil erosion and sea level rise. This crunch issue cannot be tackled by individual nations, it needs a coordinated global response. See more on this below.
How Can Land Use Help To Reduce Climate Change?
Land use is associated with three climate change mitigation strategies:
- The prevention of CO2 emissions by conserving existing carbon reservoirs in trees, vegetation and soils, or by reducing emissions of greenhouse gases like methane (from cattle, wetlands) and nitrous oxide (from fertilizers).
- Sequestration — increasing the extent of existing carbon reservoirs, thereby removing carbon dioxide (CO2) from the atmosphere.
- The substitution of biological products (biomass) for fossil fuels, thereby reducing CO2 emissions. There is disagreement between scientists as to whether wood burning is carbon neutral or a source of CO2 emissions. For more details on this critical issue, see: What is the Effect of Wood Burning on Climate Change?
IPCC Special Report On Climate Change And Land (2019)
Land Use And Land Use Change Have Been The Subject Of Two Major Reports By the Intergovernmental Panel on Climate Change (IPCC). The first one – “Land Use, Land-Use Change and Forestry” – was published in 2000. 16 The second, a landmark 1300-page study involving 107 experts from 52 countries and using data from some 7,000 scientific papers, is the “Special Report on Climate Change and Land” (SRCCL) also known as the Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. 17
What Does The Special Report On Climate Change And Land Say?
The report acknowledges the complicated relationship that exists between land use and climate change. Namely, that while land masses are natural “carbon sinks” (reservoirs), whose vegetation and trees absorb CO2 through various processes of the carbon cycle, including photosynthesis, the same vegetation and trees are also “sources” of CO2, when they decompose or burn because of land use changes.
For example, during the period 2007-2016, GHG emissions from land use (mainly from agriculture, cattle, forestry and land clearing) averaged 9-15 billion tonnes of CO2 equivalent each year. Which accounts for roughly 23 percent of the world’s greenhouse gas emissions. Indeed, if the entire food chain is factored in (including fertiliser, transport, processing, and sale) this contribution rises to 29 percent. 18
However, during the same period, land-based ecosystems absorbed an average of between 8.6 and 13.8 billion tonnes of carbon dioxide per year, through the normal processes of the carbon cycle that store carbon in soil, in all types of leafy plants, and in natural “carbon sinks” like forests, seagrasses and wetlands.
Right now, these sinks and sources are roughly in balance. But unless something is done soon to reduce land use emissions and improve the capacity of our carbon sinks, global warming, as well as an upsurge in intensive livestock and crop farming (to feed the growing population), will almost lead to increased net emissions with significant adverse impacts on global temperatures.
Already, global warming has created a powerful feedback loop: higher temperatures are degrading the land through drought, desertification and sea level rises, as well as wildfires like those that recently consumed vast swathes of Siberia, Alaska and Greenland. All of which increases the amount of greenhouse gases being released by Earth’s land, which only accelerates the warming process further.
How To Improve Land Use?
Several solutions are outlined in the Special Report. Most important is stopping deforestation – notably the deforestation in the Amazon Rainforest – and reducing food waste. Some 25-30 percent of what the world grows to eat is lost or wasted. Reducing this would significantly reduce pressure on agricultural systems.
At the same time our way of eating needs to change. In particular, we need to eat less meat, because the feeding and grazing of livestock is a huge contributor to greenhouse gas emissions. About 40 percent of the world’s man-made methane – a highly potent greenhouse gas – comes from raising cattle. 19 20 However, this – like so much of climate mitigation – can only be achieved with a carefully thought out strategy, because sometimes, making an obviously beneficial change can lead to unwanted consequences.
For example, according to one new study, a switch to 100 percent organic food production in England and Wales would result in an overall increase in greenhouse gas emissions. While going organic produces fewer direct emissions than conventional farming, researchers say it would produce insufficient food. Thus, more imports would be needed, and this would result in up to five times more land being used overseas. Overall emissions would rise by 21 percent compared to conventional farming. 21
The role of land use in limiting climate is further complicated by the feasibility of BECCS – bioenergy with carbon capture and storage. The IPCC’s Special Report on Global Warming of 1.5°C (2018) stressed that, in order to limit warming to 1.5°C, billions of tonnes of CO2 would have to be removed from the atmosphere and somehow stored away. The report recommended bioenergy with carbon capture and storage – a process which relies on power plants capturing and storing the CO2 from burning biofuel – as a way to achieve this, except that scientists are now warning that the area of land needed to grow the biofuel would be vast – probably several times the size of India.
To make matters worse, suggestions are already circulating among some fossil fuel producers that BECCS’ CO2 removals can cancel out or ‘offset’ their fossil fuel emissions. This ignores the scientific fact that any CO2 removed by a tree is temporary, whereas fossil fuel emissions remain in the atmosphere for millennia.
How Improved Agricultural Practices Can Reduce Global Warming
- Agriculture that helps to reduce global warming is called regenerative agriculture. It embraces several methods, the most notable of which are: diversity, conservation tillage, rotation and cover crops, minimizing physical disturbance, minimal use of chemicals. This sustainable approach to farming also improves the state of the soil and, as a result, boosts yields.
- This approach is also recommended by the U.S. Environmental Protection Agency who recommends improved soil management practices in respect of fertilizer usage, irrigation, tillage and animal manure management, all of which can reduce the emissions of nitrous oxide (N2O), one of the more potent greenhouse gases. See also our article: Why is Soil So Important to the Planet?
Other methods that can boost carbon sequestration in soil include: conversion of arable land to grassland, no-till farming, residue mulching, cover cropping, and crop rotation, all of which are more widely used in organic farming than in conventional farming. 22
- One of the most promising climate mitigation projects involving land use, was launched in 2019 by the “Global Evergreening Alliance”. The aim is to remove carbon from the atmosphere with Agroforestry, whereby trees or shrubs are grown around and among crops or pastureland. The project founders calculate that, by 2050, the restored land will sequestrate approximately 20 billion tonnes of carbon annually. 23
- Mitigation options for lowering GHG emissions from cattle include genetic selection, 24 rumen defaunation, the introduction of methanotrophic bacteria into the rumen, 25 diet modification and grazing management, among others. 26 Certain dietary changes – for example those involving the red algae known as Asparagopsis taxiformis – can affect a reduction of up to 99 percent of ruminant greenhouse gas emissions. 27
How To Feed A Growing Population Without Destroying The Planet?
The world’s population will reach 10 billion by 2050 and 11 billion by 2100. But unless we limit global warming – which means reducing our carbon footprint – extreme heat may destroy our crops and rising seas may swamp coastal lands and ecosystems around the world, destroying valuable agricultural land and displacing hundreds of millions. 28
An important new report from the World Resources Institute (WRI) lays out the issue and pulls no punches. Providing a healthy diet for an expected global population of nearly 10 billion people in 2050, while at the same time improving the world, will require sweeping changes to farming and how we produce food, the report says. 29
Almost half of the world’s vegetated land is already devoted to agriculture, the report says, but food needs keep rising. Agriculture is a leading cause of deforestation in Southeast Asia and also in the Congo Rainforest. Each year, it consumes 90 percent of the water used by humanity and pumps out one-quarter of all greenhouse gas emissions that are causing global warming. Yet 820 million remain undernourished because they don’t have access to an adequate diet.
“We have to produce 30 percent more food on the same land area, stop deforestation, and cut carbon emissions for food production by two-thirds,” says Richard Waite co-author of the report. And all this must be done while reducing poverty levels, preventing freshwater depletion and the loss of natural habitat, and making farming more sustainable. It’s a task that requires huge investment, as well as major improvements in feed quality and grazing management. Farmers need to produce more than one crop harvest per year, which necessitates better crop breeding techniques.
In all, 22 solutions are presented in the 565-page report. Here are some of the report’s main suggestions:
- We need to dramatically reduce the estimated one-third of food that is lost or wasted by making improvements all along the supply chain.
- We need to shift the diets of meat-eaters toward plant-based foods. Meat production is resource-greedy and in order to allow growing populations to have access to some meat, others will have to eat less. Governments provide nearly $600 billion in annual subsidies to agriculture; those that encourage meat and dairy production should be reduced or phased out.
- The farming industry needs to produce more from less. Extra crop yields and harvests are essential. To prevent yet more land from being devoted to cattle and other livestock, major improvements are needed in feed quality and grazing management.
- Wild fisheries management and aquaculture needs to be overhauled and improved in order to protect the marine food web and the fish stocks that depend upon it. The problem of overfishing should be tackled by cutting the massive $35 billion in annual global fisheries subsidies. Aquaculture might include the cultivation of algae, seaweed, or seeds-based fish foods rather than using small fish to feed bigger ones like salmon. 30
AFOLU stands for “Agriculture, Forestry and Other Land Use.” AFOLU is a term from the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines which describes a category of activities that contribute to man-made greenhouse gas emissions. Employed in national greenhouse gas inventories, the AFOLU category combines two previously separate sectors LULUCF and Agriculture.
LULUCF stands for “Land Use, Land Use Change, and Forestry”, and is also referred to as FOLU, which stands for “Forestry and Other Land Use.” LULUCF or FOLU are defined by the United Nations Climate Change Secretariat as: a greenhouse gas inventory sector that describes emissions and removals of GHGs resulting from direct human-induced land use like settlements and commercial uses, land-use change, and forestry activities. (But excluding agriculture.) 1
- IPCC, AR5, 2014: Annex II: Glossary [Mach, K.J., S. Planton and C. von Stechow (eds.)]. In: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. pp. 117-130.
- “Land Cover & Land Use.”
- The International Geosphere-Biosphere Programme (IGBP) Land Cover Classification
- Land Cover Classification System (LCCS), FAO
- “Ecosystem type and resource quality are more important than global change drivers in regulating early stages of litter decomposition”. Ochoa-Hueso, R; Delgado-Baquerizo, M; King, PTA; Benham, M; Arca, V; Power, SA (February 2019). Soil Biology and Biochemistry. 129: 144–152.
- IPCC Fifth Assessment Report. 2013-4
- Carbon Budget 2018. globalcarbonproject.org
- “Measuring the Role of Deforestation in Global Warming.” Union of Concerned Scientists. Dec 2013.
- “By the Numbers: The Value of Tropical Forests in the Climate Change Equation.” World Resources Institute. David Gibbs, Nancy Harris and Frances Seymour – October 04, 2018.
- “Dead Forests Release Less Carbon into Atmosphere Than Expected.” Daniel Stolte. UA News. March 22, 2013.”
- “Why Burning Trees for Energy Harms the Climate.” Craig Hanson, Janet Ranganathan. World Resources Institute. December 06, 2017.
- “Acclimation of methane emissions from rice paddy fields to straw addition.” Yu Jiang, et al; Science Advances. 16 Jan 2019: Vol. 5, no. 1.
- ”Investigations of methane emissions from rice cultivation in Indian context.” Environment international. 31. pp.469-82. Anand, Shalini & Dahiya, R. P. & Talyan, Vikash & Vrat, Prem. (2005).
- “World Population Prospects: The 2019 Revision”
- “Global Demand for Food Is Rising. Can We Meet It?” Harvard Business Review. April 7, 2016.
- “Land Use, Land-Use Change and Forestry.” IPCC, 2000 – Robert T. Watson, Ian R. Noble, Bert Bolin, N. H. Ravindranath, David J. Verardo and David J. Dokken (Eds.) Cambridge University Press, UK.
- Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems (SRCCL). p. 43.
- “UN climate change report: land clearing and farming contribute a third of the world’s greenhouse gases.” Mark Howden. The Conversation. August 8, 2019.
- Key Facts & Findings. FAO
- “Methane, explained.” Alejandra Borunda. National Geographic. Jan 23, 2019.
- “The greenhouse gas impacts of converting food production in England and Wales to organic methods.” Laurence G. Smith, Guy J. D. Kirk, Philip J. Jones & Adrian G. Williams. (2019) Nature Communications volume 10, Article number: 4641.
- “Environmental, Energetic, and Economic Comparisons of Organic and Conventional Farming Systems”. BioScience. 55 (7): 573–82. Pimentel, David; Hepperly, Paul; Hanson, James; Douds, David; Seidel, Rita (2005).
- “Grand African Savannah Green Up’: Major $85 Million Project Announced to Scale up Agroforestry in Africa”. Erik Hoffner. Ecowatch. Oct 25, 2019.
- “Canada Is Using Genetics to Make Cows Less Gassy.” Elen Airhart. Wired. Sept 6, 2017.
- “Exploring diet-dependent shifts in methanogen and methanotroph diversity in the rumen of Mehsani buffalo by a metagenomics approach”. Frontiers in Life Science. 8 (4): 371–378. Parmar, N.R.; Nirmal Kumar, J.I.; Joshi, C.G. (2015).
- “Options for the abatement of methane and nitrous oxide from ruminant production: A review”. Livestock Science. 130 (1–3): 47–56. Eckard, R. J.; et al. (2010).
- “Effects of Marine and Freshwater Macroalgae on In Vitro Total Gas and Methane Production”. PLoS ONE. 9 (1): e85289. Machado, Lorenna; Magnusson, Marie; Paul, Nicholas A.; de Nys, Rocky; Tomkins, Nigel (2014-01-22).
- “Sea-level rise due to polar ice-sheet mass loss during past warm periods.” A. Dutton, A. E. Carlson, A. J. Long, G. A. Milne, P. U. Clark, R. DeConto, B. P. Horton, S. Rahmstorf, M. E. Raymo. Science 10 Jul 2015: Vol. 349, Issue 6244, aaa4019.
- “Creating A Sustainable Food Future: Final Report.” (PDF) WRI 2019.
- “How to feed the world without destroying the planet.” Stephen Leahy. National Geographic. July 17, 2019.