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Biogas and its role in the energy transition

November 8, 2022 by ZCA Team Leave a Comment

Key points

Reliance on biogas and biomethane as a decarbonisation solution should be limited to hard-to-abate sectors where there are currently no feasible, economic alternatives for emissions reduction (such as petrochemical production or industrial heating)
Use of biogas in electricity generation, heating and transportation should be limited given there are already cost effective options for electrification of end-use using renewable energy
Biogas’ potential to reduce agricultural emissions is limited to sources of emissions arising from manure and crop residuals, which contribute to a minority of agricultural emissions overall. The source and sustainability of feedstock is critical to the overall lifecycle emissions and costs
Biogas deployment should be carefully weighed against known limitations and risks, which include the impact of fugitive emissions, potentially limited availability of sustainable feedstock, high cost and reliance on public investment, and safety concerns.

What are biogas and biomethane?

Biogas is produced from the controlled decomposition of organic matter (through processes like anaerobic decomposition), where the gases that form as a result are captured. These gases are usually a mixture of methane (waste and agriculture account for roughly 60% of global methane emissions) and CO2, which are both potent greenhouse gases. Additional processes can be applied to remove the CO2 from biogas, leaving only methane, which is known as biomethane. For the purpose of this briefing, the term biogas is used to encompass both biogas and biomethane.

Biogas can be a substitute for current uses of fossil fuel-based natural gas, ranging from electricity generation to heating – the IEA estimates that biogas has the potential to replace 20% of current demand for natural gas. Some argue that by capturing methane from waste and agricultural products and using it as a substitute for natural gas, biogas is a necessary renewable solution for limiting global warming to 1.5^oC. This briefing examines the potential and limitations of using biogas for reducing global emissions.

Mitigation potential of biogas

Agricultural byproducts are the main source of biogas feedstock today. However, biogas feedstock is not the only valuable use of agricultural byproducts. For example, animal waste can be used as fertiliser.

Biogas can reduce emissions in two ways:

Mitigate methane and other greenhouse gas emissions in the agriculture sector, where livestock emissions represent roughly 32% of global methane emissions
Substitute the use of natural gas by producing methane from waste materials.

Using biogas for electricity generation and heating still requires methane to be combusted, which produces CO2, the greenhouse gas driving climate change more than any other.

Therefore, the emissions benefit of biogas depend on:

The sustainability of its production method as a feedstock
The emission reduction potential compared to other low or zero-emission alternatives
Feasibility and potential for uptake given the cost and availability of feedstock
The net lifecycle emissions from the production of feedstock, including any potential leakages
Whether a high rate of carbon capture and storage is deployed if the biogas is combusted.

It is also worth noting that common technologies for producing biogas from manure management (such as anaerobic digestion) tend to be inefficient and often produce large amounts of CO2, which require processing to upgrade into biogas.

Biogas’ potential to mitigate agricultural emissions

Biogas’ potential to reduce agricultural emissions is limited to sources of emissions arising from manure and crop residuals, which contribute to a minority of agricultural emissions out of the five main sources:

Enteric fermentation: 44.3% of agricultural emissions
Manure left on pasture and management: 23% of agricultural emissions
Crop residuals: 5.9% of agricultural emissions
Feed: 13.5% of agricultural emissions
Other emissions (land use change, energy use): 13.3% of agricultural emissions.

Therefore, capturing emissions from manure and crop residuals to produce biogas will, at best, address 28.9% of global agricultural emissions, leaving the majority of emissions unabated. And this is likely to be an overestimate given that more than 80% of the world’s farms are held by smallholders in developing countries with less than two hectares of land that meet the technical and financial requirements needed to install an anaerobic digester. Comparatively, US livestock farms need to meet the following criteria to be potential candidates for anaerobic digestion:

Minimum of 500 head of cattle, 2,000 hogs with anaerobic lagoons or liquid slurry manure management systems, or 5,000 hogs with deep-pit manure management systems
Minimum of 90% of manure is regularly collected.

Beyond using manure and crop residuals as sources of feedstock, biogas production requires farming energy crops, and this has been criticised by the IPCC for causing biodiversity loss, undermining food security and excessive water use, as well as creating the potential for temperature overshoot.

The REPower EU plan

In the RePower EU plan, the European Commission announced a target of 35 billion cubic metres (bcm) of production volume in Europe by 2030. This is a twelvefold increase of the current 3 bcm biogas (specifically biomethane) produced in the EU each year.

An assessment by the Institute for Energy and Environmental Research (IFEU) for the European Climate Foundation of how much sustainable biogas could be produced in Europe found only 17 bcm could be produced by 2030.

It found that, in order to achieve the 35 bcm biomethane target, the residues available for biogas production would not be sufficient and a considerable amount of crop-based biomass would have to be used. This would have considerable disadvantages. In a realistic scenario, around five to six million hectares of arable land would be required. This equals 5% of the arable land and 20% of the land used for wheat cultivation in the EU27. It would be more than the area that is used in the Ukraine for rapeseed production. Occupying land for biomethane production would thus lower the land availability for food production significantly.

Biogas as a substitute for fossil fuel-based natural gas

Most biogas produced today (64%) is used for electricity generation, predominantly in Europe and North America. Around 27% is used for heating in buildings. Acting as a substitute for fossil fuel natural gas can help avoid the current emissions impact of natural gas extraction, and its associated environmental impact. However, this substitution effect assumes that natural gas will continue to be used in electricity generation and heating. But viable alternatives such as renewable energy and widespread electrification already exist today. A study that evaluated the lifecycle environmental impacts of biogas electricity in comparison to other renewable alternatives looked at 11 environmental indicators (including emissions, human toxicity and ozone layer depletion) found that “biogas electricity can help reduce greenhouse gas (GHG) emissions relative to a fossil-intensive electricity mix; however, some other impacts increase. If mitigation of climate change is the main aim, other renewables have a greater potential to reduce GHG emissions.”

In fact renewable energy is now the cheapest source of energy in most countries. Given the continued cost reductions in wind and solar and high implementation cost of biogas production, it is unlikely that biogas electricity generation will be competitive against renewable energy on a levelised cost of electricity (LCOE) basis.

There may be a limited role for biogas as a substitute for fossil fuel-based natural gas for hard-to-abate sectors such as petrochemical production and industrial heat, where there are fewer options for electrification using renewable energy. However, achieving the volume and cost reductions needed to supply biogas for these purposes is by no means a given.

Risks and limitations for deployment of biogas

Fugitive emissions reduce the benefits of biogas

The IPCC has found that fugitive emissions generated by biogas plants can reduce the potential benefit of biogas production from an emissions perspective. A 2022 study found that supply chains for biomethane and biogas release more than twice the amount of methane previously estimated by the International Energy Agency, with 62% of leaks originating from a small number of facilities.

Another study examined 10 biogas plants in the UK and found that the rate of fugitive emissions reached a maximum of 9%, suggesting biogas plant methane emissions may account for up to 3.8% of total UK methane emissions. The research reached the conclusion that “the sustainability of biogas plants and the UK Net Zero Commitment may be jeopardised unless robust, consistent emission measurements and legal requirements are put into practice in the near future.”

High cost and reliance on subsidies

Biogas production and consumption require significant investment for:

the construction of biodigestion facility
feedstock collection
processing
transport and conversion
application of carbon capture and storage.

The cost of each component is highly dependent on the location of feedstock and its ultimate end use. This means biogas production tends to be more economically feasible in countries where the location of the feedstock is close to the source of final conversion and use, and where there is already transportation infrastructure in place. As a result, biogas production barely exists in countries like Australia, and remains challenging to implement in other regions (such as Latin America, Africa or Southeast Asia).

In Europe and the US, the high capital cost of installing biodigesters (around 70%-95% of total biogas costs) means significant subsidies are required to make projects financially feasible. A detailed geospatial analysis recently revealed that 40% of the amount that is technically available would still be uneconomic by 2050 without subsidies. In Germany, small plants have been found uneconomic, needing combinations of 50% of investment subsidised and EUR 11.50/MWh (USD 11.30/MWh) feed-in tariffs to make the projects economic.

The application of carbon capture and storage to limit the emissions of carbon dioxide when biogas is burnt at its end use would also increase costs significantly. Given alternatives that exist to reduce waste and agricultural emissions, and limited situations where biogas can be a credible substitute for hard-to-abate sectors, the public investment in biogas should be balanced against other investment opportunities in decarbonisation.

Safety concerns

Many biogas facilities operate at small and medium scales, and they are not subject to the same safety standards as large-scale operations. Major hazards from biogas facilities include:

Explosions and fires
- When inappropriately mixed, air and methane is explosive
- Ammonia has explosive and flammable properties
- Hydrogen sulfide is extremely flammable
Toxicity
- Hydrogen sulfide is highly toxic.

A study suggests that between 1994-2015, 169 accidents occurred in the biogas sector, 12% of which could be classified as serious. One hundred and sixty-three of these occurred in Europe, mostly in Germany, which has the highest number of biogas plants. Of these, 53% resulted in fire, 40% resulted in explosion and 7% were related to toxic release.

Alternatives for reducing agricultural emissions

There are cost-effective alternatives for reducing emissions in agriculture and waste management that are ready for deployment. For example, transitioning to sustainable agriculture methods as well as a shift to a more sustainable food system are cost effective ways to reduce existing emissions in the agriculture industry. The IPCC found that economic mitigation options (less than USD 100 per tonne of CO2 reduced) such as improving soil management, agroforestry and livestock management have the mitigation potential of 4.1 GtCO2e each year. Shifting to sustainable healthy diets, reducing food waste and other demand side measures have the mitigation potential of 2.2 GtCO2e each year.

The effectiveness of animal feed supplements in cutting methane emissions

October 19, 2022 by ZCA Team Leave a Comment

Key points:

Various natural and synthetic supplements for reducing methane emissions from cattle, sheep and goats are being developed, each with its own set of positive and negative characteristics
Most supplements have only been tested in feedlots. Effectively administering them to animals on pasture, where cattle, sheep and goats spend most of their time and where most methane is produced, could prove challenging
The methane offset potential varies considerably among studies of the same supplement, highlighting the fact that impacts are difficult to predict
The lifecycle emissions of many supplements are poorly understood, and so a full understanding of their mitigation potential is lacking
Scaling-up the production of some of these supplements in the near-term comes with its own set of challenges.

Methane from ruminant (animals with four-chambered stomachs, including cows, sheep and goats) burps is the single largest human-caused methane source across all sectors, contributing 25%–30% of global methane emissions. Due to urbanisation, a growing human population and an expanding middle class, global demand for milk and meat is expected to increase by 58% and 74% respectively by 2050 compared to 2010. To combat this rise, several measures for curbing methane from burps are being developed.

One of these measures involves feeding ruminants supplements that inhibit methane production in the stomach. Cows eat carbon contained in plants, and this carbon is converted into methane in the stomach by microbes before being burped out. These supplements work either by physically disrupting methane production, or by shifting the composition of the microbial community away from methane-producing microbes.

Though some supplements have shown promise for reducing methane emissions and are already being sold as voluntary carbon credits, questions remain about the scientific credibility, practicality, scalability, safety and efficacy of these products.

Natural supplements

Red seaweed (Asparagopsis) has received a lot of media focus in recent years on the back of trials reporting methane emission reductions of up to 98% (when as little as 0.2% of the diet is supplemented with dried seaweed powder). It is estimated that if just 20% of the beef and dairy market in developed countries incorporated the supplement into feed, up to 15% of global methane emissions from burps could be avoided.

The main active ingredient in the seaweed is a compound called bromoform, which is a methane-production inhibitor and probable human carcinogen – although concerning levels of bromoform have not been detected in the tissue or milk of cows fed red seaweed. These seaweeds are also rich in iodine, excessive amounts of which can cause thyroid dysfunction in humans. Concerns have also been raised about the ozone-depleting properties of bromoform. Levels of the inhibitor vary naturally due to the environment and genetics, which could translate into variation in the efficacy of the product.

Probably the biggest barrier to rolling-out this seaweed supplement in the near term is producing enough of it. Harvesting wild populations alone would be unsustainable, so aquaculture techniques would need to be developed, along with land for growing and drying facilities. Ideally, these facilities would be located near farms to avoid transport and other processing emissions, although growing seaweed does have potential environmental benefits, such as CO2 sequestration, water quality improvement and ocean acidification reduction. The development of these aquaculture facilities could support regional economies by using local labour for seaweed growing and processing.

More modest methane reductions of up to 30% have been achieved using garlic and citrus extract supplements, marketed under the name Mootral. However, this is only based on a few animal trials. In one trial, statistically significant results were only seen after 12 weeks, although the authors attribute this to the refusal of the animals to eat the feed at the start of the experiment. However, no safety concerns have been raised with the use of this product.

The methane offsets from Mootral are being sold as voluntary carbon credits, called CowCredits, which are issued by Verra. With no lifecycle assessment available, and only a small handful of animal trials published in peer-reviewed scientific journals, it is difficult to properly evaluate the offset potential or efficacy of this product.

Methane reductions of up to 30% have also been found when adding nitrate-rich foods into the feed, as this modifies the microbial community. Nitrate has obtained better results in dairy cows than in beef cows, with a lifecycle assessment of the potential net greenhouse gas reductions in the US dairy industry estimating a 5% reduction in CO₂ equivalents. However, a major barrier to nitrate supplements is toxicity from nitrite – a by-product of nitrate metabolism in the stomach.

Synthetic supplements

One supplement that has received regulatory approval in Brazil, Chile and, soon, the EU, and for which there is substantial scientific evidence from animal trials, is 3-nitrooxypropanol, or 3-NOP. It is marketed under Bovaer (a combination of ‘bovine’ and ‘air’). The methane reduction potential averages 30% and lifecycle assessments report 11.7%–14% decreases in whole-farm dairy net greenhouse gas emission intensity when 3-NOP is used. 3-NOP also shows more promising results in dairy cattle than in beef cattle, with the same dose reducing methane emissions more in dairy cows than in beef cows.

The safety risks of 3-NOP to animals and humans are low. However, the compound degrades rapidly in the animal stomach so it needs to be supplied constantly, for example by incorporating it into feed, in order to work. This may be impractical for animals raised outside the feedlot (a yard or building where animals are fed in intensive production systems).

Typical lifecycle of beef cows in pastures and feedlots in the US

To understand how applicable these supplements may be in highly-developed, intensive beef-production systems, we can use the US as an example. The US is the largest beef-producing nation in the world (12.3 million tonnes in 2019), and the production system has a high proportion of cattle finished in feedlots – though Australia and South America are catching up.
In the beef production system in the US, a permanent herd of cattle is kept in order to produce calves (called the calf-cow operation). These cattle typically graze on inexpensive pastures such as grass. Of the calves born to this herd, about 60% will be raised on pasture for anywhere between 10 and 23 months (called the stocker operation) after which they will be finished in the feedlot (called the feedlot operation) for a further 100 to 300 days. The other 40% of calves go directly into feedlots for 240 to 280 days before going to slaughter. It is estimated that the permanent herd is responsible for up to 82% of the methane produced in the beef production system.

Methane production across the different operations of the beef production system

The feedlot issue

One obstacle shared by all the above supplements is that they have only been tested in feedlots. While they could, in theory, be given to cows raised on pasture, the practicality of doing so is likely to prove challenging, as feed is not as carefully controlled in pasture systems as it is in feedlots. Moreover, although some may consider cows raised on pasture to be more sustainable because they are eating fibrous plants that humans and other livestock otherwise cannot eat, pasture-raised cows actually burp more methane than cows that are fattened on more easily-digestible and nutrient-dense grains in feedlots. As most of the world’s cows spend the majority of their life on pasture and generally burp more methane than feedlot cows, an effective feed supplement must be effectively applicable to pasture-raised cattle.

Reducing emissions in pasture-raised animals

For pasture-raised animals, switching to more easily digestible legume forages could help reduce methane emissions. Tannin-rich forages or additives are another natural supplement option that can also be readily used in pasture systems. However, they have more modest reduction potential compared with some of the supplements mentioned above, with results varying greatly depending on the type of tannin. Tannins may negatively impact nutrient and protein digestibility and stomach health, affecting the animal’s ability to convert feed into milk and meat. It has been suggested that 3-NOP (Bovaer) could be supplied in lick-blocks or slow-release stomach devices for cattle on pasture, but the practicality of this has not been assessed. The effectiveness of 3-NOP was also found to decrease when higher amounts of fibre are eaten, implying that even if it were made available to cows on pasture, it may not be effective when low-quality forage is being eaten.

Environmental considerations

Though grain-fed feedlot cows produce less methane than grass-fed pasture cows, supplying these grains also comes with its own environmental impact. Feedlots are also significant sources of hydrogen sulphide (a toxic air pollutant) and major polluters of waterways with ammonia, pathogens and antibiotics. Concerns around increased antibiotic resistance are also growing. However, pasture systems come with their own set of concerns. For instance, if cattle production in the US were to shift from feedlot-based to pasture-based, herd size would need to increase by 30% to maintain present-day numbers because cows would take longer to fatten up and there would be less meat per cow. This shift would also result in greater methane emissions and other environmental costs, such as soil erosion, loss of native vegetation and water eutrophication (when water becomes overly enriched with nutrients, depleting oxygen levels).

Below is a table summarising the attributes of the supplements discussed, including the science (the number of studies and quality of the studies), scalability (how easily could this technology be scaled up for use in the near future), deployability (how readily could the technology be deployed), safety (potential safety concerns to humans, livestock and the environment), reduction potential (the extent to which methane could be reduced) and pasture use (the potential for the supplement to be used in pasture-based systems).

Summary of the supplements

In summary, many of these supplements are only in pilot phases or need more rigorous scientific research, especially animal trials, to fully understand their potential. There are major discrepancies in the methane reduction potentials reported among studies testing the same supplement, suggesting complex interactions of multiple variables, with impacts that are difficult to predict. Perhaps the biggest limitation of most of these supplements is that they have only been tested in feedlots. Controlling and monitoring the consumption of these supplements by cows in pasture systems, which produce the majority of global methane emissions from cattle, could prove particularly challenging, especially considering the palatability of many of them is low.

IPCC WGIII report: Bioenergy with carbon capture and storage (BECCS)

April 7, 2022 by ZCA Team Leave a Comment

This briefing summarises the main insights in the IPCC Working Group III report on Bioenergy with Carbon Capture and Storage (BECCS). The focus is on potential and feasibility of BECCS in climate mitigation, rather than the broader bioenergy sustainability topics.

Key points

BECCS can help to mitigate climate change, but it is not a silver bullet solution.
BECCS could have positive impacts, but there are many uncertainties, particularly when considering environmental and socio-economic issues.
BECCS is one of the heavily relied upon CDR methods used in climate models, but an area twice the size of Egypt could be needed to deploy BECCS in 2100 in pathways limiting warming to 1.5°C. Very large scale deployment would threaten food production and security, and damage ecosystems.
Delaying mitigation would put a lot of pressure on CDR, requiring large-scale deployment of BECCS to reduce the temperature overshoot, causing substantial land use change. Earlier mitigation would be essential to reduce the pressure on land and its associated impacts.

Bioenergy and BECCS: The basics

Bioenergy refers to energy products, such as fuels or electricity, that come from organic sources (e.g. waste, wood or crops). ¹ It is often promoted as a ‘climate neutral’ solution, as in theory these organic sources only release the carbon dioxide (CO₂) they had already absorbed when burnt. But, this characterisation depends on many assumptions, such as the type of feedstock used. Bioenergy could also help deliver other mitigation options, such as carbon sequestration from integrating trees into crop systems (e.g. agroforestry) that provide the feedstock for bioenergy.

When combined with carbon capture and storage (CCS), bioenergy is seen as a carbon dioxide removal (CDR) option. This is because the CO₂ emitted is then captured and stored in geological, terrestrial, or ocean reservoirs, or in manufactured products. BECCS may also reduce net GHG emissions by displacing the use of fossil fuels with renewable biomass in the production of heat, electricity and fuels. ²

Benefits and risks of BECCS

The IPCC is careful when talking about BECCS. It stresses that it is a crucial CDR option, but its potential depends on many social and environmental considerations (e.g. the choice of feedstock, management practice, and deployment strategy and scale). The report does not assess all these options in-depth.

BECCS could have positive impacts, the IPCC says. But only if some strategies are followed to enhance its benefits, such as adopting management practices that protect carbon stocks. ³ The use of feedstocks that do not need land (e.g. municipal organic waste or harvest residues) could also provide bioenergy at a significant, but limited, scale. ⁴ These can reduce negative impacts associated with land use. Selecting crops that can produce both protein feed and biofuels could also reduce pressure to convert lands. ⁵ Some technologies could generate co-benefits, such as anaerobic digestion of organic waste and wastewater, and those that convert indigestible biomass like algae into food and feed. ⁶

If BECCS is poorly planned, however, it can “have adverse socio-economic and environmental impacts, including on biodiversity, food and water security, local livelihoods and on the rights of Indigenous Peoples, especially if implemented at large scales and where land tenure is insecure”. ⁷ Major scale-up of bioenergy production, for example, will need more than wastes/residues and cultivation on marginal lands. This will require more land and water, harming biodiversity and, potentially harming food security. Thus, “bioenergy systems may fail to deliver near-zero emissions depending on operating conditions and regional contexts”. ⁸

The IPCC says “it is therefore not possible to precisely determine the scale of bioenergy and BECCS deployment at which negative impacts outweigh benefits”. ⁹ “As a result, bioenergy carbon neutrality is debated… and the lifecycle emissions of BECCS remain uncertain and will depend on how effectively bioenergy conversion processes are optimised”. ¹⁰ The future of BECCS also depends on the roll-out of CCS technologies, it adds. ¹¹

Mitigation potential of BECCS

Bioenergy and BECCS can represent an important share of the total mitigation potential, the IPCC says, but conclusions on how big a share vary due to the large diversity of studies and their assumptions about where and how BECCS is deployed (e.g. the associated land use). ¹² ¹³ The IPCC concludes that:

The range of recent estimates for the technical bioenergy potential when constrained by food security and environmental considerations is 5–50EJ/yr by 2050 for bioenergy that uses residues for feedstocks, and 50–250 EJ/yrby 2050 for a dedicated biomass production system. ¹⁴ For context, 250 EJ/yr is equivalent to 20%–30% of global primary energy demand.
The global technical CDR potential for BECCS by 2050 (i.e. considering only the technical capture of CO₂ and storage underground) is estimated at 0.5-11.3 billion tonnes of CO₂ a year (GtCO₂ a year). ¹⁵ ¹⁶ But, when considering cost effectiveness (less than USD100 per tonne of CO2-eq), the potential is reduced to 0.2- 9.9 GtCO₂ a year. ¹⁷ Currently, only 40 million tonnes of CO₂ is captured a year via CCS, meaning we would need nearly a 150-fold increase in CCS capacity for this amount of BECCS. Moreover, most of the captured carbon today is used for enhanced oil recovery (EOR), rather than permanent geological storage. This undermines emissions cuts as emissions from burning recovered oil could more than offset the benefits of capturing the carbon dioxide in the first place, by a factor of up to three.

Therefore, the IPCC urges caution about these estimates as they reflect only biophysical and technological conditions. These estimates can be reduced when factoring in economic, environmental, socio cultural and institutional constraints. For example, the mitigation effect of BECCS could be reduced if models start to include the diminishing ability of land to remove CO₂ from the atmosphere due to future climate change.

The role of BECCS in mitigation pathways

There has been “fervent debate” on the use of bioenergy with CCS in mitigation scenarios. ¹⁸ Reliance on it has been criticised for causing biodiversity loss, undermining food security, creating uncertain storage potential, excessive water use as well as creating the potential for temperature overshoot. ¹⁹ The overall land for bioenergy production is modelled to take place in tropical regions, where croplands for bioenergy displace land for food production (cropland and pasture) and other natural land. For example, in the 1.5°C mitigation pathway in Asia, bioenergy and forested areas together increase by about 2.1 million square kilometres – an area the size of Saudi Arabia – between 2020 and 2100, mostly at the cost of cropland and pasture. ²⁰ BECCS is also typically associated with delayed emissions reduction in the near-term. ²¹

Among CDR methods, BECCS is one the most common in climate models (i.e. integrated assessment models, or IAMs) to limit temperature rise to 2°C or lower. ²² Currently, few models represent other options, such as biochar or soil carbon sequestration. In fact, all illustrative mitigation pathways (IMPs) from the WG3 report primarily BECCS (for comparison with other land CDR options and discussion of BECCS in models, see here).

Across the scenarios reviewed by the IPCC, in those likely to limit warming to 2°C or lower, the cumulative volumes of BECCS reach 328 (median values) GtCO₂respectively for the 2020-2100 period. Translated to annual volumes, the IPCC sees BECCS removing about 2.75 GtCO₂a year. ²³ To put this into perspective, scientists predict that up to 10 GtCO₂ will need to be removed annually to reach global emissions targets by 2050.

Many IAM pathways include large increases in cropland area to supply biomass for bioenergy and BECCS, with 199 (56-482) million hectares in 2100 in pathways limiting warming to 1.5°C with no or limited overshoot. ²⁴ To put this into perspective, 102 million hectares of land – an area the size of Egypt – have been converted to cropland since the start of the 21st century.

Delaying mitigation would increase pressure on land because it would require large-scale deployment of CDR in the second half of the century to reduce temperature overshoot. The main CDR measures are BECCS and afforestation and reforestation because climate models use these measures as proxies for land-based mitigation. This will cause substantial land use change in 2050. Early mitigation reduces the amount of land required for this, though at the cost of larger land use transitions earlier in the century. Earlier action could also reduce climate impacts on agriculture and other land-mitigation options. ²⁵

1
Chapter 7, p. 77
2
Chapter 7, p. 77, Chapter 6. p.93
3
Chapter 7, p.81
4
Chapter 7, p.78, Chapter 6, p. 40
5
Chapter 12, p. 103
6
Chapter 12, p. 103
7
SPM, p.47
8
Chapter 6, p.42
9
Chapter 7, p.77-78
10
Chapter 6, p.42
11
Chapter 7, p.96 and chapter 7 , p. 6
12
Chapter 7, p.7
13
Chapter 7, p.79
14
Chapter 7, p.6
15
Excluding economic costs and/or sustainability concerns
16
Chapter 12, p. 55.”These potentials do not include avoided emissions resulting from the use of heat, electricity and/or fuels provided by the BECCS system”.
17
Chapter, 7, p.45
18
Chapter 3.2.2
19
Chapter 3, box 3.4
20
Chapter 7, figure 7.14
21
Chapter 3, box 3.4
22
Afforestation and reforestation is also widely used. See here for more info.
23
Chapter 12, p. 40
24
Chapter 3, p.6
25
Chapter 3, p.66

IPCC WGIII report: The land sector and climate mitigation

April 6, 2022 by ZCA Team Leave a Comment

This briefing summarises the Working Group III (WG3) of the IPCC’s main insights about the mitigation options with the Agriculture, Forestry and Other Land Uses (AFOLU) sector. The term “land sector” will be used throughout this briefing for clarity. The briefing also summarises the findings on the needs and limitations of land-based carbon dioxide removal (CDR).

Key points

Rapid deployment of mitigation in the land sector is essential in all 1.5°C pathways. It can provide up to 30% of the global mitigation needed for 1.5°C and 2°C pathways.
The sector offers significant near-term mitigation potential at relatively low cost. The global land-based mitigation potential is ~8–14 billion tonnes of CO₂ equivalent (GtCO₂-eq) each year between 2020-2050. About 30-50% of this potential could be achieved under USD20 per tCO2-eq. Options costing USD100 per tCO₂-eq or less could reduce global GHG emissions by at least half the 2019 level by 2030 (SPM C.12). But land-based mitigation cannot compensate for delayed emissions reductions in other sectors.
The IPCC recognises that carbon dioxide removal (CDR) is necessary to achieve net-zero GHG globally. Modelled scenarios rely heavily on forest planting and BECCs as main options to remove emissions from the atmosphere to achieve it.
But, the IPCC is not advocating for large-scale CDR. There are many uncertainties, risks and a lack of social licence for these options. It is still uncertain whether CDR through some land-based measures can be maintained in the very long term because sinks can saturate, for example. CDR cannot be deployed arbitrarily and given the time needed to ramp-up CDR, it can only make a limited contribution to reaching net zero in the timeframe required.
There is a substantial investment gap in the sector. The IPCC estimates that, to date, only USD 0.7 billion a year has been invested in land-based mitigation, well short of the more than USD 400 billion per year needed to deliver the up to 30% of global mitigation effort in deep mitigation scenarios.

The land sector is key to climate mitigation, but only within limits

The land sector is both a carbon source and a carbon sink. It accounted for ~13%-21% of global greenhouse gas (GHG) emissions between 2010-2019. ¹ But the land sector is also a carbon sink, as it draws CO₂ from the atmosphere when plants grow (through the process of photosynthesis). When the sector’s sources and sinks are added up, the land sector is considered a net sink of emissions – removing about 6.6 GtCO₂ a year for the period of 2010-2019. ²

The IPCC clearly states that the land sector has huge potential for mitigation. It can both reduce emissions – for example by changing farming and livestock practices – as well as remove them from the atmosphere, via measures like planting more forests and protecting existing ones. But the sector “cannot fully compensate for delayed action in other sectors”. (SPM C.9)

Overall, the IPCC estimates that the global land-based mitigation potential is ~8–14 billion tonnes of CO₂ equivalent (GtCO₂-eq) each year between 2020-2050, at costs below USD 100/tCO₂. ³ These estimates are slightly higher than those in AR5. Considering both integrated assessment models (IAMs) and sectoral economic potential estimates, WG3 states that “land-based mitigation could have the capacity to make the sector net-negative GHG emissions from 2036 although there are highly variable mitigation strategies for how [its] potential can be deployed for achieving climate targets”. ⁴ There are many options that can help reduce and remove emissions (Box 1). Most of the options to reduce emissions are available and ready to deploy, whereas CDR needs more investment. ⁵

The IPCC does not use the term ‘nature-based solutions’ (NbS), but ‘land-based mitigation measures’. When evaluating the mitigation potential within the sector, it discusses 20 measures, both supply and demand-side (Box 1). However, when it analyses mitigation pathways, it only includes a few options because of how climate models are currently built (see the role of CDR in mitigation pathways section for more detail).

Box 1. What are the main ways the land sector reduces and removes emissions between 2020-2050?

Forests and other ecosystems have the highest potential for carbon mitigation, according to global sectoral models. Protecting, managing and restoring these ecosystems is likely to reduce and/or sequester up to 7.4 billion tonnes of CO₂ equivalent each year between 2020 and 2050. ⁶ Crucially, the IPCC finds that protecting ecosystems has the highest potential. The report also stresses that halting deforestation and restoring peatlands is vital to keeping temperature rises below 2C.

Agriculture and demand-side measures provide the second and third highest potential for mitigation, potentially reducing and/or sequestering up to 4.1 and 3.6 billion tonnes of CO₂ equivalent a year respectively between 2020 and 2050. ⁷ For agriculture, the measures that have the greatest potential are soil carbon management in croplands and grasslands, agroforestry, biochar and rice cultivation, as well as livestock and nutrient management. On the demand-side, it’s shifting to healthy diets and reducing food waste and loss.

Land sector mitigation measures can have important co-benefits, but only if done properly. For example, “reforestation and forest conservation, avoided deforestation and restoration and conservation of natural ecosystems and biodiversity, improved sustainable forest management, agroforestry, soil carbon management and options that reduce CH₄ and N₂O emissions in agriculture from livestock and soil, can have multiple synergies with the sustainable development goals.” ⁸

But there are many risks and trade-offs. Large-scale or poorly planned deployment of bioenergy, biochar, and afforestation of naturally unforested land. (high confidence) for instance, can compete with scarce resources, such as agricultural land. ⁹ This can threaten food production and security and reduce adaptive capacity. The use of non-native species and monocultures (e.g. planting one type of tree) in forest projects can also lead to biodiversity loss, and negatively impact ecosystems. ¹⁰ There are also risks in relation to land’s ability to continue to act as a carbon sink in the future, which can reduce land sector measures’ capacity to mitigate emissions. ¹¹

Joint and rapid effort is key to achieving high levels of mitigation in the sector, the IPCC says. But there has been a lack of funds to support these efforts. The IPCC estimates that, to date, only USD 0.7 billion a year has been invested in the sector, well short of the more than USD 400 billion per year needed to deliver the up to 30% of global mitigation effort envisaged in deep mitigation scenarios.¹²

What does the IPCC say about the scale of land-based CDR?

Mitigation potential of different CDR options

CDR is defined by the IPCC as “human activities that remove emissions from the atmosphere and durably store it”. Thus, CDR excludes uptake of emissions not directly caused by humans. CDR can help in several phases of mitigation:

Reducing net CO₂ or GHG emission levels in the near-term
Counterbalancing residual emissions from hard-to-transition sectors like industry and agriculture to help reach net-zero CO₂ or GHG emissions targets in the mid-term
Achieving and sustaining net-negative CO₂ or GHG emissions in the long-term if deployed at levels exceeding annual residual emissions. ¹³ Therefore, offsets are discussed in the report as a way to counterbalance residual emissions, highlighting that hard-to-abate sectors could have more social licence to rely on CDR. ¹⁴

Currently, the only widely practised CDR methods include afforestation, reforestation, improved forest management, agroforestry and soil carbon sequestration. ¹⁵ Figure 1 presents the options that can be deployed on land as well as in the oceans. The IPCC discusses these options, presenting a summary of their mitigation potential, risks, co-benefits and costs. (Table 1 in the appendix) However, the IPCC does not go into detail on all options. For example, it mentions that the choice of feedstock for BECCS could lead to positive or negative impacts, but does not explore all feedstock options and their related consequences.

Figure 1. CDR methods across Land sector and Oceans (IPCC- WG3 Chapter 12, p.37)

The role of CDR in mitigation pathways

The WG3 report looks at what the science says about mitigating the climate crisis. As established in most scientific literature, achieving net zero by mid-century is the safest way to stay Paris aligned. There are, however, many different routes to net zero. Thus, the scope of this report is to chart the options, limits, benefits and trade-offs of pursuing a net-zero emissions society. To do this, the IPCC reviewed more than 3000 pathways, including over 1200 scenarios, to develop five “Illustrative Mitigation Pathways” (IMPs) and two high-emissions pathways for reference.

The report finds that “CDR is a necessary element to achieve net-zero CO₂ and GHG emissions, and counterbalance residual emissions from hard-to abate sectors”. ¹⁶ It is also a key element in scenarios that are likely to limit warming to 2°C or lower by 2100”. ¹⁷ All of its IMPs use land-based CDR, which is dominated by BECCS, afforestation and reforestation. ¹⁸

In most scenarios that limit temperatures to 2°C or lower, the IPCC predicts cumulative volumes of CO₂removed between 2020-2100 could reach (all median values): ¹⁹

BECCS – 328 GtCO₂
Net CO₂ removal on managed land (including afforestation and reforestation) – 252 GtCO₂
Direct Air Capture Capture and Storage (DACCS) – 29 GtCO₂

To put this into perspective, the remaining carbon budget assessed by WG1 from the beginning of 2020 onwards is 500 GtCO₂ for limiting warming to 1.5°C with a 50% chance of success. ²⁰ The IPCC also predicts that mitigation measures in 2°C or below pathways can significantly transform land all around the world. These pathways are “projected to reach net-zero CO₂ emissions in the land sector between the 2020s and 2070, with an increase in forest cover of about 322 million hectares (-67 to 890 million ha) [an area almost as big as the US and India combined] in 2050 in pathways limiting warming to 1.5°C with no or limited overshoot”. ²¹

Delaying action will result in larger and more rapid deployment of CDR later, especially if there is a temperature overshoot. Then, large-scale deployment of CDR will be needed to bring temperatures back. ²² Since IAM pathways rely on afforestation, reforestation and BECCS, delayed mitigation can lead to a lot of changes in land use, with negative impacts for sustainable development. ²³ The IPCC points out that “strong near-term mitigation to limit overshoot, and deployment of other CDR methods than afforestation / reforestation and BECCS may significantly reduce the contribution of these CDR methods in scenarios limiting warming to 1.5 or 2C”. ²⁴ “Stronger focus on demand-side mitigation implies less dependence on CDR and, consequently reduces pressure on land and biodiversity”. ²⁵ It adds that: “Within ambitious mitigation strategies…, CDR cannot serve as a substitute for deep emissions reductions”. ²⁶ To put this into perspective, the market for carbon offsets today, which include these CDR measures, reduce global emissions by about 0.1%, according to the Energy Transitions Commission.

But while most scenarios in WG3 still rely on CDR to achieve net-zero, the IPCC is not advocating for large amounts of it. Instead, the reliance on CDR reflects the state of climate modelling and research (see box 2 in appendix). The IPCC discusses the uncertainty, risks and lack of social licence for CDR, such as concerns that large-scale CDR could obstruct near-term emission reduction efforts or lead to an over-reliance on technologies that are still in their infancy. ²⁷ It stresses that there is uncertainty about how much CDR will be deployed in the future and the amount of CO₂ it can remove permanently from the atmosphere. ²⁸9 This is because some measures in the land sector cannot be maintained indefinitely as these sinks will ultimately saturate, while trees can also be cut down, burnt or die prematurely. ²⁹

Box 2. A word about climate models and the potential and limitations of land sector mitigation

Since the last IPCC reports, there have been more assessments of the total mitigation potential of the land sector. ³⁰ These can be split into:

Sectoral models: These estimate the potential of the sectors and/or individual measures. But they rarely capture cross-sector interactions, making it difficult for them to account for land competition and trade-offs. This could lead to double counting when aggregating sectoral estimates across different studies and methods. ³¹ They usually show higher mitigation potential as they include more land-based mitigation options than IAMs. ³²
IAMs and integrative land-use models (ILMs): IAMs assess multiple and interlinked practices across sectors, and thus account for interactions and trade-offs (i.e. land competition). IMLs combine different land-based mitigation options, which are only partially included in IAMs. Both have extended their coverage, but the modelling and analysis of land-based mitigation options is new compared to sectoral models. Consequently, “[Land sector] options are only partially included in these models, which mostly rely on afforestation, reforestation and BECCS”. ³³
Currently, most models do not consider, or have limited consideration of, the impact of future climate change on land. ³⁴.And there is still uncertainty about land’s ability to act as a sink in the future and how this will impact mitigation efforts. ³⁵ Bottom-up and non-IAM studies show significant potential for demand-side mitigation. ³⁶ (see Table 2 in the Appendix)

When evaluating the potential of different land-based mitigation measures, AR6 uses mainly sectoral models and compares to IAM’s, when available. But, AR6 still relies on IAMs/ILMs to devise mitigation pathways. This can be problematic in two main ways:

Climate change impacts on land and future mitigation potential: Given the IPCC WG1 finding that land sink efficiency is decreasing with climate change, relying too much on land to remove CO₂ from the atmosphere could be problematic. This could create a false sense of security and allow for land mitigation to be used as an excuse for not making deep emissions cuts. This is key as many corporations are relying on offsetting emissions in the land sector instead of reducing them.

Unrealistic CDR projections (over-reliance on BECCS and afforestation and reforestation): The volumes of future global CDR deployment assumed in IAM scenarios are large compared to current volumes of deployment. This is a challenge for scaling up. Similarly, the lack of representation of other options makes it difficult to compare different measures and envisage a different future that alters the contribution of land in terms of timing, potential and sustainability.

Appendix – Mitigation potential of different CDR measures

1
Chapter 7, p.4. This is different from emissions of the entire food system, which are estimated to account for 23-42% of global GHG emissions in 2018 – Ch.12, p.4. For sinks there is also a error of aprox +/- 5.2
2
Chapter 7, p.4. This is different from emissions of the entire food system, which are estimated to account for 23-42% of global GHG emissions in 2018 – Ch.12, p.4. For sinks there is also a error of aprox +/- 5.2. Chapter 3, p.42 : But there are still large uncertainties on net CO₂human emissions and its long-term trends. Currently, national GHG inventories (NGHGI) tend to overestimate the amount of CO₂ absorbed by sinks when compared to other global models. There is a gap of ~5.5 GtCO₂ a year between NGHGI and Bookkeeping models and dynamic global vegetation models. The difference largely results from different definitions of what “anthropogenic” means, which leads NGHGIs to estimate that more CO₂ is taken up by sinks.
3
Chapter 7, p.41. The bottom end represents the mean from IAMs and the upper end the mean estimate from global sectoral studies. The economic potential is about half of the technical potential from AFOLU, and about 30-50% could be achieved under USD20 tCO2-eq-1. Note that the IPCC uses a different methodology for individual AFOLU options than for the total sector potential.
4
Chapter 7, p.42. “Economic mitigation potential is the mitigation estimated to be possible at an annual cost of up to USD100 tCO2 -1 mitigated. This cost is the price at which society is willing to pay for mitigation and is used as a proxy to estimate the proportion of technical mitigation potential that could realistically be implemented.”
5
Chapter 7. 42
6
SPM, p.43
7
SPM, p.43
8
SPM, p. 53
9
SPM, p. 55
10
Chapter 7 of WGIII provides an overview of 20 mitigation measures, evaluating the co-benefits and risks from land-based mitigation measures, estimated global and regional mitigation potential and associated costs according to literature published over the last decade.
11
Chapter 7.4
12
Chapter 7, p.6. This is based on land-based carbon offsets (i.e. money from the Clean Development Mechanism, voluntary carbon standards, compliance markets and reduced deforestation).
13
SPM, p. 48
14
The IPCC evaluates previous offsets measures, such as REDD+, offsets within emissions trading systems, among others in chapter 7;Chapter 3, p. 14-15
15
SPM, p. 47
16
Chapter 12, p. 35
17
Chapter 12, p. 35
18
Chapter 12, p.4 and p. 55
19
Chapter 12, p. 5
20
Summary for policymakers, p. 6
21
Chapter 3, p. 6
22
Smith et al. 2019; Hasegawa et al. 2021
23
IPCC 2019, Hasegawa et al. 2021
24
Chapter 12, p. 56
25
Chapter 3, p. 7
26
Chapter 12, p. 38
27
Chapter 12, p. 39
28
Chapter 12, p. 3
29
Chapter 3, p.7
30
Chapter 7, p.40
31
Chapter 7, p.40-42
32
Chapter 3, p. 64
33
Annex III- p.29; Chapter 7, p.86
34
Chapter 7. 42
35
Chapter 7. 116
36
Chapter 3, p. 7

Eating better and less meat and dairy is key to tackling climate change

December 5, 2021 by ZCA Team Leave a Comment

The way we produce and consume livestock is fueling the nature and climate crisis. By 2050, if all other economic sectors followed a 1.5C pathway while the meat and dairy industry’s growth continued as usual, the livestock sector could eat up 80% of the remaining GHG budget in 32 years. Experts agree we need to shift diets. “To meet global climate targets, per capita consumption of meat would need to fall drastically,” says Chatham House, but it doesn’t mean meat has to be off the menu for everybody.

Veganuary is a key moment when companies and consumers think more about the personal and wider impacts of the food system. This briefing outlines the reasons we need to rapidly change how we produce animal products, and how eating less and better meat and dairy is one of the best ways for consumers to reduce the impact of their diets on the environment.

Current state of play in livestock and plant-based protein markets

Global meat consumption and production is rising across the world. This trend is expected to continue. But, as people become more concerned about the health and environmental impact of their diets, the market for Alternative Protein (AP) products is also growing. In this briefing, AP products are meat and dairy alternatives created to substitute animal products (i.e do not include fruit and vegetables) (see appendix for more stats).

Production trends: Production of meat is nearly six times higher than in 1961. This growth means that total meat production has been rising at a much faster rate than the rate of population growth. The world now produces more than triple the amount of milk than it did fifty years ago. Meat production will keep rising, reaching 374 million tonnes by 2030.
Types of meat and dairy: The world is shifting to poultry production, with its share nearly tripling to ~35% from 1961 to 2014. Poultry meat will continue to be the primary driver of growth, but at a slower rate. Beef and dairy production will also grow at a slower rate.
Geographies: The world’s top five meat producers are China, the US, the EU, Brazil and Russia. The top dairy producers are India, New Zealand, the EU, and the US. In North America, beef production is projected to grow 6% by 2030. In the EU, it is projected to fall by 5%.
Consumption: Per capita meat consumption has increased by ~20 kilograms since 1961 and it is projected to increase by 14% by 2030. Consumption has been shifting towards poultry, which is forecast to represent 41% of all the protein consumed from meat sources in 2030. Meat consumption is highest across high-income countries (see country breakdown), but per capita consumption of animal protein is expected to level off due to growing health and environmental concerns. In middle-income countries, consumption is expected to remain strong and keep rising, narrowing the consumption gap with rich countries. Despite being top producers, the EU and US milk consumption is expected to decline and increase in India and Pakistan.
AP products: The global AP market has been growing for many years, and is now worth USD 14 bn, which represents 1% of the global meat market. The EU has been at the forefront, with AP sales jumping 49% between 2018-20. In the US, it is a USD 7 bn market, and AP sales grew ~2.5x faster than total food sales between 2018 and 2020. It is estimated that 42% of global consumers are eating fewer animal products to improve their health and reduce their impact on the environment, with younger consumers driving this shift. The growth in the global AP market is expected to accelerate, with estimates from Bloomberg suggesting the market will exceed USD 162 bn within the next decade, a fivefold increase over 2020. According to global consultancy AT Kearney, 60% of meat eaten globally in 2040 will be from AP or lab-grown alternatives.

Financing and government subsidies

Governments have been subsidising meat and dairy production. For example, nearly 90% of total global farming subsidies (USD 540 bn per year) goes to the production of beef, milk and rice. In the EU, reform of farming subsidies – which account for a third of the EU’s total seven-year budget – is failing to incentivise change towards a more resilient food system. According to OECD, in high-income countries, beef receives the largest subsidies among meats, whereas in middle-income countries, these funds go to poultry, sheep and pork production. However, while many small producers would not be able to survive without this help, a lot of this money is going to support big agribusinesses. The world’s largest banks, investment firms and pension funds have also been big backers of industrialised animal agriculture. Between 2015-20, global meat and dairy companies received over USD 478 bn from over 2,500 investors in the forms of loans, insurance and securities. Two of the world’s leading development banks have pumped billions of dollars into the global livestock sector (USD 2.6 bn) in the past 10 years.
The AP market has received financing mainly from companies and investors. Many venture capital funds are investing in AP companies and research efforts. The global alternative protein companies received USD 3.1 bn in disclosed investments in 2020, which is more than three times as much as the USD 1 bn raised in 2019. Alternative protein companies have raised almost USD 6 bn in capital in the past decade (2010–2020), more than half of which was raised in 2020 alone. Traditional meat producers, newcomers and major food conglomerates (e.g Nestlé and Unilever) are increasingly adding AP alternatives to their product ranges and investing in new companies.

Major impacts from meat, dairy and AP products

Livestock production and consumption can harm the environment and people’s health. While not all types of production systems lead to negative impacts on the environment – pastoralism in the Sub-Saharan region in Africa helps to conserve biodiversity and sequester carbon, for example – large-scale industrial production contributes to the climate and nature crisis. Over-consuming meat products, especially red and processed meat, is increasing diseases and ill-health in humans. See below for some key stats.

Impacts from overproduction and consumption of meat, dairy and ultra processed AP products¹

What does science say the solutions are?

In order to reduce the emissions from our livestock, consumers and producers need to change.

Producers need to adopt land management practices to mitigate the highest impacts of production, as the world is not going to abandon livestock farming completely.² According to the IPCC, improving livestock and grazing land management as well as including mixing crop-livestock production can help to reduce climate and environmental impacts. Farming systems that shift away from industrial agriculture, such as agroforestry and organic farming, not only help to reduce emissions of all GHG, but also improve farmers’ livelihoods, food security and biodiversity. There are many questions about technological fixes, such as feed additives and anaerobic digesters to reduce methane emissions. These concern their scalability, cost and potential to reduce emissions. Even if they reduce beef’s methane emissions, these emissions would still be higher than those from pork and chicken and AP meats.

Consumers also have a key role to play.Experts agree that a shift to plant-based diets can play a key role in reducing emissions from food systems, which represent up to 37% of global greenhouse emissions . Going vegan can reduce emissions the most (e.g up to 8 GtCO2 eq/yr according to the IPCC).³ But people don’t need to completely exclude meat from their diets to reduce their dietary footprint. Eating less meat or switching to lower impact meats raised in sustainable systems, such as chicken, could also have a major impact. According to the IPCC, these diets (i.e flexitarian, vegetarian) can reduce emissions between 4.3-6.4 GtCO2 eq/yr by 2050.⁴ These diets also tend to be easier for people to adopt, healthier, have smaller land footprints and “present major opportunities for climate adaptation.” People also need to be careful about what they choose to substitute meat with to achieve large global benefits. They should opt for sourcing from farmers that practice regenerative agriculture or other agroecological methods that can support the fight against climate change and biodiversity loss. Reducing consumption in wealthy regions is also necessary to allow people across Asia and Africa to reach their nutritional goals while keeping consumption within planetary boundaries.

What governments and companies can and are doing?

Governments can support diet shifts through their own food procurement practices and policies that shape consumption (e.g. dietary guidelines and trade, food and agricultural policies). They can recommend lowering red meat consumption, promote research on alternative proteins or introduce fiscal policies to shift consumption patterns. Several European countries are investing in research on alternative proteins and changing dietary guidelines focusing on reducing consumption of meat. Policy reforms will have a greater impact if governments provide support and incentives for farmers to move away from industrial agriculture, such as redirecting public spending support and encouraging farming that produces meat in ways that benefit the environment, human health and animal welfare. At the same time, policy reforms provide a fair return for farmers and support consumers on lower incomes to access healthy and sustainable diets. However, in reality, most governments are failing to take action. For example, most of the current climate targets (NDCs) pay insufficient attention to agriculture, land-use emissions and food systems. Politicians are also afraid of conflict with farming groups and want to avoid a public backlash against policies that interfere in people’s daily lives, such as meat taxes. They also are failing to include sustainability in their dietary guidelines.

Businesses, restaurants and supermarkets can optimise the pricing and improve marketing of AP foods and dishes, while stopping promoting and discounting meat products. They can also continue to invest in development of AP products and increase efforts to reduce emissions from their supply chain. Several food companies, meatpackets and major retailers, for example, have set net zero targets, which include support for regenerative agriculture, carbon labelling or targets to increase sales of meat alternatives. But most of these net zero target are meaningless. For example, most of the top 35 global meat and dairy giants and top retailers either do not report or underreport their emissions. Also, none of the net zero commitments made by major meat and dairy companies call for reducing the number of animals in their supply chains.

1
Ultra-processed products usually have many added ingredients such as sugar, salt, fat, artificial colours, preservatives, flavours or stabilisers. Examples of these foods are frozen meals, soft drinks, hot dogs and cold cuts, fast food, packaged cookies, cakes, and salty snacks.
2
There are a number of reasons we wouldn’t want it to – it is not only an important source of income for many, but can also be a key source of nutrition in local settings. Particularly in lower-income countries where diets lack diversity, small amounts of meat and dairy can be an essential source of protein and micronutrients.
3
For comparison purposes; in 2010 the whole transport sector produced 7.0 GtCO2-eq of direct GHG emissions.
4
A flexitarian is a person who eats primarily a vegetarian diet but occasionally eats meat or fish.

The IPCC report on land use and climate change

August 10, 2019 by ZCA Team Leave a Comment

Key points

The wellbeing of the Earth’s land is key to the future of the planet. This brief draws from the latest scientific research to describe key land challenges and their relation to climate change.
Human activity affects 75% of the Earth’s land surface, causing widespread land degradation. Agriculture and timber/logging are key drivers of degradation, desertification and carbon emissions. A combination of climate change and human activity will increase pressure in the future.
Land use change already causes a quarter of man-made emissions, and climate change will have wide reaching impacts on land. At the moment, the land is a net carbon ‘sink’, but it’s possible climate change could damage land to the point where it becomes a net source of carbon emissions.
Sustainably managing land will be a key way to cut emissions and reduce the impacts of climate change. There are many options for ‘land based mitigation’ that cut emissions from land. We will need to pursue options that bring strong co-benefits, and strong synergies with each other.
Managing land well will be a key solution to climate change. Drawing on local and indigenous knowledge and gender-proofing mitigation and adaptation in this space will be vital for making good choices about how to proceed in this space.

Introduction

The land surface of the Earth provides critical resources to human society, helps regulate the climate and has the potential to play an important role in limiting climate change. Many governments have already made pledges about how they will use land to address climate change, and land-related initiatives make up 20% of current planned total emission reductions by 2030 under the Paris Climate Agreement.

But human demands¹ are driving unprecedented depletion of natural land resources. Degradation of land contributes to climate change, and could undermine the potential land has to help solve the climate crisis.

The SRCCL² is the latest special report produced by the Intergovernmental Panel on Climate Change (IPCC), the UN body responsible for assessing the latest climate change science. Released in August 2019³, it explores what climate change will mean for the future of land and human society, and explains how we can address climate change by using the Earth’s land more carefully.

The relationship between land and climate change is complicated. It’s hard to predict the future of land, and the people that rely on it. Generalisations are hard because the land system and the science that studies it is complex. Nevertheless, the SRCCL is the most comprehensive analysis of land and climate the IPCC has produced to date. It relies on the most recent scientific papers. The analysis of land and climate it contains will be a key input to the next IPCC Assessment Report (AR6), due to be published between 2021-22.

Land and climate change

Sinks and sources of emissions

Land, land use and land management are an important part of the climate system. The Earth’s soils, forests and other plants – its land system – emit greenhouse gases (GHGs), but also absorb them. Carbon cycles between the atmosphere and the land, and is stored in soil and biomass. When land is damaged or degraded – when soil becomes thinner, forests are cut down or replaced with plantations – the degraded land system releases the carbon it has stored, driving climate change through increased GHG emissions.

Land produces a lot of greenhouse gas emissions, accounting for about 23% (12 +/- 3 Gt carbon dioxide equivalent a year) of total net human emissions between 2007 and 2016. For carbon dioxide specifically, land produced the equivalent of 13% of total human carbon dioxide emissions over that period, mostly due to human activity, particularly deforestation.⁴

Land use change also emits methane (44% from human activities), and nitrous oxide (82% from human activities), both of which are powerful greenhouse gases.⁵ Agriculture is a major source for both. Agriculture emissions nearly doubled between 1961 and 2016, and make up just over half⁶ total greenhouse gas emissions in the land sector. Livestock (66%) and rice production (24%) are the major sources of methane, while about two-thirds of nitrous oxide emissions are associated with fertiliser use and manure management.⁷ Livestock emissions are split between Asia (37%), North America (26%), Latin America and the Caribbean (16%), Africa (14%) and Europe (8%).⁸

Land also absorbs greenhouse gases, acting as a ‘carbon sink’. So although the land sector produces emissions, overall it is a net sink of emissions, taking more carbon out of the atmosphere than it puts in. Between 2007 and 2016 these sinks removed 29%of total human carbon dioxide emissions from the atmosphere.⁹ There is no guarantee the land will continue to be a net carbon sink as climate change alters how natural systems work. More carbon dioxide in the atmosphere may boost plant growth leading to more uptake of carbon from the atmosphere¹⁰ but climate change will also degrade land’s capacity to store carbon, providing an opposing effect. Whether land will act as a net sink or a source in the future remains uncertain.

Climate change’s effect on land

Broadly, land use change often causes climate change, and climate change causes land change. Climate change affects land by changing weather patterns, including extreme events, which can lead to damage like vegetation loss, fire damage, or permafrost and coastal degradation.¹¹ For example:

Changes in rainfall patterns and more intense rainfall increase the risk of land degradation through landslides, extreme erosion events or flash floods.
In North America, thunderstorms could cause major landslides and flash flooding with severe economic losses (over US$20 billion annually).
Extreme events, such as heat and drought, increase the frequency and intensity of wildfires in forests.¹² In the Brazilian Amazon, during the drought of 2015, fire increased by 36% even with declining deforestation rates.

Attributing land degradation to climate change by making direct links between the two¹³can be hard, as impacts depend on local contexts and how land is managed. The effects are also often complex. For example, deforestation in the tropics will likely cause the climate to warm, but in temperate and boreal regions it will likely have a cooling effect. Climate change might even improve the state of the land in some parts of the world. Processes known as feedbacks – which amplify or dampen climate change and land degradation – further complicate the picture.

Despite the uncertainties, it is clear that climate change creates new and unprecedented risks for the land system and will likely lead to worse outcomes overall. Action is needed to protect land from climate change.

Land degradation

As well as being threatened by climate change, land is also under severe pressure from land use change. The resulting land degradation takes many forms,¹⁴ but overall reduces the land’s biological productivity, its ecological integrity and its role in providing services to humans and the planet.¹⁵ Estimates of how much of the Earth’s land is degraded vary – it could be between 7 and 40% of the land surface. When land becomes degraded, it is more likely to produce greenhouse gas emissions, and less likely to act as a carbon sink.

Degradation has many causes, from direct ones like changes to soil characteristics, deforestation or changes in plants’ composition, to changes in climate or environmental conditions, like changes in rainfall patterns, to changes in land use and management, like changing farming systems or urbanisation and infrastructure expansion.¹⁶ Overall, humans are the main cause of degradation, affecting 75% of the Earth’s land surface, with grazing, forest harvesting and forest plantations the main damaging activities.

Agriculture is a major cause of degradation. Agricultural land covers a large amount¹⁷ of the Earth’s land surface, and the amount of cropland is increasing, with most of the expansion driven by demand for livestock products. Irrigated areas have also expanded by about 50% over the last fifty years, contributing to freshwater withdrawals¹⁸ and local climate variability in many regions, and cropland expansion is also driving soil erosion, particularly in Sub-Saharan Africa, South America and Southeast Asia. An increase in mechanized agricultural systems is a major driver of deforestation in the Amazon,¹⁹ and also creates severe pressure on soils. Agriculture is also becoming more intense. The use of nitrogen fertilisers increased nine times over the same period,²⁰ driving further land degradation.

Deforestation is another important cause of degradation. Global forest area has declined by 3% since 1990 and continues to decline, although there are large uncertainties in this measurement.²¹ Between 60 and 85% of the total global forested area is used by humans at different levels of intensity. Only the tropics and northern boreal zones have large remaining areas of unused forest. Between 73 and 89% of other, non-forested natural ecosystems (natural grasslands, savannas, etc.) are used by humans.²²Around the world, pastures are replacing natural grasslands, and croplands are replacing forests.²³

Humans are having a huge effect on the planet, but it is hard to say how the overall balance of forest, savanna and grassland area is changing. For example, some research suggests forest area has actually increased globally. Taken together, human activity has had a huge and transformative effect on the Earth’s land surface and driven degradation of the land. Choices we make about future land management will be increasingly important as we address climate change; sustainable land management will be essential.²⁴

Desertification: degradation of drylands

When land degradation takes place in ‘drylands’²⁵ it is termed desertification,²⁶ a reduction in the land’s health, its productivity and its usefulness²⁷ Drylands cover nearly half the world’s land surface, are some of the most sensitive areas to climate change and human activity, and host a large and growing portion of the world’s population – nearly forty per cent – so desertification is a critical challenge.

Desertification reduces soil fertility and its capacity to sequester carbon, as warmer and drier soils release more soil carbon to the atmosphere. It can also decrease crop and livestock productivity, and contribute to food insecurity, poverty, migration and even conflict.²⁸ Countries in Africa and Asia, the Mediterranean region and Latin America and the Caribbean are particularly at risk. There are many causes. Across Africa desertification is mainly caused by drought, but in northern China it is mainly a result of human activity. Expanding croplands and unsustainable land management practices are the most important cause.

Climate change can drive desertification, but it depends on local context and interactions with other human activities.²⁹ For example, natural climate cycles were responsible for two-thirds of the expansion of the Sahara Desert between 1920 and 2003, while in China both human and climate factors have played a role in desertification. It isn’t always possible to demonstrate a clear climate link – different studies reach opposite conclusions on whether climate change has actually played a role in desertification in the Sahel region, for example. As a result, attribution of climate change to desertification is still challenging, in part because desertification is caused by multiple natural and human factors that vary between places and over time.³⁰

Land, climate and the food system

The way we produce and consume food contributes to many environmental and socio-economic problems, including climate change and land degradation. Since 1961, food supply per person has increased more than 30%. Over the same time period, use of nitrogen fertilisers has grown about eight times, and the water resources used for irrigation have more than doubled.³¹

This increase in food supply has not stopped many people globally suffering from hunger and diet-related diseases. An estimated 821 million people are undernourished worldwide – particularly in low-income countries, including parts of sub-Saharan Africa, South-Eastern Asia, Western Asia, and Latin America. At the same time, in many parts of the world an increase in the availability of food and diets higher in animal-based products have increased adult obesity rates. Globally 1.9 billion adults are overweight.

Food system³² emissions account for an estimated 25 to 30% of total human emissions,³³ with agriculture producing the largest portion of 10 to 12% from crop and livestock activities. Other emissions are produced along the food supply chain: 8 to 10% from land use and land use change including deforestation and peatland degradation, and 5 to 10% from supply chain activities.³⁴ High levels of food waste along the supply-chain and at consumer level also contribute.

Climate change already has huge impacts on the food system; future effects are likely to be very significant, but will vary widely across regions. For example, warming in India over the period 1981–2009 reduced crop yields by 5.2%, but in Australia reduction of crop yields have so far been countered by improvements in management and technology. Industrial livestock production will suffer, mostly from indirect climate change impacts, leading to rises in production costs and destruction of infrastructure. Farming systems will also suffer risks from variable grain availability and cost, and animals struggling to adapt to new climates.³⁵

Climate change will also have a negative effect on a host of issues which set the context for our food system, including poverty and vulnerability, cultural practices and gender issues. It can reduce incomes and impact farmers’ ability to endure price rises. It can affect food safety and human health in a range of ways, like lowering the nutrient content of food, or affecting contaminating organisms. It can threaten food security by increasing instability of supply due to increased frequency and severity of extreme events. It may cause widespread crop failure contributing to spikes in food prices, migration and conflict.

How will climate change affect land in the future?

Scientists use climate models and different scenarios for temperature rise and socio-economic development to try and map out the future of land and climate.³⁶ But even so, predicting the future of land and climate change is complicated. Temperatures, land processes and human society will evolve differently across regions and biomes, with different implications for land use/cover. Mitigation policies can also impact land use as well as land-based mitigation impacts other land-related challenges. All this makes it harder to create universal predictions for the future. Instead, scientists describe many possible futures, or scenarios.

What is true in most future scenarios?

Most scenarios agree that land will play a key role in the future of our climate. The choices we make about how to manage land could act as a control knob for as much as 0.5°C of temperature rise in low-emissions scenarios. With the world looking to limit temperature rise to 1.5°C, this is hugely significant.

Land degradation alone is projected to reduce global food production.³⁷ Warming is likely to reduce crop yields, productivity and livestock production, with impacts varying across regions. Each 0.5 degree Celsius of temperature rise³⁸ will likely increase the risk of lower crop yields, but the effect will depend on how temperatures fall across the year and align with growing seasons. One degree of warming (relative to a 1981–2010 baseline)³⁹ will likely reduce average wheat, rice and soybean yield globally,⁴⁰ but some regions will see an increase; past three degrees of warming⁴¹ all crop yields will be impacted, unless adaptation measures are deployed. Lower yields could lead to instability in global grain trade and international grain prices, affecting those who are most vulnerable to food price spikes. Rising carbon dioxide levels in the atmosphere will also affect food production – more carbon dioxide could increase yield productivity, for example, but reduce the nutrient content of crops.⁴²

Drylands are expected to expand as a result of climate change. A temperature rise of 4°C – our current policy trajectory – would increase the area of drylands globally by 23% to cover 56% of the total land surface, with most of this expansion in developing countries. Most scenarios show climate change will likely increase the vulnerability of drylands to desertification. Climate change is also expected to decrease carbon sequestration from land, particularly in forests.

Risks from desertification are projected to increase. Depending on assumptions made about the future, the number of people in drylands impacted by threats to water, energy or land could reach over a billion, in worst-case scenarios with more than two degrees of temperature rise. In better managed futures with lower temperature rise the number could be much lower.⁴³

What affects which future we get?

What actually happens in the future will depend on how much temperatures rise, how much carbon dioxide is in the atmosphere, on the choices we make about how aggressively to mitigate climate change, where climate impacts occur, how we use land, and different scenarios of socio-economic development.⁴⁴ The exact effects of temperature rise on land degradation, desertification and food security will also vary depending on context and location.

Without any efforts to limit climate change, global mean temperatures are expected to rise between 2 °C and 7.8 °C by 2100,⁴⁵ with warming over land 1.2 to 1.4 times higher than global mean temperature rise. Even the lower end of this spectrum will be hugely damaging and disruptive; the upper end is likely to be disastrous for humans, the biosphere and land.

Future outcomes are highly dependent on what future socio-economic, development and political pathways human society chooses. For any level of temperature rise, vulnerability and exposure of people and land to climate damage will be higher in futures where there is higher population growth and lower incomes⁴⁶ or higher consumption.⁴⁷ Such futures will likely be more affected by land degradation, desertification, and food insecurity,⁴⁸ compared to more equitable scenarios. By contrast, futures with lower demand for agricultural commodities, and/or higher levels of agricultural productivity and globalized trade⁴⁹ will likely lead to better outcomes – the lowest emissions from land, lower food prices over time, and lower levels of forest loss.⁵⁰

Impacts on food will vary, with studies showing that by the end of the century, worlds characterised by nationalism and rising inequality⁵¹ could see some 400 or 600 million people respectively suffering from malnourishment. More optimistically, food insecurity could decline substantially in futures with higher incomes.⁵² Most future socio-economic worlds see higher water stress.

How can land help solve the climate crisis?

The land sector can be part of the solution to climate change. Indeed, all future pathways that limit temperature rise to 1.5 or well-below two degrees Celcius will require land-based mitigation and land-use change.⁵³

If done sensitively, there are mitigation options in the land space that can limit climate change and provide co-benefits for land. But land-based mitigation could also create adverse side effects for land and people by changing the land use system. To be effective, land-based mitigation will need to be regionally and context- dependent,⁵⁴ as countries suffer impacts differently and have different socio-economic characteristics.

Using land to help address climate change will be complex, and also increasingly likely to run into tradeoffs. For example, to limit temperature rise to 1.5 or two degrees⁵⁵ negative emissions technologies⁵⁶may need to be deployed over very large areas of land, which could contribute to desertification and land degradation.⁵⁷ Some 1.5ºC scenarios are achieved with limited or no NETs deployment, but are associated with large scale behavioural changes (including eating less meat and reducing food waste), agricultural intensification, and mitigation in other sectors. The longer we delay action, the more we will be into the realm of exceptionally hard choices, and delay will increase the need for adaptation, and potentially make land-based solutions less viable.⁵⁸

Reducing emissions from the land use space and preparing for the effects of climate change will require a sophisticated policy approach that recognises and incorporates local and indigenous knowledge. Indigenous peoples and local communities have extensive knowledge of the land and the characteristics of their specific region and this expertise can guide policy in these complex spaces. For example, indigenous knowledge can better predict future climate change and contribute insight where data is lacking, or facilitate climate adaptation. Mainstreaming gender in policy is also essential. Addressing gender issues ensures adaptation measures can benefit those who most need them, and can also unlock mitigation options by – for example – empowering women to participate in decision-making in agriculture.

1
Land use can be understood as the set of activities carried out by humans on land, for example, changing land cover via deforestation, afforestation, or agricultural production. https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter06_FINAL.pdf
2
The full title of the report is the “Special Report on Climate Change, Desertification, Land Degradation, Sustainable Land Management, Food Security, and Greenhouse gas fluxes in Terrestrial Ecosystems”.
3
The approval plenary runs from the 2nd – 6th August – see https://www.ipcc.ch/site/assets/uploads/2019/06/Info_Note_Participants_final.pdf
4
Global models estimate net CO2 emissions of 5.2 ± 2.6 GtCO2 yr-1 (likely range) from land use and land-use change during 2007-16. These net emissions are mostly due to deforestation, partly offset by afforestation/reforestation, and emissions and removals by other land use activities (very high confidence) from Table SPM.1; SPM, A.3.1.
5
Table SPM 1.
6
Estimate is in comparison of the 24% emissions from AFOLU sector. Calculated by IPCC through a combination of models.
7
https://www.nature.com/articles/nclimate3158
8
SRCCL, Chapter 2, 2.4.2.2, p. 39, line 47-53.
9
Represents a net sink of around 11.2 GtCO2 yr-1, see Table SPM 1.
10
This is a process known as CO₂ fertilisation, which stimulates plant growth and could lead to increases in vegetation, but this “greening” trend is contested in the literature/empirical evidence. https://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.1995.tb00630.x; https://www.pnas.org/content/113/36/10019
11
https://www.nature.com/articles/17789; https://www.nature.com/articles/nature01286; https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007GL032838; https://www.sciencedirect.com/science/article/pii/S0022169413004800/; https://journals.ametsoc.org/doi/10.1175/JCLI-D-14-00324.1; https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL069896; https://www.ncbi.nlm.nih.gov/pubmed/28360268
12
https://www.pnas.org/content/113/42/11770;https://www.nature.com/articles/srep26886; http://dx.doi.org/10.1038/s41558-017-0014-8
13
When degradation of land has been associated with climate change
14
Land degradation has many definitions across the scientific literature. In this report, the IPCC uses a broad definition derived from the IPCC AR 5 definition of desertification: “A negative trend in land condition, caused by direct or indirect human-induced processes including anthropogenic climate change, expressed as long-term reduction or loss of at least one of the following: biological productivity, ecological integrity or value to humans. [Note: This definition applies to forest and non-forest land. Changes in land condition resulting solely from natural processes (such as volcanic eruptions) are not considered to be land degradation. Reduction of biological productivity or ecological integrity or value to humans can constitute degradation, but any one of these changes need not necessarily be considered degradation.]” SRCCL, Glossary, p.33.
15
https://arizona.pure.elsevier.com/en/publications/land-in-balance-the-scientific-conceptual-framework-for-land-degr; https://www.ipcc.ch/site/assets/uploads/2018/02/WGIIAR5-AnnexII_FINAL.pdf; https://www.unccd.int/sites/default/files/relevant-links/2017-01/UNCCD_Convention_ENG_0.pdf
16
SRCCL, Chapter 1, 1.2.2.3, p. 11, lines 11-14.
17
“Globally, cropland area changed by +15% and the area of permanent pastures by +8% since the early 1960s (FAOSTAT 2018), with strong regional differences” – SRCCL, Chapter 1, 1.2.2.3, p. 10, lines 17-18.
18
“Water withdrawals are defined as freshwater taken from ground or surface water sources, either permanently or temporarily, and conveyed to a place of use”. https://data.oecd.org/water/water-withdrawals.htm
19
https://www.ncbi.nlm.nih.gov/pubmed/16973742; https://www.sciencedirect.com/science/article/abs/pii/S0959378001000073; https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13068
20
SRCCL, Chapter 1, 1.2.2.3, p. 11, line 7.
21
SRCCL, Chapter 1, 1.2.2.3, p. 11, lines 25-26.
22
SRCCL, Chapter 1, 1.2.2.2, p. 9, lines 9-16.
23
SRCCL, Chapter 1, 1.2.2.3, p. 11, lines 15-16.
24
https://www.unccd.int/sites/default/files/documents/2019-06/LDN_CF_report_web-english.pdf; https://pubs.acs.org/doi/abs/10.1021/es302545b; https://pdfs.semanticscholar.org/1dcd/dcb78cb7010fedb248f8c1f402ed5a0a731c.pdf
25
Drylands areas constitute of arid, semi-arid, and dry sub-humid areas
26
https://www.jstor.org/stable/25595197?seq=1#page_scan_tab_contents; https://www.millenniumassessment.org/documents/document.291.aspx.pdf; https://www.tandfonline.com/doi/abs/10.2989/AJRF.2009.26.3.2.947
27
.This definition was developed by the IPCC to explain the specific type of land degradation – desertification – that happens in a particular part of the world – the drylands. As such, it is defined in the report as “Land degradation in arid, semi-arid, and dry sub-humid areas resulting from many factors, including climatic variations and human activities (UNCCD, 1994)”. SRCCL, Glossary, p.16 https://treaties.un.org/Pages/ShowMTDSGDetails.aspx?src=UNTSONLINE&tabid=2&mtdsg_no=XXVII-10&chapter=27&lang=en
28
https://www.sciencedirect.com/science/article/pii/S1877343513000109?via%3Dihub; https://www.nature.com/articles/nclimate2837, https://www.nature.com/articles/nclimate3275; https://www.researchgate.net/publication/287507867_Effect_of_climate_change_on_the_vulnerability_of_a_socio-ecological_system_in_an_arid_area a; https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.12581; https://www.ecologyandsociety.org/vol23/iss1/art34/; https://www.sciencedirect.com/science/article/pii/S014098831400098X; https://www.nature.com/articles/nclimate3253
29
https://wad.jrc.ec.europa.eu/sites/default/files/atlas_pdf/1_WAD_Introduction.pdf
30
https://www.sciencedirect.com/science/article/abs/pii/S0034425716302280; https://www.ncbi.nlm.nih.gov/pubmed/26525278; https://onlinelibrary.wiley.com/doi/abs/10.1002/eco.1849;http://adsabs.harvard.edu/abs/2016AGUFM.A33G0330M;https://journals.ametsoc.org/doi/full/10.1175/2010JCLI3794.1;https://www.sciencedirect.com/science/article/abs/pii/S0140196316301641?via%3Dihub; https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0187.1
31
SRCCL, Chapter 5, Executive summary, p. 5, line 4-6.
32
The High Level Panel of Experts on Food Security and Nutrition defines food system as a system that “gathers all the elements (environment, people, inputs, processes, infrastructures, institutions, etc.) and activities that relate to the production, processing, distribution, preparation and consumption of food, and the output of these activities, including socio-economic and environmental outcomes.”
33
Percentage contribution to total human greenhouse gas emissions, averaged over 2007-2016. SRCCL, Chapter 5, p.61.
34
SRCCL, Chapter 5, Executive summary, p. 6, line 16-20.
35
SRCCL, Chapter 5, Section 5.2.2.2, p. 29, line 8-10.
36
For more information see Cross-Chapter box 9 in Chapter 6 of the SRCCL report. It includes explanations of the socioeconomic scenarios used by scientists as well as the policies that can be implemented in each future world, focused on land-related challenges.
37
https://onlinelibrary.wiley.com/doi/full/10.1111/1467-8489.12072; https://onlinelibrary.wiley.com/doi/full/10.1002/fes3.99; https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0066428
38
The reference period for the modeling study is the “‘current decade’ from 2006–2015 forced by observations including observed CO2 concentrations that have increased from 380.9 parts per million (ppm) to 402.9 ppm over this decade. Mean warming over this period corresponds to about 0.9°C above the 1860–1880 period in the Berkeley Earth GMT dataset. The Future 1.5°C experiment is based on the RCP2.6 experiment and takes constant forcing for greenhouse gases and aerosols and sea-surface temperatures from the 2091–2100 decade. CO₂ concentrations in this experiment are constant at 423.4 ppm. The Future 2°C experiment uses scaled atmospheric and sea-surface temperature forcing from RCP2.6 and RCP4.5 with CO₂ concentrations set to 486.6 ppm”.
39
In comparison with 1981–2010 baseline. “The temperature impact was calculated as the yield change during the warming period relative to the yield during the baseline period normalized to +1 °C impact, assuming the impact showed a linear temperature response”.
40
A limitation of this study is the linear assumption between yield responses and temperature increase as yield response for each degree Celsius warming differs by growing season temperature level. Different CO₂concentration in the atmosphere can also affect yields.
41
“Some of the studies have associated temporal baselines, with center points typically between 1970 and 2005”, https://www.ipcc.ch/site/assets/uploads/2018/02/WGIIAR5-Chap7_FINAL.pdf, p.498.
42
https://ideas.repec.org/a/spr/climat/v124y2014i4p763-775.html; https://pubag.nal.usda.gov/catalog/237405; https://onlinelibrary.wiley.com/doi/10.1111/jac.12057; https://www.nature.com/articles/nature13179; https://advances.sciencemag.org/content/4/5/eaaq1012.abstract
43
See SRCCL, sections 2.3, 3.2.1, 3.3.2, 3.6.1, 3.6.2, 7.3.2.
44
These mitigation options can have positive or negative impacts on land and people.
45
Relative to the 1850-1900 reference period.
46
At similar temperatures, risks are higher in SSP3 than in SPP2 and SSP1. https://www.sciencedirect.com/science/article/pii/S0959378016300681
47
SSP3
48
https://www.sciencedirect.com/science/article/pii/S0959378016300681; https://www.pnas.org/content/111/9/3292/tab-article-info; https://www.sciencedirect.com/science/article/pii/S0959378016303399
49
SSP 1. https://www.sciencedirect.com/science/article/pii/S0959378016300681; https://www.sciencedirect.com/science/article/pii/S0959378016303399
50
SSP 1. https://www.sciencedirect.com/science/article/pii/S0959378016300681; https://www.sciencedirect.com/science/article/pii/S0959378016303399
51
SSP3 and SPP4, respectively.
52
SSP 1- Higher income (e.g., SSP1, SSP5), higher yields (e.g., SSP1, SSP5), and less meat intensive diets (e.g., SSP1) tend to result in reduced food insecurity SRCCL, CH.6, p.19.
53
Pathways assessed on the SRCCL.
54
SRCCL, Chapter 1, Section 1.4, p.29, line 4-10.
55
https://www.nature.com/articles/nclimate3096; https://www.sciencedirect.com/science/article/pii/S1876610217319410;https://www.nature.com/articles/nclimate2870
56
https://www.sciencedirect.com/science/article/pii/S0959378016303399; https://www.sciencedirect.com/science/article/pii/S0959378016300681; https://www.ipcc.ch/site/assets/uploads/sites/2/2019/02/SR15_Chapter2_Low_Res.pdf
57
https://www.sciencedirect.com/science/article/pii/S0959378016303399; https://iopscience.iop.org/article/10.1088/1748-9326/aabf9f
58
SRCCL, Chapter 6, Executive Summary , p.5.

Key points

What are biogas and biomethane?

Mitigation potential of biogas

Biogas’ potential to mitigate agricultural emissions

The REPower EU plan

Biogas as a substitute for fossil fuel-based natural gas

Risks and limitations for deployment of biogas

Fugitive emissions reduce the benefits of biogas

High cost and reliance on subsidies

Safety concerns

Alternatives for reducing agricultural emissions

Key points:

Natural supplements

Synthetic supplements

Typical lifecycle of beef cows in pastures and feedlots in the US

Methane production across the different operations of the beef production system

The feedlot issue

Reducing emissions in pasture-raised animals

Environmental considerations

Summary of the supplements

Key points

Bioenergy and BECCS: The basics

Benefits and risks of BECCS

Mitigation potential of BECCS

The role of BECCS in mitigation pathways

Key points

The land sector is key to climate mitigation, but only within limits

What does the IPCC say about the scale of land-based CDR?

Mitigation potential of different CDR options

The role of CDR in mitigation pathways

Current state of play in livestock and plant-based protein markets

Financing and government subsidies

Major impacts from meat, dairy and AP products

What does science say the solutions are?

What governments and companies can and are doing?

Key points

Introduction

Land and climate change

Sinks and sources of emissions

Climate change’s effect on land

Land degradation

Desertification: degradation of drylands

Land, climate and the food system

How will climate change affect land in the future?

What is true in most future scenarios?

What affects which future we get?

How can land help solve the climate crisis?

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