I recently had the honour to represent Shell as an industry observer and panellist at the 80th anniversary of the International Civil Aviation Organisation (ICAO). This important United Nations agency emerged during the final months of the Second World War, after several years of negotiation. Agreement was reached in early December 1944 at the famous Stevens Hotel in Chicago. 80 years later delegates met again at the same location, now the Hilton Chicago, to celebrate the achievement and to recognise all that ICAO has done over the years to steer civil aviation to be such a successful, safe and highly valued global enterprise.
Today civil aviation constitutes some 28,000 planes carrying nearly 5 billion passengers per year and over 60 million tonnes of cargo, but this operation runs almost exclusively on jet fuel derived from crude oil. In 2024 about 7 million barrels per day of jet fuel is consumed by civil aviation activities, with a resultant global CO2 footprint of about 1.1 billion tonnes annually, or just over 3% of global energy related CO2 emissions.
In Chicago, one of the key themes of the 80th anniversary event was sustainability, with CO2 emissions from the sector prominent within the panel discussions. While there were some fascinating discussions about short haul electric aviation and longer haul hydrogen powered planes, these upcoming technologies are not going to make any real dent in the aviation carbon footprint for some decades, so the focus for now is on the fuel used by existing planes and those being built with similar engine types over the coming twenty or more years. Given the very long lead times in aviation to develop, test and certify as safe even minor variations of the current technology set, we shouldn’t expect new technologies to displace the existing set anytime soon.
Sustainable aviation fuel (SAF) has become a key focus for the aviation industry. These are fuels that have their origin outside the fossil fuel supply chain, such as from biogenic sources, various waste streams and eventually via direct synthesis from carbon and hydrogen molecules derived from the air and water. As such, their carbon footprint can be much lower than conventional fuel. Carbon emissions can still result from land use change, when biogenic feedstocks are grown and harvested, and when energy is used in the production and transport of SAF. For example, using SAF today (the predominant current feedstock being used cooking oil) can result in a reduction of up to 80% in carbon emissions compared to conventional jet fuel, depending on the feedstock used, production methods, and supply chain logistics (IATA).
In the Sky 2050 scenario, developed as part of The Energy Security Scenarios published by Shell in 2023, SAF make major progress in replacing fossil derived fuels. Nevertheless, even with the rapid progress illustrated in Sky 2050 to limit warming to less than 1.5°C by 2100, the SAF journey for aviation is one that takes over 50 years.
Within this storyline, another discussion emerges and this featured in the panel sessions at the ICAO 80th event in Chicago. It’s the issue of land use to make the significant amount of biogenic SAF. By 2065 in the chart above, biogenic SAF production has passed 6 million barrels per day, eclipsing the current 2.7 million barrel per day production of biofuels, which are primarily for cars and trucks. Such a level of production has raised concerns about the sustainability of these fuels, given the amount of land that might be needed to grow the crops and whether or not that competes with the need to grow crops for food or leads to further deforestation for agriculture in some parts of the world.
This is a valid set of questions and to help answer them there is a new analysis conducted by MIT and co-authored by three of my colleagues; Land-use competition in 1.5°C climate stabilization: is there enough land for all potential needs?; Gurgel A, Morris J, Haigh M, Robertson AD, van der Ploeg R and Paltsev S (2024), Front. Environ. Sci. 12:1393327. doi: 10.3389/fenvs.2024.139332. The MIT earth-system integrated modelling capability is ideal for such complex questions.
In this analysis the data in the Sky 2050 scenario is used to create a deeper understanding of the land pressures that confront the world. There is a need to grow food and potentially supply much more bio-energy from the land, and consideration must also be given to continued human development, land for wind turbines and solar PV and for land management and restoration to preserve biodiversity and grow the land carbon stock. These current and future needs all intersect.
The authors found that with proper regulatory policies and radical changes in current practices, global land is sufficient to provide increased consumption of food per capita (without large diet changes and accounting for a larger population) over the century while also utilizing 2.5–3.5 billion hectares (Gha) of land for nature based practices that provide a carbon sink of 3–6 gigatonnes (Gt) of CO2 per year as well as 0.4–0.6 Gha of land for energy production—0.2–0.3 Gha for 50–65 exajoules (EJ) per year of bioenergy and 0.2–0.35 Gha for 300–600 EJ/year of wind and solar power generation.
The authors set out the case starting with the split of current global land use, shown below.
They note that global land use was quite stable before the Industrial Revolution, but in the middle of the nineteenth century, changes in land use from natural vegetation to pasture and cropland accelerated—1.08 Gha of natural forests and natural grassland that existed in 1800 became agricultural areas by 1900, and had risen to 3.41 Gha converted by 2000. The most recent 50 years have experienced declining rates of land use conversion worldwide (refer to 4.1 Global land use: 1700–2100, in the paper).
Looking forward, land use becomes a critical consideration in any scenario. There will be more demand for food, there will be more renewable energy production, urban areas will expand and we are likely to see greater demand for bioenergy. At the same time, growing societal pressure to address biodiversity loss may become overwhelming for policymakers and planners, as well as the need to manage global carbon stocks much more proactively. As such, well financed nature-based solutions (NBS) become important, as can be achieved through carbon markets. The paper finds that the two largest adopted options are related to agricultural areas, such as in cropland (including both biochar and a broad suite of regenerative agricultural practices) and optimal grazing in pasture area. Natural forest protection also increases. Other relevant NBS practices accumulate to sizeable amounts by the end of the century, which is the case for reforestation of natural forest areas. Total land managed for NBS by the end of the century is projected to be about 3.5 Gha, of which 0.77 Gha is related to forest, 1.17 Gha to cropland, 1.17 Gha to pasture, 0.26 Gha to grassland and 0.15 Gha to other land types. Globally, the analysis finds there is enough land in each category to accommodate the NBS projections from Sky 2050, while also ensuring growing demand for food and other land-based products is met.
The paper authors project that global land area dedicated to bioenergy more than doubles by mid-century. It grows from about 100 Mha in 2020 to 242 Mha in 2050 and 286 Mha by 2100. Dedicated biomass growing areas enable growing bioenergy consumption. The total commercial bioenergy use grows from about 20 EJ in 2020 to about 50 EJ in 2050, and about 70 EJ in 2100. Land use at the global level can accommodate these demands expected under a 1.5°C climate stabilization scenario. At the regional level, however, challenges to integrate all land uses may arise and the paper explores this aspect in further detail.
The novelty of the study is in providing a clear message that it is possible to meet the land needs for major human requirements such as food and energy, while protecting and restoring land more broadly. The study shows the feasibility of achieving the land-use optimization needed for a climate stabilization scenario. With all inherent uncertainty about the potential cost reductions for existing technologies and deployment of new regulatory and technological options, one message is clear: there is an urgent need for advancing sustainable land management for food, energy and nature.
Note: Shell Scenarios are not predictions or expectations of what will happen, or what will probably happen. They are not expressions of Shell’s strategy, and they are not Shell’s business plan; they are one of the many inputs used by Shell to stretch thinking whilst making decisions. Read more in the Definitions and Cautionary note. Scenarios are informed by data, constructed using models and contain insights from leading experts in the relevant fields. Ultimately, for all readers, scenarios are intended as an aid to making better decisions. They stretch minds, broaden horizons and explore assumptions.
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