Aviation fuel shifts alone fall short of planetary boundaries
A peer-reviewed Nature Communications modelling study published on 13 October assessed aviation roadmaps that mainly replace fossil kerosene with alternative fuels through 2050. All nine scenarios examined still crossed the allocated climate and biosphere boundaries, while fuel production demanded energy and land. These are conditional projections under the study’s traffic-growth, technology and environmental-allocation assumptions, rather than observed outcomes for 2050.
Science··Evening
Nine fuel paths were compared on one scale
In Nature Communications, researchers modelled nine ways aircraft could be fuelled from 2023 to 2050, counting impacts along production and use. Four represent fuel mixes in published roadmaps, four emphasize particular alternative fuels, and one represents business as usual. The model pairs 3.7 per cent yearly traffic expansion with 1.5 per cent efficiency gains. The results are pathways calculated under those assumptions, not measurements of future flights.[1]
Climate and biosphere shares were exceeded in every scenario
The researchers assessed six planetary boundaries, including climate change and biosphere integrity. They assigned aviation a share of the global safe operating space in two ways: by its contribution to economic activity and by an allocation based on basic human needs. Under the economic allocation, aviation received 2.9 per cent of the safe space. The human-needs allocation was narrower. All nine scenarios exceeded climate and biosphere budgets under both allocations.[1]
Alternative fuels shift demands to other resources
Producing biofuels uses land and water. Routes based on synthetic fuels or liquid hydrogen place heavier demands on electricity. In the study’s alternative-fuel scenarios, relative to business as usual, the models projected 20–120 times as much electricity demand and 60–200 times as much land demand. These are ranges across conditional production paths, not impacts already observed for all fuels together. The calculation also excludes non-carbon-dioxide climate effects of flying, leaving part of aviation’s climate pressure outside its model.[1]
