If global warming is to be limited to 1.5°C by 2050, the world’s transport emissions need to fall by 59% from 2020 levels, says the Intergovernmental Panel on Climate Change (IPCC), calling for “transformative” changes in the sector in its latest mitigation report.
Even if the 2050 target shifted to 2℃, the sector would need to cut its emissions by 29% from 2020 levels, the IPCC finds. But the transport sector likely won’t achieve net-zero emissions by 2100 unless it balances increases in some areas with negative emissions elsewhere. Scenarios indicate that without intervention, carbon dioxide emissions from transport would grow between 16% and 50% by 2050.
The transport sector accounts for 23% of energy-related CO2 emissions, 70% of which come from road vehicles, the IPCC says. Emissions from shipping and aviation continue to grow rapidly, and transport-related emissions from developing countries are expected to continue the trend of increasing more rapidly than in Europe or North America.
The IPCC urges a combination of better planning based on the demand for transportation services, along with new technology development and efforts to manage demand by shifting behaviours.
One solution is for cities to cut their transport-related fuel consumption by planning for more compact land use. Providing infrastructure for pedestrian and bike pathways to reduce car-dependence is another solution. The IPCC cites responses to the COVID-19 pandemic as evidence that behaviour changes can reduce transport-related greenhouse gas (GHG) emissions.
“Climate strategies at all levels of government, alongside pledges for personal choices, could create demand and supply-side mitigation strategies,” the report says.
Investments in public transport within and between cities, and “active transport” infrastructure, can cut emissions while contributing to health and wellness, the IPCC writes. Active transportation is using your own power to get from one place to another, and includes walking, biking, skateboarding, and running.
The report points to the side benefits attached to many emission reduction strategies in the transport sector, including air quality improvements, health benefits, equitable access to transportation services, reduced congestion, and reduced material demand.
Some of the systemic changes the report calls for include teleworking, more digital solutions, better supply chain management, and smart and shared mobility.
On the technology side, fuel and technology shifts are crucial, with electrification playing a key role. But the report mentions biofuels, as well as hydrogen and its derivatives, as key in decarbonizing some freight transport.
Electric vehicles, powered by low-emissions electricity, offer the largest decarbonization potential for land-based transport. “Electromobility is being rapidly implemented on a micro-mobility level (e-scooters, e-bikes) in transit systems, and to a lesser degree in personal vehicles,” the IPCC states.
Costs of electrified vehicles, including automobiles, two- and three-wheelers, and buses are decreasing and their adoption is accelerating. But, the IPCC stresses that those technologies require continued investments in infrastructure to speed up adoption.
The report points to the need for planning for a significant expansion of low-carbon energy infrastructure, including power generation and hydrogen production. That includes investments in electric vehicle charging and related grid infrastructure which will have to be integrated with planning for energy demand and constraints across all sectors, not just transportation, particularly true in developing countries.
Heavy duty trucks can be decarbonized through battery-electric haulage (including the use of electric road systems—a road which supplies electric power to vehicles travelling on it), though those efforts will have to be complemented by hydrogen, and in some cases biofuels.
Decarbonization options for shipping and aviation still require more research and development, though the report says advanced biofuels, ammonia, and synthetic fuels are emerging as viable options. Bio-based fuels, blended or unblended with fossil fuels, can provide mitigation benefits, particularly in the short and medium term, as long as they’re sourced sustainably from low-emission feedstocks, the report finds.
The IPCC calls for greater commitment to new technologies at the national and international levels for aviation and shipping transportation, but acknowledged changes to governance structures could be required. Such improvements could include, for example, the implementation of stricter efficiency and carbon intensity standards.
The report also recognizes growing concerns about critical minerals needed for batteries. Material and supply diversification, energy and material efficiency improvements, and circular material flows are options to reduce the environmental footprint.
As global battery production increases, unit costs are declining, but reducing the GHG footprint of battery production is essential, the IPCC finds. Beyond concerns around materials supply, the report acknowledges labour rights, non-climate environmental impacts, and the cost of critical minerals needed for lithium-ion batteries.
Overall, more integrated planning for transport and energy infrastructure can reduce the environmental, social, and economic impacts of decarbonizing. But developing countries will need technology transfer and financing to help them “leapfrog” to low-emissions transport systems.