Is it best to use the existing vehicles until they reach end of life or to replace them sooner to reduce their carbon footprint?

What is the most logical way to manage the change from a predominately carbon based transport fleet to a low carbon future? Is it best to use the existing vehicles until they reach end of life or to replace them sooner to reduce their carbon footprint? Where is the pay off between using a vehicle that has already been manufactured and using carbon based fuel sources and scrapping it to replace it with a new clean vehicle?

These are some of the questions that many people are asking as the world faces the urgent challenge of reducing greenhouse gas emissions and limiting global warming. Transport is one of the key sectors that needs to undergo a rapid and radical transformation, as it accounts for about 24% of global CO2 emissions from fuel combustion . Moreover, transport is the only sector that has seen its emissions increase since 2010, mainly due to the growth of road and air travel .

There is no simple or definitive answer to these questions, as different modes of transport have different impacts, benefits and trade-offs. However, some general principles can be applied to guide the decision-making process and help achieve a net-zero transition in transport.

First, it is important to consider the life cycle emissions of different vehicles and fuels, not just their tailpipe emissions. This means taking into account the emissions associated with the production, distribution, use and disposal of vehicles and fuels. For example, electric vehicles (EVs) have zero tailpipe emissions, but they still generate emissions from the electricity they use and from their battery manufacturing. Similarly, sustainable aviation fuels (SAFs) can reduce the emissions from jet engines, but they also require land, water and energy to produce them.

Second, it is important to prioritize the most efficient and low-carbon modes of transport, especially for short-distance trips. This means encouraging people to walk, cycle or use public transport whenever possible, instead of driving or flying. This can also improve health, air quality and livability in cities. For longer-distance trips, it is preferable to use trains or buses over cars or planes, as they have lower emissions per passenger-kilometer.

Third, it is important to accelerate the adoption of zero-emission vehicles and fuels for those modes of transport that cannot be easily replaced or avoided. This means increasing the market share of EVs for road transport and SAFs for aviation. This requires supportive policies, incentives and infrastructure to make these options more affordable, accessible and convenient for consumers and businesses. It also requires collaboration and innovation among stakeholders from different sectors and regions.

Finally, it is important to monitor and evaluate the impacts and outcomes of different actions and policies on transport emissions. This means collecting reliable data, setting clear targets and indicators, and using evidence-based tools and models to assess the effectiveness and efficiency of different interventions. This can help identify best practices, gaps and opportunities for improvement.

In conclusion, there is no one-size-fits-all solution for decarbonizing transport, but rather a combination of strategies that need to be tailored to different contexts and circumstances. The transition to a low-carbon future will require a systemic change in how we move people and goods around the world, involving multiple actors and sectors. The benefits of this change will not only be environmental, but also social and economic.

There are different ways to manage the change from a predominately carbon-based transport fleet to a low-carbon future. According to the Ministry of Transport in New Zealand, the government is committed to decarbonizing the public transport bus fleet. By 2025, the government will only allow zero-emission public transport buses to be purchased. This commitment targets complete decarbonization of the public transport bus fleet by 20351.

As for individual vehicles, there is no one-size-fits-all answer. According to the BBC News, living car-free saves an average of 2.04 tonnes of CO2 equivalent per person annually. This is followed by driving a battery electric car - 1.95 tonnes of CO2 equivalent per person annually - and taking one less long-haul flight each year - 1.68 tonnes of CO2 equivalent per person2.

The pay-off between using a vehicle that has already been manufactured and using carbon-based fuel sources and scrapping it to replace it with a new clean vehicle depends on several factors such as the age of the vehicle, its condition, and how much it is driven. According to The New York Times, if you have an older car that you drive infrequently, it may be better for the environment to keep it rather than buy a new one3.