Travel behaviours are the key to Engineering Net Zero

We need behavioural and technological change across all sectors to achieve the recommended ‘Balanced Pathway’ of decarbonisation and meet Net Zero objectives by 2050. By Tony Meehan, Practice Director, Transport Consultancy, Atkins

In early December, the UK’s Climate Change Committee (CCC) published their Sixth Carbon Budget report.

The CCC recommended a UK carbon budget for 2033 to 2037 and a decarbonisation pathway leading the UK to achieve Net Zero by 2050, and to make a fair contribution to meeting the Paris Agreement temperature objectives.

Many of the measures required to support behaviour change are well known and can be implemented rapidly to enable the emissions reductions we need in the 2020s and deliver associated benefits such as improved local air quality

The Paris Agreement aims to limit temperature growth to well below 2 degrees above preindustrial times.

Once average global temperature increases exceed 1.5 degrees, modelling forecasts irreversible changes in how the climate operates, resulting in immense, large scale environmental damage.

Globally, we are rapidly heading towards those levels of change, increasing the pressure to act now to help radically reduce emissions before it’s too late.

The CCC highlights we need both behavioural and technological change across all sectors to achieve their recommended ‘Balanced Pathway’ of decarbonisation to meet the Net Zero objective by 2050 and the intermediate carbon budgets.

Whilst technology has a significant role in rapid decarbonisation, the level of change that it can achieve alone isn’t sufficient given the scale of the challenge we face.

The pace and scale of the decarbonisation challenge

We often use the target of Net Zero emissions in 2050 as shorthand for the need to decarbonise. However, the decarbonisation pathway that we take between now and 2050, is more important than the endpoint. 

The pathway will determine the total additional emissions that accumulate in the atmosphere over that time, and it is those global, cumulative emissions that will drive climate change. 

We, therefore, require rapid reductions in emissions to limit the accumulation. The CCC report highlights that the 2020s will need to be the decade of decisive action leading to a 63% reduction in emissions across all sectors between 2019 and 2035 (78% reduction from 1990).  

For surface transport, which was responsible for around 22% of greenhouse gas emissions (mainly carbon) in 2019, the CCC highlights the need for the UK to achieve an 81MtCO2e (Metric tonnes of carbon dioxide equivalent) reduction against 2019 levels by 2035 as a part of its Balanced Pathway. That’s an effective reduction of around 70% from 2019 levels by 2035, or approximately 5% each year.

Other perspectives suggest we may require even more rapid rates of emissions reduction. Researchers from the University of Manchester and the Tyndall Centre for Climate Change have produced a carbon tool for local authorities across the UK to support them in setting emissions reductions targets that align with the Paris Agreement objectives. Their calculations suggest that many UK authorities would use their share of the remaining Paris aligned cumulative emissions budget within the next 7 to 9 years if emissions carry on at current rates; effectively using all their budgeted emissions by 2030!

If we are to spread those carbon budgets out to cover the years to 2050, it implies the need for aggressive and rapid reductions in annual emissions over the next few years to stay within each area’s emissions budget.

The limits of transport technology solutions

Transport technology alone simply can’t achieve the pace of transport decarbonisation needed to meet the carbon budgets and align with the Paris Agreement objectives. There are limits to the decarbonisation rates that technology can achieve given the practicalities of physically developing and rolling out technology within a short timescale. 

One example of this is the recently announced target of ceasing petrol and diesel car and van sales by 2030. Whilst this is ambitious, the decarbonisation benefits of electric vehicles will be relatively slow to build up. There will still be petrol and diesel vehicles on our roads into the 2040s, as cars have an average life of 14 years.

Yet changing the fleet much more quickly than this is unlikely to be workable because of the practicalities of delivering the vehicles and the supporting infrastructure required; such as the factories to produce batteries and the infrastructure we will need to support charging.

A recent working paper from the ICCT (the International Council on Clean Transportation) estimates that there will be nearly 1m EVs across the 32 boroughs in London by 2030. It also suggests that these vehicles will require almost 45,000 public charging points, requiring growth in the provision of over 20% each year from 2020 to deliver them.

The large-scale construction of new vehicles and infrastructure implies significant carbon emissions in its own right and brings other environmental challenges, such as demands for rare minerals from sensitive locations.

There are also limits to the pace of change possible because technological developments to decarbonise other major vehicle types are less advanced than those for the car and van sector. For instance, it is not clear whether road freight will decarbonise through using electrification, or hydrogen, or a combination. Also, the fuels required to decarbonise long distance aviation are still in their early development.

There is a limit to the pace and potential of the role of transport technological change in decarbonisation as it cannot achieve enough alone. If we want to replicate the current transport system and maintain travel patterns – developed as an integral part of a carbon-based economy - by simply replacing fossil fuels with electricity, hydrogen and synthetic fuels, we will not meet our decarbonisation targets.

The need for behaviour change

To meet our carbon budgets on the way to Net Zero, we must accompany current and developing transport technologies with behavioural shifts. 

Besides adopting new and existing technologies, the CCC identifies reductions in vehicle kilometrage as part of their Balanced Pathway to Net Zero. For car travel, they have identified the need for a 9% reduction in vehicle kilometres compared to baseline growth by 2035, reaching 17% by 2050 (equating to approximately 5% fewer kilometres per car driver than in 2019 in 2035 and 9% fewer in 2050). We can only deliver these reductions through changes in behaviour – the decisions we take about when, how often, where and how we travel.  

To achieve this shift, we will need significant changes to the context in which travel decisions are made. This will require policy action by national and local government to encourage businesses and individuals to take action. It will also require measures to ensure that attractive alternatives to high carbon journeys are available, whether through alternative modes or vehicle types, more local trips or online substitutes to travel. Technology will play a role in delivering behaviour change. Through incentivising change through apps and other means, providing online alternatives and ensuring that we understand the implications of travel choices, such as using an SUV rather than an e-scooter for a single person journey, and ensuring they are priced accordingly, where appropriate.

Many of the measures required to support behaviour change are well known and can be implemented rapidly to enable the emissions reductions we need in the 2020s and deliver associated benefits such as improved local air quality.

The CCC are optimistic about the potential for behaviour change and note evidence from the recent Climate Assembly showing that if people understand what they need to do, and why, and if they have options and involvement in decision-making processes, they will support the transition to Net Zero.  

The Covid-19 pandemic has shown that immediate and effective changes are possible. One positive side-effect of lockdowns has been the temporary reductions in global emissions with people travelling less and working from home. 

But what happens when Covid-19 is behind us? A recent report from the think tank Centre for Cities suggests that when restrictions eased, there was a rapid return to our old societal habits, undermining any temporary benefit with 80% of cities studied returning to at least pre-pandemic levels of air pollution.

Rapid action will be critical to help build on the positive elements of travel behaviour change caused by the pandemic and achieve the longer-term change required to achieve decarbonisation and tackle the climate emergency.

What needs to happen now

Meeting our Net Zero aim and carbon budgets will be a significant challenge. Success will require decisive action across many fronts. 

It will require clear direction for rapid decarbonisation from the government. This will enable manufacturers, suppliers, organisations and individuals to achieve decarbonisation through the choices they make, the vehicle types they produce and use, and how much and where they travel and by what modes. 

By combining the pace of change possible from behaviour shift with the changes possible through technology, we will have the best chance of delivering the emissions reductions we need.