Oxford researchers propose ‘Carbon Removal Budget’ to tackle climate change

Dr Ben Caldecott, the Lombard Odier Associate Professor at the University of Oxford Smith School of Enterprise and the Environment and lead author said, 'Carbon removal is the ‘net’ in ‘net zero’ and it is mission critical for tackling climate change. However, carbon removal is not in infinite supply and is certainly not free to produce.'

To limit global warming we need to level off the cumulative stock of carbon in the atmosphere and achieve the state of ‘net zero’, when all emissions that can be eliminated are, and any residual emissions are neutralised by durably removing carbon from the atmosphere.

Traditional carbon removal methods like planting trees and restoring wetlands are part of this mix, as are more novel options like biochar and technologies that directly capture and store carbon. The availability of carbon removal is, however, constrained. For example, some carbon removal methods depend on significant energy consumption and require vast tracts of land.

Caldecott added, 'The Carbon Removal Budget is the cumulative amount of carbon removal available to realise global temperature goals. We need a way to value this finite removal capacity and allocate it in a fair and effective way. The Carbon Removal Budget allows us to do this, in the same way that the Carbon Budget allows us to value remaining carbon emissions and figure out how we distribute that globally between different countries, sectors, and companies.'

Dr Injy Johnstone, Research Fellow at the Oxford Sustainable Finance Group and co-author said, 'We have seen growing interest by private and public actors alike in how we can scale carbon removal. Companies like Microsoft, for instance, are making big voluntary investments in new types of carbon removal. At the same time, many countries, including the UK, are also considering how they too can drive demand for carbon removal, including by integrating carbon removal into existing compliance emissions trading or tax regimes.' 

Dr Johnstone added, 'However, carbon removal is a scarce resource, one which not all countries or companies have the same capacity to develop and deploy, meaning we need a Carbon Removal Budget to help equitably manage both supply and demand.'

The authors argue that carbon removal budgets can help to answer several urgent questions. How much carbon removal is needed and when? What methods for carbon removal should be prioritised? What impediments exist to the different types of removal supply and how can we overcome them? Critically, how should we allocate the finite, even if growing, carbon removal supply between different countries, companies, and financial institutions?

Dr Caldecott said, 'For example, it is not clear why a fossil fuel company should be using carbon removal today when there are ways to reduce its emissions today, especially when we need to preserve removals for future emissions that are extremely hard or impossible to eliminate.'

'Embedding carbon removal budgets into decision-making is necessary for an effective response to climate change. It will become an essential part of net zero transition plans, whether for countries, companies, or financial institutions.'

Read the full article in the journal Carbon Management here.