Accounting for non-equivalence of carbon emissions and removals in meeting national net zero emissions targets in the United Kingdom

<title>Abstract</title> <p>Carbon dioxide removal is expected to play a crucial role in counterbalancing residual emissions and limiting temperature rise in line with Paris Agreement targets. Durable temperature stabilisation requires fossil CO2 emissions to be balanced by geological timescale storage – a condition defined as geological net zero (GNZ). Replicable for other countries, our analysis uses the UK as a case study, assessing how different GNZ implementations reshapes energy system pathways and mitigation strategies under strict, progressive, and cumulative policy formulations. We find that GNZ could be reached as early as 2040, delivering lower emission pathways than current carbon budgets prescribe, with savings of 0.9-2.34 GtCO2e between 2030-2050. These outcomes are challenging, vulnerable to disruptions in technology and feedstock supply-chains, and subject to the pace of emissions’ reductions and removals uptake. Yet they reflect earth system emissions accounting principles required to meet stated climate targets, and as such merit increased policy scrutiny.</p>