Assessing fair effort-sharing of Paris-compliant mitigation futures in transport

Globally, the transport sector accounts for 15% of annual CO2 emissions, with land transport comprising the vast majority, making mitigation in this sub-sector critical to achieving the Paris Agreement. This article applies five established effort-sharing approaches to allocate the remaining global land transport carbon budget across countries in alignment with 1.5 ◦C and 2 ◦C scenarios that prioritize sustainable and equitable development. The results serve as transparent, scientific and comparable evidence for countries and civil society to evaluate the fairness and significance of mitigation commitments against. For most developed countries, even if domestic emissions reductions achieved an established practical maximum rate of 5% annually, this would remain insufficient to meet their allocated fair mitigation burden. Fulfilling these fair burdens, which exceed domestic capacity, will necessitate vastly scaled-up international support for mitigation in less-developed countries which have rights to larger shares of the remaining global carbon budget. Without universally accepted effort-sharing mechanisms, countries’ self-determined equity interpretations will likely favour their least stringent allocations. Our results indicate this would result in potential global carbon budget overshoot of 489% in the 1.5 ◦C scenario, or 123% in the 2 ◦C scenario, rendering land transport’s adherence to equitable, Paris-compliant scenarios unattainable.