The Intergovernmental Panel on Climate Change (IPCC) is the international body that provides policy makers with regular assessments of the science related to climate change (Working Group I), its impacts and future risks (Working Group II), and options for adaptation and mitigation (Working Group III). In 2018, the IPCC produced a Special Report on the impact from global warming of a 1.5⁰C temperature increase compared to pre-industrial levels. It concluded that reaching and sustaining net-zero global CO2 emissions from human activities, and declining net non-CO2 radiative forcing, would halt global warming on multi- decadal time scales.
The IPCC subsequently released its 6th Assessment Report of Working Group I in 2021, which showed that emissions of greenhouse gases from human activities are responsible for approximately 1.1°C of warming since 1850-1900 and that immediate, rapid and large-scale reductions in greenhouse gas emissions are needed to limit warming to 1.5°C. The Report of Working Group II was subsequently released in February 2022 identifying that if 1.5°C is reached in the near-term, it would cause unavoidable increases in multiple climate hazards. The magnitude and rate of these hazards and associated risks would depend strongly on near-term mitigation and adaptation actions. Finally, the Report of Working Group III was published in April 2022 highlighting that many transport sector climate change mitigation strategies have co-benefits, including air quality improvements. It was also recognised that international cooperation is a critical enabler for achieving ambitious mitigation goals. These findings of the IPCC are reinforced by the World Meteorological Organization’s report on the State of the Global Climate 2021 .
Since the publication of the IPCC Special Report on ‘Aviation and the Global Atmosphere’ in 1999, the effects of aviation on climate from both its CO2 and non-CO2 emissions have been well established and continuously assessed. In order to halt aviation’s contribution to global warming, the sector needs to achieve net-zero CO2 emissions while also reducing the warming effect from non-CO2 emissions.