Carbon Offsetting and Reduction Scheme for International Aviation
Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is an emission mitigation approach for the global airline industry, developed by the International Civil Aviation Organization (ICAO) and adopted in October 2016. Measures include primarily offsets and "alternative" fuels. CORSIA addresses only emissions from international air travel that exceed the baseline of 2020 levels. The proposal has been described as "a delicate compromise between all involved in its elaboration."
As per an IPCC report published in 1999, aviation accounted for approximately two percent of global carbon emissions due to human activity, as of 1992. But the IPCC points out that climate impacts of aviation emissions are especially problematic due to chemical interactions at high altitudes. In fact the radiative forcing impacts of aviation emissions are thought to be 2-4 times that of direct CO2 emissions. Per capita emissions from air travel is one of the highest in comparison to various other modes of transportation. The industry is expecting a growth in air travel in various regions. Aviation is among the fastest growing sectors. Through CORSIA, the aviation industry is aiming for a carbon neutral growth from 2020.
Many airlines offer an option for airline passengers, for an additional payment, to offset their emissions associated with their air travel. Few airlines such as NatureAir and Harbour Air  have been carbon-neutral. There are start-up aviation ventures such as FlyPOP that are aiming to be carbon neutral.
CORSIA has three implementation phases, beginning 2021. Participation of countries until 2026 is voluntary.
On 15 February 2019, the ICAO announced an agreement on alternative fuels to reduce offsets, but details on how to reach the target of halving 2005-level emissions by 2050 remain elusive. However it has been decided that even fossil fuels produced from newer oil wells, or with some more efficient refinery processing will be eligible. It has also been decided that aviation biofuels from a variety of feedstocks including palm oil, the most likely source and a leading cause of deforestation, would be eligible for use. On 18 February, the European Council urged the ICAO to implement Corsia swiftly and to “agree on a long-term goal at its next assembly” in September. For the Air Transport Action Group, the ICAO could take three years to negotiate, until 2022.
As of January 2018, more than 70 countries representing more than 85% of international aviation activity have volunteered to participate. India and Russia are yet to join CORSIA. India, which has four of the five carbon-neutral airports in the Asia-Pacific region and the world's first fully solar powered airport, has drawn attention to "differentiated responsibilities" and the "need to ensure the transfer of financial resources, technology transfer and deployment and capacity building support to developing countries for enabling them to voluntarily undertake action plans.".
Least Developed Countries, Small Island Developing States and Landlocked Developing Countries can volunteer to participate in CORSIA, while it is not mandated on them. However, all ICAO member states "with aeroplane operators conducting international flights are required to monitor, report and verify (MRV) CO2 emissions from these flights every year from 2019". All aeroplane operators with CO2 emissions less than or equal to 10,000 tonnes are exempted from the CORSIA reporting requirements.
CORSIA would establish a global offset market with weak standards at a time when drastic reductions, not unreliable offsets are essential. CORSIA would create vast new demand for biofuels even though it is widely recognized at this time that most biofuels, especially those from palm oil, result in more emissions even than the fossil fuels they replace, as well as being a leading cause of biodiversity loss. CORSIA is a market based mechanism focusing on offsetting emissions through the process of an airline purchasing emission units equivalent to its offsetting requirements. Offsetting diverts the focus from reducing emissions, to trading on emissions. Forest offsets would most likely predominate. But forest offsets have been opposed by many as ineffective since fires, droughts, pests, illegal logging and geopolitical dynamics make it impossible to measure, verify or in any way guarantee forest carbon sequestration over time. Additionally, many forest offset projects have resulted in human rights violations. It is also said that CORSIA is not as stringent as EU ETS. While the scheme may address a significant percentage of emissions from the future expansion of international aviation, it does not fully contribute to 'carbon neutral growth'. CORSIA has also not stated any upper limit to the aviation related emissions that may be produced by an airline operator or a country.
Further, CORSIA is likely to result in massive new demand for biofuels, which currently would most likely be produced using "hydrotreated vegetable oil" - with palm oil, and the palm oil derivative "palm fatty acid distillate" (PFAD) being the most likely feedstock.Neste is the largest producer of aviation biofuels and has established a facility in Singapore, the heart of the palm oil going region, stating its goal to become the world leader in aviation biofuel production. Palm oil is already recognized as a leading cause of deforestation and human rights abuses.
Emissions from domestic aviation
Emissions from domestic air travel are not included in CORSIA. ICAO states that "Emissions from domestic aviation, as other domestic sources, are addressed under the UNFCCC and calculated as part of the national GHG inventories and are included in national totals (part of the Nationally Determined Contributions (NDCs))..." 
- Bunkers (energy in transport)
- Carbon neutrality
- Carbon offset
- Environmental impact of aviation
- Environmental impact of transport
- Electric aircraft
- Sustainable transport
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