Aviation emissions are responsible for about 5% of all global warming and aviation CO2 is projected to quadruple by 2050. So reductions from this particular sector are seriously important if we want to tackle the impacts of climate warming.
With projected growth like this it's not surprising that the debate over what to do about aviation emissions has been receiving a lot of attention recently. A report published on Tuesday by the leading aviation climate scientist, Prof David Lee, shows that the quickest and most effective way of reducing climate impacts from aviation is the controversial European Union Emissions Trading System (ETS).
The ETS is basically an agreement to limit the amount of carbon that certain sectors of the EU economy (now including aviation) can emit. Under this limit, every ton of carbon must have a permit. Those in the system can trade the permits so that the cuts in carbon will come from those sectors where it is cheapest to do so.
But this effective and fast way to cut aviation emissions has come under repeated fire from many countries, led by the US. So much so that in 2012, during its first year of operation, the EU suspended enforcement for intercontinental flights, for one year, to give the international process yet more time to come to agreement on implementing an alternative global measure.
The venue for these talks is the International Civil Aviation Organisation (ICAO) but they have already been discussing what to do about aviation emissions for 17 years. And while there is some hope that this year ICAO may agree to do a little more than just keep talking, it is unlikely that any global market based measure would enter into force until 2020 at the earliest.
However, the year's suspension of intercontinental flights in the ETS is now almost up. Meanwhile the report from David Lee shows that ICAO's focus, which is on reductions from improved technology, operations and alternative fuels can have a significant impact on mitigating emissions from aviation, but only in the long term. The physics of CO2 is such that it builds up in the atmosphere. The importance of which is that reductions from market based measures (such as the ETS) which would be immediate, far outweigh the climate impacts of ICAO's longer-term approach in 2050.
So the question that really hangs over aviation emissions now is whether ICAO will decide this autumn to be serious about taking action which will have an immediate effect through a global measure market-based measure such as emissions trading or whether they will continue simply to talk. And if something is agreed, whether it will be enough to convince the European Parliament to modify a climate law that has been shown to be the single most effective and fastest measure at tackling aviation carbon. If you are interested, you can come along to the European Parliament on 4 September to join the debate.