Bringing aviation in line with the Paris agreement: Will flying save the world’s forests?


Last week was a big week for climate policy. Last Tuesday the countries of the EU ratified the Paris agreement, taking it past the threshold required to make it legally binding – which will happen as soon as the 4th of November.

Then on Thursday, the 191 countries of the International Civil Aviation Organisation (ICAO), who’ve tended to be at the tortoise end of the decarbonisation race,  finally agreed a deal to curb emissions from international aviation, which along with shipping has steadfastly been excluded from all previous climate agreements. So this deal is a big deal.

Aviation currently accounts for around 2% of global CO2 emissions (slightly more than the UK). So why all the fuss?

Well, firstly, aviation is growing at roughly 5% a year, when most other sectors have sluggish growth. Secondly, the sector is hard to decarbonise. Together these mean that aviation emissions could use up to a quarter of the remaining carbon budget which can be emitted if we’re to keep global warming below 1.5 C, as we urgently need to do.

So what does this deal do? It effectively caps CO2 emissions at 2020 levels, by using market-based measures to offset any global emission growth beyond 2020 levels. Voluntary stages until 2026 are replaced by a compulsory stage from 2027-2035.

Even though the first stages are voluntary  – all the major nations that airlines fly to and from have agreed to take part.  Airlines are expected to be able to mitigate around two fifths of the annual growth by replacing airframes and engines with more fuel-efficient models, as well as employing better air traffic management and more efficient ground operations.  Using biofuels instead of kerosene may also slightly reduce emission growth. But these measures will still leave around three fifths of growth which will need to be managed by the Carbon Offset and Reduction Scheme for International Aviation (CORSIA – see Figure).


Figure 1: Global Aviation Emissions of CO2 (Million Tonnes per year). The red triangle is the amount of offsetting required


At first airlines will offset a proportion of global growth according to their size, but by the end of the period, airlines will be individually responsible for their own growth.  The deal is expected to add around $10 to the cost of long haul tickets and $2-3 for short haul fares, reducing the profitability of the industry by about 1%.

Two important criticisms of the deal are that it only seeks to curb growth in emissions, rather than to cut them. And it is cuts that are needed to meet the Paris targets. The deal also does not account for other emissions around aviation, especially contrails, which also warm the climate.  However, its credibility will really hinge on whether the offsetting schemes are effective.

The detail of how this offsetting will work is in the next stage of negotiations, which should be finalised by 2018.

Offsets will begin with Clean Development Mechanism projects set up under the Kyoto Protocol, and it’s likely that forest protection and restoration projects will also be allowed.

Protecting and restoring forests has been extensively proven as able to provide genuine carbon offsetting opportunities  as well as co-benefits to indigenous communities and biodiversity under REDD+. For example, work by UBoC’s/Preistley’s own Dominick Spracklen has highlighted the carbon sequestration potential of mountain forests. Tropical deforestation is the major cause of global biodiversity loss, and accounts for substantially more carbon dioxide emissions than aviation. Carbon offsets from aviation could provide a sustained and sizeable funding source to reduce carbon emissions from tropical deforestation, and may be one of the last chances we have to save remaining tropical biodiversity.

The good news is that you don’t have to wait until 2020 for airlines to start offsetting. Why not begin now by offsetting your travel? The United Bank of Carbon works with a number of projects to offer certified carbon offsets.

Please get in touch with Tom on the contact tab above right.

Prof Piers Forster and Prof Dom Spracklen