The European Union Emissions Trading System (EU ETS) is the world's frst and biggest international emissions trading scheme, accounting for trading of almost 50 percent of Europe's emissions. It came into effect in 2005 and since has developed in three phases. The frst phase was the testing or "learning by doing phase" (2005 – 2007), followed by Phase II, coinciding with the Kyoto Protocol's frst compliance period of 2008 to 2012. The current and third phase started in 2013 and will end in 2020 when Phase IV will take over.

What is covered

The EU ETS currently operates in 31 countries—the 28 EU Member States (while the UK's connection to the EU ETS post-Brexit remains to be resolved), plus Iceland, Liechtenstein and Norway. It applies to carbon dioxide (CO2) emissions from power and heat generation equal to or more than 20 MWs of capacity and energy-intensive industry sectors (including oil refneries, steel works and production of iron, aluminum, metals, cement, lime, glass, ceramics, pulp, paper, cardboard, acids and bulk organic chemicals). The EU ETS also applies to nitrous oxide from production of nitric, adipic and glyoxylic acids and glyoxal, as well as perfuorocarbons from aluminum production. All in all, approximately 11,000 energy-intensive installations, as well as intra-European Economic Area (EEA) civil aviation, are included, covering approximately 45 percent of EEA's greenhouse gas (GHG) emissions.

From 2012 to 2016, emissions from fights between airports located in the EEA fell within the EU ETS's scope. The EU legislature is currently considering extension of the EU ETS's coverage of intra-EEA fights for the 2017 to 2021 period. The EU Aviation Resolution sets the trajectory for all EU countries to join the International Civil Aviation Organization's Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), which is a global market-based measure to address CO2emissions from international aviation as of 2021, with the goal of stabilizing CO2 emissions at 2020 levels by requiring airlines to offset the growth of their emissions after 2020. Under CORSIA, airlines will be required to monitor emissions on all international routes and offset emissions from routes included in the scheme (e.g., airlines will be permitted to purchase eligible emission units generated by projects that reduce emissions in sectors such as renewable energy). Although the implementation mechanics for the scheme will be developed at the International Civil Aviation Organization level, to make CORSIA effective national measures will need to be developed, and ultimately enforced, at national domestic levels.

A market stability reserve will be established in 2018 to start operating in January 2019, to address the current surfeit of allowances and make the EU ETS resilient to shocks.

What is required

The EU ETS is a "cap-and-trade" system. It works by setting limits on overall emissions from high GHG-emitting industry sectors, with the limit reduced over time. Within that limit, companies may buy and sell emission allowances as needed for their production purposes. Each allowance represents the right to emit one ton of CO2-equivalent emissions. The overall number of allowances issued determines the volume of emissions permitted, and in that way emissions are "capped." The idea is that the cap is reduced over time, thereby reducing emissions. In the current (third) phase of the EU ETS, the number of allowances issued is declining annually. Allowances are distributed to installations by allocation and increasingly by auction. The allowances can be freely traded on the market or between covered entities. Each year, installations must surrender allowances equivalent to the amount of CO2-equivalent emissions they emit. If installations produce more emissions than covered by allowances, they face signifcant fnancial penalties amounting to €100/tCO2 (rising with EU infation from 2013); if they produce less, they can trade the surplus allowances.

For installations to receive free allocation, they must meet the relevant sector's benchmarks. For those installations that are not at a signifcant risk of carbon leakage (i.e., where, for reasons of costs related to climate policies, businesses transfer production to other countries with fewer constraints on GHG emissions), the scheme provides that free allowances decline annually, to 30 percent of all allowances in 2020. In principle, no free allowances will be available from 2027. To safeguard the competitiveness of industries, installations in sectors and sub-sectors deemed to be exposed to a signifcant risk of carbon leakage will continue to receive a higher share of free allowances in Phase IV compared to the other industrial installations, so long as they meet the relevant sector benchmark.

The power generation sector is not eligible for free allocation, except under special conditions in a few lower-income EU countries in order to modernize their power sectors.

Future outlook

The EU has committed under the Paris Agreement and for its 2030 Climate and Energy Policy Framework to reduce GHG emissions by at least 40 percent domestically by 2030. To accomplish this, it proposes to increase the pace of emissions cuts, address carbon leakage and fund low-carbon innovation. A market stability reserve will be established in 2018 to start operating in January 2019, to address the current surfeit of allowances and make the EU ETS resilient to shocks by introducing an adjustment to the supply of allowances that are to be auctioned. According to the EU's legislative proposal for the EU ETS (2021 to 2030), the annual rate of decline of total allowances would accelerate to 2.2 percent from the current 1.74 percent.

The proposal also aims to update sector benchmarks to refect technological progress, provide a more targeted carbon leakage classifcation (and develop "predictable, robust and fair rules" to address the risk of carbon leakage), and more closely align free allocation with production levels. The proposal puts in place two new funds—an innovation fund and a modernization fund—to help industry and power sectors meet the innovation and investment challenges inherent in reducing their emissions.

Linking with others

The EU ETS is linked with the Kyoto Protocol's international emissions trading system. Emission-reduction credits generated from Kyoto Protocol Clean Development Mechanism and Joint Implementation projects could be used for EU ETS compliance (with quantitative restrictions). This was designed to cover reductions in sectors not included in the EU ETS as well as help expand market access to low-cost emissions reductions and support technology transfer. The EU ETS adopts this through the 2004 EU Linking Directive, allowing operators to use Kyoto Protocol credits for compliance with the EU ETS on a one-for-one basis.

Additionally, the EU and Switzerland have fnalized technical negotiations and in principle have agreed to link their systems. However, the fnal conclusion of the Linking Agreement is dependent on negotiations on a broader package of issues with Switzerland. Once the agreement has entered into force, linking will result in the mutual recognition of EU and Swiss emissions allowances.