The new Paris Agreement provides a broad global framework to strengthen efforts to address climate change. Now, governments are working toward another agreement on a critical issue Paris doesn’t directly address – reducing greenhouse gas emissions from aviation.

The Paris Agreement, negotiated under the United Nations Framework Convention on Climate Change (UNFCCC), ties together national efforts pledged by more than 180 countries to limit or reduce their own emissions. However, international aviation is inherently a cross-border activity, and a global approach to reducing emissions from aviation is being negotiated separately under the International Civil Aviation Organisation (ICAO). A new sector-wide agreement is expected this October.

Emissions from the aviation sector comprised 2 percent of global emissions in 2013, but that share is set to expand rapidly by 2050 without policy interventions. In 2010, the aviation industry carried 2.4 billion passengers and 40 million metric tons of goods. By 2050, that could grow to 16 billion passengers and 400 million metric tons of goods.

If global aviation were a country, it would rank as the seventh largest carbon dioxide emitter. So reducing emissions from aviation is critical to meeting the global goal of limiting average temperature rise below 2 degrees Celsius.

ICAO was established in 1947 to regulate civil aviation by establishing common standards on safety, pollution, technology, and other important issues. In 2010, governments adopted a goal put forward by the airline industry to achieve carbon neutrality from 2020 onwards – known as CNG2020. This means that, from 2020 onwards, net carbon emissions from international aviation would remain constant.

Negotiations are moving toward an agreement on how to achieve this target. The key challenge will be allocating obligations to individual countries. The Chicago Convention, which established ICAO, is based on the principle of uniform application (e.g., all nations must meet the same standards), which is in contrast to the concept of common but differentiated responsibilities familiar to those involved in the UNFCCC. It will be a challenge for negotiators to find a workable compromise that apportions obligations in a manner deemed fair by all nations.

To meet the CNG2020 goal, a number of policy options are available. Technology improvements in aircraft and engine design, operational efficiency gains, and investments in new infrastructure will all reduce emissions. Additionally, the development and possible use of biofuels would drive down emissions by reducing the jet fuels burned by aircraft.

However, in the face of continued aviation sector growth, industry believes that emission reductions occurring outside the sector must also be available to count toward the goal. At the 38th ICAO Assembly in 2013, member states agreed to develop a global market-based mechanism, allowing for offsetting aviation sector emissions. A task force has been deliberating the rules and eligibility criteria that would underpin this mechanism, and it is hoped that these rules will be adopted at the October ICAO Assembly and take effect from 2020.

2016 is an opportunity to continue the momentum of international cooperation on climate change, with aviation becoming the first sector to sign a binding international agreement to reduce its emissions.