The acronym-laden gathering of 196 nations in Paris is administered by the United Nations Framework Convention on Climate Change. That’s the organization created in 1994 to rein in greenhouse gases before they caused dangerous climate interference. The UN agencies charged with overseeing the environmental impacts of international transport are the International Civil Aviation Organization (ICAO) and the International Maritime Organization(IMO).

The ICAO has said that next year at its assembly the group will decide on a global-market-based measure to reduce carbon emissions. (Meantime airlines have acted on their own; in 2009, the International Air Transport Association industry group pledged to improve fuel efficiency 1.5 percent each year until 2020, when emissions will peak, and to halve 2005-level emissions by 2050.) And the IMO has set an energy-efficiency requirement for ships built in 2025, but not an overall carbon-emissions target .

The parties at COP21 could include language to direct those organizations to cut emissions from international shipping. But, as Politico reports, that requires a delicate balancing act: Many of the maritime nations most threatened by rising sea levels also rely on shipping and air travel for their economic health. As of Thursday evening, the draft text for the Paris treaty did not contain the words “shipping” or “aviation.”

Even if world leaders could determine carbon cuts for these industries, significant advances in technology and deployment would need to happen to make them possible.

Electric cars are growing cheaper and more accessible by the day, but electric propulsion doesn’t seem likely for international transit. When you’re out at sea or up in the air, you can’t stop to plug in and recharge your batteries. Additionally, air travel is extremely sensitive to the weight of an aircraft, and the batteries needed to power a long flight will weigh too much for the foreseeable future.

The industries can cut some emissions by looking at fuel efficiency, but not a lot. Airlines already did the more attainable upgrades in that regard during the fuel price spike of 2008, says the environmental consultant Suzanne Hunt, president of Hunt Green LLC. Fuel prices impose the largest cost airlines face (up to two-fifths of total costs), so they have a strong incentive to trim their demand wherever possible.

The shipping industry doesn’t face the same pressures, because in most cases the company hiring a ship to transport cargo pays for the fuel required, says Galen Hon, who manages the shipping efficiency operation at the Carbon War Room, a D.C.-based nonprofit that advocates market-based ways to reduce carbon emissions. That means the ship owner doesn’t feel financial pressure to improve efficiency, unless customers start factoring in environmental qualities when they select a transporter (Carbon War Room developed a tool to do just that).