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Study Finds That Air Traffic Could Become a Major Factor in Global Warming

Time series of SRES aviation CO2 emission scenarios (with outlook to 2100). Credit: ACS, Owen et al. Click to enlarge.

A new study by a team at the Dalton Research Institute in the UK projects that carbon dioxide and other gases from air traffic will become a significant source of global warming as they double or triple by 2050. The study was published in the in ACS journal Environmental Science & Technology.

Bethan Owen and colleagues note that aviation is not now one of the main drivers of global warming, with international aviation (the source of 60% of carbon dioxide emissions from aircraft) not even included in the Kyoto Protocol. Global air traffic currently contributes to between 2 and 3% of carbon dioxide emissions.

However, the scientists’ computer model forecast that emissions of carbon dioxide from aviation will likely double or triple within the next 50 years. By 2100, carbon dioxide emissions could increase by up to seven times the current levels, they say.

Even though there have been significant improvements in fuel efficiency through aircraft technology and operational management, this has been outweighed by the increase in air traffic.

—Owen et al.

The calculates future global aviation emissions of carbon dioxide and NOx from air traffic under four of the IPCC/SRES (Intergovernmental Panel on Climate Change/Special Report on Emissions Scenarios) scenarios: A1B, A2, B1, and B2. In addition, a mitigation scenario has been calculated for the B1 scenario, requiring rapid and significant technology development and transition.

The team used a global model of aircraft movements and emissions (FAST) to calculate fuel use and emissions to 2050 with a further outlook to 2100. The aviation emission scenarios presented are designed to interpret the SRES and have been developed to aid in the quantification of the climate change impacts of aviation. The team made demand projections for each scenario, determined by SRES economic growth factors and the SRES storylines.

The authors examined technology trends in detail and developed for each scenario plausible projections for fuel efficiency and emissions control technology appropriate to the individual SRES storylines. The technology trends that are applied are calculated from bottom-up inventory calculations and industry technology trends and targets.

Future emissions of carbon dioxide are projected to grow between 2000 and 2050 by a factor in the range of 2.0 and 3.6 depending on the scenario. Emissions of oxides of nitrogen associated with aviation over the same period are projected to grow by between a factor of 1.2 and 2.7.


  • Bethan Owen, David S. Lee and Ling Lim (2010) Flying into the Future: Aviation Emissions Scenarios to 2050. Environ. Sci. Technol., 44 (7), pp 2255–2260 doi: 10.1021/es902530z



Studies like these get based on the availability of fuel according to the IEA, which is paid for by Governments and whose job has always been to prevent 'panic' by 'reassuring' people that there is plenty of oil, and not to upset the Saudis' by calling into question their entirely unaudited claims of reserves, which remarkably have never changed by so much as a barrel after billions have been extracted.
If air travel is going to double or triple or whatever it will do on on something other than oil.

Donough Shanahan

But the real important information is missing from the study; if air traffic is increasing then it is likely that land based traffic will also continue. Thus I would expect that the percentages would stay similar thus meaning that air traffic will be no more significant in the future than now.
Even the worst case as the report puts out air traffic will still contribute less than 10% to emissions; comparible to deforestation.


Actually Donough Shanahan it is hoped that by 2050 much of the land based traffic will be electrified, so even if it increases its GHG emissions should drop. However, unless we start building solar powered airships air travel will still need to burn hydrocarbons.


I expect by 2035 or so all jetfuel will be synthetic/bio/h2 simply due to fuel cost. I do NOT expect alot of people flying by then also again due to costs.

Sanity Chk

Both the military and commercial aviation industries have long recognized the need to find a renewable replacement for jet fuel. Different blends have already been flight tested and it's fairly evident that biofuels will be dominant within 20 years or so.

See today's GCC article:

UOP, PetroChina, Air China and Boeing to Collaborate with Government Agencies on Sustainable Aviation Biofuels Industry in China

It's too bad this article didn't take this into account, however, I believe that their projections of NOx will not be affected by renewable fuels.


Unless engines and planes are completely redesigned, we may have to do with jet engines gas guzzlers for many decades. When ground transport is electrified and greener electricity is produced, air traffic emission share may more than triple from 3% to 10++% by 2050.

Henry Gibson

It is known that automobile fuel use can be nearly eliminated by electric automobiles with an average non extended range of 20 miles. Range extenders should always be provided.

Fission reactors can produce and are producing hydrogen at relatively high cost right now, but this cost is less than the price of oil for the same amount of energy. And if the electricity is used in an electric car it may be more than five times as efficient and less expensive.

Thermal chemical processes can be developed and fitted to new and current fission reactors to produce even cheaper hydrogen. A process should be invented to produce CO from CO2 with heat or even first with electricity. This will allow the direct industrial recycling of CO2. Much of it can be done with existing processes.

Motorways can be electrified with methods invented a hundred years ago and also more modern methods at relatively low cost compared to the cost of the motor way, and the power to the contact is supplied with cheap direct current cables made with cheap sodium for the conductor. This electrification only suppliments the battery and fuel powered range extender with low cost, relative to gasoline, fission energy. There are very low losses with direct current cables and no power is being consumed.

Power can be beamed up from the earth to aircraft with radar waves very similar to the proposals to beam solar produced electricity down from space. (It would be cheaper to produce fission electricity in orbit and beam it down, and near earth space is already filled with radiation belts.) Power beam failure and take off is done with fuel in electric hybrid turbine and propellor systems. All planes with close destinations can be operated at lower speeds and higher efficiency without significant increase in total travel time considering time spent in airports and travel to and from airports.

Autotrains with the same Waggons used in the chunnel should be put in service between such cities, as LA and Las Vegas, to eliminate much of the need for and inconvenience with airtravel and extra overnight stays in hotels.

With very large battery bank locomotives now nearly economically possible with Durathon batteries, cheap non-continuous third rail electrification systems can be built, and all new light rail systems should eliminate the catenary and associated expense and distraction. Range extender engines now can garantee against electrification failure at low cost. Computer and electronic controls can eliminate cheaply most hazzards associated with third rail contact. Electronic high voltage direct current distribution cable systems are efficient and not as likely to be damaged.

The chunnel trains should be fitted with range extender engine generators that feed the motors directly without electronics for a speed of ten miles an hour. Microturbines can clean up the exhaust and supply lights.

There is a great deal of oil and even more coal and oil shale to make aircraft fuel, and every refinery should have several small nuclear reactors a hundred feet down for process heat. Using very high temperature steam from fission in gasification and refining processes can compensate more than fully for the fossil fuels used in aircraft. But then all coal now used for electric production can be diverted to liquid fuel production. ..HG..

Sanity Chk

Unlike the auto industry, aircraft manufacturers have been relentlessly driven to increase fuel economy by their customers for the past 3 decades. This has led them to lighten aircraft every way they can, and drive engine manufacturers to increase efficiency.

Today's engines must be at least twice as efficient as those of 20 or 30 years ago, and half as noisy. They are also producing substantially lower NOx emissions.

With new acft & engine design refinements, it's possible we may see 30-40% improvement in efficiency within a few decades.


Sanity Check: Something like 40,000 to 80,000 miles of high speed electrified trains could reduce short range flights to almost zero. China and EU are working at it and will meet that goal between 2020 and 2030.

That's another smart way to reduce liquid fuel consumption and GHG emissions. Electric trains are one of the lower cost and safest way to move people around.

Aaron Turpen

All we have to do to combat this is send Al Gore on continual around the world flights. Then the Gore Effect will negate any global warming caused by air traffic and probably more.

Proven science right here. Every time Gore lands somewhere to talk about AGW, it snows or the temperature drops noticeably.

AlScience to the rescue!


Harvey.. do you have any idea how much high speed rail costs per mile?

Ill give you a hint .. just replacing a useful amount of air traffic with rail would cost more then building the entire h2 economy.

Will S

Aaron, you seem to be channeling the "Goracle". Such comments are laughably dismissed.


We could have made investments in rail, but went for the Interstate Highway system instead. It was seen that the private sector would take care of rail. That is why 2/3 of all freight is carried by truck today. Some decisions are SO important for the future that they should not be left up to idiots.

Sanity Chk

Wintermane: Forget H2 for transportation. It's too inefficient to produce and too heavy and bulky to carry on a vehicle.

SJC: We are where we are wrt a lousy rail system. There are several high-speed rail systems funded in various parts of the country, including a maglev project connecting LA with SFO. If these are successful, we will likely see more in the future.


My point is that a lot of freight goes by big rigs that get 4 mpg with LOTS of roll and wind resistance when 2/3 should go by rail and not by truck. Long haul trucking may be cash flow for some, but may not be the best for the nation.

Sanity Chk

Rail freight transportation capacity is quite limited in our current system. Further, it is unreliable, relatively slow, and has to be handled by trucks on both ends for shipping and receiving. The market has decided this one but you are right, things could be a lot better if this had been a serious infrastructure priority over the past sixty years. All we can hope for is that the drive for efficiency motivates change in the infrastructure for shipping freight.

This is where we can all get involved. Write to your senator and congressional representatives and let them know how you feel about it.

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