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Study Finds Traveling by Car Increases Global Temperatures More than Traveling by Plane In the Long Term

Temperature change per transport work by mode for various years after the emissions: per passenger kilometer for passenger travel (left) and per ton-kilometer for freight transport (right). Global average values for the year 2000. Bars represent 1 SD. Credit: ACS, Borken-Kleefeld et al. Click to enlarge.

A new study comparing both the absolute and normalized climate impacts of current passenger and freight transportation finds that driving a car increases global temperatures in the long run more than making the same long-distance journey by air. However, in the short run travelling by air has a larger adverse climate impact because airplanes strongly affect short-lived warming processes at high altitudes.

The researchers used a suite of climate chemistry models to consider the climate effects of all long- and short-lived gases, aerosols and cloud effects, not just carbon dioxide, resulting from transport worldwide.

Jens Borken-Kleefeld and colleagues performed calculations for the integrated radiative forcing and mean temperature change, for different time horizons and various measures of transport work. The study was published the in ACS journal Environmental Science & Technology.

An unambiguous ranking of the specific climate impact can be established for freight transportation, with shipping and rail having lowest and light trucks and air transport having highest specific impact for all cases calculated. Passenger travel with rail, coach or two- and three-wheelers has on average the lowest specific climate impact also on short time horizons. Air travel has the highest specific impact on short-term warming, while on long-term warming car travel has an equal or higher impact per passenger-kilometer.

—Borken-Kleefeld et al.

They concluded that in the long run the global temperature increase from a car trip will be on average higher than from a plane journey of the same distance. However, in the first years after the journey, air travel increases global temperatures four times more than car travel. Passenger trains and buses cause four to five times less impact than automobile travel for every mile a passenger travels.

Findings for freight transport (year 2000) include:

  • The specific climate impact of air transport is 3 to 42 times higher, for a light truck it is 2 to 8 times higher than average truck transport.
  • Rail transport of heavy goods has a 4 to 10 times lower specific climate impact than trucking, while it varies from negligible to half to a similar impact for volume products.
  • Ship transport has by far the lowest climate impact: It exerts 5 to 10 to 30 times less warming per transport work than trucking and is even cooling on shorter time scales.

Findings for passenger transport (year 2000) include:

  • Rail travel has at least a factor 4 lower specific impact and is cooling on shorter times, bus and coach travel has 2 to 5 times lower specific impact, while travel with two- or three-wheelers has up to a factor 2 lower specific climate impact than car travel.
  • Air travel results in a lower temperature change per passenger-kilometer than car travel on the long run; the integrated radiative forcing of air travel is on short- to medium time horizons much higher than for car travel
  • Per passenger-hour traveled however, aviations climate impact is a factor 6 to 47 higher than the impact from car travel.

As planes fly at high altitudes, their impact on ozone and clouds is disproportionately high, though short lived. Although the exact magnitude is uncertain, the net effect is a strong, short-term, temperature increase. Car travel emits more carbon dioxide than air travel per passenger mile. As carbon dioxide remains in the atmosphere longer than the other gases, cars have a more harmful impact on climate change in the long term.

—Dr. Jens Borken-Kleefeld


  • Jens Borken-Kleefeld, Terje Berntsen and Jan Fuglestvedt (2010) Specific Climate Impact of Passenger and Freight Transport. Environ. Sci. Technol., 44 (15), pp 5700–5706 doi: 10.1021/es9039693



Well there's short term and then there's really short term: I remember something from 9/11, when Bush ordered all airplanes grounded for three days, the skys were clear of sunlight reflecting contrails and the average temperature went up by 3 degrees for the duration.


High speed e-trains are the cleanest way to travel over land areas. EU and Japan have realized that 30 years ago and have built many 1000 Km of new high speed lines + high speed e-trains. China is currently building 12,000+ miles of new e-lines + hundreds of new high speed e-trains. USA and Canada have not done much so far. We are 30+ years behind and catching up will be a major challenge.

EVs may come second best within a few years. Hybrid buses could also do much better than our large 4 x 4 gas guzzlers. Airplanes will stay a must over seas but they will also use less fuel.

The Goracle


"...all airplanes grounded for three days, the skys were clear of sunlight reflecting contrails and the average temperature went up by 3 degrees for the duration."

Oh, my gosh, some people on this site are so stupid... Maybe you can get the moderator to delete your post before more people read it? What better statement to broadcast to all a complete fantasy, and lack of understanding? Yikes! And people like this are trying to pass laws drastically increasing the size and scope of incompetent government bureaucracies, massively increasing taxes, and forcing people into primitive lifestyles in order to please their enviro-god.

Praise be to Crazed Poodle.



With a few more thousand Goracles, USA will fall back to stone age within one century or even less. Out of coal, oil and NG, Goracles will freeze, suffocate, go hungry and very thirsty before (others) can save them with sustainable cleaner energy sources.

Let's hope that they are a very small minority.


@ Goracle, you used a lot of characters to say absolutely nothing. If you have any relevant statements (I'd prefere somehow supported by evidence), then please tell them, otherwise you might better start informing yourself.

Flying carbon-neutral is actually quite cheap. Simply pay farmers to produce biochar (or in the short run, simply trees. they can easily start planting trees today and than make the preparations to start producing biochar within a few years.)

As an example : a boeing 747 can fly 13500km on 217000 L of fuel, transporting 500 people.
That makes 434 litres per person for 13500 km (which is a much-more-than-average distance)

434 litres of fuel makes 1371 kg of CO2 = 374kg of carbon.

if you pay the very generous price of 200$/ton of agrichar to the farmers, it would only make 75$.
(they can simply mix the agrichar with their own farming-soil to increase productivity of next year)

So, add 75$ to the ticket price (for this long-distance-flight), and pay it to farmers to increase their own soil-quality or to (re)plant forests.

Of course, many farmers can produce agrichar as a by-product of normal farming, and the production of agrichar also can produce valuable by-products. But even if you simply grow biomass-crops and only produce cheap biochar and burn the coproduced gases, 200$/ton is generous.

Considering how many trips of that distance 'normal' people make per year, the price for a green airtravel industry is peanuts compared to electric vehicles.

You could also pay people to collect burnable dead wood in forests and to produce biochar to increase soilquality of nearby farmers. Considering the heat waves of recent history and close future, even without biochar production it would be wise to 'clean' the forests of these biomasses to limit wildfire intensity and probability. (The chance of big wildfires decreases and the intensity decreases (lower heat intensity means that the trees don't die when a forest has burnt)

Flying green is easy, cheap, social, increases soil quality for generations to come, supports local economies, fights unemployment and will be supported by the farming lobby and petrol lobby. What do you need more ?
A smart politician


It is like I said, Goracle will continue to pollute this site.

The Goracle


Yes, "I hate you" is one of the most often used statements of Global Warming® (since rebranded Climate Change®, since rebranded CO2 Pollution®) "scientists."

Thank you all for that!

Along the line of no air traffic over the US for three days increasing average temperatures by 3 degrees, I helped solve that terrible problem by only walking backward while the planes were grounded (science!). Now I can claim to be in the same league as the rest of you!

Praise be to Crazed ___ Poodle.



The Goracle - You may want to look in to the very strong possibility that you have been brainwashed.

People with closed minds contribute little to discussions here. What they say, and what they will say, is totally predictable.


When I made that statement I was going solely by memory (as I said) but Google is your friend;

What really happened was that the diurnal temperature range increased. Daytime highs went up and nighttime lows went down. So that's a "mea culpa" from me.

Lucy Daniels

Wow this was extremely informative and really interesting. Thanks! I live in NYC and just sold my car so that I could personally reduce my carbon footprint. I hope that other New Yorkers will do the same. I got a great deal at Big Bucks Auto. Check out this great program they have!



"if you pay the very generous price of 200$/ton of agrichar to the farmers , it would only make 75$.
(they can simply mix the agrichar with their own farming-soil to increase productivity of next year)

So, add 75$ to the ticket price (for this long-distance-flight), and pay it to farmers to increase their own soil-quality or to (re)plant forests. "

This is the root of all the Climate change cult it is all about redistribution of capital and wealth from 1st world economies to 3rd world serfs. This has and always will be the goal of Marxists which the greens do a terrible job of hiding the blatant Marxist tactics. its one thing to be a conservationist and nature lover its another thing entirely to be a Marxist masquerading as a environmentalist. most true conservationists are all for green technologies but not at the expense of killing our standards of living and transferring our hard earned wealth to 3rd worlders who wont stop breeding themselves into trouble. I work to hard and spent to much time and money in University to let some marxist-watermellon confiscate my wealth for strangers in the 3rd world.


Just a side note to the air traffic after 9/11 and the atmosphere.

"The near-total shutdown of civil air traffic during the three days following the September 11, 2001 attacks afforded a unique opportunity in which to observe the climate of the United States absent from the effect of contrails. During this period, an increase in diurnal temperature variation of over 1 °C (1.8 °F) was observed in some parts of the U.S."


Now we can wait for Goracle to say it was a plot and conspiracy.


Wow! I haven't seen someone use the word "Marxist" that many times in one paragraph since I stopped watching FauxNews.


TX, you can lose the M word. You can make your point SO many better ways.


@ TXGeologist,

I was not talking about 3rd world farmers, but about farmers in the same country where the paying traveler lives. Although theoretically, it would be most efficient to pay low-wage farmers, it is very difficult to controll whether they actualy do produce the biochar, and not simply burn the biomass or only say they produce it or sell their biochar production to several 'clients'. Good controll of actual production will be difficult and is impossible to globalize.

This has nothing to do with distributing wealth, but to let the free market - within your own country - decide who can sequester carbon most efficiently. I used the 200$/ton just to calculate that even a rediculously high price for the farmer would be very affordable. In reality, the price to the traveler would certainly be much lower, since the free market should decide which farmer gets the job (of course the cheapest). When demand for carbon sequestration rises, and consequently the price per ton, it would become ever more economical for farmers or even big industries to start producing agrichar on ever bigger industrial scale. It should become an industry that is governed by supply and demand, thus selfregulating to maximal efficiency and productivity. The advantage of jumpstarting such an industry is that other industries can do business as usual while being carbon-neutral at minimal costs, and that eventualy, once the agrichar-industry is mature, it can be expanded cheaply to do cleaning of the air at minimal costs, while dramatically increasing soil quality in the countries that are playing the game.
If in this free market economy soil quality increases and productivity of farming increases, food prices will decrease, or exports will increase.

Anyway, don't fool yourselve. someone will pay the price of climate change if we don't prevent it. Since obviously (as long as you admit the reality of climate change) Americans and Europeans are most responsible for the total CO2-problem, we will have to carry the burden.
Also obviously, the richer you are, the more you can loose. A nice storm in New Orleans destroyed more property value than the value of all the houses of a small african country together.

If you prefer the collectivity (= state) to pay the expenses instead of the people who are responsible for the costs, than that's a vision you can try to defend, but then, who's the marxist here ?


"not at the expense of killing our standards of living and transferring our hard earned wealth to 3rd worlders who wont stop breeding themselves into trouble" [and the rest of your diatribe]


The Goracle


It's called weather. And this from the same people who shriek "THAT"S WEATHER, NOT CLIMATE" when people claim that heavy snowfalls prove or disprove something related to climate.

You people are SO silly!!!



I was hoping TX would contribute rational thought, but alas another Goracle.


Subsequent research undertaken in 2008 suggested that the original research from 2002 was mistaken:


But contrails do have a significant effect which is currently being evaluated under the EU's QUANTIFY project:



Sounds like we should all go back to flying lighter than air aircraft. Let's bring back the Hindenburg.


@ Lucas

"People with closed minds contribute little to discussions here. What they say, and what they will say, is totally predictable."

One could also apply the same as far as HarveyD is concerned.


Or Mannstein or any one of us. We all have our favorite themes. When they are negative and destructive they don't contribute anything but hate, fear and loathing.


"Also obviously, the richer you are, the more you can loose."

I'm marking this up because I see it too often and suffer from Distraught English Tutor Syndrome.

Also, who exactly is "Crazed____Poodle?"


Proper English is nice, but I am much more interested in content. It is the quality of the mind more than what teachers they had.

Account Deleted

The simplest and easiest way of cutting your carbon footprint is to walk, particularly on short journeys. Its excellent exercise, saves money on petrol and of course better for the environment!

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