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If You Are Flying, You Should Be Buying Carbon Offsets

Air travel has a gigantic carbon footprint — and contrary to popular belief, carbon offsets do make a difference

Buying carbon offsets to mitigate the impact of air travel won't reverse climate change, but it will do some good. A few caveats apply. [Image credit: Ryan Greenberg / CC BY-NC / Flickr]

This post originally appeared at Ensia.


You desperately want to book that flight for the family wedding. But the frightening Fourth National Climate Assessment released by the U.S. Global Change Research Program in November has flipped on the guilt switch for you. Climate change used to be a faint background murmur you could ignore when there were fun places to go. But November’s report is clear: It’s here, and it’s bad.

The good news is, you can offset the carbon generated by your air travel. Offsetting is simple and surprisingly cheap to do. While you put greenhouse gases into the atmosphere in one place, somebody else is paid to take them out in another.

Numerous skeptics frown upon this tool, arguing that carbon offsets are ineffective or even unethical.

The doubts are worth investigating. I have been offsetting my flying for the last few years and, as an environmental ethicist, I want to get this right. So here is how I think the arguments stack up.

Argument 1. Offsets allow the rich to keep on polluting while easing their guilt

Offsets do allow payers to keep polluting, and they are mostly used by the rich. But think about it: Stopping people from flying is not the primary purpose of the offset. In my case, I’m committed to visiting overseas family from time to time. It’s an emissions burden I’m stuck with. By buying offsets, I shrink the harm I cause no matter what. My primary goal is not to lessen the guilt but to lessen the impacts.

If an additional policy mechanism were placed on top of the offsets (for example, a very high price on carbon or an imposition of a carbon emissions cap) then people may feel some economic pressure to fly less. But changing behavior is not the primary purpose of the offset; reducing harm is. In this regard, they work.

Argument 2. Offsets don’t do anything

Do carbon offsets actually reduce harm? It would surprise me if the small amount of money I pay for an offset will actually remove all the carbon I am responsible for emitting during my flight. How can I be sure the carbon removal I’m paying for wouldn’t have happened anyway? Or that it’s not just temporary or shifted to another location?

To address this, buy offsets that are independently certified to provide precisely these assurances. Standards such as the Gold Standard, the Verified Carbon Standard, and Climate Action Reserve exist to help individuals buying carbon offsets feel confident their money is doing what they intend it to do.

Although providing this reassurance remains complicated and a healthy skepticism is appropriate, I trust that concerned and informed people are working hard to make sure that purchased offsets do what they claim.

Argument 3. Carbon offsets contribute to global injustice

Some argue that by allowing the rich to buy themselves out of their guilt, carbon offsets end up exacerbating the injustice caused by climate change.

The painful reality of climate change is that the people suffering the greatest burdens are typically those who are least responsible for the problem and least economically equipped to adapt to changing and dangerous conditions. And it’s true that if all offsets do is to validate pouring more and more carbon into the atmosphere, they might indeed make poor people’s lives worse.

Fortunately, there are reasons to think they do exactly the opposite. Carbon offsets invested in the developing world represent a transfer of wealth — albeit a small one — from the rich to the poor. Such transfers can reduce global injustice if they are invested in infrastructure that improves the lives of those at risk, for example, in forest restoration, renewable energy infrastructure, or more efficient cook stoves. To the extent they provide a buffer against the effects of climate harms already occurring, they are on the right side of the moral ledger.

Argument 4. Offsets only serve to indicate how unwilling you are to change your wasteful ways

Yes and no. Buying a carbon offset is only necessary if you are committed to carrying on emitting carbon. And the reality is that, with current transportation infrastructure, most of us are.

On the other hand, paying for a carbon offset indicates a willingness to put your money where your mouth is. It can increase renewable energy generation infrastructure and create visible examples of greenhouse gas reduction projects. Restored and protected forests, methane capture projects, and solar and wind farms are a statement about a certain kind of future. If you tell your friends what you are doing, offsetting also creates a social pressure for others to recognize there is a cost to carbon.

A few caveats

To be sure you are on the right side of the offsets debate, a few more conditions must be met:

First, any offsetting must be accompanied by continued efforts to reduce your own emissions and to persuade elected officials to pursue a less carbon-intensive path. Buying an offset is a stop-gap measure. Nobody should think this is all they have to do to address climate warming.

Second, even as you purchase offsets, remain skeptical about whether the shockingly small amount they cost is actually enough. To compensate, consider purchasing 25% or 50% more offsets than the trip demands.

Third, offsets should not provide an excuse for shifting the burden of climate change mitigation entirely to individuals. Nothing you do is going to come close to what corporations and governments must accomplish on a far larger scale.

With these conditions in place, however, the conclusion is clear. Though not a perfect fix, the moral argument leans strongly toward purchasing offsets. They are absolutely an imperfect tool. But they absolutely make a difference.  View Ensia homepage


Christopher Preston is a University of Montana philosophy professor and author.


  1. TCSDwight | | #1

    First of all, Us Global Change Research is extremely biased. The models used for this and previous studies are flawed.

    I like this website. I've been building high performance houses here in BC for the last 16 years and I, and friends of mine, enjoy reading many of the articles on here. And the discussions at the end of each article, especially.
    However, lately this site has turned more and more of its materials to the none existent "Climate Crisis".
    Climate change is happening, make no mistake about that. It's been happening since the beginning of time. But there's nothing unusual account the current climate. In fact, have you noticed the date that the base reports use for their comparisons? 1951, I believe? We haven't come close to the average temperature of the 1930's (and that wasn't man caused CO2) There's been no appreciable increase in the GAT in the last 20 years, which proves all of the early climate models wrong. If there was no global warming then, why are we still looking for it now?
    CO2 is not a villian. In fact, it's likely our Savior. It's plant food. We could use more plants.
    Oh, and contrary to the social opinions fueled by hysteria, weather related disasters are not getting worse (the real world data shows that). And a warmer GAT would actually lesson the number and severity of those events.
    Sorry for the rant. I'm just tired of climate crisis zealots trying to tell me that taking more of my money is somehow going to change the world.
    There's a lot more important things to worry about, like plastics?

    1. fourforhome | | #2

      And I'll add, "When the coin in the coffer rings, the soul from Purgatory springs." ~ Johann Tetzel, selling indulgences to pay for Rome's New Deal (St. Peter's Basilica)

    2. jason_stratton | | #14

      There are a lot of people like myself who have scientific degrees(Biochem) and have worked as a bench researcher in the past, who find the whole field of climate science to be largely unreliable(unreproduceable), which is about the worst thing science can be. I went into it with a open mind, I looked at the data, I just can't sign off on the science. The publication bias, the firing of people like Peter Ridd that don't support the consensus, it is just no longer science, its politics. The only climate scientists that are left that don't support the consensus are the ones that are tenured or greatly accomplished and cant be fired like Roy Spencer(Exceptional Scientific Achievement Medal). Spencer placed a speech by Micheal Crichton, who like me looked into the field with an open mind and was disappointed, on his blog. It is educational. I still appreciate building science as a field though. Just saying I wont be buying any offsets.

  2. this_page_left_blank | | #3

    "We haven't come close to the average temperature of the 1930's"

    If you're going to make stupid arguments, at least make sure that you don't make claims so obviously wrong that they can be debunked in under 5 seconds.

    The CO2 as plant food argument is so ridiculous, it makes me wonder whether it was originally proposed satirically. It's been debunked many times.

    "Oh, and contrary to the social opinions fueled by hysteria, weather related disasters are not getting worse (the real world data shows that)."
    Ok, let's see it.

    "And a warmer GAT would actually lesson the number and severity of those events."
    Please cite a source for this claim, which contradicts the overwhelming consensus of the climate science community.

    1. Expert Member
      Dana Dorsett | | #4

      But Trevor, you have to drink the Kool Aid to REALLY understand this stuff... ;-)

      There are zealots of all stripes, but the fringe climate change cause denial zealots are nearly impossible to convince that the risks (and solutions) are real. Facts & logic bounce off the wall of "alternative facts", and penetrating that wall is often an exercise in futility.

      The best one can do is to point out that the costs of the proposed solutions are largely negative (saves money rather than costs, but requires some changes in priority), and even where cost-positive can be viewed as an inexpensive insurance policy against the trailing edge possibility that the climates scientists might actually be onto something.

      Whether the arguments for buying carbon offsets are good enough is completely open to debate. I'd personally rather spend any carbon-offset money on things that I can personally manage and measure than hand it over to some organization that may or may not manage it as well. YMMV.

    2. jason_stratton | | #21

      I'm not going to defend someone else's comments. I will only say where I live, temps have been pretty close to 1930s temps.

      Also, plants likely evolved on a earth with significantly higher CO2 than they currently have. That article is wrong in that increasing CO2 decreases water use 5-20 percent. Most plants are not fully adapted to these recent low CO2 levels and struggle to bind carbon. Increasing CO2 will cause a greening of the earth and will plants will bind more carbon but not enough to compensate for what we are putting out.

  3. TCSDwight | | #5

    Sorry Trevor, I didn't think that this was the forum for having to provide links to every comment. especially when the science is far from "settled".

    "More than 31,000 scientists across the U.S. – including more than 9,000 Ph.D.s in fields such as atmospheric science, climatology, Earth science, environment and dozens of other specialties – have signed a petition rejecting “global warming,” the assumption that the human production of greenhouse gases is damaging Earth’s climate."


    There is so much to teach you guys.....
    When Michael Mann presented his Hockey Stick to the IPCC and the associated countries jumped on the bandwagon, I too was on that bandwagon. But when the guy that created the graph and Screamed "CRISIS" refuses to share his math behind it his findings, something in me told me to look at it further.
    Check out "climategate" for some interesting reading.

    1. GBA Editor
      1. Expert Member
        MALCOLM TAYLOR | | #8

        At some point we have to stop being apologetic about believing settled science, and pretending there is some sort of debate about climate change. There may have been some period in the past when scepticism made a little sense. That's long over. We need to move on.

  4. norm_farwell | | #7

    I searched the GBA site and found this is your first post, Dwight. So I think you are probably trolling us all, but on the off chance...

    No, 30,000 scientists have not said climate change is a hoax. That statement is actually a hoax.

    Most of the rest of us know that the Heartland Institute is a propaganda machine designed and funded by the Koch brothers to baffle and confuse peasants like ourselves so that billionaires can undermine the common good and avoid paying their fair share. Jane Mayer's book _Dark Money_ explains how the game works. Also this:

    This is an interesting article, thanks to GBA for publishing it. It reminds me of something I saw a while back in Mike Berners-Lee's book _How Bad Are Bananas? The Carbon Footprint of Everything_. According to his research the net carbon benefit of spending $1 on a well-executed rainforest protection project is 100 times greater than spending $1 on solar panels, and would actually offset something like $20 spent on air travel.

    Which also makes me think that we really should not be using rainforest woods at all in construction.

  5. jkstew | | #9

    Why should flying "flip the guilt switch"? It's an extremely efficient and safe mode of travel. Look at these charts on mpg/seat of various airliners. You can't touch the combined speed, safety, and efficiency with any ground-based transportation.

    1. this_page_left_blank | | #11

      It's not the efficiency that is the issue, it's the overall carbon cost. Comparing air travel to automobile travel in terms of kg/km per person is missing the point. The alternative to flying a 4000km round trip is not usually driving 4000km, it's not taking the trip at all. Very few people would drive across the country for a vacation, while very few would think twice about hopping on a plane for an ocean crossing flight. Air travel, while sometimes lower energy cost per distance, almost always represents a high energy expenditure, and usually a frivolous one.

  6. Expert Member
    Peter Engle | | #10

    Jay: Yes, you can. Look here:

    Air travel (at least on the corridor selected) has similar CO2 footprint to other common modes of transportation, except for buses. I suspect that you forgot to correct for the number of passengers per vehicle, and the CO2 production of the various fuels. The aircraft mpg rating shown on the wiki is per passenger. EPA MPG data on cars is per vehicle. If you put 4 people in a car, you get almost the same mpg as with only one, making the per passenger mpg 4x greater than the EPA estimate. Nat. Geo. corrected for the average passenger capacity of each mode of travel in their numbers (80% full for airlines, and 2.2 passengers per auto).

    Also, as discussed in the Nat. Geo. article, certain fuels produce more CO2 per gallon than others, and they correct for that. Jet fuels are heavier (6.7 lb/gal.) than gasoline (5.9 lb/gal.) and therefore produce more CO2 per gallon.

    Finally, our airplane trips tend to be longer than our car trips. So it's not really CO2 per passenger mile that is important here, it is CO2 per passenger trip. By that metric, our plane trips generate LOTS more CO2 than our average car ride and that's enough reason to "trip the guilt switch." For some people anyhow.

    1. jkstew | | #12

      I stand by my statement: "...You can't touch the combined speed, safety, and efficiency with any ground-based transportation"

  7. GBA Editor
    Martin Holladay | | #13

    To summarize: If you have to travel 1,000 or 2,000 or 3,000 miles, airplanes aren't an egregiously bad choice from a carbon perspective. Here are the two sticking points:
    (1) Perhaps we should we be asking ourselves "Is this trip really necessary?" before each trip -- whether by car or by airplane.
    (2) Electric vehicles charged by renewable energy sources will eventually reduce the carbon impact of most automobile miles -- but we don't yet have a good way to reduce the carbon impact of flying.

  8. TCSDwight | | #15

    Nfarwell: No I haven't been trolling websites. I've been building for 30 years and high performance homes for almost two decades. I am certified R2000, Energy Star and Built Green. I have a seat on the CHBA Net Zero Energy Council. Much of what GBA has to offer interests me and I'm thankful for the contributors. Just because I haven't posted comments before, you think me a troll?

    There's a lot of misleading information out there and most of it is regurgitated from something that has already been proven incorrect.

    There are many drivers in our climate but the three biggest are:

    First is Latitude – are you in the torrid, temperate or frigid zone? These climatic zones are defined by the intensity of heat delivered to Earth’s surface by the sun. (Much can be said of each of these)

    The second weather-maker is the local environment - geography, topography, winds, ocean currents and human activity (heat island effect)

    The third weather-maker relates to cycles in the solar system and the sun in particular.

    Nowhere have you ever heard a weather man give a forecast based on the CO2 in the atmosphere. That's because it has little effect on GAT.

    Notice one thing about the three big drivers of weather – not one is measurably affected by the trace amount of carbon dioxide gas in the atmosphere.

    No level of carbon taxes or emission targets will stop Earth’s climate from changing. Nature rules, not politicians. We must aim for resilience, but be prepared to adapt.

    On a side note, the "Global Cooling" of the 70's had scientists seriously considering ways to melt the arctic in order to avoid another ice age. Had they succeeded in implementing those measures, we may not even be here to discuss this "new" crisis.

    The science is not settled. And if trillions are going to be spent to battle this non-existent crisis, someone needs to put all the scientists and their data from both sides in a room for a serious debate and significant period of time to come up with what the science really is.

    1. GBA Editor
      Martin Holladay | | #16

      You wrote, "Nowhere have you ever heard a weather man give a forecast based on the CO2 in the atmosphere. "

      That's because a weather forecaster is concerned with weather, not climate. If you're interested in the weather, talk to a meteorologist. But if you are interested in the climate, talk to a climate scientist.

      Confusion on this issue is common. Lots of people don't realize that climate is different from weather. You seem to share this confusion -- at least to a certain extent.

  9. TCSDwight | | #17

    Sorry Martin. No confusion. We are still talking about the same thing. Isn't "Climate defined as" the composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years."?

    1. GBA Editor
      Martin Holladay | | #18

      "We are still talking about the same thing."

      No, we're not. Here's an article that explains the difference: "What’s the Difference Between Weather and Climate?"

    2. Expert Member
      Dana Dorsett | | #19

      That's a reasonable definition of climate, and that's why "Nowhere have you ever heard a weather man give a forecast based on the CO2 in the atmosphere. " is a nonsensical statement that sounds like "confusion".

      If a weather man were using the short term trends of local CO2 concentration as part of the near term weather forecasting he might be better off casting chicken guts to come up with the 10 day forecast. The daily (or average) local CO2 content is completely irrelevent for predicting the near term weather, but trends in the average global CO2 (and other atmospheric component) contents over time are very relevant for predicting the global climate trends.

      To ignore long term atmospheric gas averages when predicting the climate trends would be similarly silly. The greenhouse effect model in it's basic form is simple and powerful, but earth climate is more complex than that. One of the real questions around climate science and CO2 is where the CO2 being release from fossil burning is ending up. Only about half is hanging around in the atmosphere for any significant length of time. Most of that question has been answered the bulk of the "missing" additional CO2 is being dissolved into the ocean, not being gobbled up by plants, which has it's own set of long term consequences. If the net CO2 released by fossil fuel burning since the beginning of the industrial age were in the atmosphere we would already be cooked by the net extra heat trapped- the oceans have been a pretty good buffer, but doesn't have infinite capacity.

      Planets WITHOUT phase changing surface liquids/solids and sufficient biological activity changing atmospheric concentrations dynamically follow the simpler models pretty well, where using the characteristics of the atmosphere and solar intensity predict temperatures based at the surface. But we don't live on Venus or Mars, where the surface & upper atmosphere albedo is fairly constant, as is the atmospheric content. The climate model on this planet is considerably more complex, but that doesn't mean the fundamentals of the simple can/should be ignored. More CO2 means higher temperatures over the long term, and it's not much a mystery where the additional CO2 is coming from, only where it's going to.

      Given that non-emitting/very low-emitting energy sources are now cheaper (and getting cheaper year on year) than the "dig it up , set it on fire" method of getting energy, the cost of reducing or eliminating those emissions is negative going forward, worth doing even in the simplest economic model. But the ancillary economic & health benefits of emitting less PM2.5, NOx/SOx etc also have value beyond any climate change mitigation benefit, even when discounting the climate change benefit to zero.

      Even if for whatever reason you believe the whole climate science approach is BS and hysteria with error bars on the data too big to matter, if the solutions are cost neutral / cost negative they should be implemented "just in case" the 0.0001% chance that there is something to it the consequences can be avoided.

      1. jason_stratton | | #20

        More CO2 does mean higher temperatures. That is just simple thermodynamics. The net result is a rather modest warming that would be centuries before any real environmental consequences could result. That is because CO2 is a rather weak greenhouse gas. Centuries, at the pace of current technological development is adequate for carbon fixing technologies to develop. The models all get drastic warming by predicting that there will be a water multiplier. Simply put when temperature goes up, water vapor goes up and water vapor is a very effective greenhouse gas. They typical multiplier is about 2-3. We have not seen this level of warming. In my neck of the woods we have had a warm 30 or so years but we are not significantly warmer than the 1930s. The dust bowl was a pretty big deal here. Farmers care an awful lot about keeping accurate climate records. Their are many variables that are still not understood. The nature of clouds is perhaps the most important of many. If rising temps produce increased cloud cover, it is possible this could produce a negative multiplier instead of a positive multiplier. If someone tells you science is settled, they are a politician not a scientist.

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