A carbon offset is a payment to avoid greenhouse gas emissions by others elsewhere in the world according to the same amount that one has emitted oneself, in order to neutralize one’s own carbon footprint. There are several effective ways to compensate your carbon footprint (although carbon offsetting is focused on avoiding harm instead of doing good, and there are probably more effective ways to do good than to avoid harm, which means carbon offsetting is not the most effectively altruistic thing to do).
If carbon offsetting is permissible, is meat offsetting also permissible and positively effective? Meat offsetting means paying others to reduce their meat consumption at the same amount of ones own meat consumption. If you eat one kilogram of meat, you can financially support a campaign by an animal rights organization that reduces meat consumption by others with one kilogram. From an animal rights perspective, meat offsetting is considered as illegitimate, comparable to murder offsetting: a murderer who kills someone and then pays someone else to save a life (e.g. donate to a GiveWell recommended charity), as if this would neutralize the harm done by the killing.
The question is: is carbon offsetting comparable to meat offsetting or murder offsetting, such that carbon offsetting is also irresponsible or immoral? Here I argue that there are several morally relevant differences between meat offsetting and carbon offsetting, such that the former is immoral but the latter is permissible and good.
1. The social welfare optimum has a positive emission rate but a zero meat consumption level
The most crucial difference between carbon offsetting and meat offsetting, is that the social welfare optimum of meat consumption is at a zero consumption rate (i.e. no meat consumption) but the social welfare of greenhouse gas emissions is (at this moment, when we do not have enough climate neutral energy alternatives to fossil fuels) at a positive emission rate.
This difference focuses on social welfare. The social welfare function is a function of the activity level (e.g. fossil fuel combustion or meat consumption) and is calculated as the difference between aggregate welfare benefits and aggregate welfare costs to all sentient beings. Sentient beings include humans, livestock animals, wild animals and their future generations. The benefits involve happiness, improved well-being and saved lives, the costs involve suffering, loss of well-being and premature deaths. If the activity level increases, both the benefits and the costs increase. The benefits are usually a concave function (like a hill), the costs are usually convex (like a valley), so the difference between benefits and costs is a concave function with a maximum at a specific activity level (see figure).
The welfare benefits of carbon emissions: strong initial increase
Consider the benefits of carbon emissions. These are the benefits related to the underlying activities, such as agriculture and fossil fuel combustion for heating and transportation. There are both benefits for the agents (the emitters, those who perform the activity) as well as benefits for the patients (the populations at risk of climate change).
Concerning benefits for the agents: imagine living with a zero carbon footprint, i.e. with zero greenhouse gas emissions. That would be a huge loss of your well-being. Almost all food is produced with a non-zero carbon footprint, so you will probably starve to death. You cannot heat a room, so in some cold regions you could freeze to death. You cannot move to warmer places, because that requires carbon emitting motorized vehicles. Also building strong houses, building dikes, using air-conditioning, using health care, extinguishing fires and irrigating land all require greenhouse gas emissions (at this moment), so you will not be able to protect yourself against extreme weather events, hurricanes, floods, heat waves, infectious diseases, forest fires and droughts. This is basically the extreme climate change scenario we all want to avoid. Completely eliminating all fossil fuels at this moment could be as bad for the global economy and for human flourishing as extreme climate change. That means that fossil fuel use is very beneficial (at this moment, when we do not have enough alternatives).
But also for the patients, the populations at risk of climate change, some positive level of greenhouse gas emissions is beneficial. People in poor Southern countries are most affected by climate change, but these people can also benefit from international trade. No fossil fuels means no transport, means no export, means lower incomes for those poor people. Those poor people can also benefit from medicine and agricultural technologies, but technological research without fossil fuel use will be much less productive. The same goes for future generations: they are also mostly affected by climate change, but they also benefit from new technologies. Fossil fuel use increases economic growth (through facilitating new technologies), and future generations benefit from economic growth. With economic growth, the consumption level increases, so future generations can consume more. Finally, economic growth allows us to invest more in new technologies and scientific research that can also benefit wild animals in the far future. If we eliminate fossil fuels, we will generate less new inventions that can benefit future human and animal generations.
These considerations mean that the benefit curve has a strong slope at low levels of activity: the difference in benefits between zero emissions and a little bit of emissions is large. Society will benefit a lot if emissions increased a little bit from zero to something. But the more we emit, the lower the extra benefits from an extra increase in activity will be, so eventually the benefit curve will flatten. There is a decreasing marginal benefit from carbon emissions. In our current situation, with large amounts of carbon emissions, society will not be harmed much if we decrease emissions a little bit, neither will society be benefitted a lot if we increase emissions a little bit.
The welfare benefits of meat consumption: very small
Now we can consider the welfare benefits of meat consumption. There are no benefits for the patients, the animals who are killed for their meat. There are benefits for the agents, the meat eaters, but these are small. Imagine living without meat consumption. You can still eat healthy and delicious vegan meat alternatives, so you will not die from starvation, and you can still experience taste pleasure. Perhaps you like animal meat a little bit more than vegan alternatives, but this benefit from animal meat is much smaller than the benefit we get from using fossil fuels. Without meat consumption, you can still visit friends, travel, have a warm shower, buy clothes,…
The welfare costs of carbon emissions: slow initial increase
Carbon emissions have an increasing marginal cost: if emission levels are low, an extra ton of CO2 emitted will cause less harm, compared to a situation when emission levels are high. At very low or zero emission levels, an extra emission is basically harmless, because the Earth has a finite CO2 absorption capacity. Imagine there are no greenhouse gas emissions, and you start to emit one ton of CO2. This emission will cause no harm, because that CO2 can be easily absorbed by the soil, the trees or the ocean. But this biosphere absorption capacity is finite, so emissions become harmful above a certain level. There is a planetary safety boundary for the amount of CO2 in the atmosphere, and this boundary is not at zero CO2 but at a positive level. The more we transgress this boundary, the more harmful an extra ton of CO2 becomes. This means that the cost curve is convex (like an upward facing valley slope).
The costs of climate change are borne by the patients: the populations at risk of climate change. These include both humans and wild animals. The impact of climate change on wild animal welfare is far from clear: it can be negative but also positive. For example, if most wild animals have net-negative lives, i.e. lives with dominating experiences of suffering instead of happiness, and if climate change decreases population sizes of wild animals, climate change could in fact decrease total wild animal suffering, because fewer animals with net-negative lives will be born. Due to this highly uncertain impact of climate change on wild animal welfare, I will only focus on scientifically more established impact evaluations on human welfare.
The harm caused to humans by climate change can be measured in economic terms as the social cost of carbon (SCC): the dollar value of human harm caused by the emission of one ton of CO2. There are many estimates of the SCC, with wide ranges of variation. An average level is around 50 dollar per ton CO2, increasing yearly with 3% (because the cost curve is convex and CO2 accumulates in the atmosphere).
This social cost includes mostly economic damage, such as loss in world GDP, but it sometimes also includes the human welfare loss in terms of premature mortality. This can be done using the value of a statistical life which can be estimated using our willingness to pay to avoid a risk of dying. How much are you willing to pay for extra road safety, such that your risk of dying by a car accident decreases with say one in a million? Using these estimates, the value of a statistical life in rich countries is lower than ten million dollars. The important fact is: this is a finite (not infinite) number, because we are not maximally risk averse, we do not take overly extreme precautionary measures at infinite cost, we do not simply abolish all risky activities like walking up a staircase, driving a bike or taking a shower (these are all potentially deadly activities).
Related to the notion of the value of a statistical life, is the notion of disability-adjusted life years (DALYs): the number of years lost due to ill-health, disability or early death. There are some estimates of the DALYs from climate change. The highest estimate I encountered in the literature, was 3 DALYs per 1000 ton CO2. Note that 1000 ton CO2 is roughly the amount emitted by an average person in a developed (rich, western) country throughout his/her life (13 ton per year for 80 years). A premature death means on average a loss of more than 30 healthy life years, i.e. more than 30 DALYs, which means that the lifetime emissions of an average person in a developed country results in less than 0,1 premature deaths due to climate change. Or in other words: 10 emitters kill one person. This is a high estimate, because most estimates are an order of magnitude lower: e.g. 0,6 DALYs (Broome, Climate Matters), 0,2 DALYs or 0,12 DALYs (Giving What We Can) per 1000 ton CO2. That means 100 emitters kill one person. This is the mortality cost of climate change, but note that those 100 emitters also indirectly save lives. For example: by using fossil fuels, they contribute to economic activity, which means paying taxes, which means government income available for health care subsidies. This is one pathway included in the benefits of fossil fuel use.
Including the value of life or DALYs in the calculations of the social cost of carbon, and including potential harms from climate change such as increased murder rates or war casualties from climate conflicts, I would give a rough, higher-end estimate of the SCC of about 100 dollar per ton CO2.
This value assumes a very low (0,1% per year) pure rate of time preference. This low rate means that the welfare of future generations count as much as the welfare of the current generations. The rate is not zero, because there is a very low probability of human extinction (assumed to be 0,1% per year) due to other causes than climate change (e.g. a global nuclear war, an asteroid impact, a supervolcano eruption, a pandemic supervirus, rogue artificially superintelligent machines,…). If the human population goes extinct, there will be no further human harm from climate change, so no further climate costs.
The estimate of the SCC also assumes a continuing economic growth (increased productivity due to new information and technologies) of a few percent per year. Economic growth means that future generations can achieve higher levels of consumption. If we prefer a smoothing of consumption over time (i.e. a kind of intergenerational justice where consumption levels between generations are not wildly different), economic growth means that the consumption related welfare of future generations can be discounted a little bit. Without such discounting, our generation would have to sacrifice almost all consumption (i.e. save everything) in order to increase the consumption levels of future generations.
The pure rate of time preference and the intergenerational consumption smoothing with economic growth are the two terms of Ramsey’s social discount rate. This discount rate translates the dollar value of future climate costs into the present value. A cost of 1 dollar in 100 years counts less than a cost of 1 dollar today. The higher the social discount rate, the lower the present value of future climate costs for future generations become.
One can argue, based on population ethical issues, that the pure rate of time preference is larger than the extinction rate of 0,1% per year. Our society is a highly nonlinear, chaotic dynamic system, which means very small differences in choices have – through a butterfly effect – a large influence on who will be born in the future. Whether a boy or a girl is born depends on the exact timing of fertilization. Suppose we do not take climate measures, so we keep a high carbon footprint, e.g. by taking the car instead of the bike or the train. As a result, future generations will have a lower welfare due to climate change. They do suffer from extra extreme weather events, but suppose that overall their net welfare is still positive, i.e. they still have lives worth living, with more positive than negative experiences. Can they complain against our choice to emit a lot of greenhouse gases? No, because in the alternative universe, where we would have reduced our carbon emissions, these future people would not exist, and other people would be born. A couple takes the train from work, arrives home a bit later, goes to bed and has sex a few seconds later, a sperm cell with a Y instead of an X chromosome fertilizes the egg, and a boy instead of a girl is born. Can we say that we have harmed future people affected by climate change when we did not take sufficient climate measures? In a sense no, because the affected people have net positive lives and the alternative choice (taking climate measures) would mean that those affected people would not exist. In summary: the stronger this butterfly effect on reproduction, the higher the pure rate of time preference becomes. And the higher this time preference rate, the lower the social cost of carbon becomes. So the SCC could be lower than 100 dollar per ton CO2.
The welfare costs of meat consumption: strong constant increase
Meat consumption has huge costs, not only for the hunted or slaughtered animals, but also for humans. Meat consumption contributes to chronic diseases, infectious zoonotic diseases and climate change. In terms of economic welfare costs for humans, eating 100 grams of meat costs 4 dollars, eating one day vegan saves 8 dollars in wealth (measured as our willingness to pay for a good health and environment).
But most of the welfare costs of meat consumption are borne by the killed animals. Here we see a strongly increasing, linear cost function. The function is linear, because killing and eating an extra animal increases the harm done to the animal a lot and is independent from how many other animals were already eaten.
The social welfare of carbon emissions and meat consumption
The figure below shows the benefit and cost functions of carbon emissions and meat consumption, based on the above explanations. The difference between benefits and costs is the social welfare.
Now we can see the clear distinction between carbon offsetting and meat offsetting. Carbon emissions have a positive social optimum level, meat consumption has a zero social optimum level. With a positive level, a complete prohibition of the activity would not be optimal. To reach the socially optimal activity level, a price mechanism is economically efficient. There is a consensus among economists that a market-based mechanism such as a carbon tax is the most economically efficient way to reach climate targets and avoid dangerous climate change. Carbon offsetting can be considered as a kind of voluntary carbon tax, and the social cost of carbon could serve as an optimal tax rate for carbon emissions, so the general, average carbon offsetting price would be around 100 dollar per ton CO2 emitted, increasing with 3% per year.
As mentioned above, from an animal rights perspective, meat offsetting is like murder offsetting. Do economists propose a murder tax? No: given the high welfare costs and low benefits of murder, the optimal tax rate of murder is basically infinite. The social optimum level of murder is zero.
The fact that the optimal meat consumption level is zero, means that meat offsetting is not universalizable: only if all meat eaters offset their meat consumption, we reach the optimum level. But at this level no-one will eat meat anymore so meat offsetting becomes superfluous. Carbon offsetting is different, because there is a non-zero optimal social welfare level of carbon emissions. People can still emit some amount of greenhouse gases, and offset those emissions to reach the social optimum emission level.
One nuance is important here. As mentioned above, the social cost of carbon, and hence the general average offsetting price is around 100 dollar per ton CO2. However, most offsetting mechanisms are much cheaper. The most cost-effective mechanisms range around 1 dollar per ton CO2. This means there is at this moment low hanging fruit that is not picked by others. If no-one else picks those most cost-effective offsets, you can. But this is not universalizable: not everyone can offset his or her own emissions at such low costs. If more low hanging fruit is picked by others, the remaining higher hanging fruit will be more costly, so the carbon offset price will increase. In the end, if everyone would offset their own emissions in line with the social optimum (according to the climate targets), the offset price will be around the social cost of carbon. If the offset price becomes higher than the SCC, it is no longer economically efficient to offset: the costs of further offsetting become higher than the benefits (the avoided climate change).
There is one offsetting mechanism that is always universalizable, because it shifts the social optimum level: investments in new technologies. Some technologies decrease the cost function and hence shift the social optimum to the right. Consider animal-free, cultured (lab-grown or clean) meat: with new technologies, we can produce and consume meat, without causing animal suffering and without having to kill animals. In this case, the cost function could drop down to zero (or to the production costs of cultured meat), and we can eat as much cultured meat as we want (or with non-zero production costs: as much as where market demand equals production costs). We can also make carbon emissions harmless, by investing in carbon capture and storage techniques. The only cost of carbon emissions becomes the cost of capturing and storing that CO2. If this becomes cheap, we can continue emitting a lot of CO2. Or instead of carbon emissions, we can consider energy use as the activity: we can invent new clean energy technologies that do not have carbon emissions, and again we can use as much of that energy as is available without causing climate harms.
Investment in research and development for clean energy technologies is highly effective, because the rest of the world, for all future generations, can benefit from those new technologies. However, currently only 3 dollar per person per year is spend globally on clean energy technology R&D. Suppose we consider a carbon offset at the social cost of carbon price of 100 dollar per ton, and we invest this in clean energy R&D. If everyone would do that, we would have extra investments worth 700 dollar per person per year (7 ton CO2/person/year x 100 dollar/ton CO2). Total investments in R&D will increase with a factor of 240. With such high levels of technological research, we are very likely to invent technologies that eliminate the climate change problem and shifts the social optimum level of energy use very far to the right. Hence, such a strategy is very universalizable (comparable to planting more fruit trees, in the fruit picking analogy).
2. Carbon offsetting does not involve basic rights violations, meat offsetting does
The above considerations looked at social welfare. This is based on a welfarist (consequentialist or utilitarian) ethic. But we can also see a distinction between carbon emissions and meat consumption from a rights based (deontological) ethic. There is in fact one basic right (unique in the sense that it does not impose negative externalities on others): the right not to be used as a means to someone else’s ends against your will. This is a right to bodily autonomy: we should not use your body against your will.
Climate change does not violate this basic right: if the victims of climate change were not present, one could still emit greenhouse gases, so the presence of the bodies of climate victims is not necessary to reach our end (our activity to emit gases). But meat consumption does violate this basic right: if the killed animals were not present, they could not be killed and eaten, and hence the goal of meat consumption could not be reached. The presence of the body of the slaughtered animal is necessary for meat consumption. No body means no meat.
The total cost includes not only the loss of welfare but also the violation of rights. If we consider basic rights violations as very serious, the total cost of meat consumption strongly increases, but the total cost of carbon emissions remains the welfarist social cost of carbon.
Meat offsetting involves basic rights violations, because it involves meat consumption. Carbon offsetting is not a basic rights violation and is therefore permissible from a rights based ethic.
3. Greenhouse gas emissions involve a collective harm that lessens personal accountability, meat consumption does not
The above two arguments looked at two ethical theories: a welfare based and a rights based ethic. Apart from this, we can also consider how to morally judge people who offset their carbon emissions or meat consumption.
Suppose there are only a few humans, and you are the first one to start emitting 1 ton of CO2. This does not cause harm to the other humans, because the Earth’s biosphere can cope with those emissions. But if there are many other emitters, one extra ton of CO2 contributes to extra harm (cfr. the convex curvature of the cost function). In other words: the fact that you cause harm, depends on the presence of other people who perform the activity. With a much smaller human population, your carbon emissions would not be a problem. With the current population size, they do. But you are not responsible for the size of the human population. Your harm is part of a collective harm, collectively caused by many people. The fact that you are not responsible for the presence or absence of other emitters makes it difficult to hold you individually responsible for the harm.
Meat consumption is different: if you eat an animal, this causes extra harm to that animal (a premature death), no matter how many other meat eaters there are. Even if you were the only human, if you kill and eat an animal, you would cause harm. That means you can be held individually accountable for killing that animal.
4. Carbon offsetting involves the same victim, meat offsetting involves different victims
Meat offsetting is like murder offsetting: murderer A kills victim X and pays murderer B not to kill victim Y. For victim X, the murder offsetting was harmful: if A did not kill X and offset this murder, X would not be harmed. In short: if A did not exist, X would not be harmed. Carbon offsetting is different: polluter A emits greenhouse gases that harm victim X, and pays polluter B not to emit greenhouse gases that would have harmed victim X. If polluter A did not emit greenhouse gases and did not offset the emissions by paying B, polluter B would have emitted greenhouse gases and victim X would still be harmed. In short; if A would not exist, X would still be harmed. If emitting and offsetting greenhouse gases is the same for X (and everyone else) as not emitting and offsetting gases, emitting and offsetting gases is not harmful to X (nor to anyone else).
We can explore this idea a bit further. Suppose a butcher (person B) is going to kill animals and eat all these animals himself. Now, someone else (person A) wants to eat one of those slaughtered animals (victim X). He can offset that meat consumption by paying the butcher. In other words, he can buy the meat of that animal. In this case, buying meat from that butcher is a kind of meat offsetting that would be comparable to carbon offsetting: if person A would not exist, butcher B would have killed and eaten animal X. In reality, of course, a butcher is not going to eat all the animals that he kills. Hence, in reality, buying meat from a butcher is not an example of meat offsetting.
 Egalitarian perspective, used in SimaPro for life cycle analysis, based on Goedkoop M. e.a. (2009). ReCiPe 2008. A life cycle impact assessment method which comprises harmonised category indicators at the midpoint and the endpoint level. Report I: Characterisation. Ministry of Housing, Spatial Planning and Environment, the Netherlands.
 Anthony J. McMichael A, Campbell-Lendrum D, Kovats S, Edwards S, et al. Global Climate Change. In: Ezzati M, Lopez A, Roders A et al. Comparative Quantification of Health Risks, Global and Regional Burden of Disease Attributable to Selected Major Risk Factors, Geneva, World Health Organization, 2004, pp. 1543-1650.