Eating fewer animals reduces emissions, but by how much?

Agri­cul­ture is one of the key levers for mit­ig­at­ing cli­mate change: food pro­duc­tion is respons­ible for around a quarter of glob­al green­house gas emis­sions. Live­stock farm­ing and fish­ing are the main con­trib­ut­ors to these emis­sions. As detailed in a report, it is clear that redu­cing emis­sions from agri­cul­ture requires a reduc­tion in our con­sump­tion of anim­als. From a nutri­tion­al point of view, a plant-based diet is bene­fi­cial to health, often to a great­er extent than sug­ges­ted by health recom­mend­a­tions, which take into account para­met­ers such as cul­tur­al norms and feas­ib­il­ity in the gen­er­al pop­u­la­tion, as explained by François Mari­otti. In a study pub­lished in early 2025, Joël Aub­in and his col­leagues looked at the oth­er envir­on­ment­al bene­fits of redu­cing anim­al product con­sump­tion in France¹.

Joël Aub­in. We are assess­ing the envir­on­ment­al impacts of a reduc­tion in anim­al pro­tein con­sump­tion among adults in France over their entire life cycle. This includes all emis­sions linked to the pro­duc­tion, pro­cessing, trans­port, con­sump­tion and end-of-life of products.

Com­pared to an aver­age diet, the diet con­sidered here con­tains less pro­tein over­all (with a reduc­tion from 80 to 70 g per day) but also a lower pro­por­tion of anim­al pro­tein. The daily amount of anim­al pro­tein is thus reduced by about 20 g. This choice is based on health recom­mend­a­tions but also on the desire not to increase the cost of food by more than 5%.

Our study shows that if the French adopt this low-anim­al-pro­tein diet, the impact of food on cli­mate change, acid­i­fic­a­tion and land use will decrease. On the oth­er hand, there will be an increase in the impact on water use, fresh­wa­ter eutroph­ic­a­tion and biodiversity.

This diet, which is low in anim­al pro­tein, con­tains much more plant mat­ter. It is there­fore more depend­ent on irrig­ated crops that con­sume a lot of water, at least with our cur­rent pro­duc­tion meth­ods. In terms of biod­iversity, the pro­por­tion of beef in our low-pro­tein diet is fall­ing sharply. How­ever, cattle are the spe­cies that make the most use of grass­lands, which leads to a very high loss of pas­ture­land, an import­ant source of biod­iversity. Added to this is the need to increase cer­tain agri­cul­tur­al areas to meet food needs.

On a glob­al scale, redu­cing live­stock farm­ing would allow almost a third of the Earth’s land area to be reclaimed. But would repla­cing the land used for live­stock farm­ing be enough to meet food needs? There is no sci­entif­ic con­sensus on this issue. Finally, there are two lim­it­a­tions. The first is that not all grass­land is suit­able for cul­tiv­a­tion, and con­vert­ing it to low-yield crops would increase the envir­on­ment­al impact of plant pro­duc­tion. Finally, it would be neces­sary to ensure that grass­land is replaced by crops for human con­sump­tion, rather than urb­an­ised areas.

This is only a par­tial study and did not aim to exam­ine all the indir­ect con­sequences of this change in diet, so the repur­pos­ing of grass­lands to crop pro­duc­tion is not con­sidered. Of course, if this were the case, the impact of a diet low in anim­al pro­tein on biod­iversity would be reduced.

Chan­ging agri­cul­tur­al prac­tices, par­tic­u­larly agroe­co­logy, is an effect­ive mit­ig­a­tion solu­tion. Replant­ing hedges, rotat­ing crops, redu­cing pesti­cide use, redu­cing plot sizes, etc. All these prac­tices help to lim­it our depend­ence on nat­ur­al resources and restore the eco­lo­gic­al func­tions of environments.

No, our work does not con­tra­dict the pos­it­ive impact of a diet lower in anim­al products on the cli­mate. Our diet reduces green­house gas emis­sions by around 30%, des­pite a rel­at­ively small reduc­tion in anim­al pro­tein intake. Our study high­lights the need to con­sider all the con­sequences of soci­et­al choices.

It is import­ant to under­stand that these neg­at­ive extern­al­it­ies do not call into ques­tion, but rather lim­it, the envir­on­ment­al bene­fits of redu­cing the pro­por­tion of anim­al products in our diets. How­ever, identi­fy­ing these neg­at­ive impacts should make it pos­sible to lim­it them.

No, because des­pite what we may think, the con­sump­tion of anim­al products is not decreas­ing glob­ally, nor in France. How­ever, we are see­ing a shift in con­sump­tion, with an increase in the con­sump­tion of pork and poultry and a decrease in the con­sump­tion of beef.

They are very spe­cif­ic to France, where most cattle are raised on pas­ture, unlike in the United States, for example.

We are sci­ent­ists, and we are com­mit­ted to pro­du­cing robust know­ledge without extern­al influ­ence. The fact that our art­icle was accep­ted for pub­lic­a­tion in a sci­entif­ic journ­al shows that these res­ults are reli­able. How­ever, it did give us access to data­bases. For example, the French diet is based on more than 250 indic­at­ors. Access to this data has enabled us to study these impacts on water and biod­iversity in a way that has nev­er been done before.

Interview by Anaïs Marechal