TRUE OR FALSE. Are dogs and cats “disasters” for biodiversity and the climate?

François Gemenne, member of the IPCC, attracted the wrath of animal lovers by recalling the environmental impact of dogs and cats on LCI. However, his remarks are based on scientific studies.

These were a few words, said in a joking tone, which caused a huge uproar. On Wednesday, December 13, François Gemenne, member of the Intergovernmental Panel on Climate Change (IPCC), was a guest of LCI, as COP28 drew to a close and resulted in an agreement calling for a gradual exit from fossil fuels. The columnist for “Zéro emission” on Franceinfo was asked to react to the broadcast of a report on cats and declared this: “Cats are a disaster for biodiversity. Dogs are a disaster for the climate.”

What hadn’t he said? There SPA France shared a strong message on the social network X, formerly Twitter: “No one has yet dared to make animal lovers feel guilty. It’s done!” On the set of the show Daily on TMC, Thursday December 14, the expert even said he had received death threats from certain animal lovers. Several figures from the far right also reacted strongly. Florian Philippotpredicted by the Les Patriotes movement, denounced a supposed “anti-pet climate propaganda, in the name of ‘climate’, [qui] unfolds”. “How far will they go in their madness?”got annoyed Nicolas Dupont-Aignan“if we don’t stop them, they will soon stop us from breathing.”

However, François Gemenne’s remarks are based on several scientific studies published over the last 15 years (and he does not at all call for killing dogs and cats).

Cats, predators of birds and small mammals

The cat is by far the most popular animal in France. Some 14.9 million felines populated the territory in 2022, according to estimates from Fediaf, the European representative of the animal food industry, more commonly known as “Pet food”. And they are indeed threats to biodiversity.

An American study published in 2013 in the journal Nature Communications estimated that cats killed between one and four billion birds each year in the United States, or a median of 2.5 billion birds, and between six and 22 billion small mammals, or a median of 12 billion. It nevertheless clarified that ownerless, stray or feral cats (which have returned to the wild) were the main culprits, and not domestic cats. But these stray cats are often animals abandoned by humans or descended from abandoned animals. The study concluded that it was one of the largest, if not the largest, causes of anthropogenic mortality for small American animals.

Researchers from the French National Museum of Natural History and the Royal Belgian Institute of Natural Sciences also published an article in 2019 focusing on the impact of domestic cats on bird populations. They found that between 2000 and 2015, garden bird mortality increased by at least 50%, as there were more and more cats in France and Belgium. Between 12% and 26% of bird deaths were caused by cats. “Cat-related mortality is one of the largest causes of death observed, it is of the same magnitude as bird deaths due to collisions with windows”, explained the specialists. They also called for taking into account the potential impact of cats on urban biodiversity in the management of parks and gardens.

Cats have a bigger impact in cities and islands

This is also what the National Museum of Natural History explains on its website, after having completed a participatory program between 2015 and 2022 which made it possible to observe 38,000 prey brought back by cats (68% small mammals, including rodents, 22% birds, 8% small reptiles). According to him, “in cities, it is the concentration of felines which aggravates the impact of their catches, because they are multiplied”. This is also the case in the islands, as reported Science and Future. For example, cats introduced into the Kerguelen islands, which became wild, had a devastating effect on biodiversity there to the point that the archipelago decided to regulate them.

But “in areas where it is not an invasive species, in the French countryside for example, the cat is one predator among others”nuance the Museum. “The cat is not directly responsible for the decline of common birds. Their scarcity is primarily due to the disappearance of insects and the loss of habitat. The cat, however, represents significant additional pressure on a weakened population.”

Dogs, more polluters than SUVs?

Now, what about the dogs? Their impact on the climate has been recorded for many years. A first scientific study appeared in 2009 in the United States under the provocative title Is it time to eat the dog? It concluded that the annual meat consumption of a medium-sized dog polluted twice as much as an SUV that traveled 10,000 km every year. A conclusion which was already highly controversial at the time.

“A lot of people worry about having an SUV but they don’t worry about having a German Shepherd and what we say in this book is that, maybe, they should also worry because the environmental impact is comparable”explained the two authors Brenda and Robert Vale at the time, according to the New Zealand magazine Stuff.

Similar conclusions almost ten years later in another study on the environmental impact of the diet of dogs and cats, published in 2017. According to it, the more than 160 million American dogs and cats are responsible for 25% 30% of the environmental impact of meat consumption in the United States. The carbon impact also depends on where you live and the size of the pet. Other researchers were also interested in the climate footprint of our faithful companions in 2019 and 2022, both concluding that it was necessary to better understand this footprint.

But these conclusions are controversial. Kelly Swanson, professor of animal nutrition at the University of Illinois, estimated in 2021 to AFP that they were based on “many inaccurate assumptions”especially because “the majority of pet food comes from by-products of the human food industry”. Indeed, few cows or chickens are raised for the sole purpose of feeding dogs and cats. Their meat-based croquettes and pâtés are made from parts that humans are reluctant to eat, such as offal.

However, for the author of the 2017 study, Grégory Okin, this argument does not hold up. In fact, these parts could also be eaten by humans, if they were less wasteful.

How can we reduce the carbon impact of our animals?

Having said that, no one is calling on anyone to get rid of their dog or cat. Neither François Gemenne nor other climate defenders. The expert explained that for him it was just a matter of recalling a scientific observation and of inviting animal lovers to also question this subject which is rarely discussed.

Moreover, we must also not forget all the benefits of companion animals, which help to lower human tension, reduce their loneliness, and even their mortality.

But it is possible to find solutions to reduce the climate footprint of your animals, for example by not feeding them in too large quantities, by giving them more vegetable-based kibble, by using biodegradable litter for your cat, by playing more with your cat to limit predation or by choosing smaller, less predatory pets, such as hamsters, rabbits or birds.