Dietary change could save a quarter of tropical forest from destruction

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If our appetite for meat and dairy continues to grow, one-quarter of natural tropical land could disappear by 2100, and untold species will be destroyed as this biodiverse land is cultivated, new research shows.

The Edinburgh University-led study is the first to assess not only how our diets will impact land-use in decades to come—a common focus of research—but how consumption patterns will actually affect distinct populations of animals across geographic space.

The researchers used a food system model to predict future land-pressures according to three possible dietary trends: growing consumption of meat and dairy, lower meat consumption, and diets lower in animal products, overall. This model revealed that by 2100, nine percent of natural land will disappear if we don’t change our current obsession with dairy and meat. 

Ninety-five percent of that destroyed land would be in the tropics – one of the most biodiverse regions on the planet. So this would cause notable and hugely variable impacts on species, too.

For instance, if consumption of animal products grows and livestock pastures consequently expand, the researchers found it would drive a 30% reduction of tropical habitat that currently harbors threatened bird species. Continued high levels of meat and dairy consumption would also cause a 30% habitat decline in regions containing mammal species which have restricted geographic ranges – meaning those species wouldn’t necessarily have a back-up habitat to escape to.  

The researchers also analyzed the impact on several important biodiversity hotspots that have been identified by Conservation International. That revealed that high meat and dairy diets would cause an almost 20% reduction in habitat within these crucial zones. 

Simply eating less meat doesn’t completely solve these problems, either. If humans eat less meat but keep consuming animal products, like dairy, there would still be expansion of cropland as we’d have to keep farming feed for livestock, as well as more crops to replace the meat in human diets. And as this cropland grows, so do the ramifications for wildlife. 

Even under a lower-meat diet, the researchers estimate, for instance, that there’d be a 10% increase in the amount of harmful nitrogen fertilizer applied in places that are currently refuges for threatened birds. Looking specifically at conservation hotspots, the researchers also found that fertilizer application would even be marginally higher under a low-meat scenario than under a regular meat-heavy dietary regimen, because we’d be farming more crops to replace the meat. 

Collectively, these encroachments on natural habitat would inevitably lead to biodiversity losses. 

On the other hand, switching it up to exchange 95% of both meat and dairy products in our diets for purely plant-based alternatives would have hugely beneficial effects. This shift would reduce our overall global demand for land by 11%, saving approximately 1,687 million hectares by 2100 – along with their resident species. That shift to plant-based diets would also lead to a 68% decline in fertilizer use, compared to if we continued consuming large amounts of meat.

The researchers point out a couple of caveats in their work – mainly that they assume a 95% reduction of animal-based products in two of the dietary scenarios they consider. That’s a huge proportion that’s unlikely to be accomplished in the short-term. But it’s nevertheless useful for demonstrating what could be achieved. Also, they warn against calls for a blanket global shift from animal products to plants, because in some parts of the world, animal products are the only source of protein. Food security would therefore have to be carefully balanced with conservation, the researchers point out.

Ultimately, the study gives us a way to appreciate the power of our diets beyond reducing land use and cutting greenhouse gas emissions. Paired with conservation, choosing what food we eat might actually be one of the sharpest tools available for protecting biodiversity, in some of the most vulnerable places on earth.

Source: Arneth et. al. “The role of global dietary transitions for safeguarding biodiversity.” Global Change Biology. 2019. 
 

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