Health

Plant-based diets limit greenhouse gas emissions


“We wanted to answer a very simple question: What would be the impact of removing animal agriculture globally on greenhouse gases in the atmosphere and their global warming impact?” Patrick Brown, a professor emeritus in the department of biochemistry at Stanford University. Brown co-authored the paper with Michael Eisen, professor of genetics and development at UC Berkeley.

Model-based, published in an open-access journal PLoS Climate, The phasing out of livestock over the next 15 years would have the same effect as a 68% reduction in carbon dioxide (CO2) emissions through 2100. This would provide the 52% of the net emissions reduction needed. needed to limit global warming to 2 degrees Celsius above pre-industrial levels, which scientists say is the minimum threshold needed to avert catastrophic climate change.

The changes will stem from the spontaneous breakdown of the powerful greenhouse gases methane and nitrous oxide, the authors say, and the recovery of biomass in natural ecosystems across more than 80 percent of human land. species currently intended for livestock production. “Reducing or eliminating livestock farming should be at the top of the list of potential climate solutions,” says Brown. “I hope that others, including global entrepreneurs, scientists and policymakers, will recognize that this is our best and most immediate opportunity to reverse the trajectory.” of climate change and seize the opportunity.” Brown is also the founder and CEO of Impossible Foods, a company that develops alternatives to animals in food production. Eisen is an advisor to the company. Both Brown and Eisen benefited financially from the reduction in livestock farming.

Unlock negative emissions

Brown and Eisen are not the first to show that continued emissions from livestock farming are contributing to global warming. But what has not been recognized before, they say, is that the “climate opportunity cost” has a much larger impact – the ability to release negative emissions by eliminating livestock.

“As methane and nitrous oxide emissions from livestock decrease, the concentration of strong greenhouse gases in the atmosphere will actually decrease dramatically over decades,” Brown said. “And the CO2 released into the atmosphere as wild forests and savannas are replaced by food crops and grazing land can be converted back to biomass as livestock are phased out and forests and savannas recover. .”

Brown and Eisen used publicly available data on livestock production, livestock-related emissions, and the potential to capture biomass on land currently used to support livestock production to predict the removal of all livestock. All or parts of global livestock production will change net anthropogenic or anthropogenic emissions levels from 2019. They then use a simple climate model to predict how these changes will impact the development of greenhouse gas levels in the atmosphere and warming for the rest of the century.

They looked at four dietary scenarios: the immediate replacement of all livestock farming with a plant-only diet; Gradually, and more realistically, over 15 years, the authors say, transition to a global, plant-only diet; and beef-only versions of each place are replaced with plant-only products.

For each hypothetical scenario, the scientists assumed that non-agricultural emissions would remain constant and that land previously used for livestock production would be converted to grasslands, savannas, forests, and futures. will also absorb CO2 in the atmosphere.

“The synergistic effect is both amazingly large and – equally important – fast, with most of the benefits realized by 2050,” says Brown. “If livestock farming were eliminated within 15 years and If all other greenhouse gas emissions continue unabated, this removal would provide a 30-year pause in net greenhouse gas emissions and offset nearly 70% of the heating effect of the greenhouse gas emissions. those emissions by the end of the century.”

Although the full phase of animal-based agriculture is projected to have the greatest impact, 90% of emissions reductions could be achieved by replacing only ruminants such as cattle and sheep, modeled.

While their paper does not explore in detail what a global phase of livestock farming would lead to, the authors acknowledge that “the economic and social impacts of global transition The demand for a plant-based diet will be so severe in many regions and localities… “and that” is likely to require a substantial global investment to ensure that those currently earning livelihoods from livestock farming are not damaged when it is cut or replaced.”

However, they write, “in either case, these investments must be compared with the economic and humanitarian disruptions resulting from significant global warming.”

Change your attitude

Many would scoff at the idea that billions of people could be persuaded to switch to a plant-only diet within 15 years. To these skeptics, Eisen points out that other revolutions have occurred in less time. “We’ve gone from no cell phones to ubiquitous mobile phones in less time,” says Eisen. “Electricity, cars, solar panels – they’ve all become ubiquitous in a span of time,” says Eisen. relatively short time,” Eisen said.

Furthermore, added Brown, society’s attitudes toward food are not fixed. “Five hundred years ago, nobody in Italy had ever seen a tomato,” he said. “60 years ago, nobody in China drank Coke. Lamb used to be the most popular meat in America.” “People around the world are open to new foods, especially if they are delicious, nutritious, convenient and affordable.”

The scientists have made publicly available all the raw data they use, as well as their calculations and the computer code used to perform the calculations, so that others can decide for themselves.

“The great thing about science is that in the end it all depends on whether the conclusions are supported by the evidence,” says Brown. “And in this case, they are.”

Source: Eurekalert



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