LONDON: Giving up on beef will be more beneficial to the planet than driving cars.
Scientists have confirmed that beef's environmental impact significantly that of other meat including chicken and pork with research showing that eating less red meat would be a better way for people to cut carbon emissions than giving up their cars.
Cattle require on average 28 times more land and 11 times more irrigation water are responsible for releasing five times more greenhouse gases and consume six times as much nitrogen as eggs or poultry.
Poultry, pork, eggs and dairy all came out fairly similar. That was also surprising, because dairy production is often thought to be relatively environmentally benign.
When compared to staples like potatoes, wheat, and rice, the impact of beef per calorie is even more extreme, requiring 160 times more land and producing 11 times more greenhouse gases.
But the research shows that the price of irrigating and fertilizing the crops fed to milk cows - as well as the relative inefficiency of cows in comparison to other livestock - jacks up the cost significantly.
Agriculture is a significant driver of global warming and causes 15% of all emissions, half of which are from livestock. Furthermore, the huge amounts of grain and water needed to raise cattle is a concern to experts worried about feeding an extra 2 billion people by 2050.
New research at the Weizmann Institute of Science conducted in collaboration with scientists in the US looked at the five main sources of protein in the American diet: dairy, beef, poultry, pork and eggs. Their idea was to calculate the environmental inputs - the costs - per nutritional unit: a calorie or gram of protein.
When the numbers were in, including those for the environmental costs of different kinds of feed (pasture, roughage such as hay, and concentrates such as corn), the team developed equations that yielded values for the environmental cost - per calorie and then per unit of protein, for each food.
The calculations showed that the biggest culprit, by far, is beef. That was no surprise say scientists. The surprise was in the size of the gap: In total, eating beef is more costly to the environment by an order of magnitude - about ten times on average - than other animal-derived foods, including pork and poultry.
Carbon dioxide is the most-prevalent gas when it comes to climate change. It is released by vehicles, industry, and forest removal and comprises the greatest portion of greenhouse gas totals. But methane and nitrous oxide are also greenhouse gasses and account for approximately 28% of global warming activity.
Methane and nitrous oxide are released, in part, by livestock. Animals release methane as a result of microorganisms that are involved in their digestive processes and nitrous oxide from decomposing manure. These two gasses are responsible for a quarter of these non-carbon dioxide gas emissions and 9% of total greenhouse gas emissions overall.
The research team, including Dario Caro, formerly of Carnegie and now at the University of Siena in Italy and Carnegie's Ken Caldeira, estimated the greenhouse gas emissions related to livestock in 237 countries over a nearly half a century and found that livestock emissions increased by 51% over this period.
Breaking it down by animal, beef and dairy cattle comprised 74% of livestock-related greenhouse gas emissions, 54% coming from beef cattle and 17% from dairy cattle.
Part of this is due to the abundance of cows, but it is also because cattle emit greater quantities of methane and nitrous oxide than other animals. Sheep comprised 9%, buffalo 7%, pigs 5% and goats 4%.
"That tasty hamburger is the real culprit," Caldeira said. "It might be better for the environment if we all became vegetarians, but a lot of improvement could come from eating pork or chicken instead of beef".
