cows impact climate
July 23, 2014

Scientists Gauge Impact Of Beef Consumption On Climate, Environment

redOrbit Staff & Wire Reports - Your Universe Online

For many people, nothing beats eating a good burger or steak, but two recently-published studies caution that those carnivorous culinary habits could have a significant impact on the environment and contribute to climate change.

In the first study, researchers from the Carnegie Institution for Science and the University of Siena in Italy reported in the journal Climatic Change that greenhouse gas emissions of livestock are on the rise, and that the majority of those emissions originate from beef cattle.

While carbon dioxide is said to be the most prevalent contributing gas to climate change, methane and nitrous oxide also contribute for roughly 28 percent of global warming activity, the study authors said. Those two gases are released in part by animals and together are responsible for nine percent of total greenhouse gas emissions.

Beef cattle and other livestock emit methane because of microorganisms that are involved in their digestive processes, while nitrous oxide is released from manure as it decomposes. By tracking the emissions of livestock-related greenhouse gas emissions in 237 countries, they found a 51 percent increase over the last five decades.

They also discovered a large contrast between livestock-related emissions in developing nations, which were responsible for the majority of the increase, and those released by developed countries. This discrepancy is expected to expand due to projected demand for meat, eggs and dairy products by the year 2050.

“The developing world is getting better at reducing greenhouse emissions caused by each animal, but this improvement is not keeping up with the increasing demand for meat,” author Dario Caro, a former member of the Carnegie Institution’s Department of Global Ecology who is currently with the University of Siena’s ecodynamics group, explained in a statement Monday. “As a result, greenhouse gas emissions from livestock keep going up and up in much of the developing world.”

Caro and his colleagues also noted that 54 percent of livestock-related greenhouse gas emissions came from beef cattle, while 17 percent originated from dairy cattle. This was attributed in part to the abundance of cows, as well as to the fact that they emit more methane and nitrous oxide than other animals.

Similarly, in the second study, Dr. Ron Milo of the Weizmann Institute of Science and his colleagues set out to determine the environmental cost of the five primary sources of protein in the US diet: dairy, beef, poultry, pork and eggs. After consulting with experts, they opted to gauge each food type’s impact on land use, irrigation water, greenhouse gas emissions and nitrogen fertilizer use as measures of their overall impact to the planet.

Using that data, as well as the environmental costs of different types of feed (pasture, roughage such as hay, and concentrates like corn), Dr. Milo’s team developed a set of equations that revealed the per-calorie and per-unit of protein environmental cost for each type of food. Their findings were published in the journal Proceedings of the National Academy of Sciences (PNAS).

Beef, once again, was found to have the largest impact on the ecosystem. However, while the researchers explained in a statement that they were not surprised by the outcome, they were somewhat taken aback by the margin of the gap. In fact, they report that 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.”

“Cattle require on average 28 times more land and 11 times more irrigation water, are responsible for releasing 5 times more greenhouse gases, and consume 6 times as much nitrogen, as eggs or poultry,” they added. The findings indicated that the other four categories were all “fairly similar,” which they also hailed as a surprise “because dairy production is often thought to be relatively environmentally benign.”

However, their research indicates that the cost of irrigating and fertilizing the crops fed to milk cows, as well as the fact that most other types of livestock are more efficient than cows, increased the cost considerably. The study authors believes that their research could help people make better choices about their diet and has the potential to influence future agricultural policy, helping to promote food security through sustainable practices.