A paper made by agriculture experts, published this week in Proceedings of the National Academy of Sciences, warns of dire consequences if the US goes vegan.While the scenario created would reduce greenhouse gases, it may result in hunger.

The authors created a formula to forecast what would happen if the country ditched meat in favor of veggies.They projected a significant decline in greenhouse gas emissions of up to 28 percent, Men's Journal reported.

More food

They estimated that a plant-only agriculture system could result in 23 percent higher food production from the current output.However, despite the production of more food, a vegan-only food supply would not be sufficient to support the nutritional requirements of the American population, Robin White, the lead author and an animal sciences researcher at the Department of Animal and Poultry Science at Virginia Tech in Blacksburg, said.

White explained that the usual foods that vegans use to supplement for the key nutritional elements in meat, such as vitamin A and calcium, are not produced in sufficient quantity to feed the whole country.Citing an article in Science, the researchers said that wiping out animal agriculture will boost the need for artificial fertilizer and add 23 million tons of carbon emissions annually.

Livestock production has long been blamed by vegans for a lot of things bad for Earth.They pointed to rampant land use, water depletion, and pollution because of the methane gas production by cattle which is a major contributor to global greenhouse gas emissions, EcoWatch reported.

The Environmental Protection Administration estimates that about three percent of the greenhouse gas emissions of the US come from cattle farts.The production of methane by cattle is part of the animal's digestive processes.

To produce four hamburger patties, it would take 25 kilograms of animal feed, 25 square meters of land, and 220 liters of water.These numbers are cited by pro-vegan groups who are pushing for an animal-free diet.

Conversion of land use

White and co-author Mary Beth Hall, from the USDA's Dairy Forage Research Center in Madison, explained that if all the land used by the livestock industry would be converted to cropland for food production, the amount of agricultural waste would increase.The waste from corn stalks, potatoes, and other inedible parts of the plants would have to be burned because the animals that eat these wastes have been eliminated in the vegan-only scenario.

To burn the excess waste would add about 2 million tons of carbon to the atmosphere.Because the supply of animal manure would be gone, demand for fertilizer would also increase.Producing more artificial fertilizer will add 23 million tons of carbon emissions annually, the authors reckoned.

Yearly emissions, though, is projected to decrease to 446 million tons from the current 623 million tons because animals comprise about 49 percent of the country's agricultural emissions.But an animal-free diet would fail to meet the nutritional requirements of the US' 300 million plus population for calcium, vitamin A and B12, and a few key fatty acids.Removing animals from the equation will result in non-viable diets in the long- or short-term, the study warned.

Questions over the study's assumptions

However, some scientists question the assumptions made by Hall and White, Sciencemag reported.Joan Sabate, a nutritionist at the Loma Linda University in California, pointed out that vegetables and fruits would not comprise a larger part of the pie in an agricultural system that will rely only on plants.

But for Mario Herrero, an agricultural researcher at the Commonwealth Scientific and Industrial Research Organization in St.Lucia, Australia, the question is over the authors' estimate of cuts in greenhouse gas emissions which he thinks is too low.He noted that the research failed to take into account the effect of animal-free diets in imports which comprise a large part of the American meat market.

Herrero said that if the US would stop the importation of meat, it could lead to a reduction in greenhouse gas emissions in nations, such as Brazil, that produce the meat.But he acknowledged that the study is a valiant attempt, although "the full repercussions of doing something like this are rarely complete."

It would take more than a meat-less diet to solve the planet's problems to mitigate climate change.A recent article signed by over 15,000 scientists, titled "World Scientists' Warning to Humanity: A Second Notice," challenged global leaders to act on climate change.It updated the original version of the warning by scientists published 25 years ago.The Union of Concerned Scientists made the first notice which was signed then by 1,700 researchers.The issuance of the second notice indicates the lack of progress from the first notice.

They also suggested other individual measures to help avert a pending global environmental disaster.Other measures the scientists suggested include having fewer children and using fewer resources such as fossil fuels and meat.