Posts Tagged ‘meat’

by Quirin Schiermeier

Efforts to curb greenhouse-gas emissions and the impacts of global warming will fall significantly short without drastic changes in global land use, agriculture and human diets, leading researchers warn in a high-level report commissioned by the United Nations.

The special report on climate change and land by the Intergovernmental Panel on Climate Change (IPCC) describes plant-based diets as a major opportunity for mitigating and adapting to climate change ― and includes a policy recommendation to reduce meat consumption.

On 8 August, the IPCC released a summary of the report, which is designed to inform upcoming climate negotiations amid the worsening global climate crisis. More than 100 experts, around half of whom hail from developing countries, worked to compile the report in recent months.

“We don’t want to tell people what to eat,” says Hans-Otto Pörtner, an ecologist who co-chairs the IPCC’s working group on impacts, adaptation and vulnerability. “But it would indeed be beneficial, for both climate and human health, if people in many rich countries consumed less meat, and if politics would create appropriate incentives to that effect.”

Deforestation concerns
Researchers also note the relevance of the report to tropical rainforests, with concerns mounting about accelerating rates of deforestation. The Amazon rainforest is a huge carbon sink that acts to cool global temperature, but rates of deforestation are rising, in part because of the policies and actions of the government of Brazilian President Jair Bolsonaro.

Unless stopped, deforestation could turn much of the remaining Amazon forests into a degraded type of desert, and could release more than 50 billion tonnes of carbon into the atmosphere in 30 to 50 years, says Carlos Nobre, a climate scientist at the University of São Paolo in Brazil. “That’s very worrying,” he says.

“Unfortunately, some countries don’t seem to understand the dire need of stopping deforestation in the tropics,” says Pörtner. “We cannot force any government to interfere. But we hope that our report will sufficiently influence public opinion to that effect.”

Paris goals
Although the burning of fossil fuels for energy and transport garners the most attention, activities relating to land management, including agriculture and forestry, produce almost one-quarter of heat-trapping gases resulting from human activities. The race to limit global warming to 1.5°C above pre-industrial levels ― the goal of the international Paris climate agreement made in 2015 ― might be a lost cause unless land is used in a more sustainable and climate-friendly way, the latest IPCC report says.

The report highlights the need to preserve and restore forests, which soak up carbon from the air, and peatlands, which release carbon if dug up. Cattle raised on pastures created by clearing woodland are particularly emission-intensive. This practice often comes with large-scale deforestation, as seen in Brazil and Colombia. Cows also produce large amounts of methane, a potent greenhouse gas, as they digest their food.

The report states with high confidence that balanced diets featuring plant-based and sustainably produced animal-sourced food “present major opportunities for adaptation and mitigation while generating significant co-benefits in terms of human health”.

By 2050, dietary changes could free up several million square kilometres of land, and reduce global CO2 emissions by up to eight billion tonnes per year, relative to business as usual, the scientists estimate (see ‘What if people ate less meat?’).

“It’s really exciting that the IPCC is getting such a strong message across,” says Ruth Richardson in Toronto, Canada, the executive director at the Global Alliance for the Future of Food, a strategic coalition of philanthropic foundations. “We need a radical transformation, not incremental shifts, towards a global land-use and food system that serves our climate needs.”

Careful management
The report cautions that land must remain productive to feed a growing world population. Warming enhances plant growth in some regions, but in others ― including northern Eurasia, parts of North America, Central Asia and tropical Africa ― increasing water stress seems to reduce vegetation. So the use of biofuel crops and the creation of new forests ― seen as measures with the potential to mitigate global warming ― must be carefully managed to avoid the risk of food shortages and biodiversity loss, the report says.

Farmers and communities around the world must also grapple with more intense rainfall, floods and droughts resulting from climate change, warns the IPCC. Land degradation and expanding deserts threaten to affect food security, increase poverty and drive migration.

About one-quarter of Earth’s ice-free land area seems to be suffering from human-induced soil degradation already ― and climate change is expected to make thing worse, particularly in low-lying coastal areas, river deltas, drylands and permafrost areas. Sea-level rise is also adding to coastal erosion in some regions, the report says.

Industrialized farming practices are responsible for much of the observed soil erosion, and for soil pollution, says André Laperrière, the executive director of Global Open Data for Agriculture and Nutrition in Wallingford, UK, an initiative that aims to make relevant scientific information accessible worldwide.

The report might provide a much-needed, authoritative call to action, he says. “The biggest hurdle we face is to try and teach about half a billion farmers globally to re-work their agricultural model to be carbon sensitive.”

Nobre also hopes that the IPCC’s voice will give greater prominence to land-use issues in upcoming climate talks. “I think that the policy implications of the report will be positive in terms of pushing all tropical countries to aim at reducing deforestation rates,” he says.

Regular assessments
Since 1990, the IPCC has regularly assessed the scientific literature, producing comprehensive reports every six years or so, and special reports ― such as today’s ― on specific aspects of climate change, at irregular intervals.

A special report released last year concluded that global greenhouse-gas emissions, which hit an all-time high of more than 37 billion tonnes in 2018, must decline sharply in the very near future to limit global warming to within 1.5°C of pre-industrial levels ― and that this will require drastic action without further delay. The IPCC’s next special report, about the ocean and ice sheets in a changing climate, is due next month.

Governments from around the world will consider the IPCC’s latest findings at a UN climate summit next month in New York. The next round of climate talks of parties to the Paris agreement will then take place in December in Santiago.

António Guterres, the UN secretary-general, said last week that it is “absolutely essential” to implement that landmark agreement ― and “to do so with an enhanced ambition”.

“We need to mainstream climate-change risks across all decisions,” he said. “That is why I am telling leaders don’t come to the summit with beautiful speeches.”

Nature 572, 291-292 (2019)

doi: 10.1038/d41586-019-02409-7

https://www.nature.com/articles/d41586-019-02409-7?utm_source=Nature+Briefing&utm_campaign=8838a84803-briefing-dy-20190819&utm_medium=email&utm_term=0_c9dfd39373-8838a84803-44039353

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A Soviet cow-fattening complex pictured in 1982.Credit: Nikolai Akimov/TASS

by Quirin Schiermeier

The collapse of the Soviet Union in 1991 led to a huge drop in greenhouse-gas emissions because the resulting economic crisis meant many people stopped eating meat.

Meat from domestic livestock farming was a main food staple during communist rule in the region. In 1990, Soviet citizens each consumed an average 32 kilograms of beef a year — 27% more than Western Europeans and four times more than the global average at the time.

But meat demand and livestock production in the region fell drastically when the prices of everyday consumer products soared and the purchasing power of the rouble dwindled in the post-communist economic crisis. An estimated one-third of late-Soviet cropland has been abandoned since.

These changes in the food and agriculture system in the former Soviet nations resulted in a net reduction of 7.6 billion tonnes of greenhouse gases in carbon dioxide equivalent from 1992 to 2011, researchers find from an analysis of data on livestock consumption and international trade1 (see ‘Soviet shocks’). The drop is equivalent to one-quarter of CO2 emissions from Amazon deforestation over the same period. Russia currently emits about 2.5 billion tonnes of greenhouse gases (CO2 equivalent) per year.

The figure considers emissions that result from domestic production of livestock and imported livestock, as well as carbon locked in soils and plants on abandoned Soviet cropland.

“There was a large drop in industrial production and emissions after the collapse of the Soviet Union, so it should be no surprise the same happened with food consumption and production,” says Glen Peters, a carbon-budget specialist at the Center for International Climate Research in Oslo, who was not involved in the analysis. “The study highlights the potential for carbon uptake in the former Soviet Union but also the risks to that carbon being released if agricultural production returns.”

Today, animal agriculture is responsible for 14.5% of human-caused greenhouse-gas emissions globally. Beef is the most emissions-intensive food because pastures are often created by clearing forests and savannahs.

Meat consumption — especially beef — and land-use changes in Russia and central Asia are a widely overlooked factor in calculations of greenhouse-gas emissions from land around the globe, says study author Florian Schierhorn at the Leibniz Institute of Agricultural Development in Transition Economies in Halle, Germany.

Trends in international trade suggest that emissions associated with meat consumption are on the rise again: Russia has over the past decade become a top destination for beef exported mainly from South America.

doi: 10.1038/d41586-019-02024-6

References
1. Schierhorn, F. et al. Environ. Res. Lett. 14, 065009 (2019).

https://www.nature.com/articles/d41586-019-02024-6?utm_source=Nature+Briefing&utm_campaign=34225bcef1-briefing-dy-20190701&utm_medium=email&utm_term=0_c9dfd39373-34225bcef1-44039353

If you’re grilling meat this Memorial Day, you should seriously consider stocking up on Guinness.

Grilling meat is a warm-weather tradition in America, especially on Memorial Day weekend. It’s also an ancient human tradition, uniting friends and family around food and fire as long as our species has existed. Unfortunately, it also unites us around chemicals that can cause cancer.

Warnings like that can make it seem like scientists ruin everything — they already took sitting, late-night snacks and fireworks from us. But science works both ways, and now it has found at least a partial solution for this carnivore’s conundrum. According to a recent study, published in the Journal of Agricultural and Food Chemistry, the secret to safer grilling has been under our noses all along.

Beer is a common ingredient at backyard cookouts, usually as a beverage. But research suggests marinating meat with beer, particularly dark beer, can curb the creation of polycyclic aromatic hydrocarbons (PAHs). These carcinogenic chemicals form as fat and juices drip from meat onto flames or embers, which then send smoky PAHs wafting up to coat the surface of our food.

PAHs can exist in more than 100 different combinations, some of which are found in known toxic cocktails like cigarette smoke and car exhaust. These chemicals have caused tumors, birth defects and reproductive problems in lab animals, according to the U.S. EPA, but the same effects have not been seen in humans. The National Cancer Institute says PAHs “become capable of damaging DNA only after they are metabolized by specific enzymes in the body.” Nonetheless, health concerns raised in a 2002 report have led the European Union to set safety standards for PAHs in food.

Previous studies have shown that beer, wine, tea and rosemary marinades can reduce carcinogens in cooked meat, but until now little was known about how various beer styles affect this phenomenon. And according to the recent study, the kind of beer seems to make a pretty significant difference.

To reach that conclusion, the researchers marinated pork for four hours in one of three beer types: regular pilsner, non-alcoholic pilsner or black beer. They then grilled the pork to well-done on a charcoal grill and tested its PAH levels. Black beer had the most dramatic effect, reducing eight major PAHs to less than half the amount found in unmarinated grilled pork. (The researchers chose eight PAHs that are identified by the EU as “suitable indicators for carcinogenic potency of PAHs in food.”)

The two pilsners also showed an “inhibitory effect” on PAHs, but not as much. The regular pilsner suppressed PAHs by 13 percent, and the non-alcoholic variety went slightly further with 25 percent.

“Thus, the intake of beer-marinated meat can be a suitable mitigation strategy,” the researchers say.

The study’s authors aren’t sure why beer marinade has this effect, or why dark beer fights PAHs better than pilsner does. It isn’t the alcohol, since non-alcoholic pilsner nearly doubled the PAH suppression of its boozier relative. They suspect it might be antioxidant compounds in beer, especially darker beers, since antioxidants could restrict the movement of free radicals that are required for PAH formation. More research will be needed to know for sure, but this theory could help explain why antioxidant-rich red wine, green tea and rosemary extracts also keep carcinogens in check.

Whatever you use, the American Institute for Cancer Research already recommends marinating meat for at least 30 minutes to limit both PAHs and heterocyclic amines (HCAs), another type of chemical compound that can damage DNA. It also suggests grilling fish and poultry more often than red meat or processed meats like hot dogs, which can increase the risk for certain cancers. Reducing temperature, time on the grill and smoke exposure are other options for limiting cancer risk.

And while it can’t take the place of a juicy, beer-marinated pork chop, there’s also another, even more surefire way to cut back your risk: Save some room on the grill for fruits, vegetables and mushrooms.

http://www.mnn.com/food/healthy-eating/blogs/how-dark-beer-can-make-grilled-meat-less-carcinogenic