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Conservation Science for a Healthy Planet

Meat, diet and climate change- recent peer reviewed studies and perspectives

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Eating less meat might not be the way to go green, say researchers

January 19 2016

R. de Oliveira Silva, L. G. Barioni, J. A. J. Hall, M. Folegatti Matsuura, T. Zanett Albertini, F. A. Fernandes, D. Moran. Increasing beef production could lower greenhouse gas emissions in Brazil if decoupled from deforestation. Nature Climate Change, 2016; DOI: 10.1038/nclimate2916

Reduced meat consumption might not lower greenhouse gas emissions from one of the world’s biggest beef producing regions, new research has found. The finding may seem incongruous, as intensive agriculture is responsible for such a large proportion of global greenhouse gas emissions. According to research by University of Edinburgh, Scotland’s Rural College (SRUC) and Brazilian Agricultural Research Corporation (Embrapa), reducing beef production in the Brazilian Cerrado could actually increase global greenhouse gas emissions. The findings were published in the journal Nature Climate Change.

Lead author Rafael Silva, of the University of Edinburgh’s School of Mathematics, explains: “Much of Brazil’s grassland is in poor condition, leading to low beef productivity and high greenhouse gas emissions from cattle. However, increasing demand for meat provides an incentive for farmers to recover degraded pastures. This would boost the amount of carbon stored in the soil and increase cattle productivity. It would require less land for grazing and reduce deforestation, potentially lowering emissions.” While grasslands are not as effective as forests at storing carbon, Brazilian grass — mostly Brachiaria genus — has a greater capacity to do so than grass found in Europe, due to its long roots. High quality grasslands will cause more carbon to be stored in the soil, which will lead to a decrease in CO2 emissions. Grassland improvement involves chemical and mechanical treatment of the soil, and use of better adapted seeds along with calcium, limestone and nitrogen fertilisers. Most Brazilian grassland soils are acidic, requiring little nitrogen.

In the case of the Brazilian Cerrado, reduced meat consumption could remove the incentive for grassland improvement and therefore lead to higher emissions. The researchers worked out that if demand for beef is 30% higher by 2030 compared with current estimates, net emissions would decrease by 10%. Reducing demand by 30% would lead to 9% higher emissions, provided the deforestation rates are not altered by a higher demand. However, if deforestation rates increase along with demand, emissions could increase by as much as 60%….

 

Vegetarian and ‘healthy’ diets could be more harmful to the environment, researchers say

December 14, 2015

Michelle S. Tom, Paul S. Fischbeck, Chris T. Hendrickson. Energy use, blue water footprint, and greenhouse gas emissions for current food consumption patterns and dietary recommendations in the US. Environment Systems and Decisions, 2015; DOI: 10.1007/s10669-015-9577-y

 

….Specifically, they examined how growing, processing and transporting food, food sales and service, and household storage and use take a toll on resources in the form of energy use, water use and GHG emissions.

On one hand, the results showed that getting our weight under control and eating fewer calories, has a positive effect on the environment and reduces energy use, water use and GHG emissions from the food supply chain by approximately 9 percent.

However, eating the recommended “healthier” foods — a mix of fruits, vegetables, dairy and seafood — increased the environmental impact in all three categories: Energy use went up by 38 percent, water use by 10 percent and GHG emissions by 6 percent.

“There’s a complex relationship between diet and the environment,” Tom said. “What is good for us health-wise isn’t always what’s best for the environment. That’s important for public officials to know and for them to be cognizant of these tradeoffs as they develop or continue to develop dietary guidelines in the future.”

 

Changing global diets is vital to reducing climate change, researchers say

August 31, 2014

Bojana Bajželj, Keith S. Richards, Julian M. Allwood, Pete Smith, John S. Dennis, Elizabeth Curmi, Christopher A. Gilligan. Importance of food-demand management for climate mitigation. Nature Climate Change, 2014; DOI: 10.1038/nclimate2353

Healthier diets and reducing food waste are part of a combination of solutions needed to ensure food security and avoid dangerous climate change, say the team behind a new study.

A new study, published today in Nature Climate Change, suggests that — if current trends continue — food production alone will reach, if not exceed, the global targets for total greenhouse gas (GHG) emissions in 2050.

The study’s authors say we should all think carefully about the food we choose and its environmental impact. A shift to healthier diets across the world is just one of a number of actions that need to be taken to avoid dangerous climate change and ensure there is enough food for all.

As populations rise and global tastes shift towards meat-heavy Western diets, increasing agricultural yields will not meet projected food demands of what is expected to be 9.6 billion people — making it necessary to bring more land into cultivation.

This will come at a high price, warn the authors, as the deforestation will increase carbon emissions as well as biodiversity loss, and increased livestock production will raise methane levels. They argue that current food demand trends must change through reducing waste and encouraging balanced diets.

If we maintain ‘business as usual’, say the authors, then by 2050 cropland will have expanded by 42% and fertiliser use increased sharply by 45% over 2009 levels. A further tenth of the world’s pristine tropical forests would disappear over the next 35 years.

The study shows that increased deforestation, fertilizer use and livestock methane emissions are likely to cause GHG from food production to increase by almost 80%. This will put emissions from food production alone roughly equal to the target greenhouse gas emissions in 2050 for the entire global economy.

The study’s authors write that halving the amount of food waste and managing demand for particularly environmentally-damaging food products by changing global diets should be key aims that, if achieved, might mitigate some of the greenhouse gases causing climate change.

“There are basic laws of biophysics that we cannot evade,” said lead researcher Bojana Bajzelj from the University of Cambridge’s Department of Engineering, who authored the study with colleagues from Cambridge’s departments of Geography and Plant Sciences as well as the University of Aberdeen’s Institute of Biological and Environmental Sciences.

“The average efficiency of livestock converting plant feed to meat is less than 3%, and as we eat more meat, more arable cultivation is turned over to producing feedstock for animals that provide meat for humans. The losses at each stage are large, and as humans globally eat more and more meat, conversion from plants to food becomes less and less efficient, driving agricultural expansion and land cover conversion, and releasing more greenhouse gases. Agricultural practices are not necessarily at fault here — but our choice of food is,” said Bajzelj….

 

Meat food waste has greater negative environmental impact than vegetable waste

August 14, 2015

Christine Costello, Esma Birisci, Ronald G. McGarvey. Food waste in campus dining operations: Inventory of pre- and post-consumer mass by food category, and estimation of embodied greenhouse gas emissions. Renewable Agriculture and Food Systems, 2015; 1 DOI: 10.1017/S1742170515000071

 

Approximately 31 percent of food produced in the U.S., or 133 billion pounds of food worth $162 billion, was wasted in 2011 according to the United States Department of Agriculture (USDA). Now, University of Missouri researchers have found that the type of food wasted has a significant impact on the environment. Although less meat is wasted (on average) compared to fruits and vegetables, the researchers found that significantly more energy is used in the production of meat compared to the production of vegetables. This wasted energy is usually in the form of resources that can have negative impacts on the surrounding environment, such as diesel fuel or fertilizer being released into the environment.

“While many of us are concerned about food waste, we also need to consider the resources that are wasted when we throw away edible food,” said Christine Costello, assistant research professor at the College of Agriculture, Food and Natural Resources and co-author of the study. “Farm equipment used to feed and maintain livestock and plant and harvest crops uses a lot of diesel fuel and other utilities from fossil fuels. When people waste meat, these fuels, as well as fertilizers, are also wasted. Based on our study, we recommend that people and institutions be more conscious of not only the amount but the types of food being wasted.”

During the study, pre- and post-consumer food waste was collected from four all-you-care-to-eat dining facilities over three months in 2014. Costello and her research team created a detailed inventory of the specific types of food waste: meat, vegetables or starches. The food waste also was categorized as either edible or inedible (peels and ends of fruits and vegetables).

Once the food waste was categorized, Costello and her research team analyzed greenhouse gas (GHG) emissions resulting from fertilizer use, vehicle transportation, and utility use on the farm. GHG emission estimates were measured from cradle (land preparation or animal birth) to farm gate (when the grain or animal was sent to a processing facility). Previous studies have shown that the majority of GHG emissions occur in the production stages prior to the farm products’ leaving the farm.

“Based on the findings, we recommend consumers pay special attention to avoiding waste when purchasing and preparing meat; if consumers choose to prepare extra food ‘just in case,’ they should use plant-based foods,” said co-author Ronald G. McGarvey, assistant professor at the Harry S Truman School of Public Affairs and Department of Industrial and Manufacturing Systems Engineering.

 

 

Eating less meat: Solution to reduce water use?

August 4, 2014

M Jalava, M Kummu, M Porkka, S Siebert, O Varis. Diet change—a solution to reduce water use?
Environmental Research Letters, 2014; 9 (7): 074016 DOI: 10.1088/1748-9326/9/7/074016

Eating less meat would protect water resources in dry areas around the world, researchers at Aalto University have found.

Reducing the use of animal products can have a considerable impact on areas suffering scarce water resources, as meat production requires more water than other agricultural products.

“Diet change together with other actions, such as reduction of food losses and waste, may tackle the future challenges of food security,” states researcher Mika Jalava from Aalto University.

Growing population and climate change are likely to increase the pressure on already limited water resources and diet change has been suggested as one of the measures contributing to adequate food security for growing population.

The researchers assessed the impact of diet change on global water resources over four scenarios, where the meat consumption was gradually reduced while diet recommendations in terms of energy supply, proteins and fat were followed. The study published in Environmental Research Letters is the first global-scale analysis with a focus on changes in national diets and their impact on the blue and green water use of food consumption.

Food supply for growing population

Global population is expected to exceed 9 billion by 2050, adding over 2 billion mouths to be fed to the current population, according to the UN. By reducing the animal product contribution in the diet, global green water (rainwater) consumption decreases up to 21 % while for blue water (irrigation water) the reductions would be up to 14 %. In other words, by shifting to vegetarian diet we could secure adequate food supply for an additional 1.8 billion people without increasing the use of water resources. The potential savings are, however, distributed unevenly, and even more important, their potential alleviation on water scarcity varies widely from country to country….

 

Climate: Meat turns up the heat as livestock emit greenhouse gases

July 21, 2014

Dario Caro, Steven J. Davis, Simone Bastianoni, Ken Caldeira. Global and regional trends in greenhouse gas emissions from livestock. Climatic Change, 2014; DOI: 10.1007/s10584-014-1197-x

Eating meat contributes to climate change, due to greenhouse gasses emitted by livestock. New research finds that livestock emissions are on the rise and that beef cattle are responsible for far more greenhouse gas emissions than other types of animals. It is published by Climatic Change. 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 percent 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 percent of total greenhouse gas emissions overall.

 

Vegetarian diets produce fewer greenhouse gases and increase longevity, say new studies

June 25, 2014

  1. S. Soret, A. Mejia, M. Batech, K. Jaceldo-Siegl, H. Harwatt, J. Sabate. Climate change mitigation and health effects of varied dietary patterns in real-life settings throughout North America. American Journal of Clinical Nutrition, 2014; 100 (Supplement_1): 490S DOI: 10.3945/ajcn.113.071589
  2. J. Sabate, S. Soret. Sustainability of plant-based diets: back to the future. American Journal of Clinical Nutrition, 2014; 100 (Supplement_1): 476S DOI: 10.3945/ajcn.113.071522

Consuming a plant-based diet results in a more sustainable environment and reduces greenhouse gas emissions, while improving longevity, according to new research from Loma Linda University Health.

A study and an article, produced by researchers at Loma Linda University School of Public Health, will be published in full in the July issue of the American Journal of Clinical Nutrition, and were first presented at the 6th International Congress on Vegetarian Nutrition in 2013.

Based on findings that identified food systems as a significant contributor to global warming, the study focuses on the dietary patterns of vegetarians, semi-vegetarians and non-vegetarians to quantify and compare greenhouse gas emissions, as well as assess total mortality.

The mortality rate for non-vegetarians was almost 20 percent higher than that for vegetarians and semi-vegetarians. On top of lower mortality rates, switching from non-vegetarian diets to vegetarian diets or even semi-vegetarian diets also helps reduce greenhouse gas emissions. The vegetarian diets resulted in almost a third less emissions compared to the non-vegetarian diets. Modifying the consumption of animal-based foods can therefore be a feasible and effective tool for climate change mitigation and public health improvements, the study concluded.

“The takeaway message is that relatively small reductions in the consumption of animal products result in non-trivial environmental benefits and health benefits,” said Sam Soret, Ph.D., MPH, associate dean at Loma Linda University School of Public Health and co-author of the studies.

The study drew data from the Adventist Health Study, which is a large-scale study of the nutritional habits and practices of more than 96,000 Seventh-day Adventists throughout the United States and Canada. The study population is multi-ethnic and geographically diverse.

 

Nitrogen pollution, climate and land use: Why what we eat matters

April 25, 2014

Henk Westhoek, Jan Peter Lesschen, Trudy Rood, Susanne Wagner, Alessandra De Marco, Donal Murphy-Bokern, Adrian Leip, Hans van Grinsven, Mark A. Sutton, Oene Oenema. Food choices, health and environment: Effects of cutting Europe’s meat and dairy intake. Global Environmental Change, 2014; DOI: 10.1016/j.gloenvcha.2014.02.004

 

A new report quantifies for the first time how much our food choices affect pollutant nitrogen emissions, climate change and land-use across Europe.

The executive summary of the European Nitrogen Assessment Special Report on Nitrogen and Food, ‘Nitrogen on the Table’, was released today (Friday 25 April 2014). The Special report provides an assessment of what would happen if Europe were to decrease its consumption of meat and dairy products. It shows how much cutting down on meat and dairy in our diets would reduce nitrogen air and water pollution, and greenhouse gas emissions, while freeing up large areas of farmland for other purposes such as food export or bioenergy. It also considers the health benefits of reduced meat consumption. The full report is published next month.

Report lead author Henk Westhoek, program manager for Agriculture and Food at PBL (the Netherlands Environmental Assessment Agency) said, “The report shows that the nitrogen footprint of meat and dairy is considerably higher than that from plant-based products. If all people within the EU would halve their meat and dairy consumption, this would reduce greenhouse gas emissions from agriculture by 25 to 40%, and nitrogen emissions by 40%. The EU could become a major exporter of food products, instead of a major importer of for example soy beans.”

The work has been conducted by the ‘Task Force on Reactive Nitrogen’ of the United Nations Economic Commission for Europe (UNECE). In 2011 the Task Force produced the first ‘European Nitrogen Assessment’ (ENA) which showed that better nitrogen management will help reduce air, water and soil pollution, greenhouse gas emissions, simultaneously reducing threats to human health, biodiversity and food security.

Co-author of the report Prof Mark Sutton, an Environmental Physicist at the UK’s Centre for Ecology and Hydrology, said, “Human’s use of nitrogen is a major societal challenge that links environment, food security, and human health. There are many ways in which society could improve the way it uses nitrogen, and this includes actions by farmers and by ourselves. Our new study shows that adopting a demitarian* diet across Europe would reduce nitrogen pollution levels by about 40%, which is similar to what could be achieved by adopting low-emission farming practices.”

 

Switch from cattle fields to ‘carbon farms’ could tackle climate change, save endangered animals cheaply

April 30, 2014

James J. Gilroy, Paul Woodcock, Felicity A. Edwards, Charlotte Wheeler, Brigitte L. G. Baptiste, Claudia A. Medina Uribe, Torbjørn Haugaasen, David P. Edwards. Cheap carbon and biodiversity co-benefits from forest regeneration in a hotspot of endemism. Nature Climate Change, 2014; DOI: 10.1038/nclimate2200

 

Changing cattle fields to forests is a cheap way of tackling climate change and saving species threatened with extinction, a new study has found.

Researchers from leading universities, including the University of Sheffield, carried out a survey of carbon stocks, biodiversity and economic values from one of the world’s most threatened ecosystems, the western Andes of Colombia.

The main use of land in communities is cattle farming, but the study found farmers could make the same or more money by allowing their land to naturally regenerate.

Under carbon markets designed to stop global warming, they could get paid to change the use of their land from growing cows to ‘growing carbon’ — receiving around US$1.99 per tonne of carbon dioxide the trees remove from the atmosphere.

The move would also help boost the populations of many critically endangered species.

There are limited financial resources available to tackle climate change and biodiversity loss, so there is an urgent need to simultaneously address both issues.

“This would cost very little money,” said senior scientist, Dr David Edwards, of the University of Sheffield’s Department of Animal and Plant Sciences.

“Providing people are willing to spend the money, this could be a critical mechanism for stopping climate change and protecting some of the world’s most endangered species.

 

 

Better livestock diets to combat climate change, improve food security

February 24, 2014

P. Havlik, H. Valin, M. Herrero, M. Obersteiner, E. Schmid, M. C. Rufino, A. Mosnier, P. K. Thornton, H. Bottcher, R. T. Conant, S. Frank, S. Fritz, S. Fuss, F. Kraxner, A. Notenbaert. Climate change mitigation through livestock system transitions. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1308044111

 

Livestock production is responsible for 12% of human-related greenhouse gas emissions, primarily coming from land use change and deforestation caused by expansion of agriculture, as well as methane released by the animals themselves, with a lesser amount coming from manure management and feed production.

“There is a lot of discussion about reduction of meat in the diets as a way to reduce emissions,” says IIASA researcher Petr Havlík, who led the study “But our results show that targeting the production side of agriculture is a much more efficient way to reduce greenhouse gas emissions.”

A new study published in the journal Proceedings of the National Academy of Sciences shows that within the current systems, farmers would find it more profitable in coming years to expand livestock production in mixed systems — where livestock are fed on both grass as well as higher quality feed — rather than in pure grass-based systems. This development, would lead to a 23% reduction of emissions from land use change in the next two decades without any explicit climate mitigation policy.

Cows, sheep, and goats grow more quickly and produce more milk when they eat energy-rich diets that include grain supplements or improved forages. This means that more livestock can be raised on less land, and with fewer emissions per pound of meat or milk produced.

The new study projects that the increasing cost of land and continued yield increases in the crop sector will lead to shifts to richer animal diets in the future. Such diets are efficient not only from the perspective of greenhouse gas reduction, but also from farm profit maximization and food production.

At a moderate price of US$10 per ton of carbon dioxide equivalent, livestock system transitions within a given region, together with international relocation of production to regions with the most efficient livestock systems could also reduce the total emissions from agriculture and land use change by 25%. Most of the savings would come from avoided land use change.

Havlík says, “From the livestock sector perspective, limiting land use change seems the cheapest option both in terms of the economic cost and in terms of impact on food availability.”

 

Trade-offs between food security and climate change mitigation explored

July 16, 2013

H Valin, P Havlík, A Mosnier, M Herrero, E Schmid, M Obersteiner. Agricultural productivity and greenhouse gas emissions: trade-offs or synergies between mitigation and food security?
Environmental Research Letters, 2013; 8 (3): 035019 DOI: 10.1088/1748-9326/8/3/035019

 

Improving crop yields using sustainable methods could cut greenhouse gas emissions by as much as 12% per calorie produced according to a new study published in the journal Environmental Research Letters. At the same time, these changes could provide more food to people in need.

Agriculture and land use change contributed about 1/3 of total human greenhouse gas emissions in the past decade, through crop cultivation, animal production, and deforestation. By producing more food on less land, it may be possible to reduce these emissions, but this so-called intensification often involves increasing fertilizer use, which can lead to large emissions of nitrogen-containing gases that also contribute to global warming.

“The most efficient way to ensure sustainable intensification on the crop side is to rely on practices and technologies that are not more fertilizer-demanding, such as new varieties, improved rotations, integrated crop-livestock practices, and precision farming,” says IIASA researcher Hugo Valin, who led the study.

The study’s findings particularly apply to developing countries. In many cases farming in these countries is not as efficient as it could be, and so investing in better farming practices could lead to big benefits both in terms of food security and greenhouse gas emissions.

The study found that increasing livestock yields was more effective at reducing greenhouse gas emissions than increasing yields from crops that people eat. Overall, closing yield gaps by 50% for crops and 25% for livestock would lead to a 12% savings in greenhouse gas emission per calorie produced.

However, says Valin, “Increasing livestock yield is not as beneficial to food security as can be increase crop yield, just because meat and dairy are a small share of diets, especially in developing countries….

 

Eat less meat and farm efficiently to tackle climate change, scientists say

June 19, 2012

Thomas Powell, Tim Lenton. Future carbon dioxide removal via biomass energy constrained by agricultural efficiency and dietary trends. Energy & Environmental Science, 2012; DOI: 10.1039/C2EE21592F

We need to eat less meat and recycle our waste to rebalance the global carbon cycle and reduce our risk of dangerous levels of climate change, according to scientists.

New research from the University of Exeter shows that if today’s meat-eating habits continue, the predicted rise in the global population could spell ecological disaster. But changes in our lifestyle and our farming could make space for growing crops for bioenergy and carbon storage.

Though less efficient as an energy source than fossil fuels, plants capture and store carbon that would otherwise stay in the atmosphere and contribute to global warming. Burning our waste from organic materials, such as food and manure, and any bioenergy crops we can grow, while capturing the carbon contained within them, could be a powerful way to reduce atmospheric carbon dioxide.

Published June  20, 2012 in the journal Energy and Environmental Science, the research suggests that in order to feed a population of 9.3 billion by 2050 we need to dramatically increase the efficiency of our farming by eating less beef, recycling waste and wasting less food. These changes could reduce the amount of land needed for farming, despite the increase in population, leaving sufficient land for some bio-energy. To make a really significant difference, however, we will need to bring down the average global meat consumption from 16.6 per cent to 15 per cent of average daily calorie intake — about half that of the average western diet. The researchers argue that if we change the way we use our land, recycle waste, and dedicate enough space to growing bioenergy crops we could bring down atmospheric carbon dioxide to safe levels. Not doing this means we would lose our natural ecosystems and face increasingly dangerous levels of atmospheric carbon dioxide….

 

Grazing of cattle pastures can improve soil quality

March 3, 2011

USDA/Agricultural Research Service

 

Alan J. Franzluebbers. John A. Stuedemann. Surface Soil Changes during Twelve Years of Pasture Management in the Southern Piedmont USA.  Soil Science Society of America Journal: doi:10.2136/sssaj2010.0034

 

A team of U.S. Department of Agriculture (USDA) scientists has given growers in the Piedmont guidance on how to restore degraded soils and make the land productive. Researchers with the USDA’s Agricultural Research Service (ARS) found that if cattle are managed so that they graze moderately, soil quality can be restored and emissions of carbon dioxide (a greenhouse gas) can be reduced.

The research was recently published in the Soil Science Society of America Journal…

From an environmental standpoint, grasslands have traditionally been viewed as best managed by leaving the land unused. But the team found that while fertilizer type made little difference, different grazing scenarios produced different effects, and the grazed land produced more grass than the ungrazed land and had the greatest amount of carbon and nitrogen sequestered in soil. Sequestering carbon and nitrogen in soil has become a major goal for agriculture, because that sequestration reduces greenhouse gas emissions.

 

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