by Liz Kalaugher,, October 6, 2010
The team estimated that by 2050 the livestock sector may account for 72% of the suggested safe operating space for anthropogenic greenhouse gas emissions, 88% for biomass appropriation and 294% for reactive nitrogen mobilization. The equivalent figures for the year 2000 were 52%, 72% and 117%.
Demand for livestock has been predicted to double by 2050 as populations rise and people in developing countries become richer and begin to eat more meat.
Altering the nitrogen cycle by producing fertilizers and growing nitrogen-fixing crops to feed livestock can increase global warming, produce photochemical smog and acid rain, and lead to biodiversity loss.
"We found that there is modest mitigation potential in substituting less resource efficient – i.e., ruminant [such as cattle and sheep] – for more resource efficient – i.e., poultry – forms of livestock production," Nathan Pelletier of Dalhousie University toldenvironmentalresearchweb.
What's more, diets using only plant (soybean) protein had a cumulative impact almost two orders of magnitude less than those that were totally based on animal protein. "This underscores the considerable role of dietary choice, and policies that influence consumption patterns in helping us manage for sustainability concerns," said Pelletier.
As ecological economists, Pelletier and colleague Peter Tyedmers are keen to answer the question "how closely are we operating to biocapacity?" They believe that they have joined the dots between the contribution of the livestock sector to environmental change, growth predictions for livestock production and sustainability thresholds.
"In recent years, several researchers have begun to raise the profile of the concept of sustainability thresholds – the work of Rockstrom and colleagues published in Nature last fall, which coined the term 'safe operating space' and defined sustainability thresholds in a suite of domains, is a great example," said Pelletier.
The pair believe it's increasingly important that we incorporate the concept of sustainable scale into policy and management decisions at all levels of governance. "Policies aimed at reining in growth of the livestock sector may be necessary to ensure sustainability," said Pelletier. "Taking advantage of all leverage points will be necessary, including continued increases in efficiency in livestock production, species-substitution where appropriate, and limiting the overall scale of livestock production and consumption in both developed and developing countries."
Next the researchers, who reported their work in PNAS, would like to refine their models. They also plan to assess the mitigation potential of alternative technologies, policies and consumption patterns in helping to meet sustainability objectives at regional and global scales.