Going vegetarian: the answer to the world’s problems?

Speaking at the First International Conference on Global Food Security held last month in the Netherlands, David Tilman, Regents Professor and McKnight Presidential Chair in Ecology at the University of Minnesota and professor at University of California, Santa Barbara‘s Bren School of Environmental Science & Management, presented his views on how we can achieve global food security and environmental sustainability.

Food insecurity and unsustainable use of the environment are two of the greatest challenges we as a society face. And they are linked: how we tackle one problem will affect the other. Prof. Tilman laid out the main barriers we face to achieving food security and environmental sustainability:

1)      Increased demand driven by population and income growth

2)      Dietary shifts and health including under and over nutrition

3)      Environmental issues which include greenhouse gas emissions, nutrient pollution, ecosystem destruction and biodiversity loss.

Speaking to the second barrier in his list, Prof.Tilman explained that as income increases so does the demand for calories and animal protein. He pointed to the need for changes in dietary behaviour, without which it is unlikely we will address the world’s problems.

By 2050 global demand for crop protein will have increased by 110%, for crop calories by 100%. 30% of these increases will be a product of population growth, 70% from higher incomes, which are increasing most rapidly in poorer nations.

Changing our diets will not only address some of this growth in demand but it could also make us healthier. Recent evidence points to a 50 to 60% lower incidence of diabetes in lower meat diets. A pesco-vegetarian diet can add up to 10 years of life to a human adult, although there are multiple confounding factors that could bias this result. There is also a huge disparity in terms of access to meat, with half the global population having access to less animal protein than recommended under a low meat diet. So some people eat too much meat, some not enough.

Health benefits aside, a lower meat diet, for those with excessive meat consumption, also has environmental impacts in terms of agricultural production and how it expands. For example shifting towards greater production of fruits and vegetables, for which the whole world is underachieving in terms of eating the recommended amounts, less livestock and increased aquaculture.

Looking to the environmental sustainability challenge, Prof. Tilman explained that annual greenhouse gas emissions from fossil fuel combustion equate to almost 9 gigatonnes (Gt) of carbon equivalent, an amount that is hard to reduce given the world’s energy needs. If everybody drove a hybrid car, for example, this total amount would be reduced only by about one twentieth. At the moment it is hard to see how we will even reduce the rate at which emissions are growing each year. Greenhouse gas emissions from agriculture (not including fossil fuels which make up about 10% of agricultural emissions) are just under 4Gt of carbon equivalent per year, most of which comes from land clearing, livestock production and nitrogen fertilisation.  If diets continue to change and yields continue on their past growth trajectories, by 2050 agricultural emissions will have increased by an additional 4Gt per year. [Read more…]