I just returned from my weekly trip to the supermarket: in addition to Kenyan roses, Brazilian melons, Israeli oranges, Dutch tomatoes, Kiwis from New Zealand, and potatoes from Saudi Arabia (!), I have, for the first time, found minced beef from Botswana, sold for just over half the price of the Norwegian one. We have over the years become accustomed to the increasing variety and prettiness of food we find on supermarket shelves, regardless of the season. Meanwhile, we are generally oblivious to the ecological cost of this bounty. New scientific research now shows that, indeed, consumers in some rich countries live well above their ecological means and in the process threaten global biodiversity (see also previous post). They can do so only because of international trade.

The increasing intensity and extent of human land use is a major threat to ecosystems. Estimates by the Gobal Footprint Network show that humanity already uses two thirds of the fertile land available on this planet; calculations by the Institute of Social Ecology in Vienna demonstrate that humans in fact appropriate a full quarter of terrestrial biomass. According to the Millennium Ecosystem Assessment, habitat loss – mostly through land use – is the number reason for the extinction of species on the planet. Climate change, hunting and fishing, the release of nitrogen and phosphorus – in large part due to fertilizers used in agriculture, and alien species also contribute significantly to the largest mass extinction event since the disappearance of the dinosaurs.

In the most encompassing and detailed study of the processing, trade and consumption of products of land use, we quantify the land footprint of 87 individual countries and 26 more aggregate regions, covering the entire global economy. We express land use in terms of hectares of global average crop land productivity, the measure of the well-established Ecological Footprint. Our analysis shows that the land footprint for different countries can be largely explained by only two factors: wealth and the availability of fertile land. Richer countries have a higher footprint: the per capita footprint of Germany and France in 2004 was 2.7 global hectares per person, China’s 0.8 and India’s only 0.6 gha/p. At the same time, countries with a lot of land available use more of it; Canada’s land footprint at 3.9 gha/p was much large than Japan’s (2.0 gha/p); Brazil used 2.3 gha/p, while Bulgaria with the same GDP per person used only 1.7 gha/p. (If you want to know your country’s footprint, see our visualization.) Throughout our dataset, a doubling of per capita income increases the footprint by 35%; while a doubling of domestic land availability increases the footprint by 23%.

You are forgiven to think that, well, overall, this is not so surprising. The study, in the meantime, resolves a scientific mystery. If you measure biomass use in different countries, as the aforementioned Institute of Social Ecology has done, it varies a lot but does not depend much on wealth. If you look historically at biomass use per capita, it has gone down instead of up (see metabolic rate). This trend is contrary to the observation for food consumption, which increases with increasing wealth; just witness the present obesity epidemic. The explanation, in our eyes, lies in the displaced land use which was not fully considered in the work of the colleagues from the Institute for Social Ecology. Displaced land use, in fact, increases proportional to income per capita and does not depend at all on the domestic availability of land. The replacement of draught animals and fire wood by fossil fuels probably also plays a role for the historical development.

Paradoxically, the beef from Botswana I found in the supermarket today is a success for Friends of the Earth and other green and development groups who have long lobbied for a greater access of developing countries’ agricultural products to the markets of the rich world. We have not investigated whether the ecological impact of beef production in Botswana is higher or lower than in Norway. Looking just at a package of minced meat, it may be a good thing, not least because it provides income to a relatively poor population. The problem is that international trade moves the ecological impact out of our sight. Ecological limits disappear. Our results show that Japan and South Korea displace twice as much land use as they have fertile land available domestically. Also in Europe, we live above our biocapacity: Germany’s land footprint is 30% higher than the amount of fertile land available, the land footprint of the Netherlands and Belgium is two and a half times their biocapacity.

Our study indicates that as emerging economies get richer and the population grows further, nature will be squeezed. By 2050, basically all available fertile land will be used to satisfy increased consumption levels of a larger population. Some relief for nature may come from an intensification of land use and an increase of fertile land area through irrigation. At the same time, climate change, erosion, salinization of soils as a result of irrigation, and urbanization will reduce the available fertile land. Reduced biodiversity will make us more vulnerable to pests. Given the systematic net displacement from rich to poor countries, we can expect that biodiversity will be especially threatened in those remaining poor countries which have underdeveloped institutions and hence no capacity to protect biodiversity.

None of this is inevitable; we can reduce our land footprints by reducing the overconsumption and waste of calories, limiting the consumption of animal products which already cause 28% of global land use, preserve forests and avoid sealing too many surfaces. Avoiding a further squeeze of poor countries’ ecosystems requires changing the current global land use pattern that has been identified in our research. Displacing land use to poor countries makes us co-responsible for protecting their biodiversity, and mechanisms need to be developed for doing so.