Green Economy in a Blue World-Full Report

in a Blue World

Dead zones and fertilizers

North Atlantic Ocean

North Paci c Ocean

Fertilizer use, 2005 Kilograms per hectar of arable land

Indian Ocean

Less than 10 10 to 50 50 to 100 100 to 160 More than 160 Dead zones

South Atlantic Ocean

South Paci c Ocean

Dead zones appear as a consequence of nutrient input to the oceans. Low levels of oxygen make it di†cult for marine creatures to survive.

Source: World Bank, World Development Indicators database, accessed in October 2011; NASA Earth Observatory, data acquired in 2008.

pre-industrial times, from both agricultural run- off and poorly or untreated sewage. In theUS and EU levels of nitrates ingroundwater in some instances are above safe levels and thus posea threat tohumanhealth (Nolan, et al. 1988). The removal of nitrates from drinking water adds to both the costs and energy demands in treatment. This underscores the importance of preventing reactive nitrogen from agricultural sources from entering groundwater where the pollutants can have very long persistence. The production and use of reactive nitrogen- based artificial fertilizers has had huge global benefits providing food for billions through the green revolution. The down side of the increased availability of cheap manufactured nitrogen fertilizer products has been global environment problems associated with excess nutrients, specifically the problems of eutrophication, coastal hypoxic zones and nitrate contaminated groundwater. Tracing the formation of eutrophic and hypoxic zones across the world shows a close correlation to the growth of agricultural regions, cities and coastal development (figure above); as of 2011, UNEP had identified over 500 areas of hypoxia globally (UNEP, 2011). Until the early part of the 20th century, the agriculture sector andmany industrial processes were dependent on limited natural reserves of reactive nitrogen, for example from Peruvian guano, Chilean saltpetre and ammonium

salts extracted from coal. In 1909, Fritz Haber identified a mechanism to produce ammonia from atmospheric nitrogen and hydrogen (from natural gas) at high temperature and pressure. This process was industrialized by a chemical engineer, Carl Bosch, resulting in the Haber- Bosch process as it is known today, with about 75 per cent devoted to fertilizer production. The rapid increase in the production of reactive nitrogen via the Haber-Bosch process correlates closely with the increase in world population from about 2.6 billion in 1950 to over 6 billion in 2000 (figure page 78). Based on the figures from Dawson and Hilton (2011), over 2 billion tonnes of reactive nitrogen was manufactured in that period. The enormous increase in artificial fertilizer production catalyzed by the Haber-Bosch process has altered the flow and balance of the nitrogen cycle at a global scale, representing a roughly 150 per cent increase in new reactive nitrogen added annually to the environment compared to the pre-industrial period (figure page 80). Starting in the 1940s when man-made generation of reactive nitrogen was only around 4 Mt/yr, manufacture of reactive nitrogen began rising at an exponential rate (figure page 78). While clearly the Haber-Bosch process has delivered substantial agricultural productivity and food security benefits in terms of providing cheap nitrogen fertilizers that

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